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The twin Viking spacecraft landed on Mars in 1976. They were cleaned to a level required to explore habitable regions.


NASA planetary protection officer suggests loosening limits on exploring Mars for life

Is there life on the surface of Mars? The clock is ticking on scientists’ window to solve that long-standing question before astronauts—and the microbes that live on them—contaminate the planet. Today, at a meeting in Washington, D.C., of NASA’s planetary science advisory committee, the agency’s new planetary protection officer raised the possibility of opening up a few of the planet’s most promising regions to more aggressive exploration.

Just a few weeks into the job, Lisa Pratt, formerly a geomicrobiologist at Indiana University in Bloomington, has signaled that she wants the office to be open to the notion that a degree of contamination might be necessary to explore several of the planet’s most habitable spots. Previously, the office has served as a watchdog to prevent the contamination of Mars and other planets with microbes from Earth, and vice versa. But now, time is pressing, given NASA’s long-term goals, Pratt says. “No matter what we do, the minute we’ve got humans in the area we’ve got a less pristine, less clean state,” Pratt said at the meeting. “Let’s hope we know before the humans get there, one way or the other, if there is an ecosystem at or near the surface.”

Although no region of Mars is banned for exploration, international treaties set the allowable levels of microbial contamination on robotic spacecraft destined for other planetary environments. Some scientists say it is too costly to meet the sterilization requirements to explore the potentially warm and wet “special regions” on Mars that are most likely to harbor microbes. Only the 1970s Viking landers achieved the cleanliness necessary to explore a special region. A growing number of scientists have argued that the agency needs to rethink its plans, as Science reported last year.

Late last year, longtime Planetary Protection Officer Cassie Conley, who favored strict enforcement standards, left NASA after an agency reorganization forced her to reapply for her job. Some Mars scientists hoped that a new officer could start a fresh conversation. Pratt, who led the Mars Exploration Analysis Group from 2013 to 2016, seems to be open to one. The likelihood of human exploration, she said at the meeting, “forces us to begin—and it’s already happening—an international conversation.”  

“How do we designate,” she continued, “a few, a very small number, but a few special places on Mars [where] we can get in now with rovers and landers and do a better job asking and addressing questions of—is there present-day near-surface life on Mars? We can’t just declare every interesting place off the table. Because that means the first time we’ll know anything is when we’ve got humans there.”

It remains to be seen how Pratt’s views could translate into NASA policies. Her position exists because of international treaties; any modification would likely require international agreement. The topic will likely come up in July at a meeting of the Committee on Space Research, the international body that develops planetary protection policies. And it could face opposition from researchers like John Rummel, a biologist at the SETI Institute in Champlain, New York, who led the protection office before Conley. “I would advocate for noncontamination of special regions, of course,” Rummel says. He also suggests that Pratt learn a bit more about the cleanliness standards before mulling any changes. “She is pretty careful, but still new to the job,” he adds.

However, even hint of openness is welcome news for Alberto Fairén, a planetary scientist at Cornell University who last year called for reducing cleanliness requirements in potential special regions and drew a sharp rebuke from Conley and Rummel. “It is really nice hearing that the new [planetary protection officer] starts her tenure with NASA announcing what can only be interpreted as the inception of a very interesting and most needed change in the Mars planetary protection philosophy thus far,” he says. Pratt’s statements, he adds, are exactly what he was advocating for, “no more and no less.”

In the meantime, the Office of Planetary Protection is continuing with its duties as always, having given its blessing to the Mars Insight lander, due for launch in May. And it continues to take a close look at how the Mars 2020 rover will avoid contaminating the rock samples it collects. But the office will also develop modern techniques for assessing microbial burdens, and it will seek a less confrontational relationship with the NASA centers, Pratt added. “We have to do it in a way that we assist the missions and don’t look like we’re some kind of sheriff’s department that is constantly coming down.”