From: University of Arizona
Posted: Thursday, June 28, 2001
If there is an area of science where extreme creativity is needed, it is in planetary exploration, where the logistics are difficult, the unknowns are great and the costs are high. Perhaps for that reason, NASA has taken the exciting step of soliciting innovative, purely conceptual proposals for Mars exploration from the science community and then funding a select group to develop the concepts further.
On June 13, the agency announced that it was funding ten "promising mission concepts" for its new Mars Scout Program with six-month planning grants of up to $150,000 each to further develop the proposals. The Mars Scout Program plans to mount at least one (and perhaps several) Scout missions to Mars beginning in 2007, with budgets of up to $300 million per mission.
"In order to get to the point where there would be a lot of interesting proposals for the scout missions, NASA wanted to solicit ideas and help people bring those ideas from the 'kernel of knowledge stage' to the stage where they could be technically developed enough to be really proposed for a mission," explained Arizona State University geologist and cosmochemist Laurie Leshin, who is principal investigator for one of the selected concepts. "We are in the pre-Scout Mission Proposal stage."
The selected proposals are all highly creative approaches to answering important science questions about the planet. For example, Leshin and her team are proposing SCIM ("Sample Collection for Investigation of Mars"), a mission that would do a hit-and-run with the dusty Martian atmosphere. The proposed mission would perform the first return of a Martian sample at less cost, lower risk and in a shorter time frame than the far more complicated missions that will eventually be launched to collect samples from the planet's surface.
The proposal calls for a spacecraft to make a "high pass" of Mars, going within 25 miles of the planet's surface and to collect samples from the Martian atmosphere for about one minute at about 12,300 miles per hour, before swinging back and beginning the return to earth. On the spacecraft, a light-weight and porous high-tech substance known as "aerogel" would cushion, trap and preserve dust particles. The aerogel collection device is similar to the device on the Stardust mission to collect dust streaming off of a comet.
Leshin projects that the aerogel would capture about 1000 fine dust particles measuring 10 microns (1/100 of a millimeter) or larger.
Why expend so much effort and money for such a tiny amount of dust?
"Martian dust is an interesting thing because there is dust all over the Martian surface," said Leshin. "It's the ubiquitous layer -- it's everywhere, yet we really know very little about it. It samples virtually the whole planet, yet it is so fine-grained that it is very hard to study when you're sitting there on the surface. You really need to bring it back to Earth to characterize it grain by grain. And each grain is like a little rock from Mars."
The thousand or so "Mars rocks" contained in the sample will yield nearly as much information as larger surface samples, and in some cases provide information larger rocks cannot. "Because it's so fine-grained, this dust is an extremely sensitive indicator of Martian environmental conditions. If there's been water on the Martian surface, it's this fine-grained stuff that's going to have been altered by that. Studying this dust is key to following the water on Mars," Leshin said.
"And, with modern techniques in an Earth-based laboratory, we're capable of slicing each grain into different sized bits and sending them off to five different labs to analyze. You can bring a whole cadre of analytical tools to bear on a single 10-micron particle. You can learn a lot from things this small," she said.
Beyond the relative simplicity of the mission's logistics when compared with a surface sample return mission (which would also have to land on the planet, collect and store samples, launch from the planet, and dock with a return vehicle in orbit), SCIM would also be useful as a precursor and dry-run for the later mission, giving mission planners valuable advance geological information and testing some critical procedures for a sample return from another planet. Of particular concern are procedures for biological containment, which could be tested, but are not critical with the samples that SCIM would collect.
Leshin points out that while the surface of Mars is a very harsh environment for life, the planet's very thin atmosphere would be even worse, with extreme temperatures and extreme exposure to ultraviolet light and other lethal radiation. "Secondly," Leshin said, "the dust gets heated up as it gets collected to a level that living things could not survive. It is our opinion that this sample is probably about the most benign thing you could bring back from Mars.
"What we would bring back could tell us a lot about water and the geology of the planet though, which are critical things in the search for possible life," she said.
In addition to Leshin, the SCIM team includes Albert Yen, Amy Jurewicz and Steven Jones from the Jet Propulsion Laboratory in Pasadena, CA; Benton Clark and Terry Gamber from Lockheed Martin Astronautics in Denver, CO, the lead spacecraft contractor; Larry Forney from Georgia Tech; Mark Richardson from Caltech; Thomas Sharp from ASU; Mark Thiemens from University of California at Sand Diego; and Michael Zolensky from NASA's Johnson Space Center.
While it is by no means certain that SCIM will advance in the final competition for proposals planned for next year, Leshin is excited by the opportunity to develop the proposal further and enthusiastic about the concept's potential: "SCIM would give us a chance to test the procedures and to validate the concept of going to Mars and coming back to Earth. It would give us a chance to characterize some of the fundamental Martian surface materials, and a chance to practice handling those materials on a benign sample. Further, the human exploration people are really, really interested in this dust, because you need to know about it to design many aspects of an eventual human mission to Mars," she said.
For more information about Mars Scout missions and a list of all ten concepts selected, see the NASA announcement at: http://www.jpl.nasa.gov/releases/2001/marsscout.html
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