Building a Home Away From Home for Martian Samples
Who on this planet hasn't wondered if life exists elsewhere? Will we ever know for sure? Researchers aim to get a little closer to an answer when they retrieve samples from Mars and examine them for, among other things, signs of life.
NASA, which has already devoted substantial resources to exploration of the Red Planet, is tentatively planning its first mission to collect samples for 2011, with soil, rocks, and other materials due to arrive on Earth as early as 2014. Although the probability is low that anything brought back will be hazardous to people or the terrestrial environment, there is still a chance that they could be, making it necessary to handle these specimens with extreme care.
After a six-month excursion through space, the first stop for these samples should be a facility capable of minimizing the possible contamination of Earth's environment and the specimens themselves, says a new report from the National Research Council. Samples would be housed and examined in quarantine before being sent off to various laboratories across the United States and abroad for more in-depth and specialized study.
But creating such a facility poses enormous technical challenges. Just as Earth's environment must be protected from potentially hazardous extraterrestrial ma-terials, martian samples also must be protected from terrestrial contaminants that might confuse the results of later scientific studies. These challenges call for a seemingly incompatible system of two-way protection to be set up. In fact, establishing such a system has never been attempted before. To protect Earth's environment, the samples must be "biologically contained." This involves storing them at lower-than-ambient air pressures so that air and its contaminants move toward the sample chamber and away from the surrounding environment. At the same time, clean room conditions will be needed to protect the samples from any contamination from the outside, requiring samples to be kept at greater-than-ambient air pressures so that air and its contaminants move away from the sample chamber.
One possible solution would be to nest the biological containment room -- where the samples would be located -- within the clean room -- where the researchers would conduct their work -- and separating the two areas by a double wall. Air would flow from both rooms to a low-pressure space between the double wall, where the air would be collected, sterilized, and discharged as exhaust. This and other potential solutions need to be developed and tested, and soon, the committee said.
The committee estimated that the design, construction, and testing of the facility will take at least seven years before it is ready and capable of handling specimens. And because samples are expected to begin arriving not long thereafter, it is imperative that the planning and construction begin quickly to allow adequate time to test and staff the facility in advance.
Moreover, to reduce costs and avoid needless complexity, only the most basic operations -- such as unpacking, weighing, taking photos, splitting, repacking, and storing the martian samples -- should be conducted at the quarantine facility, the committee said. As a fundamental precaution, all of the samples should be treated as though they contain dangerous microorganisms or other hazardous materials until preliminary examinations are performed. If unmistakable signs of life are found, the specimens should not be released until an expert panel of scientists is convened to discuss in detail how to deal with them. If possible signs of life are present, the specimens should be sterilized by heat or radiation before being shipped out for biological study. And if no life is found, specimens could then be sent to specialized labs for further study. -- Mark Chesnek & Jennifer Wenger
The Quarantine and Certification of Martian Samples. Committee on Planetary and Lunar Exploration, Space Studies Board, Division on Engineering and Physical Sciences (2001, 132 pp.; ISBN 0-309-07571-8; available from National Academy Press, tel. 1-800-624-6242; $30.00 plus $4.50 shipping for single copies).
The committee was chaired by John A. Wood, senior scientist, Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass. The study was sponsored by NASA.