NASA’s Plan To Reduce Planetary Protection For Mars Risks Accidentally Extinguishing Second Genesis Of Life Before We Find It – Science 2.0

Posted: November 23, 2019 at 11:59 am

Right now all our missions to Mars are sterilized to protect it from any Earth life that could hitch a ride and confuse the searches. A report by the Planetary Protection Independent Review Board recommends that NASA treats most of Mars similarly to the Moon for planetary protection. It comes with a cover letter from NASA recommending to their planetary protection officer that they implement the proposal. This would be fine if Mars was like the Moon. However, new discoveries show that Mars has liquid water there, in the form of brines, just a few centimeters below the surface. The measurements are indirect because we can't visit most of these locations yet and can't drill down even a few centimeters. There is now clear evidence of very cold brines even beneath the surface of the sand dunes that Curiosity drives over.

Their suggestion is to reclassify large parts of Mars as Category II (current classification for the Moon), meaning that there are no niches where terrestrial microorganisms could proliferate, or a very low likelihood of transfer to such places.

where there is only a remote chance that contamination carried by a spacecraft could jeopardize future exploration. In this case we define remote chance as the absence of niches (places where terrestrial microorganisms could proliferate) and/or a very low likelihood of transfer to those places.

COSPAR Workshop on Planetary Protection for Outer Planet Satellites and Small Solar System Bodies European Space Policy Institute (ESPI), 1517 April 2009

As far as I know mine is the only article to suggest that there may be very significant downsides to dropping planetary protection - most of what you see are articles praising NASA for moving with the times, and making things easier for commercial space and future planetary colonization.

(skip to What about the forwards direction? )

Curiosity can't drill down to examine the brines it detected indirectly, and also is not equipped with any specific life detection instruments. It can detect some organics related to life, but only after heating them up in a small oven until they decompose, then it analyses the evolving gases. Those particular brines are probably too cold for Earth life, but biofilms could create microhabitats to make them more habitable and there are suggestions for several other microhabitats in the equatorial regions that may be more habitable than the Curiosity brines.

The Moon has nothing like that.

The new report has few cites, and its main cite for this proposal is a controversial 2014 report. While the 2014 report was in process of publication, NASA and ESA took steps to get it independently reviewed. This 2015 independent review said the maps from the 2014 report are most useful if they accompanied by cautionary remarks that they represent incomplete knowledge. This new report by the Planetary Protection Independent Review Board doesn't cite the 2015 review or mention these criticisms of the main cite they rely on.

Overlay in white text: : "2015 review says maps represent incomplete knowledge. Extraterrestrial microbes may be here in salty brines just below the surface. Introduced Earth microbes could extinguish second genesis on Mars". Map from the 2014 report. Text summarizes one of the main criticisms of this report in the 2015 review.

Its important to get this right as there is no way to do a do over. It would be so sad to get to Mars, find life there, and then realize it was just life we brought ourselves. For many, the search for other lifeforms in our solar system is one of the major motivating reasons to explore Mars and other parts of our solar system with a potential for life.

This would also impact on the science interests of other countries. That includes the future discoveries of ESA (Europe), ROSCOSMOS (Russia), JAXA (Japan), ISRO (India), CNSA (China) and any other nation with an interest in exploring Mars. It's far easier to detect martian life, and know that it is from Mars, if there is no introduced Earth life there.

What we find on Mars could be absolutely unique. We can't make even the simplest of living cells from non living chemicals. We can make, or modify DNA, and we can insert DNA into a cell and use it to modify how it functions. However this only works if we have a pre-existing cell to modify. We can't make a new living cell from scratch. We don't know the details of all the chemical and physical processes that make up the simplest living cell, but even if we did, we still can't make it. Any attempt to build even the simplest RNA world cell, even if we knew the exact position of every atom in it, would fail. As soon as we start to assemble the chemical constituents they would react together to make a chemical mush. Our attempts to assemble early life in the laboratory (e.g. in the Szostack lab) are based on trying to accelerate chemical evolution, not assembling it from scratch. As Cairns-Smith put it in his "Seven Clues to the Origin of Life" (which approaches the problem of the origin of life like a detective puzzle modeled after Sherlock Holmes novels):

"Subsystems are highly INTERLOCKED within the universal system. For example, proteins are needed to make catalysts, yet catalysts are needed to make proteins. Nucleic acids are needed to make proteins, yet proteins are needed to make nucleic acids. Proteins and lipids are needed to make membranes, yet membranes are needed to provide protection for all the chemical processes going on in a cell. It goes on and on. The manufacturing procedures for key small molecules are highly interdependent: again and again this has to be made before that can be made - but that had to be there already. The whole is presupposed by all the parts. The interlocking is tight and critical. At the centre everything depends on everything"

(page 39 of Seven Clues to the Origin of Life)

If native martian life is especially vulnerable, for instance some form of early life, pre-DNA, we might make it extinct. There would then be no way to reconstruct it, even if we later found clues to how it worked before we made it extinct. This could also impact on the future commercial potential for Mars. Enzymes derived from extremophiles are already the basis for a billion dollar global industry. If we can find life based on a different biochemistry, this has a vast commercial potential. For details see Billions of dollars commercial potential of extraterrestrial biology (below).

Microhabitats for life and shallow subsurface habitats on Mars are likely to be undetectable from orbit. The harsh ultraviolet light would cause even surface lichens to huddle into partial shade in cracks and crevices. as they do in the high Antarctic mountains. Similarly it would be impossible to see life hidden beneath the surface of rocks, or beneath a mm or so of dust or deeper down in the top few centimeters of the Martian surface where, as we'll see, there are possibilities that conditions may be habitable for native as well as introduced Earth life.

The 2015 review found that maps of surface features" can only represent the current (and incomplete) state of knowledge for a specific time".

Text on image: Lichens on Mars would huddle in partial shade protected from UV, like this lichen in high mountains in Antarctica. It could not be seen from orbit with 30 cm resolution.

Pleopsidium chlorophanum in Antarctica From DLR press release Surviving the conditions on Mars

Pleopsidium chlorophanum on granite, collected at an altitude of 1492 m above sea level at "Black Ridge" in North Victoria Land, Antarctica. This photograph shows its semi-endolithic growth in Antarctic conditions. You can see that it has fragmented the granite, and that pieces of the granite are partly covering it, possibly helping to protect from UV light. Photograph credit DLR

See Lichens, cyanobacteria and molds growing in humidity of simulated Martian atmosphere

There are some dark hillside streaks near to the Curiosity landing site that grew and shifted in ways that suggested the presence of flowing water below the surface. Because of the possibility that these streaks could be habitable, Curiosity has to avoid them, because it is not sterilized sufficiently to go up to them to examine them. Importantly, these streaks were not discovered until after Curiosity landed on Mars. Also they are not proven to be dust cascades, as some say. It's one hypothesis that may have some truth to it, but there are many issues with it, such as the seasonality correlated with warmth and not correlated with winds, that the streaks fade too quickly over weeks rather than decades, and are too narrow for dust, and the problem of resupply from the top every year. Though the stopping angle matches the motion of cohesionless dust, there is likely to be liquid brines involved as well. See Dust cascades explanation,

If there is life on Mars, it's likely to be sparse and slow growing, like the life in our coldest driest deserts. Depending how much life is there, it may have almost no effect on the atmosphere, but it might have some effects we can notice. Curiosity has recently discovered variations in oxygen. Some process on Mars is creating more oxygen than expected in spring to summer, and less in mid winter, and the only correleation they have found is that less oxygen is produced when there is more dust in the atmosphere. They didn't find a correlation with seasonal and interannual pressure vartiation, or temperature variation. Could it be photosynthetic life? We also have the intriguing methane plumes also confirmed by ESA's trace gas orbiter.

Cassie Conley who used to be planetary protection officer for NASA puts it like this, as reported by Scientific American

Weve got engineers who are convinced that they know everything and biologists who still acknowledge that we still dont know very much. Fundamentally, that is the dispute.

Here is a video I made for this article (while working on the draft)

(click to watch on Youtube)

This article will focus on the forwards direction, the risk of sending Earth microbes to Mars because the legal protection in that direction is very weak.

In the backwards direction the legal protection is very strong indeed, far more than it was at the time of Apollo. Margaret Race of the SETI institute mapped out the laws that NASA would have to navigate to return a sample to Earth. I figure out, based on her list, that they should have started work on the legal process in 2010 or earlier to return a sample by 2032 as they plan. So, I don't think they are going to return it to Earth unsterilized myself. Most likely sterilize it, or return it to somewhere not in contact with Earth such as telerobotic study above GEO.

At any rate there is no risk of harm to Earth's biosphere. It would be looked at in great detail over a period of years and expert astrobiologists would be called as witnesses to testify and help keep Earth safe. For details about that, skip to Earth has strong legal protection/

Skip to: 2015 review and problems with maps

Since Earth is well protected in the backwards direction, for a sample returned from Mars, the main concern is for the forwards direction. Unlike the backwards case, there isnt any other legislation here to protect Martian life apart from the weak Outer Space Treaty. All the rules for planetary protection are based on a few phrases about harmful contamination. They have been interpreted as including "harmful to the scientific experiments of other parties to the treaty".

I think the way ahead here is to make sure everyone is on board and understands the importance of planetary protection - for scientists - and for colonization enthusiasts too. It's important for all of us to know what is there, and if there is life there that could harm humans or Earth's biosphere, or whether astronauts could impact adversely on martian life.

If these proposals were adopted in the forwards direction, you could send what you like to these regions of Mars, tardigrades, and extremophile blue green algae that have already been tested in Mars simulation chambers. The only requirement would be to document what you do. Eventually you could send humans too, with this category II classification, though returning them would be another matter if they had made contact with extraterrestrial microbes on Mars.

The report is here together with a cover letter from NASA recommending to their planetary protection officer that they implement the proposal:

One of their main cites is a report from 2014 by Rummel et al which proposed the use of maps to divide Mars into special regions which need especially careful planetary protection measures such as was used for the Voyager landers in the 1970s, and others that have less stringent requirements such as is used for Curiosity:

This is the basis for their proposal that Mars could be subdivided into regions some reclassified as category II. Although they dont go into detail, presumably they would use a map like the one in the 2014 review, and classify all except the uncertain regions as category II:

Map from the 2014 report. Purple is low in elevation, and grey is higher elevation. Red and blue lines delineating regions are approximately 50 km in width

In the text overlay I summarize the objection to this map in the 2015 review "2014 map of uncertain regions of habitability. 2015 review says maps can only represent incomplete knowledge."

Skip to: Vigorous debate in Nature and Astrobiology journal

Even before Rummel et als report was published, both NASA and ESA took steps to have it reviewed independently.

This 2015 review overturned several of the findings of the 2014 report, and in particular, it recommended against the use of maps [49] saying:

In general, the review committee contends that the use of maps to delineate regions with a lower or higher probability to host Special Regions is most useful if the maps are accompanied by cautionary remarks on their limitations. Maps [of] surface features can only represent the current (and incomplete) state of knowledge for a specific timeknowledge that will certainly be subject to change or be updated as new information is obtained.

5 Generalization of Special Regions and the Utility of Maps

This new NASA report doesnt mention the 2015 review. Its an extraordinary omission from a report that is recommending the use of maps for category II.

I dont know the reason for this omission. They certainly should have looked at this 2015 review, and not just at the original 2014 report, before making this recommendation to NASA to map out large parts of Mars as category II like the Moon.

The 2015 report used the example of Recurring Slope Lineae (RSLs) to explain why maps are not enough by themselves. These are seasonal streaks that form on sun facing Martian slopes. They appear in the Martian spring, grow and broaden through the summer and fade away in autumn.

These dark features are not themselves damp and may be dust flows. However, they are associated with hydrated salts and they may also be linked with salty water (brines) in some form. Sadly the HiRISE instrument can only observe them in the early afternoon locally, the driest time for the Martian surface, because of its high inclination sun synchronous orbit. This makes it especially hard to know if there are any brines moving down these slopes.

Warm Season Flows on Slope in Newton Crater (animated)

The first ones were found in higher latitudes, but many of these have now been found in the Martian tropics, especially on the slopes of the Valles Marineres. Their status is unknown, whether they could have habitats for Earth life or not. At present they are classified as

As such they meet the criteria for Uncertain Regions, to be treated as Special Regions. [a Special region is one that Earth microbes could potentially inhabit]

The 2015 review gives the example of the ExoMars Schiaparelli lander. All HiRISE images of the landing site were inspected for the possible presence of RSL's. [50]

As another example of this, 58 RSLs were found on Mount Sharp close to the Curiosity landing site.

Here are some of them:

Possible RSLs on mount Sharp not far from the Curiosity rover. These photos are taken at a similar time in the Martian year, they are less prominent in the earlier one in 09 March 2010 and more prominent with some new ones in the later image August 6 2012. Photo from supplementary information for Transient liquid water and water activity at Gale crater on Mars

Importantly, these were not discovered until after the Curiosity landing in 2012. See Slope activity in Gale crater, Mars (2015) and Nature article: Mars contamination fear could divert Curiosity rover

This shows that we mightnt always be able to rule out potential uncertain regions that could be habitats at a landing site. They may be discovered later, after the landing itself.

More RSLs have been found in the Mawrth Vallis region, one of the two final candidates for ExoMars landing site

These results denote the plausible presence of transient liquid brines close to the previously proposed landing ellipse of the ExoMars rover, rendering this site particularly relevant to the search of life. Further investigations of Mawrth Vallis carried out at higher spatial and temporal resolutions are needed to , to prevent probable biological contamination during rover operations,

Discovery of recurring slope lineae candidates in Mawrth Vallis, Mars

ExoMars isnt going to Mawrth Vallis, because they chose the other candidate Oxia Planum. I cant find anything about RSLs in Oxia Planum, but how confident can we be that this doesnt have RSLs or other potential habitats? Does non detection so far mean they arent there?

Skip to: Important habitats not covered by 2014 report

This new report also doesnt mention the long running and vigorous debate on the topic of whether we should relax sterilization requirements for spacecraft sent to Mars.

This debate started in two Nature articles in 2013 and has continued in Astrobiology journal through to 2019.

Both sides in this debate were in agreement that there is a significant possibility that Earth microbes can contaminate Mars.

Surely neither side in this debate would support classifying most of Mars as category II like the Moon.

Rather, the argument in Nature and Astrobiology journal is about whether we should reduce sterilization requirements for Mars in order to study these potential habitats quickly before human missions get there and make it impossible to study them in their pristine condition without Earth life.

The other side in this debate argue that we have a fair bit of time before humans get there, and that if we relax planetary protection we risk finding Earth microbes we brought there ourselves.

Those arguing for relaxing planetary protection are:


This debate is not mentioned in this report.

Nor does it mention the many new potential surface or near surface habitats that have been proposed / indirectly detected / theorized since 2008. We have had more of these than there have been years since 2008.

Skip to: Nilton Renno's droplets

The 2014 report briefly considers these. The 2015 review expands on this topic, and says that to identify such potential habitats requires a better understanding of the temperature and water activity of potential microenvironments on Mars, for instance in the interior of craters, or microenvironments underneath rocks. These may provide favourable conditions for establishing life on Mars even when the landscape-scale temperature and humidity conditions would not permit it. [46]

The 2014 report looked at distributions of ice and concluded that ice in the tropics is buried too deep to be a consideration[47]

However the 2014/5 review corrected this due to evidence of ice present at depths of less than one meter in pole-facing slopes[48]

Research since then still hasnt resolved these issues.

Even the 2014 report acknowledged limitations:

"Claims that reducing planetary protection requirements wouldn't be harmful, because Earth life can't grow on Mars, may be reassuring as opinion, but the facts are that we keep dis4g life growing in extreme conditions on Earth that resemble conditions on Mars. We also keep discovering conditions on Mars that are more similarthough perhaps only at microbial scalesto inhabited environments on Earth, which is where the concept of Special Regions initially came from."

"A New Analysis of Mars "Special Regions": Findings of the Second MEPAG Special Regions Science Analysis Group (SR-SAG2)" (PDF).

Skip to: Does this matter:

Id like to cover a couple of these potential habitats to motivate this, then Ill look at why it is so important to protect Mars from Earth life - is it really so important to make sure we dont mix Earth life with Mars life before we canstudy it?

Skip to: Curiosity brines

Nilton Renno's droplets that form where salt touches ice - why did he call a droplet of salty water on Mars "a swimming pool for a bacteria"?

This is perhaps one of the most striking discoveries in recent years because of its implications for habitability of Mars. Nilton Renno found that liquid water can form very quickly on salt / ice interfaces. Within a few tens of minutes in Mars simulation


Erik Fischer, doctoral student at University of Michigan, sets up a Mars Atmospheric Chamber on June 18, 2014. These experiments showed that tiny "swimming pools for bacteria" can form readily on Mars wherever there is ice and salt in contact.

This is striking as it could open large areas of Mars up as potential sites for microhabitats that life could exploit. The professor says

"If we have ice, and then the salt on top of the ice, in a few tens of minutes liquid water forms. Our measurements clearly indicate that. And it's really a proof that liquid water forms at the conditions of the Phoenix landing site when this salt is in contact with the ice.

"Based on the results of our experiment, we expect this soft ice that can liquefy perhaps a few days per year, perhaps a few hours a day, almost anywhere on Mars. So going from mid latitudes all the way to the polar regions.

" This is a small amount of liquid water. But for a bacteria, that would be a huge swimming pool - a little droplet of water is a huge amount of water for a bacteria. So, a small amount of water is enough for you to be able to create conditions for Mars to be habitable today'. And we believe this is possible in the shallow subsurface, and even the surface of the Mars polar region for a few hours per day during the spring."

(transcript from 1:48 onwards)

(click to watch on Youtube)

Excerpt from:
NASA's Plan To Reduce Planetary Protection For Mars Risks Accidentally Extinguishing Second Genesis Of Life Before We Find It - Science 2.0

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