Abstracts for Ongoing Research Projects
Paul Abell
Planetary Astronomy Program (NASA)
Detailed Spectroscopic Investigation of Comet - Asteroid Transition Objects, Extinct Comets, and Their Possible Source Regions
This investigation's objective is to obtain spectroscopic observations of potential comet-asteroid transition objects and extinct comet candidates using ground-based telescopes to attain the following goals:
1) Identify potential cometary candidates within the NEO population and estimate the contribution from different cometary source regions.
2) Constrain the physical and spectral characteristics of cometary candidates to better assess their relationships to meteorites, interplanetary dust particles, and asteroids.
3) Examine possible relationships of the objects determined to be comets with known source regions (e.g., Jupiter-family comets [Kuiper belt] and Halley-type comets [Oort Cloud]).
This study will obtain spectra of objects selected on the basis of their comet-like orbits, which are defined as having a Tisserand invariant under 3, and only includes objects that are members of the NEO population, or which are otherwise unusual (e.g., Damocloids). A list of 51 targets have been selected with ~1/3 of these being NEOs and includes those objects with low (< 10 deg) and high (> 10 deg) inclinations, which are indicative of Jupiter-family comets and Halley-type comets, respectively. Some targets with comet-like albedos and low heliocentric distances will produce thermal emission in their infrared spectra. Analyses of these spectra from such targets will help determine their albedos (or constrain their albedos if no thermal emission is detected) and further aid in the characterization of these objects as potential extinct/dormant comets.
Results from objects already observed suggest that there are differences in the spectral signatures between objects that have originated from the Kuiper belt and Oort Cloud. The planned observations should be sufficient to sample the materials present among comet-asteroid transition objects, and constrain the relative contributions of specific cometary source regions to these populations. This investigation will lead to better understandings of the final stages of cometary evolution, and contribute to the overall physical characterization of cometary nuclei.
Paul Abell
Hyabusa Mission Support (NASA)
Transfer of Processed Hayabusa Near-Infrared Spectrometer (NIRS) Data of Asteroid (25143) Itokawa to the NASA Planetary Data System (PDS) Archive
A large body of near-infrared spectral data was gathered during this mission via the Hayabusa near-infrared spectrometer (NIRS). The spectral data acquired by this instrument covered a wavelength range from 0.85 to 2.1 µm, and were obtained of various aspects of the asteroid's surface. Tens of thousands of spectra have been collected and downloaded from the Hayabusa NIRS instrument. Currently the spectral data are being prepared for the Japanese Aerospace Exploration Agency (JAXA) archive and plans have been made to also transfer this data set to the NASA Planetary Data System (PDS) Small Bodies Node. However, JAXA has not finalized the data format, or identified which parameters will be included in this data set. In order to facilitate the smooth transition of the NIRS data from the JAXA archives to the PDS, the NIRS data will need to be formatted to the appropriate specifications and standards of the PDS. It would be useful to have a point of contact that would enable the NIRS data to be effectively transferred from JAXA to the PDS archive. Dr. Paul Abell is a member of the Hayabusa Joint Science Team who is familiar with the mission, spacecraft, and specifically the NIRS instrument. He would be able to interface with the JAXA scientists and would closely work with Dr. Faith Vilas, the lead US investigator on the NIRS instrument to ensure that the data would be in the proper format and standard for the NASA PDS archive. Specific goals of this proposal are: 1) to facilitate communication between representatives of JAXA and NASA PDS personnel; 2) to identify any omissions of essential data parameters from the NIRS data set that would delay incorporation of the data into the PDS archive; 3) to aid JAXA in the standardization of the NIRS data format for incorporation into the PDS archive; and 4) to compose a final report outlining the activities performed under this proposal, which may help guide future data archive agreements for joint NASA and JAXA spacecraft missions.
Natalia Artemieva
Planetary Geology & Geophysics Program (NASA)
Planetary Impact Ejecta and the Physico-Chemical Evolution of Expansion Plumes: A Multidisciplinary Approach
We propose a multidisciplinary project that combines for the first time physical and chemical models with field data for an in-depth study of impact plume development and evolution. High resolution 3D simulations with the hydrocode SOVA will model the physical distribution of target and projectile materials in different states of shock and the evolution of expansion plumes in planetary impacts. Hydrocode results will then be coupled to the condensation code VAPORS to parameterize the chemical evolution of the modeled plume and investigate condensation sequences over time and at various plume locations.
Model results for the KT impact will be compared directly to existing observations and to new data (to be acquired as part of this study) on the KT boundary ejecta layer. We will then be able to generalize the model to significantly different ejecta layers such those of the Neoarchean and Paleoproterozoic.
A better understanding of the physical and chemical evolution of impact expansion plumes and the ejecta deposition will provide better constraints for the investigation of environmental and climatic effects of large impacts on Earth and other planetary bodies. This study will also help us understand what impact ejecta characteristics to look for in stratigraphic layers coincident with suspected impact events, such as the controversial Permian-Triassic boundary.
Once tested and validated using terrestrial impact layers, the physico-chemical model of the evolution of expansion plumes developed in this study can be used in support of NASA's Vision for Space Exploration. On planetary surfaces targeted for in situ exploration, like the Moon and Mars, this model can be used to predict and/or identify impact horizons, providing an important tool in the study of their surface characteristics, stratigraphy and history.
Matthew Balme
Mars Fundamental Research Program (NASA)
In-situ studies of terrestrial dust devils and ambient meteorology: application to Mars' climate
Dust devils are small-scale, particle-loaded convective vortices common on both Earth and Mars. They carry substantial airborne particle loads and are effective agents of aeolian erosion. On Earth, dust devils threaten air quality in arid regions and might have a global effect through transport of dust into the mid-atmosphere where it can affect absorption and scattering of radiation and serve as cloud or ice nucleation sites. On Mars, models suggest that dust devil activity might support the persistent dustiness in the atmosphere.
This proposal requests support for a three-year project to study terrestrial dust devils with the goal of improving our understanding of dust devils on Mars, how much dust they lift, and how this affects the martian climate. Current parameterizations of dust devils in martain General Circulation Models (GCMs) are over simplified, being based upon models that have not been well-tested. Empirical data are required to verify the models and fine-tune the parameterizations. This proposal will provide ground-truth field measurements of dust devils to test models of their formation, structure, dust lifting and intensity. The strategy is to correlate in-situ measurements with ambient meteorological conditions. We propose a series of field studies, in two well-characterized field sites, that include both a mobile sampling platform and an array of static meteorology stations.
Key objectives: 1) Test existing models of dust devil formation, structure and intensity, including 1a) Can intensity of dust devils be linked to ambient conditions such as sensible surface heat flux and convective boundary layer height? 1b) Does ambient vertical vorticity correlate with dust devil size? 1c) Does the cyclostrophic approximation hold true in dust devils? 2) Measure dust flux within dust devils and the relationships between ambient conditions and dust flux; 3) Use these data to constrain or modify parameterizations of dust devils in Mars GCMs.
Matthew Balme
Mars Data Analysis Program (NASA)
Transverse Aeolian Ridges on Mars: age, orientation and sediment source
Small, bright, transverse aeolian bedforms (here termed Transverse Aeolian Ridges -- TARs) are widespread on Mars and form a population morphologically distinct from the large, dark dunes of the northern sand sea and intracrater dunefields. While much attention has been paid to the formation mechanisms of TARs (do they form in the same way as terrestrial ripples or in the same way as terrestrial dunes?) little is known about their distribution, sediment source, age, or the volumes of sediment that they represent. The objectives for this proposal are: 1) to determine if there are identifiable discrete sediment sources for TARs on Mars; 2) to estimate the volume of aeolian sediment stored in TARs; 3) to investigate whether geologic or meteorologic factors control the distribution and orientation of TARs' and 4) to determine the spatial and temporal assocation of TARs with large dark dunes. We will accomplish these objectives primarily by measuring the orientation and distribution of TARs in a large pole-to-pole swath, interrogating all Mars Orbiter Camera Narrow-Angle images in this study area with resolution better than 10m per pixel. We will weight each measurement by the area of the image TARs actually occupy and compare our results with global datasets of physical properties (e.g., elevation, albedo, geologic unit, thermal inertia, surface roughness) and with the results from Global Circulation and Mesoscale models of martian atmospheric dynamics.
Leslie Bleamaster
Mars Data Analysis Program (NASA)
Arabia Terra Dichotomy Boundary: Structurally Controlled Degredation and Modification
The objectives of this research are to evaluate the role and extent of spatially variable modification processes (e.g., fluvial, volcanic, tectonic, glacial, mass wasting) on potentially deep and long-lived crustal structure along the Arabia Terra dichotomy boundary. Revealing underlying macro-scale structural patterns along the boundary may bring light to the formation mechanisms responsible for the crustal dichotomy itself. Using Viking Orbiter, Mars Orbiter Camera (MOC) and Mars Thermal Emission Imaging System (THEMIS) images, and Mars Orbiter Laser Altimeter (MOLA) and Thermal Emission Spectrometer (TES) data, this investigation will compare morphologic, morphometric, and geologic (including detailed stratigraphic analyses) differences along the Arabia Terra dichotomy boundary with special focus on three specific transitional zones that span the topographic demarcation of the boundary: 1) Arabia Terra to Acidalia Planitia (20 N, 20 W), 2) Arabia Terra to Vastitas Borealis through Deuteronilus Mensae (45 N, 325 W), and 3) Arabia Terra to Vastitas Borealis north of Syrtis Major Planum (40 N, 290 W). Each of these sections display different surface morphologies and provide areas of study that encompass the broad spectrum of surficial processes that have acted along the dichotomy. This project will synthesize existing geologic and geomorphic maps as well as provide new information (digital geologic map coverages, crater size frequency distributions, valley morphology and morphometry (size, depth, width, orientation, and fill material properties)), necessary to both formulate new and evaluate existing hypotheses that address the relative contributions of mass wasting, aeolian, glacial, fluvial, volcanic, and/or tectonic modification processes, as well as the role crustal structure plays on modification along the Arabia Terra dichotomy boundary. This new investigation will draw on team members' experience in geologic mapping, crater counting, and in evaluation of highland degradation, volcanism, and tectonics around Hellas basin and Deuteronilus Mensae. Data acquired through this study will contribute to ongoing investigations aimed at understanding the formation and subsequent modification of the crustal dichotomy boundary.
Leslie Bleamaster
Mars Data Analysis Program (NASA)
Geologic Investigations of Hellas Planitia and the Circum-Hellas Highlands: Spatial and Temporal Patterns in Topography, Crater Morphology, and Layered Deposits
The objective of this research is to evaluate the perimeter and interior of Hellas basin to 1) map the distribution, examine the morphologic variability, and assess the topographic and slope characteristics of local depositional sinks, layered deposits, and topographic benches, and 2) address spatial and temporal correlations (or lack thereof) of these features within the context of basin-wide evolution. If geomorphic evidence suggests the potential for paleolake shorelines along the Hellas rim, the context of these locations will also be assessed. Using Viking Orbiter, MGS Mars Orbiter Camera, MO Thermal Emission Imaging System, and MEX High Resolution Stereo Camera images, and Mars Orbiter Laser Altimeter, Thermal Emission Spectrometer, Gamma Ray Spectrometer, and MEX Omega data we will:
1) Analyze morphologic, morphometric, topographic, and thermophysical characteristics of craters larger than 10 km within four major circum-Hellas highland sectors (Noachis Terra, Terra Sabaea, Tyrrhena Terra, and Promethei Terra) including,
a. floor and rim deposits to locate layered outcrops and assess degradation history,
b. rim height measurements looking for asymmetry (i.e., with respect to Hellas basin interior), and
c. size-frequency distributions to identify
i. differences in distribution with respect to distance from basin interior and elevation, and
ii. variations of individual crater floor deposits.
2) Assess the distribution of layered deposits around the rim and across the floor of Hellas to,
a. characterize morphology and morphometry, determine thermophysical properties,
b. evaluate age variability with respect to geographic location and elevation level in Hellas Planitia,
c. assess layered deposit origin(s) (lacustrine, volcanic, aeolian) and address implications, and
3) Perform statistical analyses of topographic data from local to regional scales, specifically targeting crater rim diameter and height, characteristic root mean slope variability, crater floor deposit thickness, volume, and asymmetry over elevation changes.
Whether or not specific geomorphic features (shorelines, deltas, etc.) representative of lacustrine activity can be identified, a detailed examination of basin topography, including highland craters around the basin perimeter, and the distribution, age(s), and morphologic variability of layered deposits defining circum-Hellas depositional environments will provide critical evidence for deciphering the sedimentary history of the region, including testing and refining the paleolake hypothesis.
Relationships between highland crater morphology and layered deposits will be particularly useful for examining the potential extent(s) of large-scale Hellas-centered lakes, for determining whether isolated lacustrine basins developed around Hellas, and for examining spatial and temporal relationships between depositional centers within the basin and around its rim.
Leslie Bleamaster
Planetary Geology & Geophysics Program (NASA)
Volcano-Tectonism of Helen Planitia, Venus
The objective of this research is to characterize and improve our knowledge of the nature and timing of geologic processes that have shaped the surface of Venus and to compare the inferred processes across different physiographic regions at a variety of scales. Specific goals include: I) evaluation of spatial and temporal associations between: deformation belts (focused contraction), wrinkle ridges (diffuse contraction), and small shield volcanoes in Wawalag and Nsomeka Plainitae, II) use of the distribution and relative timing of macro-scale volcanic and tectonic centers (and their associated geologic units) in Helen Planitia to evaluate spatial relationships with highlands to a) various crustal and lithospheric provinces inferred from geophysical analyses, and b) region-specific Average Model Surface Ages, and III) detailed investigation of volcanically modified craters and craters with outflows to assess proposed emplacement scenarios with respect to resurfacing hypotheses (e.g., buried by surface lava flows, embayed from below by dike-fed flows, and/or impact generated melt). These goals will be accomplished by: 1) the generation of a 1:5M scale geologic map of Isabella (V50) Quadrangle, 2) the synthesis of existing 1:5M maps and new mapping into a 1:10M scale geologic map of Helen Planitia (I-2477), 3) the compilation of a comprehensive Geographic Information Systems (GIS) layered database including: data products (Synthetic Aperture Radar (SAR) images, altimetry, RMS slope, emmisivity, gravity, and synthetic stereo) and mapping products (geologic units, structures, craters), 4) large scale (highest resolution) mapping of select local regions within both Isabella Quadrangle and Helen Planitia (specifically craters with outflows) documenting local stratigraphic and tectonic temporal relations, and 5) descriptive, kinematic, and dynamic analyses of the major physiographic provinces within Helen Planitia and their associated volcanotectonic features including: Phoebe, Themis, Imdr and southern Atla Regiones, Aditi Dorsum, Jokwa and Thauknud Lineae, and southern Devana and Parga Chasmata.
Leslie Bleamaster
Planetary Geology & Geophysics Program (NASA)
Geologic Mapping Along the Arabia Terra Dichotomy Boundary: Mawrth Vallis and Nili Fossae, Mars
The objectives of this research are to constrain the geologic evolution of Mawrth Vallis, Nili Fossae, and their immediate surroundings along the Arabia Terra Dichotomy Boundary through: 1) geologic mapping, geomorphic analyses, and chronologic studies, 2) evaluation of the distribution, stratigraphic position, and lateral continuity of compositionally distinct outcrops as seen in spectral datasets, and 3) characterization of the role and extent of volatile-driven, aeolian, volcanic, and tectonic modification and degradation processes on Mawrth Vallis and Nili Fossae. Placing these landscapes, their material units, structural features, and unique compositional outcrops into spatial and temporal context with the remainder of the Arabia Terra dichotomy boundary will provide the ability to: 1) further test original dichotomy formation hypotheses, 2) constrain ancient paleo-environments and climate conditions, and 3) evaluate various fluvial-nival modification processes related to past and present volatile distribution and their putative reservoirs (aquifers, lakes and oceans, surface and ground ice), and the hydrologic significance of nearby volcanic and tectonic provinces. This research will result in the production of two 1:1,000,000 (1:1M) scale geologic maps of twelve MTM quadrangles (Mawrth Vallis: 20022, 20017, 20012, 25022, 25017, and 25012; and Nili Fossae: 20287, 20282, 25287, 25282, 30287, 30282).
Mary Bourke
Planetary Geology & Geophysics Program (NASA)
Rock Breakdown on Earth and Mars: Further Investigations Using a Combined Field and Experimental Approach
In this successor proposal to Grant # NNG05GJ91G, we propose a research campaign that will integrate field and experimental studies to test the uniqueness and persistence of rock breakdown morphologies, at a range of scales, in environments that are analogous to Lander sites on Mars. To investigate the controls on boulder surface morphology we will 1) characterize the morphological and morphometric attributes of basalt boulders in specific geomorphic environments on Earth, 2) determine the persistence and uniqueness of specific rock breakdown features under different process regimes, using both laboratory and field experiments, and 3) characterize the morphological and morphometric properties of boulders on Mars.
The proposed research will apply innovative techniques and analysis routines to topographic datasets obtained by high resolution laser scanning on basalt boulders in field and experimental conditions. The data will be used to characterize and discriminate rock breakdown caused by aeolian abrasion and weathering. We aim to provide clear quantitative descriptors of diagnostic signatures of specific breakdown forms in pristine and weathered samples. Our approach will be the first to consider the relative efficacy of weathering and erosion together in the persistence of signatures of erosion, transport and weathering on boulder surfaces. Our results will enable a more confident association to be made between form and process for boulders on planetary surfaces. A range of morphological and morphometric techniques developed in our previous funding cycle will be used to identify any scale dependence in surface roughness, and to compare individual breakdown features. The analyses will contribute to NASA's broad goal of increasing the scientific understanding of planetary surfaces.
Mary Bourke
Mars Fundamental Research Program (NASA)
Volatile-Rich Aeolian Deposits: A Field-Based Analog Study
Aeolian dunes on Mars may contain significant volatile reservoirs of ice, snow, or chemically bound hydrogen. Understanding the origin, age and process dynamics of these deposits is important for determining volatile reservoir location, magnitude and stability on Mars. The proposed research will undertake a detailed study of volatile-rich aeolian deposits at four sites on Earth. Our aims are to characterize the morphology, morphometry and internal structure of volatile-rich aeolian dunes and to determine the volume, location and residency time of volatiles within dunes. We will use state of the art technologies (e.g., Ground Penetrating Radar, Optical Stimulated Luminescence, Differential Global Positioning System surveying). We will undertake remote sensing analysis and field sediment transport experiments to assess how volatiles influence sediment transport and dune geomorphology. Each filed site represents a different mechanism of volatile emplacement (snowfall, rainfall, fog precipitation) and retention (burial, penetration of a wetting front and chemical precipitation). By selecting a range of emplacement and retention mechanisms, we will get a better understanding of the volatile reservoir and its preservation potential in aeolian deposits. This quantitative data set can be used to assess potential volatile reservoirs in Martian dunes. This research will follow the guiding principal in NASA's Mars Exploration Program: to understand the planet's geology and search for past and present life and life environments, to "follow the water" in all of its phases. It meets the requirements of the Mars Fundamental Research Program to provide the basis for a better understanding of data that are returned from NASA missions that are concerned with atmospheric, climate, geological and geochemical, processes on Mars.
Mary Bourke
Mars Data Analysis Program (NASA)
The Geomorphology and Evolution of the North Polar Sand Seas on Mars
The circum-polar sand seas potentially preserve a rich geological record of Martian paleo-climate. Their location at the North Pole is likely to be sensitive to past variations in obliquity and orbital variations.
We propose to use satellite data released by recent NASA and European missions to determine the characteristics and evolution of aeolian landforms in the North Polar Sand Seas (NPSS). Specifically, we will measure dune dimensions (including length, width, height, spacing and orientation) and use this data to estimate individual and massed dune volume. We will describe and classify dune forms and search for evidence of induration by volatiles. We will apply 2 and 3d computational fluid dynamic modelling of flow structure across Martian dunes associated with a variety of dune topographies. We will use Ergodic principals to infer dune process dynamics and use aspects of dune form (e.g. curvature, asymmetry, merging) to assess local environment conditions (e.g. relative wind speed and sediment supply). We will apply new approaches to analyzing sand sea patterns that will enable the determination, for the first time, of the relative ages of the NPSS. These data will also be used to establish paleo-wind directions preserved in the complex dune patterns. We will identify sediment sources and test competing hypothesis for the evolution of the sand seas.
These combined analyses will advance our understanding of landform evolution on Mars, thereby fulfilling the guiding principle in NASA's Mars Exploration Program: to understand the planet's geology and to search for past and present life and life environments, specifically Goal III, Objective A: To determine the nature and sequences of the various geological processes that have created and modified the Martian crust and surface.
Mary Bourke
Mars Data Analysis Program (NASA)
Pseudokarst on Mars: The Evolution of the Hephaestus Fossae and Hebrus Vallis
Groundwater-fed hydrology has been an important part of the surface hydrological regime on Mars. In particular, outflow resulting from disruption of a confining cryosphere is hypothesized to be an important phenomenon. Often these processes are coupled with surface collapse. Understanding the origin, age and process dynamics of these types of fluvial system is paramount for determining volatile reservoir location, magnitude and stability on Mars. We propose to determin the geomorphic evolution of the Hebrus Vallis and Hephaestus Fossae, in Utopia Planitia. In particular, we will investigate the role o pseudokarst in the development and evolution of the surface landforms.
Mary Bourke
Mars Fundamental Research Program (NASA)
Fissure-Related Flow Channels and Mound Springs: An Analog for Martian Groundwater-Fed Channels
Fissure-released flows are one of four types of channels on Mars that are hypothesized to be fed from groundwater sources. Understanding the origin, age and process dynamics of these channels is important for determining volatile resrvoir location, magnitude and stability. Studies of these channels on Mars are hampered by the limited availability of suitable analogs. There are no terrestrial studies that relate channel geomorpholgy and sedimentology to fissure flow hydrology. The proposed research will address this gap in the literature by undertaking a detailed study of groundwater-fed channels in Australia. The site is uniquely analogous as it is the only known location where catastrophic groundwater-fed flows are reported. This is similar to the proposed paleohydrology of channels on the Cerberus Plains on Mars.
David Crown
Planetary Geology & Geophysics Program (NASA)
Geologic Investigations of the Martian Highlands: Mapping the NW Hellas Rim and Northern Circum-Hellas Highlands
This investigation is a geologic mapping study of parts of Terra Sabaea and Tyrrhena Terra, north of the Hellas Basin. The project includes (Task 1) production of a formal USGS map publication of eight Mars Transverse Mercator quadrangles (-25312, -25307, -25302, -25297, -30312, -30307, -30302, -30297) along the NW Hellas rim at 1:1.5M-scale. The map region (22.5-32.5 S, 45-65 E) includes the transition from rugged cratered highland terrain in SE Terra Sabaea to low-lying plains on the basin floor at the NW margin of Hellas Planitia. Scientific objectives of the mapping include: 1) evaluation and comparisons of geologic history and surface degradation styles in topographic zones along the Hellas basin rim, 2) detailed characterization of crater degradation and crater interior deposits within large craters found on Hellas’ NW rim, 3) analysis of intercrater plains and their associated fluvial valley systems, and 4) assessment of the nature and stratigraphic position of spectroscopically interesting outcrops, including phyllosilicate deposits as identified by OMEGA and CRISM in the region. Task 2 includes production of a series of stratigraphic context maps for local areas surrounding specific phyllosilicate exposures identified in the Martian highlands north of Hellas. These maps will characterize phyllosilicate exposures from a geomorphic and stratigraphic perspective, providing geologic context as well as age constraints from photogeologic observations and crater size-frequency distributions. This mapping study will provide new constraints on the geologic evolution of the Martian highlands with a focus on volatile inventories and history.
David Crown
Planetary Geology & Geophysics Program (NASA)
Geologic Mapping of Reull Vallis and SE Hesperia Planum, Mars
This proposals requests funding to integrate new datasets for Mars, including MOC, THEMIS, and HRSC images and MOLA profiles and DEMs, into existing geologic maps of two regions that have been compiled using Viking Orbiter images: 1) the source region of the Reull Vallis canyon system (MTM -30247, -35247, and -40247 quadrangles) and 2) MTM -35237, -40237, and -45237 quadrangles covering SE Hesperia Planum. The proposed geologic mapping study will provide constraints on the evolution of the Martian highlands as well as volatile inventories and history by evaluating landforms and deposits resulting from modification of highland terrains by volatile-driven degradataion.
David Crown
Planetary Geology & Geophysics Program (NASA)
Investigations of Terrestrial and Planetary Lava Flows
The proposed investigation is a study of lava flow morphology and emplacement processes utilizing a combination of geomorphic analyses of spacecraft and satellite images and aerial photographs, field studies, laboratory experiments, statistical analyses, and application of theoretical models. The research tasks are focused on the volcanic processes involved in the formation of leveed lava flows and compound pahoehoe lobes. Task 1 includes: a) geomorphic analysis of the Arsia Mons flowfield on Mars, b) morphometric characterization of individual Arsia Mons lava flows, c) detailed mapping of Arsia Mons lava flows showing flow branches and channel and levee systems, d) remote sensing and field studies of a set of terrestrial lava flows, e) characterization of branching and channel/levee development in lunar lava flows, and f) application of a leveed flow emplacement model to martian, lunar, and terrestrial flows. Task 2 includes studies of compound flow lobes through comparative morphologic and statistical analyses of a series of analog flows generated in the laboratory, active pahoehoe lobes in the Puu Oo flow field, and compound flows simulated using stochastic models. This project will provide fundamental information on volcanic processes that operate on the terrestrial planets as well as provide new methods for interpreting eruptive actively remotely.
David Crown
Mars Data Analysis Program (NASA)
Investigations of Ice-Driven Degradation Styles on Mars
This investigation explores specific aspects of the geology of mid- latitude regions in the northern and southern hemispheres of Mars with the intent to advance our knowledge of the history, abundance, distribution, and role of water/ice. This study consists of a series of related tasks that focus on ice-driven degradation styles in Martian highland terrains east of the Hellas basin and along the highland-lowland boundary in the Tempe/Mareotis and Deuteronilus Mensae regions. This research combines geomorphic analyses, models for the emplacement of ice-rich flows, and observations and statistical analyses of impact craters. The investigation includes: 1) a geomorphic survey of mid-latitude highland impact craters and analysis of features indicative of volatile-driven degradation (e.g., gullies, debris aprons, flow lobes); 2) numerical modeling studies of the emplacement of ice-rich flow features such as lineated valley fill, debris aprons, and small flow lobes; and 3) development of model, surface history, and age constraints using populations of small Martian craters.
Donald R. Davis
Hyabusa Mission Support (NASA)
Muses-C Project Extended Mission
Activities of this Subcontract:1. Assure that Hayabusa/Muses-C data is properly archived in NASA's Planetary Data System (PDS).
2. Assist in the development of the International Planetary Data Alliance (IPDA) by using the Hayabusa/Muses-C data as a test data set.
3. Attend and participate in Hayabusa/Muses-C Joint Science Team (JST) meetings, as appropriate.
Proposed Statement of Work:
To perform the following duties:
1. Support the development of the Hayabusa/Muses-C data for deposition in NASA's Planetary Data System.
2. Assist in the development of the International Planetary Data Alliance (IPDA) by using the Hayabusa/Muses-C data as a test data set.
3. Attend and participate in Hayabusa/Muses-C Joint Science Team (JST) meetings, as appropriate.
4. Conduct a PDS Review of Muses-C/Hayabusa PDS products (new-February 2008).
Donald R. Davis
Planetary Data System (NASA)
The Asteroid/Dust Subnode of the Small Bodies Discipline Node of the NASA Planetary Data System
In this proposal we discuss the general state of the science of small bodies, what this implies for likely future missions, and how the research at the node fits into both the overall scientific picture and also the archiving role that SBN must fulfill. Following that, we discuss the technical issues related to archiving the data from small bodies within the PDS. It is important to discuss the scientific context because this affects how one should approach archiving. It is also important to spell out the research being done at SBN related to the archives, since this is a key part of ensuring that the SBN understands the needs of scientific users.
William C. Feldman
NASA Discovery Program
Science Team Support for the MESSENGER Mission
Task Item 1: Ground Calibration Data Analysis and Sensor Model
Calibration of the MESSENGER NS was run at RARAF for the fast-neutron energy calibration and at LANL for the thermal, epithermal, and fast-neutron energy-angle efficiencies and the spectral shapes of the characteristic neutron absorption response functions. A preliminary calibration report has already been submitted and the results will be included in an instrument paper. Additional analysis is required to incorporate the results into the data reduction codes necessary to produce the CODMAC levels 2 through 6 data products listed in the MESSENGER Concept Study. We will: (1) use the RARAF data to derive an absolute efficiency from measured fast-neutron spectra by using the quantitative operating parameters of the Van de Graff, and by accounting for and subtracting off the room background, which was severe for all energies but worse at the highest energy, (2) model the sensor and the LANL calibration facility using MCNPX to derive the accurate absolute detection efficiencies as a function of neutron energy and angle of incidence, and (3) integrate these simulation results back into the measured calibration data and assemble them into an instrument paper that will be archived through a written publication in the refereed literature.
Task Item 2: Data Reduction Code
A major input needed to derive scientific results from the NS is to write, validate, and optimize a data reduction code that is capable of being run automatically on the SOC at APL. This code is to be provided in IDL. This task has many components and needs to be approached and validated in an iterative manner. Judging from our experiences with Mars Odyssey and Lunar Prospector, updates and improvements are to be expected throughout the mission (through 2012). We expect the first such significant update to occur just after the second Venus flyby when we first have calibration data from the Venusian atmosphere. As part of this task we will contribute to the development of science operations at all of the flybys and during the Mercury orbital phase of the mission.
Task Item 3: Instrument and Spacecraft Modeling
An important component to our ability to interpret the reduced data in terms of planetary composition will be to be able to recognize and subtract off the various solar and space backgrounds (e.g., due to solar flares - neutrons and gamma rays-, SEPs and gamma-ray bursts), and to account for neutrons that are processed by the spacecraft and returned to the NS sensor. The second Venus flyby will help to calibrate the neutron flux from the spacecraft since we will know the composition of the atmosphere and the time-varying distance to Venus. We will document and append these validation improvements to the code in five separate reports: the first during cruise right after turn on and after the S/C is flipped into the proper solar orientation, the second to document the second Venus flyby data, and the third through fifth reports after each of the three Mercury flybys. The results of these analyses will be included in subsequent publications in the refereed literature.
Task Item 4: Data Analysis
Monitor, analyze, and interpret data collected in flight, during planetary encounters (Venus), and during operations at Mercury (flybys and orbit), and to help plan and coordinate Mercury data acquisition.
Task Item 5: PDS Data Delivery
To support the definition and processing of the data to be archived to the PDS in accordance with the MESSENGER Concept Study Proposal and as outlined in the MESSENGER Data Management and Science Analysis Plan.
Task Item 6: Science Team/Professional Meetings to Support and Communicate with the Larger MESSENGER Science Team
To coordinate efforts and share results within the MESSENGER group. One Science-Team meeting/year for fiscal years 2006 through 2008, two meetings per year from fiscal years 2009 through 2013. One professional meeting per year from 2006 to 2013.
William C. Feldman
NASA Discovery Program
Odyssey Gamma Ray Spectrometer (GRS) Instrument Suite-Mission Operations for Extended Mission II
A global map of water-equivalent hydrogen (WEH) has been developed from epithermal neutron data measured using the Mars Odyssey Neutron Spectrometer MONS) and distributed to the Planetary community at the Mars-6 International Conference in July, 2003, and to many collaborating planetary scientists ever since. These data have been compared with the morphology of surface features to develop an understanding of the delivery mechanisms of WEH from existing reservoirs of water ice to the locations that they now occupy, the molecular associations of the hydrogen in near surface layers, the stratigraphy of these layers as a function of latitude and longitude, and the likely time scales for potential past hydration/dehydration cycles on Mars. The seasonal variations of CO2 ice deposits at high Martian latitudes have also been studied and documented. The work to date has been summarized in 21 publications in the refereed literature, which are appended to this input.
Robert W. Gaskell
Cassini Data Analysis Program (NASA)
Global Topography of Selected Saturnian Satellites
We are proposing to construst high-resolution digital topography for eight of Saturn's satellites in the form of hundreds of overlapping digital topography/albedo maps. The ensemble of these landmark maps (L-maps) can be used to construct global topography models and local high-resolution maps to a user's specification. They can also be used as navigation points to refine the spacecraft and satellite ephemerides.
We will be using a technique known as stereophotoclinometry, in which brightness variations in many images are used to determine the local slopes and albedo variations. The slopes are then integrated to produce the topography. This state-of-the-art technique has been used to characterize the surface and shapes of Phobos, Eros and Itokawa. It has proven to be at least two orders of magnitude better than previous methods.
The high accuracy of the shapes may place constraints on internal structure and on rotational and orbital histories for some of the larger satellites, and correlation of topography with local rotational-gravitational potential gradients for the smaller satellites. In the special case of Hyperion, better estimates of its orientation and its moment of inertia tensor would help in studies of its chaotic rotation. The topography has almost the same resolution as the images, and can be displayed in a variety of ways. It may shed new light on the structure and distribution of craters.
The use of L-maps for navigation proved very successful at Itokawa, allowing the spacecraft location to be determined to a few meters. While we cannot expect such accuracy with these larger objects, it is possible that refinements in the satellite-relative spacecraft position will improve the satellite ephemeris, in particular for Mimas and Tethys, whose 30-year period resonance is difficult to extract. This would benefit an extended mission, since less DSN time and fewer maneuvers would be necessary.
Robert W. Gaskell
JPL Consultation
Support of OBIRON (OnBoard Image Registration for Optical Navigation)
OBIRON (Onboard Image Registration for Optical Navigation) is based on a paper Robert Gaskell gave in 2001 at the Quebec City AIAA/AAS "Automated Landmark Identification for Spacecraft Navigation" (AAS_01_422). High resolution digital Topographic/Albedo maps of portion of a body are uploaded to the spacecraft. These are constructed on the ground with stereophotoclinometry using imaging data from earlier missions or from survey orbits. On board the spacecraft, the map is illuminated in the same way as as a current image and identified and located in that image. This allows the spacecraft attitude and position to be determined autonomously in a matter of seconds. A ground based version of this method will be used during the MESSENGER and Dawn orbital phases and for the upcoming Cassini flyby on Enceladus. It was also used in conjunction with LIDAR to determine the location of the Hayabusa spacecraft to the meter level.
Robert W. Gaskell
Lunar Advanced Science and Exploration Research Program (NASA)
Lunar Mapping With Stereophotoclinometry
In applications to planetary mapping, ordinary sterography typically chooses a few images with similar illumination at viewing angles differing by about 30 degrees. Control points are specified by a few tens of pixels, and various algorithms are used to match them to images. In our processing, a control point is typically defined by a derived 99x99 pixel topographic/albedo landmark map (L-map). Since L-maps completely model portions of the body's surface, they can be rendered to make artificial images, allowing them to be correlated with actual images to sub-pixel precision and over a wide range of illuminations and geometries. In addition, L-maps can be unambiguously locasted on the lit limbs of other images and, because they share common topography, overlapping L-maps can be correlated. This larger number of constraints on the control points results in orders of magnitude improvement in solutions for their body-fixed locations and camera position and orientation. The L-maps themselves are determined by solving for slope and albedo at each L-map pixel, minimizing the sum square residuals between predicted and observed brightness over many images in a process known as stereophotoclinometry. The resulting slopes are then integrated to produce the final topography. The resolution is nearly as good as the best imaging and an order of magnitude better than ordinary stereography. We propose to apply these techniques to the Mon, using Clementine and Lunar Orbiter imaging to map the surface at 220 meter resolution with better than 100 meter position knowledge. This resolution has proven itself in initial studies with Clementine data, and lies midway between the medium and high resolution LO imaging. Over 4000 Lunar L-maps have been constructed to date, and it is estimated that about 250,000 will ultimately be needed, representing 2.5 billion surface vectors.
Robert W. Gaskell
MESSENGER Mission Participating Scientist Program (NASA)
Shape, Topography and Internal Structure of Mercury from MDIS Data
During the past two decades, I have developed techniques for combining stereography and stereo-photoclinometry to create high-resolution digital topographic maps from imaging data. I have used these methods to construct shape and topography models for Phobos, Eros and, as a member of the Hayabusa science team, the asteroid Itokawa. I am currently using Mariner 10 data to construct the topography of the known portions of Mercury.
My software determines the topography and relative albedo variations for small landmark maps (L-maps) whose centers are used as control points on the body. The central vectors are determined in an estimation process which fits their locations in multiple images, offsets from neighboring map vectors determined from mutual topography in the overlap regions, and their limb positions in other images. Since each map represents about 10,000 surface points rigidly tied to the control point, the 2500 maps tiling Mercury so far represent about 25 million surface vectors.
Originally developed as a navagation tool, the software also determines the spacecraft position and orientation from the ensemble of landmarks in a given image. With additional apriori information from radiometric and dynamical data included, the solution is the most accurate available. During the Itokawa encounter, laser ranging was added as a data type. This technology is still evolving, with work under way to use imaging and NLR data to improve both the knowlege of Eros's topography and the NEAR spacecraft ephemeris.
I am proposing to join the MESSENGER Geology and Geophysics groups in order to determine the topography of Mercury from MDIS data. The fundamental data product will be the ensemble of L-maps, which can be used to construct an accurate global model, as well as high-resolution regional maps. The precise determination of topography and overall shape, on a scale comparable to the highest resolution of the images, will be used constrain the active and historical geologic processes on Mercury.
In addition, I hope to collaborate with members of the Radio Science and Mercury Laser Altimeter groups to improve both the spacecraft ephemeris and landmark locations. This would be of great value in the gravitational harmonic analysis and in the determination of Mercury's rotational dynamics, especially for determining the amplitude of its physical libration. My experience with the Hayabusa mission showed that such a collaboration could prove invaluable, increasing the scientific output from both instruments. Control point uncertainties on Itokawa were about 20 centimeters RMS, the spacecraft position was determined to about 1.5 meters, and the LIDAR footprint was located to less than a meter on the surface.
Robert W. Gaskell
Discovery Data Analysis Program (NASA)
High resolution shape and topography of Eros from NEAR imaging data
A program has been developed for determining small body shape and topography from imaging data, using multiple image stereography and photoclinometry. A preliminary study using 1600 F4 images of Eros, 90% of them between 10 and 30 m/pxel, has produced a 1.57 million vector model with an avegage resolution of about 30 m. The post fit residual of the 7.2 million map vectors which went into the model was < 8 m/dof. The model predictions correlate better with observed gravity harmonics than does the laser altimetry model, its coverage is more uniform, and it has far less noise. We intend to use these techniques to add between 10 and 20 times the imagery, including the higher resolution frames, in order to construct a 100 million vector model with average resolution of about 4 m. The model will be used to separate out albedo effects in order to study color and photometric properties, to predict new gravity harmonics for comparison with observed values, and to provide geologists with very high resolution maps of any area of interest. These latter can be formed directly from the raw mapping data, and can therefore have higher resolution than the global shape model. An outgrowth of the study is the production of more accurate camera pointing information, with will be given to NAIF for the production of new C-Kernels. Finally, inclusion of large amounts of data will point the way to better methodologies which can be used in future mission operations.
Lijie Han
Planetary Geology & Geophysics Program (NASA)
Numerical Modeling of Convection in Europa's Icy Shell With Salinity and its Impact on Surface Features
Galileo sata show that Europa's cy surface consists primarily of subdued plains, ridges, bands, chaos, and craters. In addition, Galileo images indicate that Europa's surface has numerous small (3-30 km-diameter) landforms, including uplifts, pits, and irregular lobate features. Europa formation scenarios and Galileo NIMS spectra provide evidence for the existence of salts within the ice shell, but up to now, only preliminary numerical simulations of convection in Europa's ice shell have included the effects of salinity to study pit/dome formation in two-dimensional geometry. This is a major issue, because the current best hypothesis for explaining Europa's surface features requires compositional density contrasts due to salinity variations in the ice shell. Also, to fully determine the nature of surface disruption (if any) and topography caused by the convection and diapirism, it is essential to consider the more realistic viscous plus plastic rheology and to perform simulations, not only in two dimensions, but in three dimensions as well. We propose to extend our investigations about convection and diapirism in Europa's saline ice shell, with the goal of understanding the formation of Europa's surface features, especially the abundant pits, domes, chaos, and ridges. We will perform numerical simulations of thermal-compositional convection using the existing Particle-In-Cell (PIC) finite element code Ellipsis. The simulations will be performed in both two dimensional and three dimensional geometry and will include tidal heating, temperature-dependent viscosity, pseudo-plasticity, and sources and sinks of salinity. With a careful exploration of parameter space, we will predict the geological and geophysical structures and compare them with the observations. This research will emphasize the role of salinity in the convection and the extent to which convection impacts Europa's surface features. The research will thereby provide a major breakthrough in our understanding of the geologic and tectonic history of Europa's ice shell.
William Hartmann
Mars Data Analysis Program (NASA)
Crater-count Chronometry and the Martian Geologic Timescale
This proposal is aimed at continuing my work on the technique of interpreting ages of Martian surface features and timescales of resurfacing processes. This work has been funded at only a low, partial level for several years because previous MDAP and PGG proposal were rejected. The rejections cited published criticisms of the technique, but these criticisms appear to be at least partly in error, especially in view the report by Malin et al. (2006) of small Martian craters forming at close to the rates we have used in our system. Tasks include (1) updating the system by incorporating the Malin work, as well as new work by the author and colleagues; (2) responding to remaining critiques by a new study of effects of secondary cratering on crater counts around young Martian ray craters (approved for two workshop at the International Space Science Institute in Bern); (3) applications to putative ice-flow features and mantled areas on Mars; and (4) application of the techniques to much older features, in efforts to understand long-term erosion, deposition, exhumation, and similar resurfacing processes by studying losses of small craters. Task 3, in particular, extends my recent collaboration with French colleagues on apparent ice flows and ice-rich mantles in the region east of Hellas - exactly the area where climate models of Francois Forget show a pronounced maximum of ice deposition during the last high obliquity period about 5 My ago. Both my data and Malin's data both show ages of a few My for the upper few meters of surface material on the putative ice flows in these regions, in support of the models.
William K. Hartmann
Mars Data Analysis Program (NASA)
Chronology and Analysis of Recent and Ancient Martian Geological Features and Processes
This is a multi-task project designed to conduct tests of the accuracy of the crater count method for analyzing relative ages, absolute ages, and deposition/erosion processes acting on various selected terrains. One task (with C. Quantin, S. Werner, and O. Popova) responds to critiques my McEwen et al. (Icarus 2005) and others, who state that the method is erroneous. We use a test suggested by McEwen et al. to examine whether ages derived from decameter scale craters inside young Zunil-like ray craters are consistent with expected ages for the ray craters. We also show how crater counts can used to analyze effects of mantling and other deposition/erosion processes.
William K. Hartmann
Mars Express Mission Support (NASA)
High Resolution Stereo Camera Experiment Onboard the European Space Agency Mars Express Mission
This project involves the P.I.'s appointment to the imaging team of the Mars Express mission. The project includes working with HRSC images in conjunction with other imaging data bases to improve the technique of estimating relative and absolute ages and crater production functions through crater counts. One joint project with Gerhard Neukum and Stephanie Werner uses an area selected by Ken Tanaka, in Eastern Amazonis, to test the production function we have been using in our isochron system.
Keith Holsapple
Discovery Data Analysis Program (NASA)
Analyses of the Deep Impact Event at Comet Tempel 1
This is a proposal to use theory, modeling, experiments and computers to study and interpret the outcome of the Deep Impact event in the comet Tempel 1. The research will be performed under the auspices of the University of Washington, with experimental work performed under a subcontract to the Boeing Company. It includes five primary components:
1. We will gather all published data to date on high speed impact cratering, including measurements on ejecta masses and velocities. We will formulate the ejecta scaling in a general way, and will make it available to the community by publishing a modern update to the Housen et al. 1983 paper on ejecta scaling.
2. We will apply those scaling results to a study of the dependence on the target material on cratering for the Deep Impact conditions. We will construct results showing the nature, the extent, the distribution, the brightness and the temporal evolution of an ejecta plume for different material assumptions. We will compare those results to the DI observations.
3. The first two tasks are expected to uncover certain holes in our complete understanding of cratering, especially in the transition in a very low gravity environment from gravity to strength effects. In order to address these deficiencies, we will design and conduct impact experiments in appropriate materials with tailored strengths. In all cases we will make measurements of the material strengths using common geological material techniques. We will record high-speed digital movies especially designed to look at the question of the lift-off of the ejecta plume from the target surface, in order to quantify that important aspect.
4. We will explore the possibilities of conducting experiments with target materials with sufficient volatiles to affect the cratering processes. We will investigate the possibilities of using embedded dry ice or pressurized micro-sphere targets. We will conduct theoretical studies of the acceleration of dust particles by expanding vapor clouds. We will study the results of previous researchers, particularly those concerned with comet outburst mechanisms. We will conduct computer studies to model those mechanisms.
We will use our collective expertise in these areas, and the data that has been collected during and after the mission to address the fundamental questions about the nature of the comet material: the raison d'etre for the mission. We expect that the application of modern scaling theories and data, the interpretation of existing and planned experiments, and the modeling and code calculations of identified important physical factors will make significant contributions to the science return for that important event.
Anton Ivanov
ESA Mars Express/NASA Project Extended Mission (NASA)
MARSIS Team Member
Work with Jeff Plaut, Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) Co-Principal Investigator to continue production of MARSIS Level-2 Data Products. Attend and participate in MARSIS team meetings.
Anton Ivanov
Mars Odyssey Participating Scientists Program (NASA)
Analysis of Polar Processes for the Mars Odyssey THEMIS Investigation
Sumita Jayaraman
Spitzer Guest Investigator Program - Cycle 2 (NASA)
Continued Observations of Earth's Resonant Ring
We propose continuing observations for a multi-wavelength study of the Earth's Resonant Ring. The unique Earth trailing orbit of Spitzer traverses this Resonant Ring - a heliocentric ring of dust particles at 1 AU. The dust particles in this ring, produced by the grinding down of asteroids in the main belt, spiral into the inner Solar System due to drag forces and are trapped into resonant orbits in the vicinity of Earth. Azimuthal structures in the ring result in a dust cloud that follows the Earth in its wake. This trailing dust cloud produces a flux asymmetry - the radiation in the direction trailing the Earth's orbital motion is higher than the flux in the leading direction by approximately 1.7 MJy/Sr (2-3%). The only confirmed detection of a structure in a disk caused by a known planet, it constrains the mass and location of a planetary perturber embedded in a circumstellar disk. As Spitzer starts to penetrate the trailing dust cloud, the next 1.5 years are critical because the dynamical model predicts that the flux asymmetry will increase dramatically to >7 MJy/Sr and then start to reverse in direction. This project, started in Jan 2004, has been monitoring the ring with MIPS TPM data. We will extend it to a multi-wavelength study with MIPS and IRAC - stare mode at the poles and 10 & 12 deg scans across the ecliptic to filter the asteroidal dust bands. Since the resonant trapping of particles into the ring is a function of particle size, these observations will constrain particle size-frequency distribution using our dynamical model of the ring. The study of Earth's resonant ring will(1) measure the variations of the local zodiacal foreground over the lifetime of Spitzer; (2) constrain the size-frequency distribution, and estimate the number density, of dust in the near-Earth interplanetary environment; (3) act as a case study for the formation and structure of resonant rings in debris disks, associated with the existence of planets embedded in nearby stars.
Sumita Jayaraman
Spitzer Guest Investigator Program - Cycle 3 (NASA)
Creating the Spitzer Zodiacal Database
We propose to develop the Spitzer Zodiacal Database, a sparse, high resolution map of the zodiacal emission using all relevant Legacy, and available GTO and GO, data from MIPS, IRAC as well as IRS. The final product will include a) time-tagged images and for studies of asteroids, comet trails, dust bands, b) coadded images for precise estimates of the background emission for the broader astronomical community as a whole and c) 1-D scans for the study of the large scale zodiacal background as well as fine structure. In addition, there will be a catalog of comet trails using software specifically developed for trail detection - including trails associated with comets and 'orphan' trails (with no detected source). This database will be web-accessible and searchable through the Planetary Data System's Dust Subnode. This is a unique data product giving the extended emission maps (away from the Galactic plane) that will be applicable to other areas of research beyond the Solar System. It will characterize the foreground zodiacal emission especially near the poles and give us insight into distant background emissions like the Cosmic Infrared Background.
Sumita Jayaraman
Spitzer Guest Investigator Program - Cycle 3 (NASA)
Traversing the Trailing Dust Cloud in the Earth's Resonant Ring - Part 3
We propose continuing observations for monitoring the Earth's Resonant Ring. The unique Earth trailing orbit of Spitzer traverses this heliocentric ring of dust particles at 1 AU. The dust particles in this ring, produced by the grinding down of asteroids in the main belt, spiral into the inner Solar System due to drag forces and are trapped into resonant orbits in the vicinity of Earth. Azimuthal structures in the ring result in a dust cloud that follows the Earth in its wake. This trailing dust cloud produces a flux asymmetry - the radiation in the direction trailing the Earth's orbital motion is higher than the flux in the leading direction by approximately 1.7 MJy/Sr (2-3%). The only confirmed detection of a structure in a disk caused by a known planet, it constrains the mass and location of a planetary perturber embedded in a circumstellar disk. As Spitzer is entering this trailing cloud, the next year is critical because the dynamical model predicts that the flux asymmetry will increase to >7 MJy/Sr, reversing direction in 2006. In Cycles 3 as in 1 & 2 we propose 3 sets of observations : TPM mode at the eclipitic, at the poles, and 12 deg scans across the ecliptic to filter the asteroidal dust bands. These will be combined with calibration observations from IRS and IRAC for a multi-wavelength study of the ring. Since the resonant trapping of particles into the ring is a function of particle size, these observations will constrain particle size-frequency distribution using our dynamical model of the ring. The study of Earth's resonant ring will(1) measure the variations of the local zodiacal foreground over the lifetime of Spitzer; (2) constrain the size-frequency distribution, and estimate the number density, of dust in the near-Earth interplanetary environment; (3) act as a case study for the formation and structure of resonant rings in debris disks, associated with the existence of planets embedded in nearby stars.
Sumita Jayaraman
Spitzer Guest Investigator Program - Cycle 4 (NASA)
Traversing the Trailing Dust Cloud in the Earth's Resonant Ring - Part 4
In 4th set of continuing observations for monitoring the Earth's Resonant Ring during the Spitzer mission, the earth-trailing orbit of Spitzer traverses the solar ring of dust at 1 AU. These particles in the ring, produced by the grinding down of asteroids in the main belt, spiral into the inner Solar System due to drag forces and are trapped into Earth's mean motion resonances. Structures in this heliocentric ring result in a dust cloud that follows the Earth in its wake. producing a flux asymmetry: The radiation in the direction trailing the Earth's orbital motion is higher than the flux in the leading direction by approximately 1.7 MJy/Sr (2-3%). The only confirmed detection of a structure in a disk caused by a known planet, it constrains the mass and location of a planetary perturber embedded in a circumstellar disk. Spitzer entered the trailing cloud,at the end of 2005 and traverse pastthe center of the cloud in early 2007. After that point the flux asymmetry will slowly reverse its direction allowing us to measure the spatial extent of the dust distribution. In Cycles 4 we propose 3 sets of observations : TPM mode at the eclipitic, at the poles, and 12 deg scans across the ecliptic to filter the asteroidal dust bands. These will be combined with calibration observations IRAC for a multi-wavelength study of the ring. Since the resonant trapping of particles is a function of particle size, these observations will constrain particle size-frequency distribution using our dynamical model of the ring. The study will will(1) measure the variations of the local zodiacal foreground over the lifetime of Spitzer; (2) constrain the size-frequency distribution, and estimate the number density, of dust in the near-Earth interplanetary environment; (3) act as a case study for the formation and structure of resonant rings in debris disks, associated with the existence of planets embedded in nearby stars.
Steve Kortenkamp
Origins of Solar Systems Program (NASA)
Studying The Origins of Small Bodies to Aid Theories of Planet Formation and Early Evolution
We propose to use Trojan-type companions of Jupiter, Neptune, and Mars to help constrain models of the early evolution of the solar system. In particular, we proposed to study four distinct problems: 1) Consequences of Planetary Migration for Jupiter Trojans: Our preliminary modeling suggests that Jupiter's Trojan population would have been significantly depleted during the migration phase. We will study this problem to determine the likely initial Jovian population of Trojans that is consistent with the final post-migration population seen today. 2) Migration-Induced Redistribution of Trojans (L4 to/from L5): Jupiter's current Trojan population is asymmetrical, with the ratio of leading L4 Trojans to trailing L5 Trojans running about 60/40. Our preliminary modeling shows that planetary migration is effective at redistributing Trojans between the L4 and L5 regions. We will investigate a range of conditions to determine if any might lead to a preferred redistribution into the leading L4 region. 3) Trapping of Ex-Trojans in Outer Resonances with Neptune: Our new preliminary modeling shows that a significant fraction of Neptune Trojans that escape the 1:1 resonance during the late stages of planetary migration can become permanently trapped in outer mean-motion resonances with Neptune. We will study this effect to determine if it can help explain the range of eccentricities and inclinations seen in the resonant population of trans-neptunian object such as the twotinos and plutinos. 4) Constraints on Planetary Evolution Models from Mars Trojans: Our goal here is to determine whether the existence, abundance, and orbital characteristics of Mars Trojans can help constrain scenarios for the early evolution of the solar system. To accomplish our proposed tasks we will conduct a large number of computer simulations of the orbital evolution of the planets and their resonant Trojan companions. We will use N-body numerical integration codes already in use by us for similar purposes. We will also collaborate in an observing program to survey the Lagrange regions of Mars in order to better understand the abundance and orbital characteristics of Mars Trojans. The outcome of our work will lead to a better understanding of the origin and early evolution of our solar system, which is directly relevant to the scope of NASA's Origins program. Additionally, our proposed research addresses the greater strategic objectives of NASA in that 1) we seek to understand the origin of small solar system bodies including Trojan-type asteroids associated with several different planets as well as distant resonant objects in the Kuiper belt similar to those being targeted by the upcoming New Horizons mission, and 2) we are pursuing opportunities for international participation in support of U.S. space goals by inviting international collaborators to join our team.
Steve Kortenkamp
Planetary Astronomy (NSF)
Investigation of a Resonant Mechanism for Capture of Irregular Satellites During Planetary Migration
OBJECTIVES & METHODS: Kortenkamp and Tricarico propose to examine a resonant mechanism for capture of irregular satellites during planetary migration. The mechanism involves an unusual 1:1 coorbital resonance between the planet and object to be captured. Their primary objective is to determine whether this resonant mechanism will enable giant planets to capture irregular satellites during the late stages of planetary migration. A secondary objective is to determine whether this resonant mechanism can help explain the capture of Phobos and Deimos by Mars. Throughout the proposed research, Kortenkamp and Tricarico will utilize computer intensive numerical simulations. These methods include direct N-body numerical integration and modified N-body integrations that incorporate algorithms to simulate effects such as planetary migration.
INTELLECTUAL MERIT: Understanding the origin of irregular satellites is a long standing problem in planetary science. The merit of this objective is all the more timely considering the dozens of new irregular satellites recently discovered orbiting all four giant planets in our solar system. Kortenkamp and Tricarico each have experience modeling solar system dynamics using a variety of numerical techniques and their publication record demonstrates that they are well qualified in the methods they propose to use. An additional strength of the proposed research is that it will help constrain recent theories regarding the primordial orbital evolution of the giant planets. One consequence of these theories is that irregular satellites were likely captured at a much later time than previously believed and thus without assistance from primordial dissipative mediums vital to other capture mechanisms. Kortenkamp and Tricarico propose a unique solution to this problem by exploring a new resonant mechanism for capture of irregular satellites during the late stages of planetary migration. Also, owing to the proximity of Mars to the asteroid belt, their secondary objective of studying capture of Phobos and Deimos may provide insight into the mechanisms responsible for excitation and depletion of the asteroid belt. Thus, while they will be studying the capture of irregular satellites, Kortenkamp and Tricarico recognize that their work will have a much broader impact on general models of early solar system evolution.
Kim Kuhlman
Lunar Advanced Science and Exploration Research Program (NASA)
Simulation of Space Weathering Effects on the Moon
The goal of the proposed effort is the analytical characterization of the individual physical processes involved in space weathering occurring on the lunar surface: sputtering, solar-wind implantation and impact vaporization. We hypothesize that space weathering is a convolution of these processes that may be dominated by any one of them, or may be a result of their interactions. The work proposed here will provide a better understanding of how space weathering affects the composition of the surface of the Moon. This work will provide a baseline for the space weathering effects on the individual mineral components of the lunar regolith and the spectral effects caused by the various mechanisms of space weathering. This work is important for interpretation of remote reflectance spectroscopy of lunar surfaces, the mining of lunar volatiles and the trapping of hydrogen in lunar materials.
This investigation will use hydrogen and argon sputtering to simulate sputtering by the solar-wind, plasma source ion implantation (PSII) to simulate solar-wind implantation, and electron-beam evaporation to simulate impact vaporization. The visible and near-IR reflectance spectra of the source and weathered materials will be measured and HRTEM and EELS will be used to determine crystallinity (amorphization) and elemental ratios of phases present in the weathering products. Finally, the diffusivity and activation energies of solar wind implanted hydrogen, helium and other lunar volatiles will be measured for the major minerals that compose the lunar regolith
Kimberly Kuhlman
Sample Return Laboratory Instruments and Data Analaysis Program (NASA)
Quantitative Analysis of Genesis Contamination
The Genesis mission collected solar wind and brought it back to Earth in order to provide precise knowledge of solar isotopic and elemental compositions, a cornerstone data set around which theories for materials, processes, events and time scales in the solar nebula are built, and from which theories about the evolution of planets begin. The ions in the solar wind were stopped at very shallow depths, on the order of 10 to a few hundred nanometers. Because this shallow implantation layer is critical for scientific analysis of the composition of the solar wind, it must be preserved throughout sample handling, cleaning, processing, distribution, preparation and analysis.
We propose a laboratory study designed to enhance the science return from the Genesis samples. It is motivated by the need to quantitatively characterize the nanoscale contamination on the collectors in the Genesis payload. The proposed work is complementary to the work currently being done by the Genesis team. It will enable the Genesis curator to more efficiently evaluate samples for allocation, and individual laboratories to more fully understand and either eliminate or mitigate analytical interferences from the contamination, which has thus far restricted the full science return of the Genesis mission. The two types of contaminants are a molecular film now known as 'brown stain' deposited during flight, and a multitude of submicron particulates composed of pulverized spacecraft and lakebed materials and localized precipitates from brine deposited as a result of the unfortunate hard-landing of Genesis at the Utah Test and Training Range (UTTR). Both types of contamination will be quantitatively analyzed using nanoanalytical tools, Local Electrode Atom Probe (LEAP) microscopy and Transmission Electron Microscopy (TEM). These analyses will give both composition and structure of the contaminants. The goals of this project address NASA Strategic Goal 3.3: To advance scientific knowledge of the origin and history of the solar system, the potential for life elsewhere, and the hazards and resources present as humans explore space.
Melissa Lane
Mars Fundamental Research Program (NASA)
Analysis and Characterization of Phosphates Using Multiple Spectral Techniques
Phosphate minerals occur on Mars as evidenced by their presence in Martian meteorites and high levels of P in Martian soils, float rocks, and bedrock. The remotely acquired chemical data, however, do not allow the phosphate mineralogy to be identified. Knowledge of the specific minerals present will provide critical information about the diverse environments in which they formed (e.g., acidic/alkaline, hydrated/dehydrated, degree of oxidation, etc.) Phosphates commonly occur together with sulfates because both mineral classes are based on tetrahedral anion groups of similar size and charge. Sulfates are widespread on Mars; hence, it is likely that phosphate minerals will continue to be identified at many locations on Mars, too.
The purpose of this work is to analyze and characterize a large suite of phosphate minerals using a wide variety of techniques including electron microprobe, X-ray diffraction, extended-visible/near infrared/midinfrared reflectance spectroscopy, thermal emission spectroscopy, and Mössbauer spectroscopy. Such a complete study of phosphates will provide well-characterized sample spectra that will be critical for interpreting past and future data from Mars. The results of this proposal will lay the necessary groundwork for future mission data and meteorite data interpretation that will allow for the determination of which phosphates exist on Mars and their environments of formation.
Currently our team is funded to study sulfates in a similar manner (i.e., an extensive sample suite analyzed by multiple spectral techniques). We have been productive in the study of sulfates and their application to the Martian data sets. Phosphates are an important mineral phase on Mars and require a similar amount of intense study to understand the mineral species and to develop useful spectral libraries that will be available online to interested scientists. We expect to continue disseminating our research results through online libraries, conference presentations, and peer-reviewed publications.
Melissa Lane
Mars Fundamental Research Program (NASA)
Further Analysis and Characterization of Sulfates and Sulfides Using Multiple Spectral Techniques
There exists theoretical, chemical, and spectroscopic evidence that abundant sulfate occurs on Mars; however, only a few specific types (chemistries) of sulfate minerals have been identified in only a few places on Mars. For example, jarosite has been reported to occur in Meridiani Planum (Mars Exploration Rover Moessbauer instrument) and kieserite or gypsum or both are thought to be present in northeast Meridiani, Aram, Valles Marineris, and the northern circumpolar deposit (Mars Express OMEGA instrument). The sulfate chemistry in the Martian dust and soil is uncertain but has been suggested to include magnesium, calcium, iron, and sodium varieties with unknown degrees of hydration. On Earth, sulfate minerals are found in a variety of geologic settings including volcanic, hydrothermal, evaporitic, and low-temperature chemical weathering environments. The key to understanding the sulfate history on Mars is to first identify and determine the sulfate composition, then to draw from geologic clues about the environment of formation. The purpose of this work is to analyze and characterize a large suite of sulfates and potential precursor sulfide minerals using a wide variety of techniques including major element analysis, X-ray diffraction, extended-visible/near infrared/midinfrared reflectance spectroscopy, thermal emission spectroscopy, Moessbauer spectroscopy and midinfrared micro-transmission spectroscopy. Such a complete study of sulfates using these various techniques will provide well-characterized sample spectra that will be critical for interpreting past and future data from Mars. The results of this proposal will lay the necessary groundwork for future mission data interpretation that will allow for the determination of which sulfates exist on Mars and their environments of formation. We previously received one year of funding for a pilot study of the work we propose here to continue. In that year, our team has produced 3 peer-reviewed scientific papers and 5 conference abstracts. Products of this proposed continued research will include additional scientific papers describing our results, and well-characterized VNIR and midinfrared reflectance, midinfrared emission, Moessbauer, and micro-transmission spectra of a suite of sulfate and sulfide minerals, most of which are neither currently in relevant spectral libraries nor well-represented in the literature. The resulting mineral spectra will be available to interested scientists by accessing the online Arizona State University thermal emission spectral library, the Mount Holyoke College Moessbauer spectral library, the VNIR spectral library at the SETI Institute, and the University of Western Ontario online Planetary Science Data Repository (microtransmission). We expect to continue disseminating our research results through these avenues.
Melissa Lane
Mars Odyssey Participating Scientist Program (NASA)
Investigation of Salts on the Martian Surface Using THEMIS Data: Determining Mineralogy, Geologic Setting, and Age
The purpose of this work is to identify salt deposits on Mars using THEMIS data, with a particular focus on sulfate, carbonate, and chloride mineralogy, and to determine their mode and age of origin. These mineral groups will be the focus of this study because they typically originate through deposition in water or through water/rock interaction. Understanding the complex and enigmatic role of water as it relates to volatile history and the potential for past or present life on Mars would satisfy the overarching objectives of the Mars Odyssey mission. The presence of sulfate, carbonate, and chloride minerals on Mars will be investigated primarily through the interpretation of the THEMIS thermal infrared data. The THEMIS data analysis will be interleaved with a continuation of thermal emission laboratory analyses of a larger range of minerals from the sulfate, carbonate, and chloride classes so their spectra are available for comparison to Mars.
Not only will the salt mineralogy on Mars be targeted for identification, but also these deposits will be studied extensively to determine their geologic setting (e.g., are the deposits within a basin, interspersed in the dust fraction, confined to specific stratigraphic units, near volcanic vents), mode of origin, and age. To accomplish these tasks, the THEMIS 100-m-resolution infrared images will be used in concert with the THEMIS visible 20-m-resolution images of the target units and the THEMIS visible images will also be used for performing crater population studies.
It is anticipated that the results of this study will reveal areas on Mars that exhibit strong mineralogical evidence for the past occurrence of water and will provide insight into Martian water chemistry. The crater population studies will produce relative and rough absolute age estimates for these deposits that can increase our understanding of the timing and duration of the water-related processing on Mars. This knowledge will be quite useful in determining where future biological and water-inventory investigations (e.g., Mars landers) could be targeted with a greater likelihood of mission success.
In addition to achieving these science objectives, the proposer (Lane) would assist with operational tasks, such as the validation of the THEMIS data prior to them being archived. Because Lane will be utilizing the THEMIS data off-site, her 'remote' location provides the opportunity to test the off-site data archiving/retrieval system and offer recommendations to the THEMIS team.
Lane would also aid the THEMIS team with further investigation of Mars (mineralogy, crater counts, geological interpretation) specifically for landing site characterization. Lane will contribute the thermal emission laboratory spectra of many simple and complex carbonate, sulfate, and chloride minerals acquired through this work to the Arizona State University online thermal emission spectral library.
Jeffrey Morgenthaler
GALEX Guest Investigator Program (NASA)
GALEX Observations of Comet 8P/Tuttle
Comets are primordial objects left over from the formation of the Solar System. Their study is therefore directly relevant to NASA strategic Sub-goal 3C: "Advance scientific knowledge of the origin and history of the solar system...." Comet 8P/Tuttle is a short-period Halley-family comet well positioned for GALEX study as it approaches its next perihelion, 2008 January 26. GALEX has successfully observed two Jupiter family short period comets (9P/Tempel 1 and 73P/Schwassmann-Wachmann 3) and one long-period comet (C/2004 Q2 Machholz). GALEX is sensitive to several cometary emission lines, the brightest of which include C I 1561 A and 1657 A, CS 2576 A, and OH 3080 A. Operated in grism mode, with its 1.2 degree diameter FOV, GALEX can simultaneously provide high-quality surface brightness and radial profile information. In the case of the C I lines, radial profiles provide critical information on the lifetimes of parent carbon-containing molecules. One of these molecules, CS, will be simultaneously studied, providing insight into its own enigmatic production rate variation vs. heliocentric distance as 8P/Tuttle moves from 1.5 AU to 1 AU. The brightest emission, OH 3080 A, is a well-known proxy for water, the primary constituent of comets. As very few wide-field studies of OH have been done in low production rate comets, GALEX observations of OH in 8P/Tuttle will provide an important benchmark for past and future observations.
Beatrice Mueller
Planetary Astronomy Program (NASA)
Post-Encounter Follow-up Observations of NASA Mission Targets, Comets 9P/Tempel 1, 19P/Borrelly, and 81P/Wild 2
We will carry out follow-up observations of recent NASA mission targets, comets 9P/Tempel 1, 19P/Borrelly, and 81P/Wild 2. Comet 9P/Tempel 1 will be encountered on July 4, 2005 by the Deep Impact (DI) spacecraft and an impactor will be delivered to the comet. We will obtain observations of the comet after the encounter from August through December, 2006, when it again becomes observable from the ground for several hours. We will determine the level of activity and compare it with pre-encounter images that were obtained monthly from January through July 2005. We will determine the effect the impact had on the activity of the comet and if substantial activity is present, compare the gross coma morphology in broad-band and narrow-band filters with pre-encounter conditions. We will observe comet 19P/Borrelly in 2007 to determine a precise rotation period. We will compare the derived result with that determined from the 2000 apparition. Schleicher et al. (2003) and Farnham and Cochran (2002) found indications of a change in the spin axis direction of comet 19P/Borrelly between several apparitions, and this may have also resulted in a change in the rotation period. We will investigate if this has indeed occurred, using the same techniques that were used to find the changes in comet 10P/Tempel 2 (Mueller and Ferrin 1996). Comet 81P/Wild 2 will be observed in 2008 to determine its activity status and to deduce the dust production rate. We will compare these results with those from pre-encounter and ground-based encounter data. This apparition also offers an optimum opportunity in fall of 2007 in which to look for rotational variations in the lightcurve (Farnham and Schleicher 2005), so we can determine the rotation period for the nucleus. This research will add new observational data for three resent NASA spacecraft target comets which will put the encounter data into broader context and will add nuclear parameters not known for these comets. Our results together with the spacecraft and other data will increase our understanding of comets.
Eldar Noe Dobrea
Mars Data Analysis Program (NASA)
Focused Investigations of the Geologic State of Aqueous Alteration on Mars
1)"learning how the Sun's family of planets evolved"
2)"understanding the history of habitability in the Solar System"
3)"investigating past ... habitable environments on Mars"
David O'Brien
Outer Planets Research Program (NASA)
The Primordial Excitation and Clearing of the Asteroid Belt: Implications of Current Outer Planet Migration Models
The asteroid belt was originally much more massive than it currently is. Dynamical processes in the early solar system, driven in part by the outer planets, were responsible for removing most of the original mass and putting the asteroid belt in its current dynamical state. Current models of outer planet orbital evolution predict that the original orbits and positions of the planets were substantially different than they were today, and thus models of the the dynamical processes occuring in the primordial asteroid belt, which generally assume that the outer planets were always on their current orbits, must be re-examined. We propose to re-evaluate the excitation and depletion of the asteroid belt by two processes: (1) sweeping secular resonances as the solar nebula was dissipating and (2) embedded planetary embryos residing in the asteroid belt. In both cases, we will use orbital configurations for the outer planets that are consistent with the best current model of outer planet orbital evolution. We will first simulate each effect separately, and then perform simulations incorporating both effects---something that has not yet been done. To accomplish this task, we will use the well-tested SyMBA N-body integrator, which we will modify to incorporate the effects of gas drag and the gravitational potential due to a time-dependent solar nebula profile. The work here focuses on the dynamical connections between the outer planets and the asteroids, two groups of planetary bodies specifically identified in the NRA. The work proposed here is directly related to goals 2 and 3 of the Outer Planets Research Program as stated in the NRA, "improving our understanding of the evolution of the outer solar system, including the giant planets, their satellites, and other small bodies", and "defining the dynamical processes operating in the outer solar system." This is being submitted as a Sagan Fellowship proposal.
David O'Brien
Planetary Geology & Geophysics Program (NASA)
Exploring the Collisional and Dynamical Implications of Current Outer Planet Migration Models
Current models suggest that the outer planets migrated significantly over the first ~700 Myr of the solar systems history, starting from an initially compact system on close-tocircular orbits. Such a scenario has a number of important implications for the dynamical and collisional history of the solar system. We propose to explore a range of those implications: The collisional/dynamical state of the primordial trans-Neptunian disk that drives the planetary migration and later populates the Kuiper belt and scattered disk; The consequences for the collisional history of the Jupiter Trojan asteroids, which the current model predicts should be populated equally but in reality have substantially different size distributions at small sizes; And the effect of the initial outer planet configuration on terrestrial planet accretion To conduct our investigation, we will perform numerical simulations using a modified version of our current collisional evolution code and modified versions of the Swift numerical integrator. To determine the collisional/dynamical state of the primordial trans-Neptunian disk, we will perform dynamical simulations of the excitation of the disk and use our collisional evolution code to determine the collisional state of the disk for different parameters as it evolves for hundreds of Myr. To model the collisional evolution of the Trojan asteroids, we will modify our collisional code to treat the effects of stochastic large breakups and use it to determine if the differences between the leading and trailing Trojan swarms can be explained by stochastic breakups. Finally, to model the implications for terrestrial planet accretion, we will use a modified version of Swift to study the effect of sweeping secular resonances on the the inner solar system during the depletion of the solar nebula, given the predicted initial orbits of the outer planets. This work will be an important step towards integrating current models of the migration of the outer planets with other aspects of solar system evolution, and in turn will allow those other aspects of the solar system to be used to constrain outer planet migration models. This work is significant for the goals of the Planetary Geology and Geophysics Program in that it integrates the dynamics of small bodies, the terrestrial planets, and the giant planets in an effort to better understand the history and evolution of the solar system. This proposal will be submitted as a Sagan fellowship proposal.
Asmin Pathare
Mars Data Analysis Program (NASA)
The Recent Mass Balance History of the Martian North Polar Layered Deposits
The largest actively-exchanging reservoir of water on Mars is the North Polar Layered Deposits (NPLD), which undergoes widespread sublimation during northern summer.
The ultimate goal of this proposal is to constrain the recent north polar mass balance history by performing a comprehensive analysis of the ablation and accumulation of water ice across the NPLD. First, we will incorporate CRISM and OMEGA spectral observations of surface water ice and atmospheric water vapor into our sublimation model in order to map the surface mass balance at numerous locations throughout the NPLD. Secondly, we will systematically study exposures of anomalous NPLD trough stratigraphy using HiRISE and SHARAD data, which will allow us to compare the three-dimensional orientations of surface layers to those of subsurface dielectric discontinuities. Lastly, we will calculate the effects of orbital variations on water ice accumulation and sublimation in all of our study regions, in order to constrain the recent mass balance history of the NPLD over the last 10 Myr.
Elisabetta Pierazzo
Planetary Geology & Geophysics Program (NASA)
Validation and Benchmarking of Impact Codes: a Broadbased Effort of the Impact Cratering Modeling Community
This project brings together a collective expertise in numerical modeling of impact and explosion events, continuum mechanics, and numerical analysis in an unprecedented effort to uniformly compare, validate and benchmark the computer models ("hydrocodes") widely used by the impact community to model planetary scale impacts and their consequences, as well as by the defense community to model large explosions and the threat to civilization due to asteroid impact. The project identifies a two-part base of standards for comparing and validating hydrocodes. The first part consists in initially identifying sets of well-documented laboratory and field experiments that can be used as type-cases and then use them to validate code calculations over a wide range of event sizes, geological materials and problem types. The second part consists of hypothetical explosive and impact events of varying complexity that will serve as benchmarks for comparison of the numerical and physical models employed in various codes. Simulations will test a range of physical mechanisms involved in impact events. The validation tests are expected to spur new developments and improvements of code components, especially in the material models used in the codes. This effort has not been undertaken before for two reasons. First, the extensive experimental data necessary for validation of the computer models is often buried in reports that are difficult to access. Second, most modelers have specific experience with only one or two computer models. This project brings together 15 scientists from various U.S. and international universities, research institutes and national laboratories, each with extensive experience in numerical modeling of impact and explosion craters. This study will have a broad impact both from the scientific and educational point of view. By providing this information to the broad scientific and defense community this project will help prevent the incorrect and misinformed use of the codes, especially those with free distribution, thus benefiting theoretical investigations that use these codes. Identified standards, code simulations and results will be made widely available to the scientific community through the development of a website dedicated to the project. Future generations of modelers will benefit from this effort by learning from examples of the correct applications of different codes and will be provided with a set of rules and test cases to follow in order to benchmark and validate hydrocodes to come.
Elisabetta Pierazzo
Planetary Geology & Geophysics Program (NASA)
Effects of Lithologies on Impact Cratering: Numerical Modeling of Known Terrestrial Craters
The study of crater populations is an important tool for understanding the geologic history of planetary surfaces. Impact cratering modifies locally and temporally the physical and thermal state of the target and ejects and distributes material in various physical states (melted, shocked, pulverized, etc.) over a wide region around the excavated crater. At the same time, the physical and chemical properties of target material, including porosity, volatile content and natural mixtures of diverse rocks strongly affect the cratering process. On Earth craters in water-saturated sediments are larger than their energy-equivalents in dry soils, which, in turn, are larger than their energy-equivalents in crystalline rocks. Melt production also appears to be strongly influenced by target lithology. A thorough understanding of the behavior and influence of material characteristics on the impact process is crucial for using impact cratering as a tool to better understand the physical, geological and biogeochemical processes on a given planetary body. Numerical simulations, and to a somewhat lesser degree, due to scaling limitations, laboratory experiments are the best tools for such and undertaking. Over the past two cycles we have accumulated valuable experience in understanding the influence of target properties on the impact process by modeling the formation of specific terrestrial craters. In the process, we have significantly improved our numerical codes (SOVA and SALEB) and material models. Overall, current material and hydrodynamic models allow us to reproduce the main features of crater morphology versus impact size. At the same time,our results indicate that there are still limitations in the models that must be improved for an accurate reproduction of impact events. During this cycle we plan to take our investigation to the next logical step by: 1) Improve material models to reproduce simultaneously the thermodynamic properties of solid-solid transitions, melting and vaporization; 2) Model craters in complex lithologies by investigating the role of mixing materials with very different thermodynamic properties. Our investigation will involve modeling vertically layered targets, complex targets with radial as well as vertical material variations, and intrinsically mixed targets (e.g., targets with significant pore water). 3) Investigate the role of material properties, target complexity and impact conditions on material ejection and formation of proximal and distal ejecta. We will address these scientific objectives by modeling the formation of specific small and large terrestrial craters taking advantage of the recent progress in geological and geophysical studies of many terrestrial impact structures, to test and validate our refined models against observational data. Large craters cover extended targets and are thus more sensitive to spatial variations in target lithologies. Crater collapse, melt production, distal material ejection may provide clues on how target complexity affects the cratering process. On Earth large craters tend to be old, and either strongly eroded or of buried under thick sedimentary covers. Well preserved accessible terrestrial structures are generally young and small, like Meteor Crater and Lonar. In small impact events the cratering process is simplified (limited crater collapse), yet these small craters present differences that are ultimately explained by differences in target lithologies. Furthermore,young structures tend to have a well-preserved ejecta blanket (limited erosion), which allows us to compare the process of ejecta blanket emplacement with ground truth data.
Elisabetta Pierazzo
Mars Fundamental Research Program (NASA)
Impact Cratering on Mars: Hydrothermal Systems, Ejecta, and Ramparts
We will carry out high-resolution impact simulations to investigate the role of impact cratering in: 1) affecting the distribution of subsurface water (crucial for origin of life on Mars); 2) asymmetric distribution of ejecta; and 3) formation of ramparts. We will model both asteroidal and cometary impacts at various impact angles and with typical impact velocities for Mars. We will continue our work on materials models, equations of state and constitutive equations, to best represent mixed targets (rock+ice/water), and their response to shocks and impact cratering flow. The entire cratering event formation, i.e., contact/compression, excavation (including material ejection), and transient crater modification will be modeled with the three-dimensional hydrocode SOVA for vertical and oblique impacts. For testing and validation purposes, vertical impacts will be modeled up to final crater formation and ejecta deposition with the two-dimensional Eulerian code SALEB, which is optimized for crater collapse studies. The goal of task #1 is to continue our initial work to characterize the post-impact target's thermal environment (with particular attention to water/ice phase state) around impact craters. At this time we will focus on large craters, with the goal of comparing results of our study to the recent data from the MER/MEX missions relative to the environment at Gusev crater. This study should help characterize the volatile content of the region at the time of impact. In task #2 we want to model very oblique impacts in an attempt to understand the observed asymmetries in ejecta distribution. This work will coordinate with Collaborator Herrick's detailed study of oblique impact ejecta distribution at Martian craters (funded through MDAP). This will also allow us to characterize the distribution of shocked ejecta around crater and compare with results of previous spectral studies (e.g., work by J.R. Johnson). Finally, task #3 will focus on the formation of ramparts around craters. This is a natural extension of our recent work on modeling mixed target materials, and will address the debate on atmospheric versus target composition origin of ramparts.
Tom Prettyman
NASA Discovery Program (NASA)
DAWN Gamma Ray and Neutron Detector (GRaND) Investigation, Phase E
The Dawn mission has entered Phase E (science and operations) following successful launch and Initial Check Out (ICO) of the payload. During Phase E, Tom Prettyman of the Planetary Science Institute (PSI) will be responsible for the GRaND investigation, including operations, data reduction, analysis, and scientific interpretation in collaboration with the Dawn Science Team, and delivery of data products to the Science Team and Planetary Data System (PDS). This work involves overall project management for GRaND, in coordination with Dawn Science Center and Jet Propulsion Laboratory, including subcontracting to Los Alamos National Laboratory (LANL) for engineering support, as well as carrying out technical work needed to prepare for encounters and to execute the science plan. We will work with the project to update appropriate documentation for mission planning operations and science data analysis, as needed to reflect PSI's new role in the project.
Throughout the mission, the PSI-led team will be responsible for operating the instrument, processing and delivering the data to the PDS according to the mission time-line, and developing scientific data products, according to the science plan. This scope of work (SOW) document describes tasks to be carried out in FY08, starting in January 2008. Tasked labeled 'to be completed' (TBC) will be completed before the end of the fiscal year (by 30-September-2008). Tasks labeled 'ongoing' are routine tasks that will be carried out routinely throughout the mission, including FY08. Tasks labeled 'initiated' will be completed in subsequent fiscal years. A separate SOW will be developed for subsequent years.
For FY08, the project will involve effort at PSI (led by Dawn co-investigator Tom Prettyman) and engineering support from LANL. Specific tasks for FY08 include:
Ongoing: Support GRaND operations during cruise (involves remote monitoring of state of health telemetry data, development of command plans for cruise, anomaly resolution, and on site support of operations at the DSC as required by the project);
Ongoing: Reduce and analyze science data acquired during ICO and cruise, and deliver the data for distribution to the science team and Planetary Data System (involves development and validation of computer codes for data reduction and analysis); (delivery of ICO data and available cruise data TBC in FY08);
TBC: Deliver the final report for Initial Check Out of GRaND to the project;
TBC: Archive documents, data and flight components needed for GRaND operations and experimental characterization of sensor response;
Ongoing: Analyze and interpret space background data acquired during ICO and cruise to monitor state of health, and in preparation for encounters with Mars, Vesta and Ceres; compare data acquired during previous missions and publish/present results;
Ongoing: Support science team and operations planning meetings;
Draft TBC; submitted for review in FY09: Write a comprehensive paper on the GRaND instrument to be submitted to Space Science Reviews;
Ongoing: Collaborate with the science team to begin preparation for science data analysis, interpretation, and data delivery at Mars, Vesta, and Ceres;
-- Develop a detailed model of the GRaND instrument to determine response functions for neutron and gamma ray sensors; validate the model against experimental data acquired prior to delivery and during ATLO (preliminary model and data intercomparison TBC; detailed model ongoing);
-- Calculate the response of GRaND for different geophysical and geochemical models of Vesta and Ceres, incorporating data from meteorites and telescopic observations; investigate systematic trends in GRaND data products to determine the sensitivity of GRaND to different scenarios for planetary formation and evolution (ongoing);
-- Begin development analytical methods to reduce GRaND data, including the development of techniques for forward modeling and spatial deconvolution (ongoing);
-- Begin development of methods to combine GRaND data with VIR and FC observations, in collaboration with the instrument and science teams (ongoing).
Tom Prettyman
Mars Odyssey Participating Scientists Program (NASA)
Analysis of Mars Odyssey Gamma Ray Neutron Spectroscopy data: Constraints on Geochemistry, Atmospheric Processes and the Water Cycle
The goal of my research is to characterize Mars' high latitude surface composition, water ice table, and seasonal/inter-annual variations, including the polar caps and atmosphere, as described in the proposal for the extended mission. Specific tasks include:
- Determine the local CO2 column abundance of the seasonal caps in the northern and southern hemisphere;
- Characterize the south polar residual cap (CO2 mass, thickness, and area of exposed water ice);
- Characterize the high latitude water ice table as a function of latitude and longitude;
- Map the seasonal cycle of enrichment and depletion of noncondensable gases in the atmosphere at high latitudes.
The proposed work described in this document is a continuation of the work presently underway, and the scope is similar to that originally proposed; however, I also propose to expand my effort to include synthesis of the neutron and gamma ray data sets to more accurately constrain surface layering and composition. The new effort leverages experience from Lunar Prospector, and will require close collaboration with members of the GRS team. The proposed analysis will be applied to the global Mars Odyssey data set.
Tom Prettyman
Mars Data Analysis Program (NASA)
Determining the Mars Polar Energy Balance by Combining Nuclear Spectroscopy with Thermal Observations
Objectives. The Mars polar energy balance must be determined if we are to understand the Mars climate. Nuclear spectroscopy, combined with thermal observations will enable our ability to constrain the seasonal polar cap mass and the local column abundance of CO2, the composition, stratigraphy and thermal properties of the regolith, the solar energy absorbed by the surface, and the thermal energy lost to space. The remainder of the energy is the heat advected by the atmosphere, which presently is not well understood.
Methods. To accomplish this objective, nuclear spectroscopy, combined with seasonal thermal trends, will be used to model the stratigraphy of the regolith. This includes calculating the thermal inertia, water content and depth for a 2 layer model, where the lower layer is the ice table. Once the thermal and nuclear properties of the regolith have been established, such quantities as CO2 mass accumulation and sublimation rates can be more accurately calculated. The only quantity of polar energy balance that cannot be directly measured or inferred from observation is the amount of heat transferred by the atmosphere. We will compare our energy balance residuals to GCM outputs.
Significance. This work will produce a more detailed description of the stratigraphy of the near surface regolith in the polar region, to include thermal inertia, water ice content, and depths to the ice table. A better time-dependent estimate of the seasonal CO2 distribution will result as regolith effects can be removed from both the thermal and nuclear data. Heat transport will be inferred from the residuals of the polar energy balance and compared to GCMs. Atmospheric dynamics and transport plays a significant role in the formation and dissipation of the polar caps, perhaps even being the cause of both the SPRC offset and the location of the Cryptic region.
Jose Alexis Palmero Rodriguez
Mars Data Analysis Program (NASA)
Types and Origins of the Martian Outflow Channels
During the Noachian epoch (~4.5 to 3.7 Ga) the surface of Mars appears to have been modified by rates of surface erosion and deposition similar to those prevalent on Earth which have led many authors to postulate the existence of "warmer and wetter" early Martian environment. Endogenic hydrologic processes during the Hesperian (~3.7 to 3.0 Ga) and early Amazonian (~3.0 to 1.7 Ga) are thought to have resulted in the in the formation of the Martian outflow channels, which comprise some of the largest known channels in the solar system. The Martian outflow channels has been the subject of numerous studies since the early acquisition of orbital images of the Martian surface and their origin is typically attributed to large-scale surface flow and erosion as pressurized subsurface fluids were released to the surface. They generally originate full bore at discrete troughs, tend to be several kilometers to 10's of kilometers across (and even wider) and hundreds to thousands of kilometers long, have fluvial bedforms on their floors, as well as sinuous streamlined walls and teardrop-shaped 'islands'. Various models have been proposed regarding the mechanisms that led to outflow channel formation. These include: Outflow activity induced by intrusive magmatism, extensional tectonism, elevated hydrologic heads induced by topographic gradient between highlands and lowlands, and superlithostatic pressures produced a thickening cryosphere over confined aquifers. The outflow channel floods were likely important in redistributing the volatile inventory of Mars, and may have been a significant driver of climate change and ocean formation. The Martian outflow channels are primarily clustered in circum-Chryse, eastern Hellas, and western Elysium. The circum Chryse outflow channels are located in the eastern portion of the Tharsis trough, and the eastern Hellas and Elysium outflow channels occur in the flanks of volcanic rises. Whereas this spatial correlation is suggestive of a causal relationship between the outflow and the formation of Tharsis and the Elysium rises, as well as the volcanic centers in Hellas. Nevertheless, their diverse morphologies, their global and regional distributions and their broad range of ages remains poorly understood. Thus, in order to understand the geologic conditions that triggered outflow channel formation on Mars and the diversity of the processes involved in outflow channel formation, we propose a comparative geomorphologic study of the outflow channels in circum- Chryse, eastern Hellas, and western Elysium, coupled with chemical and thermal modeling.
Jose Alexis Palmero Rodriguez
Mars Data Analysis Program (NASA)
Hydrogeologic Significance of the Association of Chasmata, Chaotic Terrains and Surface Flow Landforms
We foresee this investigation fulfilling its stated goals as well as contributing to the understanding of the mechanism that resulted in the formation and interconnection of the chasmata and chaotic terrains in the circum Chryse region, as well as to the understanding of the volatile history of these regions. The temporal and morphologic diversity of these features is not currently understood in a broad framework, but through our spatially variable observations a synthesis of the evolution may emerge. Regions where the Coprates Chasma and the Eos and Capri Chasmata merge, and regions where the Eos, Capri, and Ganges Chasmata merge with the Aureum Chaos, are of particular interest; they may represent significant variations in the characteristics of the cryolithosphere and hydrosphere in these regions, significant variations in the types and/or duration of the processes that modified these regions of the hydrosphere and cryolithosphere, and this study will evaluate these hypotheses.The chasmata and chaotic terrains have been sculpted by surface collapse and subsidence and outflow floods, as well as by other secondary processes such as volcanism, tectonism, mass-wasting, erosion and deposition; this investigation will attempt to define the stages and duration of surface collapse and surface subsidence involved in the formation of chasmata and chaotic terrains, as well as the stages and duration of subsurface fluids release within the chasmata and associated chaotic terrains. And finally, the understanding of the formation and interconnection of the chasmata systems and chaotic terrains as well as of their outflow history is of fundamental importance to our understanding of the cryolithospheric and hydrospheric characteristics of Mars, well as the depositional history of northern plains.
Nalin Samarasinha
Outer Planets Research Program (NASA)
Determination of Densities of Comets from Rotational and Orbital Evolutions
The primary goals of this study are: (a) To develop realistic rotational evolution models for comets 9P/Tempel 1 and 19P/Borrelly constrained by both spacecraft and groundbased observations, (b) to determine well-constrained bulk densities for the nuclei of comets 9P/Tempel 1 and 19P/Borrelly by simultaneously applying observational constraints from changes in nuclear rotational states as well as in orbital motions, and (c) to place constraints on other nuclear structural parameters (product of shear modulus and quality factor) by numerically monitoring possible rotational excitations.
The bulk densities and other structural parameters help us understand the formation of comets and their evolutionary processes as well as the environment of the early solar system during its formation era. In addition, the proposed research will provide interpretations of an extensive array of data and will put the results in a larger context for small bodies. The computer models will use products available at NASA Planetary Data System and existing and future supplementary groundbased observations. This investigation will allow meaningful comparisons of bulk densities of two Jupiter-family comets, 9P/Tempel 1 and 19P/Borrelly, which are compositionally different from each other (the latter is "depleted" in carbon chain molecules while the former is not).
The proposed work investigates the dynamical processes (both rotational and orbital) operating for comets and involves the development of theory and modeling relevant to dynamics of small bodies. This together with determination of the bulk densities and other structural parameters is consistent with the objectives of NASA as well as of the Outer Planets Research Program.
Matt Staid
NASA Discovery Program
Moon Mineralogy Mapper Team
"The Moon Mineralogy Mapper (M3) is one of two instruments that NASA is contributing to India's first mission to the Moon, Chandrayaan-1, which is scheduled to be launched in 2008. M3 is a state-of-the-art imaging spectrometer that will provide the first map of the entire lunar surface at high spatial and spectral resolution, revealing the minerals of which it is made.
Scientists will use this information to answer questions about the Moon's origin and development and the evolution of terrestrial planets in the early solar system. Future astronauts will use it to locate resources, possibly including water, that can support exploration of the Moon and beyond."
(http://moonmineralogymapper.jpl.nasa.gov)
Matt Staid
Planetary Geology & Geophysics Program (NASA)
Remote Sensing of Lunar Mare Craters Using Clementine and ROLO Spectral Data
Proposed work would investigate the mineralogy of several spectrally unique basalt types on the lunar nearside using Clementine UVVIS and NIR multispectral data and complementary ground based spectral measurements acquired by the USGS Robotic Lunar Observatory (ROLO). High spatial resolution Clementine data would be used to map highland contamination and optical maturity within six mare regions, including the late-stage high titanium basalts on the western nearside and anomalously red and bright basalts that lie outside of the major lunar basins. Uncontaminated mare soil and crater sites identified in the Clementine abundance maps would be further studied through spectral analysis of ROLO telescopic data. ROLO, designed for on-orbit calibration of spacecraft instruments, provides precisely calibrated exoatmospheric radiance images of the Moon in 32 spectral bands from 0.35 to 2.5 microns; these represent an as yet untapped resource for lunar science applications. The Clementine and ROLO datasets would then be further integrated through sub-pixel analysis techniques to derive high spectral resolution endmembers for the least weathered mare crater materials within each basalt type. Spectral information derived from both datasets would be used to investigate the mineralogy of the mare study regions through a variety of analytical techniques and comparisons with spectral measurements of lunar samples and soils. Objectives include confirmation of abundant olivine within the last major phases of lunar mare volcanism and mineralogic characterization of a spectrally distinct basalt type associated with emplacement through regions of thick feldspathic crust. Improved understanding of the mineralogy of these deposits would provide new constraints for the evolution of mare source regions over time and models of mare emplacement.
Mark V. Sykes
NASA Discovery Program
Dawn Science Team
"Dawn's goal is to characterize the conditions and processes of the solar system's earliest epoch by investigating in detail two of the largest protoplanets remaining intact since their formations. Ceres and Vesta reside in the extensive zone between Mars and Jupiter together with many other smaller bodies, called the asteroid belt. Each has followed a very different evolutionary path constrained by the diversity of processes that operated during the first few million years of solar system evolution." (http://dawn.jpl.nasa.gov/mission/index.asp)
Mark V. Sykes
Hubble Space Telescope Guest Observer Program (NASA)
Photometric Mapping of Vesta's Southern Hemisphere
We propose to carry out a study of Vesta similar to the one just completed of Ceres, building on recent experience using and analyzing data from the ACS. The proposed program improves knowledge of the spin pole, shape, size and photometric properties of asteroid 4 Vesta. We include the I-band filter which will allow us to correlate the visible and ultraviolet albedo with mafic silicate composition across the asteroid's surface. We conduct a satellite search and will map the longitudinal variations in the UV absorption reported by Cochran and Vilas, (1998) and Hendrix et al. (2003). Improvements in knowledge of the pole orientation allow us to plan orbital observations for the Dawn mission with knowledge of lighting conditions. It facilitates combining different data sets taken over time spans of many years and separating the effects due to geometry and orientation in space, from intrinsic albedo features of the asteroid. Knowledge of its size and shape provides the best pre-encounter gravity model necessary for operating the spacecraft and maintaining its orbit. Improved knowledge of the shape, combined with a more accurate mass determination (carried out independently via ground-based astrometry) will result in a better density determination, a fundamental scientific result. This particular opposition of Vesta extends photometric mapping into the southern hemisphere and its prominent southern basin. This feature was reported by Thomas et al. (1997) but has not been mapped and analyzed in terms of photometric models. (Lead: L. McFadden, UMd)
Mark V. Sykes
Planetary Astronomy Program (NASA)
Mapping the Surface Thermophysical Properties of Surviving Protoplanets
We will create predictive thermophysical models for three surviving protoplanets, Ceres, Pallas, and Vesta for their use as astrophysical calibration sources at thermal wavelengths. These models will be tested and constrained by observations over all solar illumination conditions and all observing geometries available from Earth. Hemispheric variations in thermophysical properties will be identified and correlated with sub-hemispheric albedo and other structures identified separately from HST and groundbased AO. To achieve this goal, we will conduct a long-term lightcurve observing campaign from mid-infrared to millimeter wavelengths over a several year period, with near-simultaneous visible photometry. Models will incorporate independently determined shape and rotational pole orientation.
Mark V. Sykes
Spitzer Guest Investigator Program - Cycle 1 (NASA)
Determining Albedos and Sizes for Irregular Satellites of Jupiter and Saturn
Determining sizes and albedos for the irregular satellites of the giant planets is essential in understanding their origins and capturing processes. The Multiband Imaging Photometer (MIPS) aboard the Spitzer InfraRed Telescope Facility (SIRTF) is the only instrument available that makes photometric observation of a large number of irregular satellites in the mid-infrared possible. We propose to perform mid-infrared photometric observations of 23 Jovian and 9 Saturnian irregular satellites, over half of the known irregulars around these two planets. This sample will give us a uniqe sample of accurate sizes and albedos that will provide us with the capability to compare them with other solar system bodies in the search for their origins and processes of evolution. (Lead: T. Grav, UHaw)
Mark V. Sykes
Spitzer Guest Investigator Program - Cycle 2 (NASA)
High Latitude Dust Bands in the Main Asteroid Belt: Fingerprints of Recent Breakup Events
The present population of main belt asteroids is largely the result of many past collisions. Ideally, the fragments produced by each impact event could help us understand the collisional processes that shaped the planets during early epochs. Most known asteroid fragment families, however, are very old and thus have undergone significant collisional and dynamical evolution since their formation. This evolution masks the properties of the original collisions. To overcome this problem, our team has used numerical methods and a large database of asteroid orbits to identify several families produced by recent disruption events (<< few tens of My). Not only have these young families undergone little collisional and dynamical evolution, but several of them appear to be the source of dust bands observed by IRAS (e.g., the Karin and Veritas families, both which are < 10 My old; Nesvorny et al. 2002; 2003). Here we propose to use Spitzer observations to investigate the structure of high latitude dust bands in the main asteroid belt. Our results indicate that 2 faint dust bands identified by IRAS, the J/K band at proper inclination i = 12 deg and the M/N band at i = 15 deg, were produced by break up events associated with asteroids (4652) Iannini and (1521) Seinajoki, respectively. Numerical integration work by our team suggests the former family is < 5 My old, making it the youngest family yet discovered in the main belt. Taking advantage of the increased sensitivity of Spitzer over IRAS, we will determine the dust production rate and size distribution in the high latitude bands, relate them to the Zodiacal Cloud, and use this data to constrain main belt collisional processes. (Lead: W. Bottke, SWRI)
Mark V. Sykes
Spitzer Guest Investigator Program - Cycle 3 (NASA)
The Large Particle Emission History of Rosetta Target P/Churyumov-Gerasimenko
We propose to map the dust trail of comet 67P/Churyumov-Gerasimenko (C-G) with SST/MIPS at 24, 70 and 160 micron. This observation extends the earlier COMDUST observation PI Fazio of this comet in two important aspects: it quantifies the dust emission at large heliocentric distances which is indicated in the earlier observation, and it extends the characterization of large particles' emissions during previous apparitions of this comet. Both aspects are of crucial importance for the international Rosetta mission which will pass through the trail region during its approach to this comet in 2013. (Lead: J. Argawal, ESA)
Mark V. Sykes
Spitzer Guest Investigator Program - Cycle 3 (NASA)
A New Source of Interplanetary Dust: Type II Dust Trails
Studies of the circumsolar (zodiacal) cloud serve as an important baseline for interpreting observations of extrasolar debris disks. The cometary trails and asteroid dust bands, both analyzed to a great detail in the past, provide vital information on the contribution of cometary activity and large asteroid collisions to the zodiacal cloud. Now, in our Cycle 1 Spitzer program, we detected a new important source of interplanetary dust particles that have not been seen since IRAS mission more than two decades ago, the Type II trails. Unlike narrow (~1 arcminute) comet trails, Type II trails are extremely wide (0.5-2 degrees) and were found by IRAS to extend over tens of degrees. Surface brightness estimates indicate that Type II trails could be supplying more dust to the interplanetary dust complex that all short-period comets combined. Using the IRAS and Spitzer data on detected Type II, our orbital elements fitting to these observations indicate a possible asteroid origin for these structures. Here we propose observations of Type II trails to determine their origin. We propose to make a series of three scan traverses of regions on the sky near the expected locations of the trails. By combining these data with our Cycle 1 observations, we will be able to determine the orbits of Type II trails precisely and to clearly distinguish between asteroidal and cometary sources. Moreover, the determined orbits will be used to pinpoint the exact location of sources of the observed dust particles. The detail structure of trails in different scans, when properly analyzed, will provide valuable insights into the details of their underlying dust production mechanism and formation history. Taken together, the observations proposed here will substantially contribute to our understanding of the zodiacal cloud and its evolution over time. (Lead: D. Nesvorny, SWRI)
Mark V. Sykes
Spitzer Guest Investigator Program - Cycle 3 (NASA)
The Spitzer Asteroid Catalog
We propose to catalog fluxes and derive sizes and albedos for all asteroids with small positional uncertainties that appear serendipitously in publicly available IRAC and MIPS archive data. We will make at least 25,000 independent measurements. Our results will help extend the small end of the asteroid size frequency distribution of main belt and Jupiter Trojan asteroids; reveal compositional gradients and remove compositional degeneracies; look for common properties among asteroid families; and serve as a fundamental database of asteroid properties for the coming decades. The SSC asteroid identification tools are inadequate for this task and furthermore provide no analysis of asteroid data. We have developed and demonstrate a pilot automated pipeline capable of extracting asteroid detections from IRAC and MIPS imaging data products and generating a first order catalog of fluxes, albedos, and diameters. This pipeline will be applied to the entire publicly accessible Spitzer imaging archive. The results will be published in refereed papers and in NASA's peer-reviewed Planetary Data System. (Lead: D. Trilling, UAz)
Mark V. Sykes
Spitzer Guest Investigator Program - Cycle 4 (NASA)
Thermophysical Mapping of 25143 Itokawa
We have a unique opportunity to map at subhemispheric resolution the thermophysical properties of the small Earth-crossing asteroid 25143 Itokawa this April/May 2007 by combining high-resolution shape and topography models, recently derived from imagery of the asteroid obtained by the Japanese Hyabusa mission, with rotationally well-sampled thermal spectra obtained with Spitzer IRS. Prior groundbased observations in the N and Q bands (limited in rotational coverage, wavelength coverage, with substantially lower signal-to-noise) provide only a single global value of thermal inertia, compared to the possible 40 surface resolution elements this program may obtain. Itokawa has a block-strewn surface combined with smooth areas with no definitive large craters and an apparent deficiency of small craters - the first clear example of a 'rubble-pile', that may be characteristic of most small NEOs. Itokawa makes its closest and best approach to the Spitzer spacecraft (0.09 AU) in April at an observational phase angle providing an excellent view of the terminator across which surface temperature changes are maximum. Significant changes in shape and spectral peak of Itokawa's SED as the asteroid rotates are simulated. The high signal-to-noise of the proposed Spitzer IRS observations will well-resolve these spectral differences. Though Itokawa is not spatially resolved by Spitzer, a priori knowledge of its detailed shape and topography from the Hyabusa mission allows us to divide its surface into subunits with independent thermal properties, and constrain them by grid search, finding those values or range of values that reproduce the numerous spectra obtained, where different combinations of surface units contribute to each spectrum as they move from evening to morning to afternoon and in and out of view (sometimes blocked by nearby units). Maximizing rotational sampling maximizes the longitudinal resolution of our thermophysical maps and the number of resolution elements covering its surface.
Mark V. Sykes
Spitzer Guest Investigator Program - Cycle 5 (NASA)
The Spitzer Asteroid Catalog: 10,000 More Asteroids
Understanding the global properties of the asteroid population today gives us insight into the processes, compositions, and timescales of planet formation as well as the post-formation dynamical evolution that sculpted our Solar System. Asteroids appear serendipitously in a significant fraction of every Spitzer image taken. We propose to continue building the Spitzer Asteroid Catalog by identifying, extracting, cataloging, and analyzing serendipitous observations of asteroids in the Spitzer archive by extending our work into the revolutionizing Pan-STARRS 1 era. Our results to date show that the the biggest source of error by far is bad visible magnitudes. It is also clear that our catalog is limited by the sensitivity of current ground-based surveys. Data from Pan-STARRS 1 will improve orbits and photometry to such an extent that the useful size of the Spitzer Asteroid Catalog will at least double, and in time increase to ~100,000 asteroids. We will derive sizes and albedos for all of these asteroids. The resulting databases will allow rich science investigations into the composition, evolution, and dynamical history of the asteroid belt and be a legacy of the Spitzer Space Telescope for decades to come. (Lead: D. Trilling, UAz)
Ed Tedesco
International Space Science Institute Program (NASA)
Light Scattering Phenomena in Small Body Surfaces
The PI (together with five colleagues from Europe) is starting an interdisciplinary program to derive a calibration of the relation between asteroid albedos and the observable properties of the polarization of their reflected light. Although this has been done for larger asteroids, the quality of the polarization data is generally poor and little data is available on small asteroids.
This interdisciplinary collaboration is being supported by the International Space Science Institute (ISSI) in Bern, Switzerland (http://www.issibern.ch). This proposal requests support for the PIs participation in this effort. In addition, Commission 15 of the International Astronomical Union (IAU) has established two Task Groups (one of which is co-chaired by the PI) devoted to finding solutions to, or at least rigorously defining, issues in determining diameters and albedos for small asteroids, e.g., NEOs, from remote mid-infrared and visual polarimetric observations. The authors of this ISSI project represent a major fraction of the members of these two IAU Task Groups.
Pasquale Tricarico
Applied Information Systems Research Program (NASA)
A Distributed Computing System Supporting Near Earth Asteroids Research
We will develop a Distributed Computing system dedicated to Near Earth Asteroids (NEAs) research. This system will incorporate a mature tool for Celestial Mechanics computations (ORSA) into a well established Distributed Computing infrastructure (BOINC), and will be used in two different problems.
The first application of this system is in the improvement of the performance of NEAs surveys, by implementing a search strategy that maximizes the volume covered in the NEAs orbital elements space. This produces a very accurate estimate of the unbiased NEAs population, and uses the entire set of astrometric observations of reference surveys to determine the optimum scheduling that maximizes probability to detect new NEAs.
The second application is the monitoring of the impact hazard by NEAs, improving on standard systems in terms of response time, accuracy, and accounting for non-gravitational effects. It uses a distributed version of the Monte Carlo sampling method, which tracks the dynamical evolution of virtual asteroids to determine the statistical probability of an impact with Earth.
This proposal addresses the AISR goal to demonstrate the degree of relevance, applicability, and potential impact of distributed computing (an emerging information technology) to the NEA SMD program. This proposal also addresses the NASA strategic sub-goal 3C: Advance scientific knowledge of the origin and history of the solar system, the potential for life elsewhere, and the hazards and resources present as humans explore space, by advancing our knowledge about the NEAs population and its impact threat.
Stuart Weidenschilling
Planetary Geology & Geophysics Program (NASA)
Planetesimal Formation vs. Planetary Accretion
The proposed mechanisms of planetesimal formation - gravitational instability, collisional coagulation, and turbulent concentration - predict very different initial size distributions, formation timescales, and variations with heliocentric distance. We will use numerical simulations to examine effects of these inputs on accretional growth of planetary embryos, and compare the results with constraints inferred from the early asteroid population. We will develop algorithms for size and velocity distributions of fragments from oblique impacts and incorporate them into a stochastic accretion code. We will evaluate the relative rates of accretion vs. collisional disruption to determine the efficiency of planetary formation and the effective minimum mass of the solar nebula.
Stuart Weidenschilling
Origins of Solar Systems Program (NASA)
Circumstellar Dust as an Indicator of Planetary Formation
Dust grains in circumstellar debris disks are rapidly depleted by Poynting-Robertson drag, collisions, and radiation pressure blowout, and must be constanly renewed. The visible dust is the product of collisions between unseen parent bodies, which cannot be detected directly. Their sizes and abundances can be constrained by modeling their collisional lifetimes and the orbital evolution of their fragments, with realistic scaling of collisional outcomes and loss mechanisms. Impact velocities needed to account for the visible dust may indicate the presence of larger perturbers, i.e., planets. A multi-zone collisional code will be modified to include radiative forces; a hierarchical approach will be developed to allow explicit modeling of the collisional and orbital evolution of small grains. Self-consistent models will be constructed for debris disks around stars with a range of masses and luminosities. The production of potentially observable features, such as inner holes, gaps due to planets, and transient enhancements due to giant impacts will be evaluated. The results will clarify the relationship between observable matter (dust) in circumstellar environments and the formation of planetary bodies.
Stuart Weidenschilling
Planetary Geology & Geophysics Program (NASA)
Turbulence and Planetesimal Formation
We investigate the formation of planetesimals in turbulent solar nebula environments, to determine whether turbulence can account for the discrepancy between coagulation timescales and the CAI-chondrule age difference inferred from meteoritic evidence. Numerical simulations of particle coagulation are used to establish the minimum level of collisional strength needed to grow bodies larger than meter size. The code is modified to include two populations of particles with different aerodynamic properties, e.g., compact CAIs and low-density dust aggregates. Their evolution is modeled, including competition between inward drift by gas drag and outward transport by turbulent diffusion.
Stuart Weidenschilling
Spitzer Guest Investigator Program - Cycle 3 (NASA)
Collisional Evolution of Circumstellar Debris Disks
A large number of circumstellar debris disks have been observed and characterized by Spitzer. The dust seen in these systems must be the product of collisions among larger parent bodies, which are not detected directly. We will constrain the properties of these bodies by collisional modeling, using a multi-zone code with realistic scaling of collisional outcomes. Dust production rates and depletion lifetimes will be computed for a selected set of debris disks having well-defined luminosities and radial extents, orbiting a variety of stellar types. The results will constrain the total mass of each disk and the sizes of the unseen parent bodies that are the source of the observed dust. The stochastic nature of the collisional code will allow us to estimate the likelihood that the observed dust abundance represents a steady state or a transient event due to a giant impact. The impact velocities (i.e., orbital eccentricities) required to match the observed dust production may allow us to infer the presence of planets in these systems.
Catherine Weitz
Mars Data Analysis Program (NASA)
Geologic Mapping of a Proposed Mars Science Laboratory Landing Site in Southwestern Melas Chasma
The objective of this proposal is to perform geologic analyses of southwestern Melas Chasma, which includes a proposed Mars Science Laboratory (MSL) landing site. We will produce a geologic map of the MSL landing ellipse region and also study features of interest in the terrain surrounding the landing site. Geologic analyses will be performed using multiple data sets (THEMIS, MOC, HRSC, CTX, HiRISE, OMEGA, CRISM, MOLA). The proposed MSL landing site ellipse is located on layered beds in a postulated paleolake in a basin along the wallrock in southwestern Melas Chasma. To the west of the landing ellipse are extensive Hesperian-aged valley networks and to the northwest is an unusual blocky deposit composed of light-toned layered deposits. Folded beds, sulfate deposits, and depositional fans are also features of interest within the study region. We expect to be able to infer information about the timing, duration, and nature of sedimentary and fluvial cycles and to some extent determine the climate environment in which those units were laid down. The fluvial landforms under investigation in this study are a record of the past, local environmental conditions on Mars and analyses of them is of fundamental importance to unraveling the history of water on Mars. Even if not selected as the MSL landing site, our study and mapping will provide important results about this fascinating region that will aid in interpreting the sedimentary and fluvial history of Mars. This work addresses the MDAP goal to broaden scientific participation in the analysis of mission data sets and areas of research that support planning for future Mars missions.
Catherine Weitz
Mars Data Analysis Program (NASA)
Distribution and Formation of Gray Hematite in Eastern Valles Marineris
This 2-yr proposal represents a continuation of prior work from a previous MDAP to study the distribution and formation of crystalline gray hematite in central Valles Marineris. The goal of the proposed investigation is to map out the distribution of gray hematite in Eos and Capri Chasmata in eastern Valles Marineris, identify geologic units associated with the hematite, and propose possible formation processes for the hematite. We will use several data sets, including TES, HiRISE, CTX, HRSC, MOC, THEMIS, OMEGA, and CRISM. The results of our study will determine if the gray hematite results from surface lags where hematite has been concentrated by erosion and wind or if the hematite is associated with specific layers of light-toned rocks or other geologic units. Completion of this work will enable us to provide a thorough analysis of hematite within Valles Marineris in combination with our completed work in central Valles Marineris. Comparison of our results to other locations on Mars with gray hematite will show what makes these particular locations on Mars sites for hematite formation and concentration. An improved understanding of the distribution and formation of gray hematite at Valles Marineris gained through stratigraphic, morphologic and mineralogic characterization has the potential to reveal important information about the fluvial and sedimentary history of Mars, which is of broad interest to the planetary science community. This work addresses the MDAP goal to broaden scientific participation in the analysis of mission data.
Catherine Weitz
Planetary Geology & Geophysics Program (NASA)
Geologic History of Light-Toned Layered Deposits at Valles Marineris
This proposal seeks to explore and characterize a range of different ages of light-toned layered deposits (LTLD) in and around Valles Marineris. We will focus on Oudemans Crater (old), select locations of LTLD within Valles Marineris (unknown ages), and LTLD on the plains adjacent to the troughs (young). We will use a variety of data sets to perform this investigation, including HiRISE, MOC, HRSC, CTX, THEMIS, CRISM, and OMEGA data sets to produce geologic maps and constrain compositions of the deposits. The scale and nature of bedding in the LTLD will be assessed in detail and used to evaluate and distinguish processes responsible for their emplacement. For over three decades, scientists have debated the origin and ages of the LTLD in Valles Marineris. We intend to use all available data sets from Mars to address these issues and hope to resolve them as well. The results of our study may show how deposition of the LTLD varied (if at all) with time, perhaps reflecting different climates or environmental conditions during the geologic history of Mars. We expect to be able to infer information about the timing, duration, and nature of major depositional cycles and to some extent determine the climate environment in which those units were laid down. Although focusing on specific locations may not capture the entire geologic history of Valles Marineris, it will provide a framework for deciphering some of the mysteries behind this vast landscape, especially in different geologic eras. An improved understanding of the LTLD at Valles Marineris through stratigraphic, morphologic and mineralogic characterization has the potential to reveal important information about the climate and sedimentary history of Mars.
Catherine Weitz
HiRISE Team (NASA)
Phase E HiRISE (High Resolution Imaging Science Experiment) for the Mars Reconnaissance Orbiter
The HiRISE science goals are to investigate a wide range of geologic and climatic processes, with emphasis on distinguishing between deposits and landforms resulting from aqueous, eolian, volcanic, or other processes. The instrument is optimized for these objectives and for the evaluation of landing sites. The camera will provide an unprecedented combination of spatial sampling (25.5 -32.0 cm/pixel) capable of detecting meter scale objects on the surface, signal-to-noise ratio (>100:1 at all latitudes), swath width (5 - 6.4 kilometers), color (1 - 1.3 kilometers swath at 25.5 - 32.0 cm/pixel sampling), and stereo coverage. The HiRISE science team is an integral part of HiRISE operations. Each Co-I will be responsible for a particular science theme and objective. That responsibility includes prioritization of target requests received from scientists external to the project, participation in observation planning ensuring theme scientific goals are achieved, a monthly rotation in sequence development, validation of data received, and leadership in papers, workshops, and presentations centered on their theme. Science themes identified for Co-I Weitz include (1) Sedimentary and Layering Processes and (2) Geologic Contacts and Stratigraphy.
Rebecca Williams
Mars Data Analysis Program (NASA)
Characterizing the Paleo-fluvial Environments of Fine-scale Martian Network Systems
Constraining the magnitude and time scales of past fluvial activity on the martian surface is important for achieving NASA's Mars Exploration Program strategy to "follow the water." Fine-scale, dense martian drainage networks have recently been recognized in Mars Orbiter Camera (MOC) and Thermal EMission Imaging System (THEMIS) images at multiple locations around the globe, with some of the best preserved examples in inverted relief. The diverse stratigraphic and geologic settings of these landforms enable a detailed spatial and temporal reconstruction of the martian paleo-fluvial history not previously obtainable. The proposed investigation seeks to quantitatively characterize these landforms, and building on empirical relations from terrestrial analogs, determine their depositional environment, paleohydrology and paleoclimate conditions. The specific approach is to document the fine-scale channel morphology and geologic setting. Estimates of paleo-discharge and simple landscape evolution models will be used to constrain the magnitude and time scale of fluvial activity in martian fine-scale channel networks at specific sites. The anticipated results of this study will have implications for the climate conditions suitable to sustain these fluvial systems, and how these conditions changed with time. This work will contribute to understanding the past distribution of fluvial water on Mars, and the processes by which such water has changed Mars' surface geology over its history. Thus, this work is directly relevant to Strategic Goal 3.3 from the Science Plan For NASA's Science Mission Directorate 2007-2016: "Advance scientific knowledge of the origin and history of the solar system, the potential for life elsewhere, and the hazards and resources present as humans explore space."
Rebecca Williams
Mars Fundamental Research Program (NASA)
Assessing the Preservation of Fluvial Pathways in the Terrestrial Geologic Record: Analogs for the Investigation of Martian Raised Channels
Constraining the magnitude and timescales of fluvial activity on the martian surface is important for achieving NASA's Mars Exploration Program broad goal to "follow the water." Some of the best preserved, fine-scale dense martian networks are in inverted relief. In order to accurately interpret the martian fluvial history preserved in these landforms, a better understanding based on terrestrial analogs is needed. We propose to use a Differential Global Positioning System (DGPS) to obtain precision topographic surveys of inverted channel networks in the United States and Australia. This data combined with sedimentary particle analysis in the field will enable the evaluation of multiple paleohydrology models. Through quantitative characterization of terrestrial analogs, this study seeks to identify the morphological attributes diagnostic of the paleofluvial environment.
Rebecca Williams
Mars Reconnaissance Orbiter Participating Scientist Program (NASA)
Fluvial Investigations Using Imagers Aboard Mars Reconnaissance Orbiter
Despite several decades of investigation, questions persist regarding the amount, duration and timing of fluvial activity on Mars. Recent discoveries of a variety of fine-scale fluvial landforms observed in high-resolution Mars Orbiter Camera (MOC) and Thermal Emission Imaging System (THEMIS) images contributes to our understanding of the extent of fluvial erosion on Mars. The proposed investigation seeks to capitalize on these observations through acquisition of new data from instruments aboard the Mars Reconnaissance Orbiter (MRO). The specific approach is to expand coverage at meter and sub-meter resolution with the High Resolution Imaging Science Experiment (HiRISE) and Context Camera (CTX) instruments through a focused image campaign of fluvial landforms including gullies, fans, and fine-scale channel networks. An improved understanding of these features through qualitative and quantitative characterization has the potential to reveal important information about the hydrological system on Mars, which is of general interest to the planetary science community as well as the field of astrobiology and the search for life on Mars. This investigation meets several of the scientific objectives of the MRO mission including the goal to search for evidence of aqueous activity and the desire to characterize in detail the geology and stratigraphy of Mars surface features. The proposed work is consistent with NASA’s Strategic Objectives (2005) to increase knowledge about destinations for future robotic or manned Mars mission. Water is the unifying theme of the Mars Exploration Program (MEP) of NASA, and an improved understanding of the past history of water on Mars directly supports present and future NASA objectives.
Rebecca Williams
Mars Odyssey Participating Scientist Program (NASA)
Morphological Investigations of Martian Fluvial Landforms with THEMIS
Despite several decades of investigation, questions persist regarding the amount, duration and timing of fluvial activity on Mars. Recent discoveries of a variety of fine-scale fluvial landforms observed in high-resolution Mars Orbiter Camera (MOC) and Thermal Emission Imaging System (THEMIS) images contributes to our understanding of the extent of fluvial erosion on Mars. The proposed investigation seeks to capitalize on the objectives of the Mars Odyssey extended mission to expand coverage of decameter-scale images with the THEMIS instrument through a focused image campaign of fluvial landforms including gullies, alluvial fans and fine-scale channel networks. An improved understanding of these features through qualitative and quantitative characterization has the potential to reveal important information about the hydrological system on Mars, which is of general interest to the planetary science community as well as the field of astrobiology and the search for life on Mars. The proposed work is consistent with NASA's Strategic Objectives (2005) to increase knowledge about destinations for future robotic or manned Mars mission. Water is the unifying theme of the Mars Exploration Program (MEP) of NASA, and an improved understanding of the past history of water on Mars directly supports present and future NASA objectives.
Charles Wood
NASA Cassini Mission
Cassini RADAR Team Participant
"The Cassini Radar (RADAR) will be used to investigate the surface of Saturn's moon Titan by taking four types of observations: imaging, altimetry, backscatter, and radiometry. In the imaging mode of operation, the RADAR instrument will bounce pulses of microwave energy off the surface of Titan from different incidence angles and record the time it takes the pulses to return to the spacecraft. These measurements, when converted to distances (by dividing by the speed of light), will allow the construction of visual images of the target surface. Radar will be used to image Titan because the moon's surface is hidden from optical view by a thick, cloud-infested atmosphere: radar can 'see' through such cloud cover." (http://saturn.jpl.nasa.gov/spacecraft/inst-cassini-radar-details.cfm)
