The Mars Science Laboratory rover gets the clean-room treatment. (NASA/JPL-Caltech)After completing its mission, a satellite re-enters the Earth’s atmosphere and lands, kicking up a cloud of dust in the American southwest. The recovery team mobilizes, but when they begin to inspect the spacecraft, things start to go horribly wrong. Team members suddenly collapse, dead, and it soon becomes clear that the entire population of the nearest town has suffered a similar fate.
Michael Crichton completionists will recognize the above scenario as the plot of the 1969 thriller The Andromeda Strain, but to a select group of scientists and engineers, it represents a real – if remote – possibility of harmful interplanetary contamination. That’s right, all that lies between you and this horror story is NASA’s Planetary Protection Office (PPO), with its understated motto to keep watch over “all of the planets, all of the time.”
Planetary protection deals with both sides of the interplanetary coin: it must prevent the transfer of Earth-based life to other celestial bodies (known as forward-contamination, which would complicate the detection of any native biology), and avoid the introduction of any extraterrestrial biota to life on this planet (back-contamination).
To the more sober-minded members of the public, planetary protection seems foolhardy at best and wasteful at worst: after all, both forward- and back-contamination of sites like Mars has almost certainly already happened.
The protocol for sterilizing the Viking Landers involved cooking the spacecraft to 111.7 degrees Celsius for 30 hours, and the team searched for potential contaminants by trying to culture microbes in pre-defined nutrient mixes. What 1970s scientists didn’t realize is that some organisms can survive such high temperatures, and the tests for survivors may have missed the hardiest microbes. Dr. Moogega Cooper, a planetary protection engineer at JPL, believes the dependence on culturing is a problem. “It is a well known fact that only 1% of microbes can be grown on culture media,” she notes. “Using our culture-based methods may not be enough in my opinion to effectively assess how much contamination we are transporting to other solar bodies.”
In the case of back-contamination, about 40 kilograms of Mars snows down on Earth every year, mostly as micrometeorites, slipping in under the PPO’s radar.
Of course, none of this means we shouldn’t seek to limit contamination in the future, and NASA’s Planetary Protection team thinks about their directive in terms of probabilities and risk-benefit analyses. In general, risk can be evaluated as a balance between the likelihood of a negative event happening and the severity of that event. Back-contamination of planet Earth presents an extremely low risk, but the seriousness of that risk – an interplanetary pandemic – is extremely high. Given this calculus, it’s worth investing in safeguards for all of the samples we can control.
Dr. John Rummel, a Professor of Biology at East Carolina University, is the author of NASA’s draft protocol for handling martian samples, written during a fit of budgetary optimism in 2002. (Reading from a slide during last week’s Conference on Life Detection in Extraterrestrial Samples, Rummel referred to a mission plan that would “return no earlier than 2011. So far so good,” he quipped, sardonically acknowledging the endless delays that have characterized the elusive sample return mission.)
The protocol calls for sterilization by heat and gamma irradiation in proportions that would kill any viable organisms but leave geochemical traits – like isotopic ratios, elemental compositions, or crystal structures – unchanged. High radiation doses or high temperatures can irreversibly alter rock samples, but using moderate radiation levels at elevated temperatures allows you to combine the killing power of both without the deleterious effects of either.
The Planetary Protection team would be the first line of defense against potential biological contaminants, but it would also be the first – and possibly only – team to study pristine martian samples, a fact that irks some scientists. After all, the thinking goes, sterilization would destroy any primary evidence of viable cells, obscuring critical information from the most valuable cargo to ever be acquired from an interplanetary mission.
What much of the scientific community is overlooking is that both planetary protection officers and scientists have the same overall goal: to find and describe any biological organisms that may be inside martian rocks. Secondary motivations aren’t quite as synergistic, but scientists and the PPO must find workable compromises. Determining which instruments to include in the quarantined laboratories, developing sterilization techniques that are minimally destructive, and establishing a workflow that follows the “first life detection, then biohazard analysis” mantra are all important opportunities to bring the two groups together. Such coordination would improve everyone’s ability to do his job, maximizing scientific yield and minimizing the risk of an Andromeda Strain reality show.
Jeff Marlow is a graduate student in Geological and Planetary Sciences at the California Institute of Technology where he studies exotic microbial metabolisms in an attempt to understand the limits of life on Earth and beyond.
The Commodity Futures Trading Commission will hold a public roundtable next week to discuss policy changes, including a plan that would allow customers to trade through futures brokerage firms without keeping their excess cash there, according to a copy of the agenda provided to The New York Times. The plan, which would allow customers to keep their cash at clearinghouses rather than brokerage firms, is gaining support in pockets of the regulatory world. The commission is also circulating an internal list of more than 10 other ideas, including keeping customers updated on the whereabouts of their money and creating an insurance fund to backstop losses in customer accounts. People close to the agency cautioned that the list was preliminary and could be whittled down. The agency, the people said, might issue a release in the coming weeks that outlines a few favored policy options. A few new rules were already under way before MF Global [MF.F Loading... () 
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