NASA have put a great deal of work into the engineering for a sample return but I can't find any papers or blog posts or any sign of prepration for the legal side of the return mission. We are strongly protected by many environmental laws and laws to protect human health that we didn’t have at the time of Apollo. These laws don’t rely on the Outer Space Treaty for their legal basis. How NASA categorizes Mars makes no difference to them. See the article by Margaret Race of the SETI institute.

NASA is going to send a sample caching rover to Mars in 2020 and they hope to send a second mission in the 2020s to return some of these samples back to Earth for analysis. They plan to return them unsterilized (a sterilized sample would not trigger environmental laws, but would be just like the sample returns from meteorites, comets, and the Moon). Their current plans are to return it in 2032.

This is based on extracts from my longer article:

Here is a video I made for while working on the draft of that previous article - the first quarter of an hour or so is about the environmental protection of Earth.

(click to watch on Youtube)

skip to How Extraterrestrial microbes could be hazardous to humans or Earth's environment

I tried to estimate a timetable for the legislation, based on Margaret Race's article. Assuming the process goes through with no hold ups or objections, they probably should have started in 2010 or earlier if they want a sample return by 2032. If you know of anything on this do say in the comments.

These laws don't depend on the wording of the Outer Space Treaty in any form, but are independent legislation to protect Earth.

Text: NASA have left it too late to complete the legal process for a 2032 unsterilized sample return. They should have started around 2010.

Mars sample return concept - credit NASA. If NASA wants to return an unsterilized sample by 2030 they should have started the legal preparation for this around 2010 at the latest. There is no sign they have even done any planning for the legal process yet.

Perhaps they expect it to be like Apollo 11 where they published the sample return precautions as an informal document on the day of the launch to the Moon and didn’t go through any proper legal process? This would not be permitted today.

This takes into account the likely time requirements for constructing the receiving facility, based on the previous sample return studies. NASA would not start the expensive build (half a billion dollars facility) until it knows what it is legally required to do. I did this calculation back in 2018 for my article: Why we are unlikely to return an unsterilized sample before 2040. Let's look at it again:

The requirements for a sample return facility have increased with each review. In 1999 then they recommended use of Class III Bio Safety Cabinets (BSC's) in combination with HEPA filters. This was still the general idea in 2002. They described the facility like this:

"The initial processing of returned martian samples should be restricted to a BSL-4 laboratory in the quarantine facility. A very modest gas-tight glove box (Class III cabinet) in a "clean room" (class 10; however see following g section) will be sufficient for this purpose. "

These requirements were made increasingly more stringent as a result of the discoveries of ultramicrobacteria, the studies of the minimal possible size of extraterrestrial microbes (thought to be around 50 nanometers, a quarter of the minimum size for modern Earth life) and the discovery of how easily capabilities can be transferred through lateral gene transfer, to the most distantly related microbes. It's now thought that even distant cousins on Mars, separated from Earth life for billions of years, could easily swap genes with Earth life overnight in warm salty brines such as sea water. Even if they were dead. Even if particles only a few tens of nanometers in size from martian life got into the sea that could still be enough to transfer a capability to Earth life.

The most recent study by the European Space Foundation required a $500 million facility with design requirements never fulfilled before that has to prevent escape of any particle of 50 nanometers diameter or more (a quarter of the resolution limit of 200 nm for a diffraction limited optical microscope) under any circumstances. They leave it for further discussion whether a 10 nm particle can escape from the facility, recommending that they also should be contained, and that if this is not practical, that the situation needs to be reviewed. These are extraordinarily demanding requirements, especially when you combine them with the requirement to keep the martian life uncontaminated by Earth life so that it can be studied.

For a summary of their conclusions with links to the sources, see

It's perhaps not surprising, however, that the process is so complex and difficult. What makes it such a challenge is that we have to contain any conceivable extraterrestrial biology, when so far, we only have knowledge of Earth based life. We would build the same facility to receive an unsterilized sample from a habitat in the Proxima Centauri system!

The most recent European Science Foundation - study. was in 2010, and a sample return mission launched in the 2020s would likely need a new study. This is not likely to reduce these requirements, but instead would be expected to increase the requirements further, at least each previous study has done so. Then the law, whatever it is, would be likely to be based on their recommendations, after much deliberation during which the public would be involved at every stage in a full and open way.

The recommendations so far are that the facility also has to be operational and in use at least two years before the mission to collect the sample is launched from Earth. This requirement is the result of studying the many lapses of protocol during the Apollo mission sample handling, due to staff that were not sufficiently familiar with the procedures. For details of these lapses see When Biospheres Collide, A History of NASA's Planetary Protection Programs ..

However the National Research Council study in 2009 estimated a longer period of 7 to 10 years to get operational, followed by an estimated 5-6 years to become familiar with the procedures

It has been estimated that the planning, design, site selection, environmental reviews, approvals, construction, commissioning, and pre-testing of a proposed SRF will occur 7 to 10 years before actual operations begin. In addition, 5 to 6 years will likely be required for refinement and maturation of SRF-associated technologies for safely containing and handling samples to avoid contamination and to further develop and refine biohazard-test protocols. Many of the capabilities and technologies will either be entirely new or will be required to meet the unusual challenges of integration into an overall (end-to-end) Mars sample return program.

Timescale for establishing a sample-receiving facility

It is not likely that the process of designing and building the facility would start until the legal provisions are in place with the details of the design requirements.

Margaret Race looked in detail at the legal processes that would have to be completed before we can return a sample from Mars to Earth, even to a purpose built receiving facility.

Before a sample return, we have to accomplish, in this order

  • Several years: Formal environment impact statement for NEPA + laws on quarantine to be enacted, involving broad public consultation. The average length of time for an EIS in the twelve months ending 30th September 2016 was 46 months (see the DOE's Lessons Learned Quarterly Report).
  • Several years: Presidential review of potential large scale effects on the environment. This has to be done after all the other domestic legislation is completed.
  • Can be done alongside the other work: International treaties to be negotiated and domestic laws of other countries

I have only mentioned a few of the main points there.

In more detail, summary of Margaret Race's findings:

She found that under the National Environmental Policy Act (NEPA) (which did not exist in the Apollo era) a formal environment impact statement is likely to be required, and public hearings during which all the issues would be aired openly. This process is likely to take up to several years to complete.

During this process, she found, the full range of worst accident scenarios, impact, and project alternatives would be played out in the public arena. Other agencies such as the Environment Protection Agency, Occupational Health and Safety Administration, etc, may also get involved in the decision making process.

The laws on quarantine will also need to be clarified as the regulations for the Apollo program were rescinded. In the Apollo era, NASA delayed announcement of its quarantine regulations until the day Apollo was launched, so bypassing the requirement for public debate - something that would be unlikely to be tolerated today.

It is also probable that the presidential directive NSC-25 will apply which requires a review of large scale alleged effects on the environment and is carried out subsequent to the other domestic reviews and through a long process, leads eventually to presidential approval of the launch.

Then apart from those domestic legal hurdles, there are numerous international regulations and treaties to be negotiated in the case of a Mars Sample Return, especially those relating to environmental protection and health. She concluded that the public of necessity has a significant role to play in the development of the policies governing Mars Sample Return

Margaret Race does not estimate a total time for all this. But we need a figure to work with here, so let's say, as a a rough estimate, that a decade would seem optimistic to complete it all.

Once the legal situation is sorted out and the design requirements of the facility are required the next steps are:

  • 7 - 10 years: building the facility
  • 2 years: operational before launch (minimum requirement, more likely 5-6 years)
  • 2 - 4 years: to collect the sample and return it
    (if we follow the Mars 2020 plan then the follow up rover has to retrace at least part of the path of Mars 2020 to retrieve the samples, in tubes that are dropped on the surface of Mars in small caches from time to time).

That add up to an extra 11 - 20 years after the legal process has completed. Total 21 to 30 years. The process of building and testing the facility alone could take 20 years if we go by the upper estimates there. Do say in the comments if you see anything to correct in this estimate of the timescale.

If this calculation is correct, this means that if we want a sample returned to Earth by 2032 we should have started this process already in 2010. Indeed, it is probably already a year or two too late to achieve a sample return date of 2040. Also, this assumes that there are no delays. It would be no great surprise if it was delayed to 2050 or later through either legal delays or delays in building the facility and getting it operational.

If anyone reading this knows of any work NASA has done by way of preparing for the legal situation do say. I have searched and found nothing and with my previous articles I've asked readers to comment and asked knowledgeable friends, and not found anyone who knows of anything they have done on this topic or are doing on this topic.


Skip to: Curiosity brines

Of course if they could prove Mars is sterile, or that any martian life is harmless to Earth, then this would not be needed. However, at least with the current state of knowledge of Mars, astrobiologists would tell the legislators that Mars could have extraterrestrial life there. It’s not known to be sterile, and the dust can carry spores almost anywhere on the planet (more on this later). Over the years of legal process, this would be looked into in great detail from all angles.

New discoveries have opened up the possibility of native microbial life on Mars hidden from our orbital telescopes just centimeters below the dust. This may be possible even in the exceedingly dry tropical areas where Curiosity is roving, especially if martian life has a biochemistry adapted to lower temperatures than Earth life.

This life could be hazardous to humans or our biosphere. To take a simple example, legionnaires disease is an infection of biofilms that can use the same methods to infect human lungs, seeing it as a warm biofilm -

Astrobiologists say that though it is possible that Mars life could be mystified by an alien biochemistry, it’s also possible that it hasn’t evolved any resistance to it, never having encountered it before. Joshua Lederberg put it like this:

it is not adapted to humans. Some strains of it are now adapting to our environments, spread by humans infected by it, but the same could happen with Martian life that invades the lungs of an astronaut.

"If Martian microorganisms ever make it here, will they be totally mystified and defeated by terrestrial metabolism, perhaps even before they challenge immune defenses? Or will they have a field day in light of our own total naivete in dealing with their “aggressins”?

from: "Paradoxes of the Host-Parasite Relationship"

Our lungs might offer no resistance, not even recognizing it as life as it munches away at them, and with a different biochemistry they would be likely to be naturally resistant to our antibiotics, which target particular processes of the pathogens.

Some Mars colonization enthusiasts and space engineers will tell you that any life we find on Mars will be from Earth, but they have not persuaded the astrobiologists of this. The designers of instruments to look for indigenous life there are careful not to make any assumptions about its biochemistry or whether it is related to Earth life.

We can’t assume that any life in a sample returned from Mars is related to Earth life unless we have studied it already on Mars.

There would also be risk of larger scale environmental disruption, even if the martian microbes are harmless to humans. As the National Research Council put it in 2009:

The risks of environmental disruption resulting from the inadvertent contamination of Earth with putative martian microbes are still considered to be low. But since the risk cannot be demonstrated to be zero, due care and caution must be exercised in handling any martian materials returned to Earth

Assessment of Planetary Protection Requirements for Mars Sample Return Missions

These reports haven't gone into details of how the environment could be disrupted. To give some points to think over right away (I will come back to this later), would our ecosystems work the same way if eventually half the microbes in the soil, half the plankton in our oceans and half the microbes in the guts of animals and ourselves were mirror DNA, say, or PNA, or TNA, or had novel amino acids that Earth life doesn't use, or didn't use proteins, to give a few examples? How would Earth life respond to eating food with novel amino acids it never encountered before or with mirror versions of the amino acids it has already? What about accidental poisons, like the way that cyanobacteria can kill dogs and cows? This is especially so if the extraterrestrial microbes have a different biochemistry; they seem unlikely to be exact "drop in" replacements to terrestrial microbes. There would be changes in their composition and how they function. Microbes with their shorter lifespans would adapt relatively quickly, but higher lifeforms might find it a significant challenge.

The legislators would not ignore arguments such as these. There would be extensive public debate, and Earth would be protected.

Robert Zubrin (president of the Mars society) tells his space colonization enthusiasts that for Mars life to survive on Earth is like Sharks in the savannah (see What are Zubrin's arguments? in my Touch Mars? book). But they could also be like rabbits in Australia, and microbes aren't like sharks. Microbes able to thrive in extreme heat and extreme cold have been found in human belly buttons . You need to listen to astrobiologists, not space engineers, and for sure the legislators would listen to the astrobiologists. There is a reason why we protect Earth.

Yes, there are scenarios according to which martian life would be harmless to us. It could be that what we find on Mars is an early form of life, so feeble it can't compete with Earth life, or it's adapted to very low temperatures and self destructs when it is warmed up. You can invent other scenarios where martian life is harmless to Earth, or even beneficial in some way. However, before an unsterilized sample return, we will need much more by way of evidence than optimistic scenarios or colourful analogies. Legislators would invite the astrobiologist experts to give evidence, and would not ignore what they say.

For these reasons I’m not concerned about the backwards direction as far as safety is concerned. I expect NASA to sterilize their sample if they do return those samples from Mars to Earth, or return them to somewhere isolated from contact with Earth, such as a satellite set up for telerobotic study of the sample above GEO. They can use either of those approaches within the Outer Space Treaty. If there is no possibility of an unsterilized sample contacting Earth's biosphere, or Earth entering into the chain of contact with an unsterilized sample, it wouldn't trigger this legislation to protect our Earth.

Of course if we could prove that Mars is sterile, or that there is no life in the region the 2020 rover will be exploring, then it wouldn't trigger this legislation. But we can't do that.

NASA's plan to categorize much of Mars as category II for the purpose of the Outer Space Treaty would make no difference here as the legislation Margaret Race looked at doesn't depend on the Outer Space Treaty. Instead astrobiologists would be called as witnesses to say whether they think there is a possibility of life in the sample returned to Earth and they won't be able to say that it is sterile. There are many possible habitats in the equatorial regions and as well as that then there's the possibility of life traveling around Mars imbedded in the Martian dust grains during the dust storms that block out much of the sunlight for weeks on end some years.


Skip to: Effects of biofilms

This was a serendipitous discovery announced in April 2015. Liquid brines that form through deliquescing salts (perchlorates) - the salts take in water from the atmosphere (same principle as the salts you use to keep equipment dry).

They noticed that when Curiosity drives over sand dunes, then the air above them is drier than it is normally. When it leaves the sandy areas the humidity increases.

Rover Environmental Monitoring Station (REMS) on NASA's Curiosity Mars rover

It’s temperature and humidity sensors are located on these booms on the rover’s mast

NASA Mars Rover's Weather Data Bolster Case for Brine

This shows that something in the sand dunes is taking up water vapour from the air, and rather a lot of it too. They calculated that the perchlorates in the sand must take up so much water at night that the liquid brines would be habitable, except that they are too cold for Earth life. This shows how it works:

As the day progresses the brines warm up but any brines close to the surface (in the top five centimeters or so) would dry out, and become too salty for Earth life. That's for any water in the top five centimeters or so.

They found conditions for liquid water in the top 5 cms at various times in the morning for most of the year from 2 am to after 8 am, and in the evening in winter from 6 pm to around midnight (just reading off from their figure 3b)

However, when temperatures in the top 5 cms reach conditions habitable for Earth life, they find that the water activity has dropped to zero, making it impossible for Earth microbes to replicate (Earth life requires a water activity level of at least 0.6). More strictly speaking, microbes may be able to replicate at lower temperatures but if so, it’s exceedingly slow, centuries to thousands of years.

Planetary protection at present at least is based on keeping Mars free of Earth life only for our own purposes and not for future generations thousands of years from now, so they count habitats as being okay for planetary protection if the conditions are so cold that life would take millennia to colonize it.

They suggest that it could have permanently hydrated brines below about 15 centimeters below the surface, and at that depth, the liquid would never get warm enough for metabolic activity for Earth microbes, never mind replication.

Top temperatures in summer at 15 cms depth would be around -40 °C (I'm reading this off their figure 2a, grey shows the temperature range 15 cm below the surface).

The authors of the paper concluded that the conditions in the Curiosity region were probably beyond the habitability range for replication and metabolism of known terrestrial micro-organisms. However this is in the tropics where the air is (comparatively) warm and dry, and it leads to the possibility of habitable brines in conditions that are colder, with greater atmospheric water content.

As perchlorates are widely distributed on the surfaceof Mars, this discovery implies that the rest of the planet should possess even more abundant brines owing to the expected greater atmospheric water content and lower temperatures

For a summary see "Evidence of liquid water found on Mars (BBC)" and for the article in Nature "Transient liquid water and water activity at Gale crater on Mars" (abstract, the paper is behind a paywall, but you can read it via the link in the BBC article through Springer Nature Sharedit,. or researchgate).

"Gale Crater is one of the least likely places on Mars to have conditions for brines to form, compared to sites at higher latitudes or with more shading. So if brines can exist there, that strengthens the case they could form and persist even longer at many other locations, perhaps enough to explain RSL activity,"

Principal Investigator Alfred McEwen

NASA Mars Rover's Weather Data Bolster Case for Brine


Skip to: What are these recurring slope lineae?

Does this really mean that the brines are sterile though - for either Mars or Earth life?

Nilton Renno, who is an expert on Mars surface conditions suggests that Earth microbes may still be able to exploit this liquid brine layer through biofilms::

"Life as we know it needs liquid water to survive. While the new study interprets Curiosity's results to show that microorganisms from Earth would not be able to survive and replicate in the subsurface of Mars, Rennó sees the findings as inconclusive. He points to biofilms—colonies of tiny organisms that can make their own microenvironment."

Mars liquid water: Curiosity confirms favorable conditions.

The 2015 review makes a similar point about the ability of multi-species microbial communities to alter dispersed small-scale habitats.

Cells in biofilms are embedded in a matrix of externally produced substances (such as polysaccharides, proteins, lipids and DNA) and adjust environmental parameters to make them more habitable[45]. There are many examples of small-scale and even microscale communities on Earth including biofilms only a few cells thick. Microbes can propagate in these biofilms despite adverse and extreme surrounding conditions.

NOTE ON FOOTNOTES: the footnotes here link to my Astrobiology Encyclopedia. This has corrected and extended versions of Wikipedia articles on the same topic, which have many mistakes and omissions (for instance, Wikipedia doesn’t mention the 2015 review).

I don’t know if Nilton Renno meant a martian biofilm or one for Earth life. However both could work.

Martian life would surely be adjusted to live at the lowest temperatures on Mars. It could do that using the chaotropic agents such as the perchlorates which are naturally present on Mars - these are chemicals that help processes to continue at lower temperatures than they usually do. Earth life may be able to use these too. 2014 report mentions these:

3.1.3. Chaotropic substances. Numerous types of com-pounds increase the flexibility of molecules, destabilizing and/or fluidizing them

Mars has abundant chaotropic agents

Chaotropes such as MgCl2, CaCl2, FeCl3, FeCl2, FeCl, LiCl, perchlorate, and perchlorate salts are, collectively, abundant in the regolith of Mars.

These would permit faster metabolic processes at lower temperatures.

The 2014 report has a finding

Finding 3-3: Chaotropic compounds can lower the temperature limit for cell division below that observed in their absence. There exists the possibility that chaotropic substances could decrease the lower temperature limit for cell division of some microbes to below-18°C (255 K), but such a result has not been published.

I haven’t found much research on the topic since then. Here are a couple of relevant papers but these are preliminary results:

If you know of more on this topic do say.

If it is possible for life to evolve to live in these habitats, then conditions on Mars would seem to be optimal to drive such evolution

  • Chaotropic agents abundant in the Martian salts
  • Salty brines rich in these chaotropic agents with extreme low temperatures also likely abundant, in the top 15 cms throughout the equatorial regions.

Surely there is a possibility here that martian biofilms have evolved to take advantage of these brines.

If they have done so they would likely trap the water at night at those low temperatures below - 40 C and then retain it in the films through to daytime as the brines warm up to temperatures conducive to Earth life.

So, the Curiosity brines could well be habitable to martian life. They may be habitable to Earth life too - though at those low temperatures it would likely reproduce only slowly. But if the biofilm retains liquid water through to daytime there isn’t really any limit on how warm it could get and still retain liquid within the biofilm that perhaps Earth life could colonize.

There are many other potential microhabitats on Mars, even in equatorial regions. For a couple of examples see Microhabitats - such as micropores in salt pillars and ground hugging water vapour as morning frosts evaporate in my preprint.

Also there may be underground caves that communicate with the surface. These would be of many different types on Mars, as varied as on Earth and some formed by processes unique to Mars involving dry ice, or rare on Earth involving sulfuric acid. Most of them won’t be easy to spot from orbit, just as caves on Earth are hard to spot from orbit, with entrances that are often hard to see even when you approach them on the ground. Penelope Boston lists some of the types of cave possible on Mars (Boston, 2010)

  1. Solutional caves (e.g. on Earth, caves in limestone and other materials that can be dissolved, either through acid, or water). The abundance of sulfur on Mars may make sulfuric acid caves more common than they are on Mars.
  2. Melt caves (e.g. lava tubes and glacier caves)
  3. Fracture caves (e.g. due to faulting)
  4. Erosional caves (e.g. wind scoured caves, and coastal caves eroded by the seas on ancient Mars)
  5. Suffosional caves - a rare type of cave on the Earth, where fine particles are moved by water, leaving the larger particles behind - so the rock does not dissolve, just the fine particles are removed.
  6. Sublimational caves caused by dry ice and ordinary ice subliming directly into the atmosphere (a process that doesn’t occur on Earth).

See also these sections of my preprint:

Some think that it is possible that Mars has fresh liquid water in polar regions, a few tens of centimeters below the surface, protected from the surface vacuum by clear ice and melted by the solid state greenhouse effect. This should happen according to the models if Mars has ice similar in properties to the clear blue ice in Antarctica (where a similar process occurs).

Perhaps there could even be liquid water in equatorial regions too when the early morning frost (discovered by Viking) melts. This is preliminary unpublished research at present.

Andrew Schuerger’s lab at the University of Florida recently made a startling, albeit preliminary, discovery. He tested the effect of frost (first discovered on Mars by the Viking mission) on rocks under Martian conditions, and found that liquid water flowed on the rocks for about 15 minutes, before all the water turned into the gas phase.

Life could exist on Mars today, very close to the surface - AirSpace magazine

There have been at least as many new proposed near surface habitats for Mars since the striking Phoenix leg droplet observations in 2008 as there have been years.

Then let’s look briefly at the RSLs, top candidate for many astrobiologists.


Skip to: Dust cascades explanation

Many dark streaks form seasonally on Mars. Most of these are thought to be due to dry ice and wind effects. This image shows an example, probably the result of avalanche slides and not thought to have anything to do with water:

Slope Streaks in Acheron Fossae on Mars - these streaks are thought to be possibly due to avalanches of dark sand flowing down the slope

Notice that these avalanche streaks are dark, and broad. They take decades to fade away.

However a few of the streaks form in conditions that rule out all the usual mechanisms. These are the Warm Seasonal Flows, also known as Recurrent Slope Lineae.[100]

  • They form on sun facing slopes in the summer when the local temperatures rise above 0C so far too warm for dry ice.
  • They are not correlated at all with the winds and dust storms.
  • They are also remarkably narrow and consistent in width through the length of the streak, when compared to a typical avalanche scar.
  • They develop seasonally over many weeks, gradually extending down the slopes through summer - and then fade away in autumn

  • Warm Season Flows on Slope in Horowitz Crater (animated)

The leading hypotheses for these remains that they are correlated in some way with the seasonal presence of liquid water - probably salty brines.


Skip to: Why life on Mars need not be related to Earth life

A 2017 paper did show that the some aspects of these features are more consistent with dust cascades. That got widely reported (if you follow the news on Mars astrobiology), but what hasn’t been reported so much are the many difficulties with this explanation, which suggest it is only part of the picture. I found those through literature searches rather than news stories.

These papers suggest they are not yet fully understood and may still contain substantial amounts of brines. I wrote a summary of this research for a draft astrobiology article I’m working on myself (work in progress) (cites here take you to my version of the article in google docs)

The Recurring Slope Lineae (RSL’s) remain a leading candidate for brines that could be habitable, although there is considerable debate in the literature about the amount of brines present and whether they may be habitable. In planetary protection discussions since they may be the result of aqueous processes they are treated as “an Uncertain Region that is to be treated as a Special Region until proven” (Rettberg et al, 2016).

A study of RSLs in Eos Chasma shows that the features are consistent with dust cascades, since they terminate at slopes matching the stopping angle for granular flows of cohesionless dust, and they also ruled out formation of substantial quantities of crust‐forming evaporitic salt deposits, though the hydrated salts and seasonal nature continue to suggest some role for water in their formation (Dundas et al, 2017).

Difficulties with the dust explanation include the rapid fading away of the streaks at the end of the season, instead of the more usual decades, and a lack of an explanation of how the dust is resupplied year after year. Resupply also remains a major question for the models involving substantial amounts of liquid brines (Stillman quoted in David, 2017). A study of RSLs in the Valles Marineres finds that they seem to traverse bedrock rather than the regolith of other RSLs, and that if water is involved in their formation, then substantial amounts must be needed to sustain lengthening throughout the season (Stillman et al, 2017).

I will be citing from my preprint here, registered with the Open Science Foundation, but will just be using it here for its literature summaries:

Potential Severe Effects of a Biosphere Collision and Planetary Protection Implications


Skip to: Why astrobiologists are not so keen on a sample return right now

The Chicxulub impactor did send material from a shallow tropical ocean to Mars, 66 million years ago, but it would be hard for a microbe to withstand the shock of impact, fireball of ejection from our atmosphere, ionizing radiation, cold and vacuum of space, and then to find a home on present day dry and dusty Mars congenial to it.

If there is Earth life there, it’s most likely transferred billions of years ago when Mars had seas and big asteroids tens to hundreds of kilometers in diameter hit Earth able to punch a hole in our atmosphere and send rocks all the way to Mars with relatively little by way of shock or atmospheric heating.

In the other direction, if it is native Mars life we don’t know its capabilities but it could easily be damaged beyond recovery by the instant shock of ejection from the Mars surface - and all of the meteorites we have at present come from at least a couple of meters below the surface and ejected from the southern uplands where the air is thinner so that smaller impacts can send material all the way to Earth. The most likely habitats for martian life are also fragile - dust, ice, salts, and it would not be easy for life in those to get to Earth.

Again the easiest time for martian life to get to Earth is in the early solar system when Mars had seas, and later, lakes, and then it depends on its capabilities back then, whether it could do this.


Skip to: Colliding biospheres could be beneficial

Although not concerned about the safety issue for a sample return, I do think it is not the best of strategies from an astrobiological standpoint, because astrobiologists don't seem to be keen on a sample return at present, not until we first find life on Mars.

They think it is likely to return rocks not that different from the martian meteorites we have already. Indeed, our two most interesting Martian meteorites, ALH84001 and the Tissint meteorite would be marked as top priority targets to return from Mars. The context might give some useful information but they would be likely to be as inconclusive to astrobiology as the meteorites we already have. From their perspective, it seems like an extremely expensive way to possibly add some small fragments of meteorites to the ones we already have. Or, perhaps it is a demo mission for a future time when we might know what it is we want to return from Mars for the purposes of astrobiology.

The astrobiologists want to send life detection instruments to search for life in situ on Mars. Only after that, they would then look into sample returns.

I haven't found any recent papers by astrobiologists in favour of a sample return.

As Chris McKay put it, in this interview

If we’re going to search for life, let’s search for life. I’ve been saying this to the point of exhaustion in the Mars community. The geologists win hands down as they are entrenched in the Mars program...

...Right now, as far as I’m concerned, there is no alignment between the Mars strategy and astrobiology.

See my:

Astrobiologists arguing strongly for an in situ search on Mars first

Anyway there doesn't seem much one can do about this. NASA are set in this direction and it would take a lot to change it, with the rover built and ready to go.


Skip to: Possibility of hazardous life for astronauts on Mars

If you are optijmistic, it might be that humans, by going to Mars and shedding micro-organisms, just provide a wider range of habitats for martian life - and that in turn the martian life never harms us either but is only beneficial in its effects on Earth life too. Perhaps it may be a wonderful symbiosis of the two biospheres. For example, introduced lichens, if Mars has never evolved them, could provide habitat, shelter (from the UV) and food, as a prime producer, using just carbon dioxide, water vapour, and trace elements from the basalt. If Mars had lichens in the past and they went extinct, it could help through taxon substitution.

Schlaepfer et al did a survey of invasive species and in their table 1 they find many non native species that are actually beneficial. Some were deliberately introduced for their value for conservation. Many of the best examples were introduced unintentionally. Here are some of their categories.

  • Habitat, shelter, and food for native species (e.g. non native tamarisk as nesting sites for nesting birds, and non native plants in California for native butterflies to lay their eggs and for the caterpillars to feed).
  • Catalysts for restoration - e.g. non native guava trees in Kenya support fruit eating birds and encourage seed dispersal leading to forest restoration
  • Ecosystem engineers - e.g. non-native sea squirts (ascidian) in intertidal waters in Chile creating three dimensional matrix that increases species richness
  • Taxon substitution - e.g. Aldabra giant tortoise replacing extinct Cylindraspis giant tortoise in the Mascarene island (this one was intentional)

    The potential conservation value of non‐native species.

Perhaps non native life from Mars could benefit Earth ecosystems too in some way. For instance, it could, help challenged ecosystems to take up nitrogen more efficiently for instance (nitrogen is rare in the Martian atmosphere and it is just on the verge of possible for Earth microbes to fix it at those pressures, for a survey of the literature, see my section Sources of nitrogen - essential for life on Mars , in Okay to Touch Mars?: or my Sources of nitrogen on Mars in my preprint Potential Severe Effects of a Biosphere Collision).

But it could be harmful.


Skip to: Value of interesting indigenous martian life

Enthusiasts for humans on Mars should also care about making sure that it is a safe place for humans to land. If there is life there, they need to know what precautions to take.

Sometimes enthusiasts argue that martian life is not likely to be able to survive in human habitats because of the lack of oxygen, warmth etc. Robert Zubrin compares this with sharks trying to survive in the savannah.

However, it’s not so different as it seems. The surface of Mars is highly oxygenated with perchlorates, hydrogen peroxide, a small amount of oxygen in the air and potentially significant amounts in the brines, according to the work of Vlada Stamenković. This is an interview I did via email with him:

Also Earth is not likely to be too warm. Mars probably has hydrothermal vents, and so, at least some microbes that in the past have lived in very hot conditions and pre-adapted to live in such conditions. What’s more the surface is often well above zero degrees centigrade in the equatorial regions in daytime.

Until we know more it’s reasonable to suppose that Martian life is able to survive on Earth. Also, after returning it to Earth then over a period of time, if it is able to compete on equal terms with Earth life, it can spread and adapt perhaps to all or most of our ecosystems.

Would an ecosystem work the same way if half the microbes are Earth originated and half are martian life? If the martian life is based on a different biochemistry? Perhaps with perchlorates used internally instead of chlorides, and producing different chemicals that make sense on Mars but are unfamiliar with Earth life?

If it spread through Earth’s biospheres and most microbiomes became a mix of Earth and martian microbes, many or all higher life on Earth might not be adapted to coexist with these microbiomes with their alien chemistries (for instance their cells might well incorporate perchlorates instead of salts and chemical signals and toxins from an alien biochemistry). Toxic algal blooms in the Great Lakes kill dogs and cows that eat them, so for sure, alien life could harm us if it spread through our ecosystems.

From the example of legionnaires’ disease it could be harmful to humans directly too. Amongst other points, antibiotics would be likely to do nothing to stop life based on an alien biochemistry. After all, Earth microbes evolve resistance by using alternatives to the particular cell processes targeted by the antibiotics. Alien life, if based on a different biochemistry, would likely already use different cell processes from the ones targeted by the antibiotics. Our medicines would most likely offer no or little protection to us.

Also, there could be acidophiles on Mars as well. It’s likely to have acidic sulfate caves for instance. Martian life might perhaps be able to live in our guts too. Would our digestion system work the same way if half the microbes in our guts, eventually, originated on Mars?

So, it could be harmless, yes, but there is a distinct possibility that we find life on Mars that is hazardous to humans. It is because of this possibility that we are required to check it is safe before returning any to Earth.

The physicist Claudius Gros briefly describes the potential results of a clash of biospheres in his "Genesis project" to develop ecospheres on transiently habitable planets (see section 4.2 Biosphere compatibilities of this paper). Here, he makes an interesting additional point. Generally our biology only evolves defense mechanisms for a threat which is actually present, not just one that is a theoretical possibility that the life has never encountered.

If martian life is unrelated to Earth life, especially, then any threat it presents has so far only ever been a theoretical possibility as far as any Earth life is concerned.

He is using this argument for Earth life introduced to a foreign extraterrestrial biosphere, but you can equally apply it the other way around for martian life returned to Earth.

"Here we presume, that general evolutionary principles hold. Namely, that biological defense mechanisms evolve only when the threat is actually present and not just a theoretical possibility. Under this assumption the outlook for two clashing complex biospheres becomes quite dire."

"In the best case scenario the microbes of one of the biospheres will eat at first through the higher multicellular organism of the other biosphere. Primitive multicellular organism may however survive the onslaught through a strategy involving rapid reproduction and adaption. ... "

"In the worst case scenario more or less all multicellular organism of the planet targeted for human settlement would be eradicated. The host planet would then be reduced to a microbial slush in a pre-cambrian state, with considerably prolonged recovery times. The leftovers of the terrestrial and the indigenous biospheres may coexist in the end in terms of ‘shadow biospheres’ "

If this is all accepted, it makes sense for the enthusiasts too to find out what is on the Mars surface before landing humans there.

It could be that it is totally harmless, or indeed beneficial. Or it could be harmful. We need to know.


Skip to: The spectacular HERRO telerobotics orbit

This may seem bad news to potential colonization enthusiasts. But if we can protect Mars and it has interesting indigenous life this would be a huge incentive to send humans there, to study it from orbit. They could explore the surface via telepresence far more thoroughly and rapidly than robots on the surface.

This approach is safe, practical, seems likely to do most science return for the least cost and also is the only reasonably sure way to protect both any native Martian life and the environment of Earth. It was highlighted in the NASA Telerobotics symposium for its planetary protection credentials, and as a fast effective way to do the science.

Telerobotics Could Help Humanity Explore Space Credit NASA / GSFC. "Safely tucked inside orbiting habitat, space explorers use telepresence to operate machinery on Mars, even lobbing a sample of the Red Planet to the outpost for detailed study." - I've added the HERRO image of a tele-operated Centaur as an insert.

The astrobiologists say we need to look for life in situ first, so that we can distinguish the organics that fall on Mars from space from any indigenous abiotic organics, and the probably faint and scattered traces from indigenous past or present day life. See How do we search for life from orbit? - The amazing advances in the technology for In situ biosignature detection instruments. Geological samples could be sterilized on the surface, perhaps with a portable gamma ray source, equivalent to a few million years of surface ionizing radiation (which would still preserve some of the organics, similarly to the organics in Martian meteorites).. As for biologically interesting samples, they could be returned to separate telerobotic facilities around Mars or Earth, or back to the habitat itself if by then they know enough to be sure that it is okay for humans and Earth to enter the chain of contact.

See my Will First Mars Astronauts Stay In Orbit - Tele-operating Sterile Rovers - To Protect Earth And Mars From Colliding Biospheres

Is This Why We Haven't Found Life On Mars Yet? Value Of Actually Looking


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Telerobotics lets us explore Mars much more quickly with humans in the loop. The early stages of telerobotic exploration of Mars would use an exciting and spectacular orbit if we follow the HERRO plans. Every day the Mars space station would come in close to the poles of Mars, swing around over the sunny side in the equatorial regions and then out again close to the other pole, until Mars dwindles again into a small distant planet - and not only once. It does this twice every day. This "sun synchronous" orbit always approaches Mars on its sunny side so you get to see both sides of Mars in daylight from close up, every single day.

Imagine the view! From space Mars looks quite home-like, and the telerobotics will let you experience the Martian surface more directly than you could with spacecraft. You'll be able to touch and see things on the surface without the spacesuit in your way and with enhanced vision, and adjust the colours to show a blue sky also if you like. It's like being in the ISS, but orbiting another planet.

12th April 2011: International Space Station astronaut Cady Coleman takes pictures of the Earth from inside the cupola viewing window.- I've "photoshopped" in Hubble's photograph of Mars from 2003 to give an impression of the view of an astronaut exploring Mars from orbit.

This is a video I did which simulates the orbit they would use. I use a futuristic spacecraft as that was the easiest way to do it in the program I used to make the video. Apart from that, it is the same as the orbit suggested for HERRO.

(Click to watch on YouTube)

It would be a spectacular orbit and a tremendously humanly interesting and exciting mission to explore Mars this way. The comparison study for HERRO, completed in 2013, finds that a single orbital mission for a crew of six does more science than three similar missions on the surface, for far less infrastructure and only a little over a third of the total number of launches (you don't have to land the large human rated habitats on the surface of Mars) Here is a powerpoint presentation from the HERRO team, with details of the comparison. This is their 2011 paper and this is their 2013 paper on the topic.

Then, if you have humans orbiting for Mars, then for sure, you'd also have broadband streaming of everything back to Earth from Mars. As well as being very safe, also comfortable for the crew, you'd also have wide-field 3D binocular vision, which we can all share at home back on Earth.

It's amazing what a difference this makes, I recently tried out the HT Vive 3D recreation of Apollo 11. We'd have similar 3D virtual reality experience of the Mars surface. It would actually be a much clearer vision than you'd have from the surface in spacesuits, digitally enhanced to make it easier to distinguish colours (without white balancing the Mars surface is an almost uniform reddish grayish brown to human eyes), and so that we can see bright colours even as it gets dark, and indeed, with false colour you could see ultraviolet, infrared etc as well if you want to.

Here is a hololens vision, which though it's not telepresence, I think gives a good idea of what it might be like for those operating rovers on Mars in real time from orbit, some time in the future with this vision.

(Click to watch on YouTube)

And not only that. Everything you see on the Mars surface is streamed back to you via broadband of course. This means it can also be streamed right back to Earth. We will definitely have optical broadband between our Mars missions and Earth by then. There was proposal to do this in the early 2020s with a mission that would have streamed back 100 gigabytes a day, over 4 gigabytes an hour.

By then it will surely be gigabytes a minute or faster.

This means though, that we can build up copies of the 3D landscape back on Earth as you explore it and experts on Earth can walk into the very landscape you are in on Mars, and inspect the rocks, from all angles (if you have walked around them previously so that they have seen all sides). With multigigabyte images they can also be high enough resolution for scientists to study them close up as if they were looking at them with a geologist’s hand lens, higher resolution than you can yourself unless you choose to do the same while navigating in VR from orbit.


See also my

Read online for free here: OK to Touch? Mars? Europa? Enceladus? Or a Tale of Missteps?

Or buy here Touch Mars? Europa? Enceladus? Or a Tale of Missteps -

Read online for free here: Case For Moon First:

Or buy here: Case For Moon First: -

Read online for free here: Why Humans on Mars Right Now are Bad for Science. Includes: Astronaut gardener on the Moon

Or buy here: Why Humans on Mars Right Now Are Bad for Science-

And here is my astrobiology article that I’m working on - it may have some points of interest. It is not peer reviewed - this is an early stage, where I’m sharing it for comments and reactions but hope to submit parts of it for publication at some point.

Potential Severe Effects of a Biosphere Collision and Planetary Protection Implications

This is an extract from my