Report recommends quarantine of Mars samples

Posted: May 30, 2001

John Wood speaks to American Geophysical Union spring meeting in Boston on Tuesday. Photo: Jeff Foust
BOSTON, Mass. - A report released Tuesday urges NASA to begin planning a system to quarantine Martian samples even through missions to return such samples are at least a decade in the future.

The report "The Quarantine and Certification of Mars Samples", by the National Research Council's Committee on Planetary and Lunar Exploration (COMPLEX), expanded on a 1997 report that recommended creating a quarantine system to protect from the chance, however small, that Martian organisms could infect the Earth.

"Building this type of quarantine facility is a project of enormous complexity," said John Wood, chairman of COMPLEX and staff scientist at the Harvard-Smithsonian Center for Astrophysics. "We strongly recommend that this process get underway as soon as possible."

The committee's report recommended that the quarantine facility be similar to Biosafety Laboratory Level 4 (BSL-4) facilities that currently exist to deal with dangerous terrestrial organisms such as the Ebola virus. Planning and building BSL-4 facilities, like those at the Centers for Disease Control in Atlanta and a U.S. Army base in Maryland, can take at least seven years. The report noted that such a facility should be up and running for at least two years before launching a sample return mission, which NASA plans for no sooner that 2011.

"Because many questions will still need to be resolved before design and construction can even begin, it is essential for work to commence as soon as possible in order for the facility to be ready in time for the first samples' return," Wood said. "This is the strongest point our report tries to make."

One of the unresolved questions is how to not only prevent contamination of the terrestrial environment by any Martian organisms, but to keep the terrestrial environment away from the Martian sample. BSL-4 facilities keep samples in containers with low air pressure, so that any leak in the containment will keep contaminated air from leaking out. However, such a system would allow the terrestrial environment to leak in, contaminating the sample.

Other than the requirement to keep the Mars sample away from the environment, the committee recommended that such a containment facility be as simple as possible. They noted that the Lunar Receiving Laboratory (LRL), a NASA facility established to handle samples returned from the Apollo missions, attempted to duplicate the lunar environment to the point of storing samples in a vacuum chamber. "The vacuum chamber caused great difficulty in the preparation and use of the LRL, and it turned out to be unnecessary," Wood said.

One type of BSL-4 laboratory at U.S. Army Medical Research Institute for Infectious Diseases (USAMRIID). Here the potentially infectious agents are enclosed in a tightly sealed chamber. Courtesy of Steve Ferando, USAMRIID
Working in such a containment facility will likely be difficult in any case based on experience with existing BSL-4 labs, where technicians have to wear "spacesuits" that protect them from exposure to hazardous organisms but are tiring to use. The committee concluded that the containment center do only the bare minimum of work on the samples, including testing for life, and let more detailed studies be performed elsewhere.

How the samples are transferred to other labs for those studies will depend on the results of tests for biological activity. If the tests show no sign of past or present life, including a lack of any organic material, the samples can be sent elsewhere without any additional preventative measures. However, if definitive proof of life was found, the samples would likely remain in the quarantine facility until a larger, more elaborate containment facility is ready to accept the samples for additional testing.

The most likely case, the committee concluded, is that there is no conclusive evidence for or against life in the sample. In that case, the committee recommended that the samples be sterilized‹through exposure to heat, solvents, or gamma rays‹before releasing them for additional study. Additional work is needed, the report noted, to determine the most effective way to sterilize samples without reducing their scientific usefulness.

The complexity of the samples and disagreement among researchers makes this ambiguous case the most likely. "In the climate of desire to find life in the samples, workers examining them will be reluctant to declare them unmistakably barren of viable entities, organic matter or structures that might be fossils," the report noted. "There will be ample latitude for disagreement among workers as to the biological significance of the observations made."

Wood noted that there is still disagreement whether Martian meteorite ALH84001 contains evidence of past Martian life, nearly five years after the original studies of the meteorite were published. "It was that example that led us to recommend that you shouldn't wait for everyone to be satisfied with the answer, that there should be ways to sterilize samples and let them out so that people can be studying them instead of just sitting on it," he said.

The cost of building such a containment facility was not addressed in the report, but Wood estimated it would cost "a small fraction" of the estimated billion-dollar cost of the sample return mission, possibly on the order of $20-50 million. The report recommends co-locating the quarantine lab with an existing BSL-4 facility to share resources and speed up the process of getting the necessary approvals to build the lab, but that the facility should be operated and funded by NASA.

The report attempts to find a middle ground between critics on either side of the planetary protection issue. Some, such as the International Committee Against Mars Sample Return (ICAMSR), argue that many more missions to study any Martian life should be mounted before any samples are returned. They also believe that any samples that are eventually returned should be first studied in an Earth-orbiting lab, such as the International Space Station, before sending them down to the surface. Wood said that a space-based quarantine center, while a popular idea, would be too difficult to operate in microgravity conditions to make it worthwhile.

At the other extreme are people like Mars Society founder Robert Zubrin, who have argued that the Martian surface is hostile to any known form of life. Moreover, even if there was life on the Martian surface, it would have already been transported to Earth via meteorites like ALH84001, with no apparent ill effects.

Wood acknowledged that the apparent lack of problems arising from past Martian meteorite impacts makes their job easier, but does not entirely eliminate the need for a containment facility. "If Earth has survived this involuntary sample return all this time, maybe there's not anything to worry about," he said. "But we're not so sure of that that we're going to dispense with the idea of a quarantine facility."

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