NASA are planning to return its Mars samples of rock and some dust / soil to biosafety level 4 facilities. That was fine in 2009. But the problem is that it doesn’t contain the very small microbes we now know exist called ultramicrobacteria which can get through a very tiny 0.1 micron nanopore and still be viable.

The samples are in tubes on Mars. They want to return them some time around 2033. The chance of returning life on those mainly geological samples is low. The chance it is dangerous if returned is also likely low. To give an idea of the order of risk I use Margaret Race's analogy of a smoke alarm. The risk of a fire in your house is so low most people don't panic about it. But you still install smoke alarms just in case.

Text on graphic: We need to install “smoke detectors” to protect Earth.

The risk of large scale effects from NASA’s mission is likely very low - indeed unlikely it returns life at all but it’s not demonstrably zero.

The risk of a fire to your house is also low.

We need the smoke detectors just in case. Especially for a “house” for billions of people.

Especially as we likely have many future missions like this from many countries.

Background graphics:

. Smoke detector.JPG - Wikimedia Commons

And this photo of a fire from the Los Angeles fire department, “Smoke alarm saves residents of a Bel Air home”

And fire extinguisher File:Fire-Extinguisher.JPG - Wikimedia Commons

What NASA is planning to do is like building a house but without smoke alarms or only dummy smoke alarms that don't really do much. That would be okay if it was their own house but it's a house for billions of people.

Also NASA is doing this quickly, "under the radar" for almost everyone in the world, and without the planning and oversight agency experts have said they should set up. They expect to have the legal process all done and dusted (as they say, English expression) by spring to summer 2023.

To see what I mean here, compare what NASA's draft Environmental Impact Statement (EIS) says with what the National Research Council said in 2009 about the risk of large scale effects to the environment or human health, if we do return a viable martian organism to Earth.

National Research Council:

The committee found that the potential for large-scale negative effects on Earth’s inhabitants or environments by a returned martian life form appears to be low, but is not demonstrably zero

NASA’s draft EIS:

… the potential environmental impacts would not be significant.

This difference isn't because of new understanding since 2009 - which if anything increases the chance of life from Mars with many new proposed microhabitats and small scale habitats on Mars. It's just because of mistakes in NASA's use of cites.

I don't know how it is even possible for something like this to get through NASA's internal review processes, but I can only describe what I found in the draft EIS. If you find any mistakes in this however small do let me know, at

National Research Council: The committee found that the potential for large-scale negative effects on Earth’s inhabitants or environments by a returned martian life form appears to be low, but is not demonstrably zero

Although exchanges of essentially unaltered crustal materials have occurred routinely throughout the history of Earth and Mars, it is not known whether putative martian microorganisms could survive ejection, transit and impact delivery to Earth or would be sterilized by shock pressure heating during ejection or by radiation damage accumulated during transit. Likewise, it is not possible to assess past or future negative impacts caused by the delivery of putative extraterrestrial life, based on current evidence.

NASA’s draft EIS: The relatively low probability of an inadvertent reentry combined with the assessment that samples are unlikely to pose a risk of significant ecological impact or other significant harmful effects support the judgement that the potential environmental impacts would not be significant.

You can visit the National Research Council page here: page 48 (just click the X close button to close the banner for other ways to access the report to visit the page)

They are doing this without the permission or knowledge of those billions of people either. They have skimped in other ways too - they haven’t done the study to check whether the size limit needs to be updated for the smallest particles to contain. The big ESF Mars sample return study in 2012 said they need to update this size limit periodically, and a decade later, NASA don't even seem to know that it needs to be looked at and are using evidence still from the limits of size workshop from 1999 from before we knew how tiny the pores are that ultramicrobacteria can get through.

You can comment yourself, go here, and click on the blue button to the left of the page to add a comment:

. National Environmental Policy Act; Mars Sample Return Campaign

You don't need to be an expert to comment. It's an opportunity for feedback from the general public as for any big project like building a bridge, or a reservoir or an oil pipline.

This is my public comment to them in May - they show no indication that they read it.

Are you aware of the ESF Mars Sample Return study (Ammann et al, 2012:14ff)? It said "The release of a single unsterilized particle larger than 0.05 μm is not acceptable under any circumstances”. This is to contain starvation limited ultramicrobacteria which pass through 0.1 micron filters (Miteva et al, 2005). Any Martian microbes may be starvation limited.

This 100% containment at 0.05 microns is well beyond capabilities of BSL4 facilities. Even ULPA level 17 filters only contain 99.999995 percent of particles tested only to 0.12 microns (BS, 2009:4).

It IS possible to filter 0.05 micron particles from water, under high pressure. One study used carbon nanotubes loaded with silver. It eliminated polioviruses at 0.03 microns in diameter (Kim et al, 2016) (Singh et al, 2020:6.3).

However, this technology doesn't seem to exist for aerosol filters.


My first sentence alerted them to the 2012 European Space Foundation study which said that a particle of 0.05 microns must not be released under any circumstances.

The ESF also said we need periodic review and another review is certainly needed a decade later.

… the ESF-ESSC Study Group recommends that values on level of assurance and maximum size of released particle are re-evaluated on a regular basis.

The release of a single unsterilised particle larger than 0.05 microns is not acceptable under any circumstance

WELL BELOW Biosafety 4 limits - we don’t have ANY air filters yet that can do this

Page 48 of 2012. Mars Sample Return backward contamination–Strategic advice and requirements

I checked the papers on filters and 0.05 microns is beyond the capability of even the best experimental air filters today.

There are many environmental laws now to protect Earth. So this shouldn't be permitted. So, I don't think NASA will be permitted to do this mission as planned.

They might be able to get through NEPA is by using this incorrect Environmental Impact Statement with many mistakes in it. It might fool the other agencies if they don't give it more than a few minutes read and don't check the cites or check it with independent experts or if independent experts don’t look at it closely enough. If anyone challenges it in the courts and it gets a detailed investigation, it will surely fall apart.

If they do get it through NEPA there's the Presidential directive where the president has to look at it if there is any risk of allegations of large scale or long term effects even if the agency thinks these are impossible. That then will stop it. It would then get the attention of numerous agencies in the USA and internationally and international treaties and organizations to protect human health, earth's environment, crops, seas etc.

The obvious solution is to sterilized any samples returned to Earth. Then the mission will be totally safe.

However, the EIS is written to make it impossible for them to look at this option. That is because they say in the Need and Purpose section that there is a need for safety testing of unsterilized samples and that this need can only be achieved in terrestrial laboratories.

I think this safety testing requirement is likely illegal by a 7th circuit case in the US in 1997, that an EIS Need and Purpose section can't be defined so narrowly as to exclude reasonable alternatives.

A sterilized sample return

  • does NOT need safety testing,
  • would cost less,
  • would achieve virtually all the science objectives
  • and is definitely a reasonable alternative.

Also they don't even explain how to do this safety testing. The permitted levels of contamination from Earth life is enough to completely fill thousands of ultramicrobacteria with each biosignature. It will be impossible for astrobiologists to certify them as free from native Martian lie so this safety testing is even impossible.

Text on image: Example of how design decisions for Perseverance were based on engineering and geology rather than astrobiology.

This tube was used to collect the first sample from Mars.

For a geologist, it is exceptionally clean, at most 8.1 nanograms of organics and at most 0.7 nanograms per biosignature.

For an astrobiologist, 0.7 nanograms per biosignature is enough to fill at least 7,000 ultramicrobacteria with just that biosignature, e.g. glycine, or DNA (maximum volume 0.1 cubic microns per ultramicrobacteria)

Astrobiologists need 100% clean sample containers with no organics. Their life detection instruments designed for in situ searches on Mrs can detect a single amino acid in a gram.

For engineers, sterilization would add an extra mission critical failure point because they would need to open the sterile container for the tube on Mars.

I am not sure what to do about this.

Meanwhile you can all help by commenting here saying you want them to keep Earth safe as top priority. It is fine to link to my article as a reason.

Do feel free to comment on their comments page. They aren't getting many -public comments as the whole thing has had very little publicity.

And just to add this is VERY unlike NASA. They are normally so careful, open, and accurate. It is hard to understand how it got through their internal processes for quality control.

So how did this happen? I think Margaret Race (of the SETI institute) hit the nail on the head way back in 1996.. She says scientists are likely to focus on

  • technical details
  • mission requirements
  • engineering details
  • costs of the space operations and hardware

General public are likely to focus on

  • risks and accidents
  • whether NASA and other institutions can be trusted to do the mission
  • worst case scenarios
  • whether the methods of handing the sample, quarantine and containment of any Martian life are adequate

We see the results of this different focus in the report. It is just not something that greatly occupies the minds of the engineers and scientists who work on space projects, yet it is the main thing on the minds of members of the public.

The report gives the impression that it was hastily put together and that they are not giving it much attention and just want it all out of the way to move on.

If so, they are in for a rude shock there as the public DO care about the safety of Earth and to keep it safe even if the risk may be very low. And the result would be a mission that is better not worse for the science too.

They can make it far more interesting for astrobiology by returning samples of soil, dust and atmosphere in STERILE containers

NASA could greatly increase the interest of this mission for astrobiologists by digging a scoop of dirt and returning it in a STERILE container.

Perhaps this gripper could double as a scoop somehow?

The digging tool, lower center, was used by Viking to scoop up material from the surface soil for the Viking experiments , Mars - Viking 1 Lander

Inset: Frame at 17 seconds from video of an artist’s impression of the ESA fetch rover collecting a sample left on the surface by Perseverance

NASA could use this to return a sample of dirt in a STERILE container.

Then they could return these bonus samples to a satellite above GEO where astrobiologists can send their exquisitely sensitive miniaturized instruments they hope to send to Mars eventually to search for life.

Text on graphic:

Mars may resemble Earth's coldest driest deserts: small niches for life adapted to extreme conditions, perhaps habitable at microbial scales only.

Earth is protected from a Mars sample return by numerous laws to protect Earth's biosphere that didn't exist in 1969.

Solution 2: study in a safe orbit above Geostationary Earth Orbit (GEO) first.

Humans never go near the satellite.

Samples stay above GEO.

No risk to Earth's biosphere.

Astrobiologists study samples in orbit much as they would do controlling a rover on Mars.

Sterilized subsamples can be returned immediately.

How to keep Earth 100% safe with minimal impact on science or cost – technology doesn’t exist to contain ultramicrobactieria.

So we can

1. sterilize all samples or

2. check for life first - to do this, return samples to a safe orbit above GEO to study remotely with miniature instruments like those designed by astrobiologists to search for life on Mars.

With 2. we can return sterilized sub-samples from the orbital facility immediately.

In 2, a return to the ISS doesn't break the chain of containment with Mars and COSPAR decided the Moon must be kept free of contamination for future astronauts and tourists. Above GEO solves both these issues.

1. and 2. both have simple legal processes.

By NASA regulations, build can't start until technology is decided. Build estimate: 9+ years + 2 years to train technicians.

Earliest date ready: 2023 + 11 = 2034

However, the technology doesn't exist yet for the 2012 European Space Foundation requirement of 100% containment of 0.05 micron particles even a decade later. This limit may also be reduced further on review.

Also added text to ESA graphic (Oldenburg, 2019) showing current proposed timeline (NASA, 2022mpfs) and time until the facility is ready to receive sample

They can detect a single amino acid in a gram with those instruments. Do gene sequencing (end to end including sample preparation). Superesolution imaging that means better than optical. Even a miniaturized scanning electron microscope, and an off axis holographic microscope which lets you refocus the image to look at 3D details of microscopic specimens AFTER the image is returned to Earth and many other instruments - and these are a kilogram or less most of them, and we can send multi-ton satellites now to above GEO and more than that by the 20230s. This has no risk to Earth as the unsterilized samples remain in orbit and no human goes near them.

So, unlike geology, the astrobiologists can do a lot of their work in space remotely even on Mars and can do it above GEO with much less latency. With Ariane 5 we have sent spacecraft of over 7 tons to above GEO. These instruments weigh fractions of a kilogram up to a few kilograms. We can send between hundreds and thousands of these instruments to above GEO in one payload.

The largest satellites in GEO are over 7 tons List of heaviest spacecraft - Wikipedia

The Ariane 5 can send payloads up to 9.6 tons to GEO Ariane 5 – Largest-ever telecommunications satellite launched

Also from NASA's point of view - these are all expenses for the 2030s and not only that, they are expenses that universities would be likely to take on similarly to the way they fund large terrestrial telescopes. For NASA it would add very little to the mission cost.

I think even this expanded mission with extra samples might turn out to cost less for NASA than their proposed mission. The sterilized sample return surely would, as it would eliminate all their expensive, elaborate and ineffective precautions and be 100% safe for Earth and the samples could be sterilized on the journey back using nanoscale X-ray emitters.

Anyway do comment on the NASA website saying whatever your own thoughts are on the project, such as that you care and it's important to keep Earth safe. They aren't likely to stop this buggy EIS just because of that but along with the other things I'm doing it will help. They aren't getting many -public comments as the whole thing has had very little publicity.

Everyone - do comment if you have thoughts about the project - go here, and click on the blue button to the left:

. National Environmental Policy Act; Mars Sample Return Campaign

You don't need to be an expert. It's a request for public feedback as for any big project like building a reservoir or an oil pipeline.

Text in red: Comment period ends on 20th December

(blue button to the left, circled with a red dashed line)

Click here to comment

Page is here: National Environmental Policy Act; Mars Sample Return Campaign

I've got an open letter to experts and the general public here where I've focused it very strongly on the particular passages in the report of most concern that I want to draw everyone's attention to, it also links to a copy of the EIS with annotations and a long detailed academic analysis I did.

Blog post for space colonization enthusiasts:

And longer blog post here for the general public.

And my video here, where I talk about that second blog post:

(click to watch on Youtube)

This post as a tweet thread:


However though Mars looks completely dry, it has some briny seeps just below the surface of the sand dunes in places. In Jezero crater they probably form only briefly in the early morning and late at night but in other places they can last longer. Most of the brines are far too salty for life and they take up the water at night - but at times they take up enough water for life as we know it to be possible except that it is then very cold, -70 C because the atmosphere gets most humid when it is very cold.

Modern Mars looks totally inhospitable from space – but it has a thin atmosphere and Curiosity found very cold salty brines that sometimes form overnight in Gale crater – the same process should happen in Jezero crater – though too cold for terrestrial life these brines might be habitable to biofilms that retain the water through to daytime when it gets warmer.

[Arrow points to Gale crater]

These brines may also be habitable to Martian life if it can withstand lower temperatures.

Image from How to Search for Life on Mars,

However we get life in very inhospitable places using biofilms where microbes work together in a community to make a kind of microbial home that is wetter or has more organics or protected from UV or in other ways more habitable. Possibly even Jezero crater might have these little biofilm homes especially for Martian microbes that adapted and evolved on Mars for billions of years.

How EPS (extrapolymeric substances) can make a “home” of the hostile Martian surface.

Some of the environment stressors

100% humidity varies to 0%

Heat, cold, UV, dust storms

Oxidants, nutrients

Algae may add oxygen

Retains moisture from night to daytime when temperature soars from -70°C to above 0°C.

Cryoprotectants - protects from cold shock

Extrapolymeric substances (EPS): proteins, DNA, lipids, polysaccharides, other large organic molecules.

A biofilm is like a microbe’s “house” which can keep it warm, wet, protected from UV and which it shares with other microbes.


So you get many different ideas about how possible or not present day Mars life is. If you go by the most optimistic it’s possible that Perseverance returns life, perhaps as viable spores in the dust. If you go by the least optimistic there may be almost no life or none at all, there may well be habitats, but perhaps life went extinct millions of years ago or spreads so slowly it never got to them and only lives deep below the surface today. So those are basically the two main streams of thought in modern astrobiology, life deep below the surface or not there at all, and life much more common - but even the most optimistic would say it’s still rare, patchy, a few patches here and there in a vast desert, sometimes a thin biofilm, sometimes a few thousand cells per gram of dirt - that’s by analogy with the most inhospitable deserts on Earth which are probably roughly as habitable as the most hospitable deserts on Mars.


So - you’d think that sounds harmless. And perhaps it is. Maybe even beneficial to Earth life, it may be able to live in places terrestrial life can’t and help green our most barren deserts or the deserted areas of our seas. The entire domain of achaea is largely beneficial to other forms of life.

But we don’t know what is there and you can think of other scenarios where it might be harmful. Individual species, opportunistic molds, say, or pathogens of biofilms that can also live in human lungs, molds that can grow on crops. Algal blooms that could be toxic. Or it might be a novel type of life with e.g. more or different bases like Hachimoji DNA with 8 bases instead of 4 which has been made in the labs but is safe because it depends on chemicals that only exist in the lab. Or, and this is my example, mirror life. That is life which evolved from the get go in the opposite direction with its DNA spiralling the other way, and all its starches, proteins, enzymes reflected as in a mirror. So what happens if half the microbes in a biosphere are mirror life? Itr might not work very well. Even worse the mirror life might eat ordinary organics but ordinary life not be able to eat it.


That doesn’t mean any of that is likely. It is just that we do need to know what is there, what lives on Mars before we know what precautions we need to take, if any.

Until we know that it’s safest of all to just pre-sterilize everything returned from Mars before it gets here.

Anyway NASA are usually so careful and I’m baffled at what is happening here. They are cutting corners and that’s the puzzle..

So - given that we know how to keep Earth 100% safe by pre-sterilizing the samples before they come to Earth - why not do that? That’s the simplest solution and it makes so little difference to the science - the motivation for doing anything else isn’t; very compelling if y ou have that as an option.

But NASA has made it not an option in this statement.

That is what is so baffling about it, that it doesn’t have a sterilization option and it downplays the very low risk of returning life when all the big sample return studies are clear that we do need to protect Earth.

See also my

. Many Serious Mistakes In NASA's Samples From Mars Environmental Impact Statement - Proposals For A Way Forward