Mars true-color globe showing Terra Meridiani.
Credits: NASA/Greg Shirah


There’s a biological battle brewing involving life on Mars, decades-old Viking Mars data, projected return to Earth of Martian samples, as well as future robotic looks for life on ocean-worlds.

At the nexus of the debate is whether or not planetary protection rules are stifling our exploratory space missions.

Loosen restrictions?

For example, in the August 11 issue of Science, staff writer Paul Voosen wrote about the fear of microbial taint that curbs Mars explorers.

Look, but do not touch? NASA’s Curiosity rover is on the prowl within Gale Crater/Mt. Sharp area that appears to have Recurring Slope Lineae (RSL).
Credit: NASA/JPL-Caltech

In summary, the Science story explains: “In the coming years, NASA’s Curiosity rover will pass rocks on Mars that, seen from orbit, seem to host mysteriously intermittent dark streaks – perhaps marking seasonal water seeps that could host martian life. But NASA’s planetary protection office, charged with keeping earthly microbes from colonizing other bodies, has said it may nix a visit. It fears that Curiosity could contaminate this so-called special region because the rover was not fully sterilized before launch.”

The Science article summary explains that “many planetary scientists, however, believe that now is the time to loosen restrictions on visiting these areas, before human exploration contaminates the planet. And, after years of stasis, the planetary protection office seems primed for a shakeup, thanks to an internal move and potential change in leadership, along with outside review of its policies by independent scientists.”

NASA’s two Viking landers were designed and built by Martin Marietta (now Lockheed Martin) at its facility near Denver. This image shows some Martin Marietta employees in a Viking lander test center.
Credit: Lockheed Martin

Upcoming article

Stepping into the astrobiological discussion is an upcoming commentary next week in the journal Astrobiology by Alberto G. Fairén, a visiting scientist at Cornell University. It reportedly questions the Committee on Space Research (COSPAR)-imposed and NASA-accepted requirement for sterilization of spacecraft landing on Mars.

That prospect and the Science article has stirred up the International Committee Against Mars Sample Return (ICAMSR), issuing an August 20 statement titled: “Veteran Astrobiologists Criticize Article Calling for Relief of Anti-Contamination Requirements for the Return Mars Sample Mission.”

This retort is led by Gilbert Levin, experimenter on the Viking Labeled Release Life Detection Experiment – one experiment among a package of devices that landed on Mars in 1976 via two Viking landers. Levin is now an adjunct professor at Arizona State University.


Strong evidence for Mars life?

“The contention is made that the extreme unlikeliness that Earth microorganisms could survive on Mars makes spacecraft sterilization unnecessary, and imposes a high cost on such missions,” the ICAMSR statement explains.

It continues, noting that the Science magazine article points to the Viking Mars landers as an example of the high cost of spacecraft sterilization.

That article “neglects to say that the Viking Labeled Release (LR) experiment found strong evidence for extant microbial life on the surface of Mars,” the ICAMSR statement points out. “The results were not accepted by NASA, because Viking failed to find organic matter in the Martian material…and in the 41 years since Viking, NASA has rejected all proposals for further life detection experiments to confirm or deny the LR findings. Moreover, none of the attempts to duplicate the LR results has succeeded.”

Loaded to the brim with samples, a robotic Mars Ascent Vehicle rockets off the planet under the watchful eye of an accompanying mini-rover.
Credit: NASA/JPL

Cavalier return of Mars samples

Other landers since Viking have found organic matter on Mars, adds the ICAMSR statement, supporting the contention that the Viking LR detected life.

Therefore, continues the ICAMSR statement, a small chance that life exists on Mars “should prohibit a cavalier return of Mars material to Earth because of the horrendous damage to Earth’s biosphere potential Martian microorganisms might do if they were pathogenic.”

The Andromeda Strain – the 1971 movie, but how real for a 21st century return to
Earth of Mars samples?
Credit: Universal Pictures

All that said, Levin and Patricia Straat, co-experimenter on the Viking Labeled Release Life Detection Experiment, now retired, argue for the “classical dictate of science: when an experiment produces a new result, repeat that experiment to check its validity, and, if it proves true, expand the experiment to gain new facts.”

Note that both Levin and Straat are science advisors for the International Committee Against Mars Sample Return (ICAMSR), but have no financial interest in ICAMSR.

Other worlds

Another biological shoe to drop is whether the exploration of other worlds beyond Mars is also being inhibited by too stringent of planetary protection rules – such as investigating Europa, a moon of Jupiter, or Saturn’s Enceladus?

This artist’s rendering shows a NASA concept of a Europa lander.
Credit: NASA/JPL-Caltech/M. Carroll

Earlier this year, at the Astrobiology Science Conference (AbSciCon) held in Mesa, Arizona, Brent Sherwood, a program manager at NASA’s Jet Propulsion Laboratory, was lead author of a paper noting that the planetary-protection requirement governing future ocean-worlds exploration missions limits to one in ten thousand the probability that a single viable Earth organism will enter an alien liquid water reservoir.

“This 10-4 requirement, enforceable under international treaty, binds NASA,” the paper explains. “Many aspects of projects intended to explore Europa, Enceladus, and other potentially habitable ocean worlds revolve around this single requirement. Thus, it is important both to understand its origin and periodically to revisit the assumptions behind it.”

To view the Science article, go to:

Go to the International Committee Against Mars Sample Return (ICAMSR) at:

Also, go to The overprotection of Mars commentary in Nature Geoscience by Alberto G. Fairén and Dirk Schulze-Makuch at:

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