SCIENCE TEAM SAYS GIANT METEORITE, NOT VOLCANOES, KILLED DINOSAURS
March 4, 2010 - A team of scientists, including Elisabetta Pierazzo, a senior scientist at the Tucson-based Planetary Science Institute, has concluded that a giant meteorite impact is still the best explanation for the disappearance of dinosaurs and many other species 65.5 million years ago.
The 41 scientists, from Europe, Mexico, Canada, Japan and the United States, published their results today in the highly respected scientific journal Science, concluding that alternative hypotheses are inadequate in explaining the abrupt mass extinction at the end of the Cretaceous period.
Scientists refer to this point in the geologic record as the K/Pg boundary, and attribute it to extreme climate change caused by the Chicxulub (Chick-shuh-loob) meteorite impact.
Pierazzo, who began modeling the impact as a Ph.D. student, was the first scientist to develop high-resolution, 3-D simulations of the Chicxulub event as an oblique impact. This work was done in collaboration with David Crawford, of Sandia National Laboratory. The results clearly showed that the effects on Earth's climate were even more dramatic than had been previously hypothesized. The simulation showed huge amounts of sulfur oxides were ejected into the upper atmosphere, drastically altering the Earth's climate.
However, some scientists have disputed the Chicxulub hypothesis, attributing the climate change and mass extinctions to volcanic activity in the Deccan Traps, an area on the Indian subcontinent. They theorize that global cooling and acid rain resulting from this volcanic activity were the major cause of mass extinctions, not the Chicxulub impact in Mexico.
"Large amounts of sulfur oxides were injected into the atmosphere during the Deccan volcanism," Pierazzo said. "But they were distributed in several pulses that extended over several hundred thousand years before - and after - the K/Pg boundary. Yet, the major, large biotic changes at the end of the Cretaceous era appear to have happened abruptly and exactly at the K/Pg boundary, when Chicxulub hit."
Marine and terrestrial ecosystems showed only minor changes during the 500,000 years leading up to the K/Pg boundary, the researchers conclude in the Science article. But an abrupt and major decrease in the mass of living things and species diversity occurs precisely at the boundary.
This data, along with new data derived from ocean drilling samples and continental sites, as well as reanalysis of previous K/Pg boundary studies, leads the research team to conclude that the Chicxulub impact hypothesis has grown stronger than ever.
"Combining all available data from different science disciplines led us to conclude that a large asteroid impact 65 million years ago in modern-day Mexico was the major cause of the mass extinctions," says Peter Schulte, assistant professor at the University of Erlangen in Germany and lead author of the review paper.
According to analysis of the Chicxulub crater in Yucatan, Mexico and other data from the geologic record, scientists conclude that the meteorite was between 10 and 15 kilometers in diameter and hit Earth at a speed 20 times faster than a rifle bullet. The resulting explosion was a billion times larger than the Hiroshima atomic bomb and a million times larger than the biggest nuclear bomb ever tested.
NASA Awards PSI $750,000 to Help Teachers Improve Science Education
Feb. 18, 2010 - The Tucson-based Planetary Science Institute has received a $750,000 NASA grant to help teachers improve science education. The grant will fund professional development workshops and creation of teaching resources for elementary and middle school teachers in Arizona, Texas and Wisconsin.
PSI scientists are collaborating on the project with the Tucson Regional Science Center, a partnership of three independent school districts and several charter schools that is led by Tucson Unified School District. The RSC supports member districts with nationally recognized instructional kits that include books, readers, teachers' guides and other materials that support science curricula.
"This collaboration will lead to further opportunities to engage teachers and students in space science, and will increase innovative and effective educational efforts to apply real-life applications to how we learn science," said RSC Coordinator Joan Gilbert.
Recent budget cuts to education have reduced or eliminated many professional development opportunities in Arizona, which makes the PSI workshops even more important, said Larry Lebofsky, a PSI senior education specialist.
"Our workshops give teachers the credit hours they need to renew teaching certificates, as required by the State of Arizona," Lebofsky said. "The workshops also provide teachers with experience and knowledge that will help them pass the AEPA (Arizona Educator Proficiency Assessments) Middle Grades General Science Test. This test is a state requirement for those who teach science at the middle-school level."
Materials developed through the grant also will be used to enhance science education in Texas and Wisconsin, where some of PSI's scientists are located, said David Crown, PSI assistant director and principal investigator on the project. PSI includes researchers in 15 states, the United Kingdom, France, Switzerland, Russia and Australia. "PSI's distributed nature makes it possible for us to easily expand our programs and provide resources to many other communities" Crown said.
He noted that NASA received 103 proposals for its newly created program -- Opportunities in Education and Public Outreach for Earth and Space Science -- and PSI's proposal was among the 28 selected.
Crown said the funding will allow PSI to:
- Offer a series of professional development workshops that target elementary and middle school teachers in the Tucson area.
- Create a series of instructional rock kits to be used in the workshops and that teachers can take to their classrooms.
- Generate materials, including scientific visualizations and web-based virtual tours of planetary surfaces, to teach key concepts in earth and space science.
- Establish a web-based "Ask-An-Expert" site where students, teachers, and the public can directly interact with PSI scientists.
The grant will help PSI to further develop and expand the NASA-supported teacher workshops (www.psi.edu/epo/papt) it has been conducting since September 2008. So far, 57 science teachers from 42 schools in Tucson have attended six offerings of three different workshops in the "Planets are Places Too" series: "Moon- Earth System," "Exploring the Terrestrial Planets," and "Impact Cratering." Teachers who attended the workshops teach approximately 3,600 students in grades 1 through 9.
"Most elementary school teachers have limited backgrounds and training in the sciences" said Thea Cañizo, a PSI education support specialist. "These workshops help teachers gain knowledge about astronomy, geology, and planetary science. They participate in hands-on exercises using images, maps, and the results from their own experiments, modeling the processes and skills scientists use. They can then take this knowledge of how science is conducted into their classrooms with greater confidence in their ability to teach science."
Teachers who have attended the workshops cite hands-on activities, learning the scientific process, and interaction with scientists as the top three benefits, Lebofsky said.
Marguerite Samples, a teacher at Tucson's Dunham elementary school said, "Recently I took a class offered at PSI and was thrilled with my experience. Not only did I gain insight about Mars and our neighboring planets, but I discovered a new resource that I can tap into to enrich the minds of my students. Besides offering classes to teachers, PSI has wonderful resources you can bring into the classroom and guest speakers who can come and talk with students."
"It was a great experience and I am excited to see what other classes they have to offer," she said.
In addition to principal investigator David Crown, the project team includes PSI educators Lebofsky, Cañizo, Sanlyn Buxner and Steven Croft, as well as PSI scientists Alice Baldridge, Les Bleamaster, Frank Chuang, Steve Kortenkamp, Elisabetta Pierazzo, and Aileen Yingst. Others involved in the project include Steven Anderson, director of the University of Northern Colorado's Mathematics and Science Teaching Institute, and Christopher Andersen and Bill Schmitt of the Science Center of Inquiry.
Teachers work with a radionuclide decay chart during one of PSI's "Planets Are Places, Too" workshops.
PSI Scientist Describes Wind-Driven Rovers in Chapter of New Mars Book
Jan. 11, 2010 - Wind-driven research platforms that could roll like tumbleweeds across the surface of Mars are the subject of a 38-page book chapter written by Kim Kuhlman and her colleagues.
Kuhlman, a senior scientist with the Tucson-based Planetary Science Institute, is the lead author on "Tumbleweed: A New Paradigm for Surveying the Surface of Mars for In-situ Resources." The chapter appears in "Mars: Prospective Energy and Materials Resources," published today by Springer Publishing Co.
Tumbleweeds are lightweight, inexpensive vehicles that can carry a variety of instruments and cover large swaths of terrain as winds push them across the landscape. They are designed to bridge the gap between large-scale surveys done by orbital platforms and intensive, small-scale research conducted by rovers, Kuhlman said.
The vehicles, some of which resemble beach balls on steroids, are based on well-developed and tested technology, Kuhlman added.
An inflatable Tumbleweed was tested in Greenland in 2003 and in Antarctica in 2004 by the Jet Propulsion Laboratory. The latest version, deployed in Greenland in 2004, covered more than 200km across an ice sheet on a four-day run. During that time, it communicated via the Iridium satellite network to a ground station at the JPL. The Tumbleweed gathered data on temperature, pressure, and its GPS location.
Since Tumbleweeds are light and relatively inexpensive, several could fly on one mission, and they could hitch rides on larger missions, she noted.
Other scientists who contributed to the chapter include: Alberto Behar, Jack Jones, Max Coleman and Daniel W. Wilson, of the Jet Propulsion Laboratory; Penelope Boston, of New Mexico Tech; Jeffrey Antol, Gregory Hajos and Warren Kelliher, of NASA Langley Research Center; Ronald Crawford, of the University of Idaho; Lynn Rothschild, of the NASA-Ames Research Center; Martin Buehler, of Decagon Devices; and Greg Bearman, of Snapshot Spectra.
The Jet Propulsion Laboratory's six-foot tumbleweed rover took a seven- day, 80-mile journey across Antarctica in 2004. Credit: NASA
PSI Receives $2.5 Million NASA Grant to Archive Asteroid and Dust Data
Jan. 5, 2010 - The Tucson-based Planetary Science Institute has received a NASA grant of nearly $2.5 million to continue archiving data relating to asteroids and space dust.
PSI has been part of NASA's Planetary Data System (PDS) effort to preserve, organize and make mission data available to the scientific community since the PDS was formed in the early 1990s.
The grant, which runs for five years, will fund PSI work on the Asteroid/Dust Subnode of the PDS Small Bodies Node, said Donald R. Davis, a PSI senior scientist who is the principal investigator on the project. The Small Bodies Node is one of a half dozen groups in PDS, and each group includes additional Subnodes, such as the one administered by PSI.
"NASA established PDS as a long-term archive for data collected on planetary missions," Davis explained. "NASA's Planetary Science Division spends more than a billion dollars each year to acquire data, and the PDS is the primary way in which this data is made available to the scientific community, both for immediate analysis and for future use."
There's a lot more to archiving than simply tossing data into a computer file and noting where it is, Davis explained. Data must be archived in a way that makes it easy to retrieve and scientifically useful.
"We make sure the data is well described so that scientists ten, 15 or even 50 years from now can understand how it was taken, the instrument used, the spacecraft and the mission objectives," Davis said. "All of this has to be adequately described and documented. Without this background, a bunch of tables, numbers or images are much less useful. We also include published papers that are based on a particular dataset."
PSI has developed an On-Line Archiving Facility (OLAF) that guides mission scientists in preparing their datasets for inclusion in the Asteroid/Dust Subnode. The data and its accompanying support material is then peer reviewed and any weaknesses in the dataset are referred back to the researcher or researchers for further clarification before the data is added to the archive.
All this generally takes place quickly because researchers can apply for NASA funding to analyze the data only after it has been archived in PDS, Davis explained. "So it's important that the data gets in, gets validated and gets peer reviewed in a timely manner," he said.
PSI also is developing a Data Ferret that will make it much easier for a scientist to sift through the increasingly voluminous holdings in the Asteroid/Dust Subnode to find what he or she is looking for.
This tool, which should be operational sometime in 2010, will allow a scientist to query the archive using standard scientific terms, rather than computer-specific terminology. The Data Ferret will then search through the holdings and return a list of datasets, which the scientist can ask the Data Ferret to further sift and refine.
The Small Bodies Group also includes ground-based observations in the archive to make it even more useful, Davis said. "A mission can tell you an awful lot about a single body, but you really want to be able to extrapolate that to the entire population of thousands of comets, millions of asteroids, and endless amounts of space dust," he said. "We're really interested in populations, not just individuals visited by missions, and the larger datasets in small bodies are taken primarily by ground-based observations."
The group also is including data gathered by amateur astronomers, who have the knowledge and sophisticated equipment -- CCDs and half-meter class telescopes, for instance -- to do professional quality work. Nearly all the data on asteroid light curves, for instance, is now collected by amateur astronomers, Davis noted.
All of this effort to preserve data in a scientifically useful archive will be as important in the future as it is now. "After all, there is no use-by date on scientific data, and researchers frequently want to re-examine old data as new theories and data analysis techniques are developed," Davis explained.
Reprocessing data with modern data-reduction techniques can lead to new discoveries, he noted. In addition, comparing current observations with previous ones identifies changes that have occurred, which gives scientists new insights into processes working on solar system bodies.
Fifty years from now, this data will form a priceless archive to help future generations in their quest to understand the solar system and their place in it, Davis said.
The Planetary Science Institute is a private, nonprofit corporation founded in 1972 and dedicated to solar system exploration. It is headquartered in Tucson, Arizona.
PSI scientists are involved in numerous NASA and international missions, the study of Mars and other planets, the Moon, asteroids, comets, interplanetary dust, impact physics, the origin of the solar system, extra-solar planet formation, dynamics, the rise of life, and other areas of research. They conduct fieldwork in North America, Australia and Africa. They also are actively involved in science education and public outreach through school programs, children's books, popular science books and art.
The Institute's researchers are based in 15 states, the United Kingdom, France, Russia, Switzerland and Australia.