The Red Planet as seen by Europe’s Mars Express.
Credit: ESA/D. O’Donnell – CC BY-SA IGO

A recent article in the journal Astrobiology has caused a dust-up about Mars.

Titled “Searching for Life on Mars Before It Is Too Late” the article makes the case that planetary protection policies as we conceive them today “will no longer be valid as human arrival will inevitably increase the introduction of terrestrial and organic contaminants and that could jeopardize the identification of indigenous Mars life.”

Lead author of the forum article is Alberto G. Fairén, a visiting scientist at Cornell University.

Change of strategy

The forum article, in short form, proposed a twofold change of strategy regarding exploration of the Red Planet:

New planetary prowler – the NASA Mars 2020 rover – scouring the Red Planet for select samples for eventual return to Earth.
Credit: NASA/JPL

First – allow immediate access to the Special Regions for vehicles with the cleanliness level of Curiosity, Mars2020, or Europe’s ExoMars.

Second – existing laboratory robotic technology must be made flight ready in the search for biochemical evidence of life, and in particular, the development of robotic nucleic acid sequencing instrumentations for future in situ detection and/or sample return.


In response, a new fast-track forum article in Astrobiology – “Four Fallacies and an Oversight: Searching for Martian Life” — has been authored by John Rummel of the SETI Institute and Catharine “Cassie” Conley, head of NASA’s Office of Planetary Protection.

Those fallacies as flagged by Rummel and Conley are:

  • The contention that evidence of martian life would best be found in Special Regions is not well supported
  • Evidence and cost estimations based on real mission systems suggest that cleaning robotic missions to currently required levels is in fact not a significant impediment to accessing candidate Special Regions
  • The claim that martian life could convincingly be identified by nucleic acid sequence comparison, if it were obtained from a Special Region contaminated with Earth life, is invalidated by recent evidence of highly divergent life on Earth
  • The idea that exploration with dirty robots is urgent because human exploration is imminent seems to ignore the possibility that contamination from poorly prepared robotic missions could spread as easily as contamination associated with human missions.

Mars expedition probes the promise that Mars was a home address for past, possibly life today.
Credit: NASA


Explore Mars properly

Additionally, Rummel and Conley write that an oversight in the earlier forum article is that it failed to acknowledge the possibility that introduced Earth organisms could cause damage both to martian resources we hope will be available to future human explorers and—considering that many Earth organisms are facultative pathogens (e.g., Clostridium tetani)—potentially to the explorers themselves.

“There is still time to explore Mars properly,” the Mars experts in the new article conclude.

Careful contamination control

“Without careful contamination control, however, robotic life-detection instruments could obtain a false positive or equivocal detection of life on Mars,” they write. In fact, they add that the Sample Analysis at Mars (SAM) instrument on the NASA Curiosity Mars rover has already detected Earth contamination at levels that swamp out possible signals from Mars.

“If an astronaut exploring Mars is likely to run into martian organisms, that fact should be well understood before landing there. Inadvertent exposure might affect astronaut health and their permission to return to Earth. Exposure to unknown Earth organisms could be a source of confusion in that circumstance,” Rummel and Conley state.


To access both of these important Astrobiology papers, go to:


“Four Fallacies and an Oversight: Searching for Martian Life” at:



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