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this generally takes place quickly because researchers can apply for NASA funding to analyze the data only after it has been archived in PDS, Davis explained.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.
