Planetary Protection Policy: Useful or Counterproductive?

Today’s post is not about law but policy. Alberto G. Fairén, a visiting scientist in astronomy at Cornell and a research scientist at Centro de Astrobiología in Spain, argues that planetary protection protocols should be revisited. Because reasonable scientists can disagree about their value and efficacy, Congress might want to think twice before requiring the private sector to follow current planetary protection protocols.

Planetary protection protocols. Article IX of the Outer Space Treaty provides that States Parties must pursue their studies and explorations so as to avoid “harmful contamination” of the moon and other celestial bodies and “adverse changes in the environment of the Earth resulting from the introduction of extraterrestrial matter and, where necessary, shall adopt appropriate measures for this purpose.” As a science agency that is part of the U.S. Government, NASA has applied this to its missions so that it not only avoids what the ordinary person might consider harmful contamination, but microbial contamination as well, limiting the presence of bacterial spores on any surface to no more than 300,000. Accordingly, NASA requires the sterilization of its spacecraft to avoid bringing microorganisms to Mars. ESA, the European Space Agency, follows similar measures.

Counterproductive?  Fairén explains the argument for protecting scientific interests through planetary protection:

How will we know what’s native Martian if we unintentionally seed the place with Earth organisms? A popular analogy points out that Europeans unknowingly brought smallpox to the New World, and they took home syphilis. Similarly, it is argued, our robotic explorations could contaminate Mars with terrestrial microorganisms.

As an astrobiologist who researches the environments of early Mars, I suggest these arguments are misleading. The current danger of contamination via unmanned robots is actually quite low. But contamination will become unavoidable once astronauts get there. NASA, other agencies and the private sector hope to send human missions to Mars by the 2030s.

Fairén wants the protocols assessed and updated before humans reach Mars.  He sees a window closing on the science:

Strict cleaning procedures are required on our spacecraft before they’re allowed to sample regions on Mars which could be a habitat for microorganisms, either native to Mars or brought there from Earth. These areas are labeled by the planetary protection offices as “Special Regions.”


The sad consequence of these policies is that the multi-billion-dollar Mars spacecraft programs run by space agencies in the West have not proactively looked for life on the planet since the late 1970s.


That’s when NASA’s Viking landers made the only attempt ever to find life on Mars (or on any planet outside Earth, for that matter). They carried out specific biological experiments looking for evidence of microbial life. Since then, that incipient biological exploration has shifted to less ambitious geological surveys that try to demonstrate only that Mars was “habitable” in the past, meaning it had conditions that could likely support life.

Even worse, if a dedicated life-seeking spacecraft ever does get to Mars, planetary protection policies will allow it to search for life everywhere on the Martian surface, except in the very places we suspect life may exist: the Special Regions. The concern is that exploration could contaminate them with terrestrial microorganisms.

Fairén focuses on two points to argue that the protocols are counterproductive:  the logical and the technical.  First, he points out that here on Earth organisms can evolve to survive in very hostile environments.  Likewise on Mars, any organisms that can survive the rigors of Mars can likely stand down any invaders from Earth.   If, on the other hand, Earth microorganisms can survive Mars, “we can then presume that terrestrial microorganisms are already there, carried by any one of the dozens of spacecraft sent from Earth in the last decades, or by the natural exchange of rocks pulled out from one planet by a meteoritic impact and transported to the other.”  In that  case, the protocols are overly cautious since contamination has already happened.

He also maintains that the protocols don’t make sense technically because we don’t actually completely sterilize the spacecraft we send to Mars.  We don’t know how.

The cleaning procedures we use on our robots rely on pretty much the same stresses prevailing on the Martian surface: oxidizing chemicals and radiation. They end up killing only those microorganisms with no chance of surviving on Mars anyway. So current cleaning protocols are essentially conducting an artificial selection experiment, with the result that we carry to Mars only the most hardy microorganisms. This should put into question the whole cleaning procedure.

Additionally, we now know how to tell the difference between Martian and Earth life:

[T]echnology has advanced enough that distinguishing between Earthlings and Martians is no longer a problem. If Martian life is biochemically similar to Earth life, we could sequence genomes of any organisms located. If they don’t match anything we know is on Earth, we can surmise it’s native to Mars.


The microbes we know persist in clean spacecraft assembly rooms provide an excellent control with which to monitor potential contamination. Any microorganism found in a Martian sample identical or highly similar to those present in the clean rooms would very likely indicate contamination – not indigenous life on Mars.

Although Fairén makes these points to argue for exploring the special regions now, his points also apply to why Congress should ask some very serious questions before it attempts to impose planetary protection protocols on the private sector.  The first question of course, must center on whether Congress seeks to prohibit human settlement or even any human presence?  All indications are that it does not.  The second question is whether the scientific interest in ascertaining the presence of life is stronger than the interest in human settlement?   This is a particularly important question if Farién is correct that no one is looking for life in the places most likely to have it.   Why impose constraints and costs if those constraints don’t further the purported goal?  This is a policy debate we must have as a society.  Congress is the proper place to have that debate since it is the legislative body.