On Mars with just an Oxygen Breather - requires 1000 years of terraforming

[robertinventor]

Hi there, just to say on last night's "Back to Earth" for "Star gazing live", Brian Cox said he thought that you'd be able to survive on Mars with just an oxygen breather. So presumably many people must think this.

Actually, there is no chance of that at all. Its "atmosphere" is a laboratory vacuum on Earth.

The atmospheric pressure at the bottom of Hellas Planitia is 1.24% of Earth normal. 

1.  "...the maximum surface pressure in the baseline simulation is only 12.4 mbar. This occurs in the bottom of the Hellas basin during northern summer",
   
   From On the possibility of liquid water on present day Mars (2001)

The Armstrong limit is 6.18% of Earth's atmosphere - the temperature at which water boils at the typical temperature of a human being. So everywhere on Mars then your saliva, and the moisture lining your lungs would boil. 

You would have to wear a suit like Felix Baumgartner in his leap from the edge of space. And if your suit developed a leak, you'd die quickly, even with plenty of oxygen to breath.

29% of the surface is above the triple point of water, meaning that water wouldn't boil instantly at 0C but would still evaporate quickly. There may be thin mms thick layers of liquid water there on salt / ice boundaries (Nilton Renno's team's recent simulations last year) and in the warm seasonal flows where it is kept liquid through presence of salt - also it could happen under ice, pure water but kept liquid because it is shielded from the atmosphere by the ice and in a few places near the southern polar region it could be liquid due to the solid state greenhouse effect where clear ice acts like glass retaining heat (Best Places For Droplets, Films And Shallow Flows Of Liquid Water On Mars - Where Microbial Life May Flourish).

So - it may be habitable for microbial life. Even for lichens. In very favourable locations. But not for humans, at all, even with oxygen breathers.

As for terraforming - just to get to the point where you can grow trees, and survive out of doors with an oxygen breather is 1000 years of high technology (space mirrors and greenhouse gas factories) according to the Mars Society plans - with a lot that could go wrong. See my Trouble with Terraforming Mars.

It's not nearly as habitable as many people seem to think. I'm in favour of free space settlement in orbit around Mars rather than on the surface - Deimos for instance probably has a lot of ice, (not yet confirmed but if it is a carbonaceous chrondite as it seems to be it may well have) - I wonder if it might even have nitrogen also, not impossible, something in short supply on the Moon or on Mars. I could imagine that being a basis for a settlement and space economy exporting ice to LEO perhaps. But hard to see anything working on Mars right now.

But as well as that - if you land humans on Mars you pretty much have put an end to planet protection from Earth life - especially as there has to be a high probability of the spaceship crashing and spilling dead bodies and everything in the spaceship across the surface of Mars. After that, then if you found life on Mars you'd never be sure if it was from Earth or from Mars especially since most microbial life on Earth is not yet DNA sequenced or characterized in any way at all.

And - it's not like we are looking for fossils on Mars, would be extremely lucky to get those. And present day life may well be microbial (lichens if we are very lucky).

So, what they are looking for, in case of past life, are chiral imbalances of amino acids, and chemicals that can only be produced by life, in deposits that are expected to be degraded by cosmic radiation. And present day life is in minute concentrations if it exists, like the life at the hyper-arid heart of the Atacama desert.

So - I think myself it is just far too soon to think about sending humans anywhere near the surface of Mars. Just as we wouldn't think of sending humans to explore the subsurface lakes in Antarctica. In that case the habitat has been insulated from the surface for just millions of years, but there is so much scientific interest in what happens in those conditions that we are extremely careful not to contaminate them with present day Earth surface life.

In case of Mars, if there has been any life exchanged, it's not happened for at least tens of millions of years (a meteorite impacting on Earth large enough to send a small amount of debris to Mars is about 10 km across or more) and given the challenges involved, may not have happened for billions of years and not known for sure of course if it ever happened.

So we surely don't want to send a bunch of trillions of microbes in tens of thousands of species to Mars before we know what is there! Which is what humans are, no way we can be sterilized, and 90% of the cells of a human being, by number, are microbes, not human at all. With some of those at least extremophiles too, you get them everywhere, microbes that can survive in extreme conditions, e.g. cliff faces in Antarctica or hydrothermal vents or whatever, but are also quite happy in our clothes, soil, or on our skin etc.

But we could explore it by telepresence from orbit. Which is as good as being there on the surface, indeed better, enhanced vision, haptic feedback, no need to wear spacesuit gloves, can "teleport"  to any lander or rover on the surface, live broadband streaming of everything you see, and no danger of dying due to a minor accident tearing your spacesuit or breaking your helmet glass etc, and avoids the most dangerous part of landing on the surface etc. Just seems a win win win situation to me, and I think that if we do send humans to Mars they will be in orbit for planetary protection reasons and all these others as well.  

Though doing that also is a major challenge - I think that when we reach the point where we can have people on the Moon who can stay there with resupply from the Earth only every two years or less, then we would be close to the point where it might possibly be safe to send humans to Mars orbit. If we still hae to supply multiple tons every three months to keep humans alive, as for the ISS, I don't see how we can go to Mars except at huge expense.

[robertinventor]

Sorry, typos etc, seems I can't edit it, should have said:

 

"That's well below the pressure at which water boils at the typical temperature of a human being - that's the Armstrong limit at 6.18% of Earth's atmosphere - 

 

So the atmospheric pressure everywhere on Mars is so low that your saliva, and the moisture lining your lungs would boil

 

You would have to wear a suit like Felix Baumgartner in his leap from the edge of space. And if your suit developed a leak, you'd die quickly, even with plenty of oxygen to breath

It's true that 29% of the surface is above the triple point of water, meaning that water wouldn't boil instantly but would still evaporate quickly. However that's at 0C

There may be thin mms thick layers of liquid water there on salt / ice boundaries (Nilton Renno's team's recent simulations last year) and in the warm seasonal flows where it is kept liquid through presence of salt - also it could happen under ice, pure water but kept liquid because it is shielded from the atmosphere by the ice and in a few places near the southern polar region it could be liquid due to the solid state greenhouse effect where clear ice acts like glass retaining heat (Best Places For Droplets, Films And Shallow Flows Of Liquid Water On Mars - Where Microbial Life May Flourish).

...
"

[ronin]

Why 1000 years?

It took one or two billion to terraform the earth.

We did not start with this atmosphere or much else that we have now. The perception is that it has always been like this and that is the first big misconception.

[robertinventor]

I don't think there are really strong reasons for it. That 1000 years is a round figure that is often used, e.g. Terraforming Mars (Mars Society), The Big Idea (National Geographic)

It's asssuming big technology such as making greenhouse gas manufacturing plants on Mars, moving Ammonia rich comets to Mars, large space mirrors in orbit around the planet to warm it up, etc. Some of the mega-engineering ideas described here: TEchnological Requirements for Terraforming Mars.

It's making many assumptions which you can challenge. For one thing, that there is enough CO2 in the form of dry ice on Mars to make a thick atmosphere when it warms up. 

And - it's based on idea of seeding Mars with life and - often they have the idea of somehow going through similar stages of evolution of the atmosphere to Earth - but hugely speeded up.

In my  Trouble with Terraforming Mars. I talk a bit about some of the things that could go wrong with it. LIke you, I'm skeptical about the idea myself, that we are anywhere near the level of technology or understanding to do this, or that it could be done anything like as quickly as 1000 years .

But in any case I think we probably won't send humans to the surface of Mars in the near future because I can't see how COSPAR could ever pass it for planetary protection - and how could all the nation states who are signatories of the OST say that the need for planetary protection of Mars is over when we have barely started to explore it at ground level and there is every chance still that it may have undiscovered past and present life?

[spartan45]

This topic interests me because, as mentioned in the post, all logic seems to point that sending people to Mars in the next decade or anytime soon is a disaster waiting to happen. Yet there are many clever people in the space industry apparrently seriously planning for such an endeavour. I am curious if they have an agenda or, more exciting, do they know something we don't.    

[robertinventor]

Hi spartan45,

I've talked to quite a few of the enthusiasts on quora and other places. The main motivation seems to be the idea of colonization. It's a bit like the old US idea of "Manifest Destiny" I think. Here in the UK most people haven't heard about it, so here is a link to a page about it. Basically the idea is that humans are destined to colonize, almost that we have a moral obligation to do this.

I think it is hard for us in the UK to understand quite how strongly this notion is held in the US. Then in addition they have the idea that there may be an acopalypse due. Many in the US - and probably in the UK also - greatly overestimate the chance of an incoming civilization threatening asteroid before the end of the century - say 15 km across or larger (the actual probability is about 0.0001%). And risk of an extinction causing asteroid - planetesimal rather than an asteroid - is surely just about zero as there are no recent impact craters that large in the inner solar system. And supernovas - the nearest potential near future candidates are just too far away to be a threat. As they say on the show, if Betelgeuse or Eta Carina were to go supernova, that would be of tremendous interest to scientists, but hardly a threat to the Earth at that distance. And even for Type 1a supernovae, we are getting to know our local stellar neighbourhood quite well now, and AFAIK there are no candidates close enough to be a significant threat to us, never mind threatening human extinction.

So - that's the reality of the situation I think. But they see it differently.

So - they have this idea that we have to colonize Mars quickly or we will go extinct. Based on greatly over estimating the habitability of Mars and greatly over estimating the possibilities of natural disasters and their effects on us. Plus this idea of manifest destiny that we have to colonize.

For instance in a recent discussion of planetary protection issues in a US conference on Mars, the planetary protection issues were bending over backwards to say that they think that the planetary protection issues would not hold back humans on Mars. But how can they say that in advance of COSPAR workshops etc on the subject? All the workshops so far have been inconclusive saying more research is needed, and it's not a proper evaluation if you start with this motive in advance that you have to somehow prove that it is acceptable to land humans on Mars.

So - I don't think that when it gets to the stage that the international community and COSPAR have to do the evaluations - just don't see how human missions to the surface can be approved.

But I think the likes of Elon Musk - they are probably influenced by the Mars Society and Robert Zubrin. And they in turn are confident that in one way or another their vision of human colonization of Mars will be fulfilled. Of course Robert Zubrin wrote the very influential "The Case for Mars". So that's the background also that many just accept what he says there. Though a lot of it is very controversial I think.

As for Mars One, it seems increasingly that it is probably - even verging on dishonest. At least hugely optimistic and far more focused on short term finance than the long term objectives. See this article which has been going the rounds recently: Mars One Finalist Explains Exactly How It‘s Ripping Off Supporters

So - I think - a mixture of optimism, and these background ideas that this is what the US should be doing in space - preparing for settlement and colonization - and also the idea that somehow or other, not exactly specified how - that the planetary protection issues will prove to be a minor hurdle easily overcome.

Robert Zubrin did publish a paper where he says that he thinks life on Mars is identical to life on Earth in the same locations. Based on meteorite transfer. He also says that we would find it easy to distinguish native Martian life (I'm not sure how those two statements are consistent with each other).

But his arguments don't hold up to close scrutiny, most would say. After all we don't have any confirmed examples yet of life transferred between planets on a meteorite and most lifeforms would be unable to do this even if it turns out that a few hardy ones can. The NRC report on Mars Sample Return for instance refutes his arguments against dangers of a sample return (without actually naming him as the originator of them). 

He repeats them often in his talks and I think has convinced a fair few who don't have much background in exobiology. 

This topic interests me because, as mentioned in the post, all logic seems to point that sending people to Mars in the next decade or anytime soon is a disaster waiting to happen. Yet there are many clever people in the space industry apparrently seriously planning for such an endeavour. I am curious if they have an agenda or, more exciting, do they know something we don't.    

So, I think that's about the size of it. And for some reason, though planetary protection is often mentioned in discussion of unmanned rovers to Mars - it is almost NEVER mentioned at all when the topic of human missions come up. Though of course it is a far greater issue for manned than unmanned missions. For instance Star Gazing Live didn't mention this at all in the discussion with Buzz Aldrin. That's not an isolated case. I can hardly remember a single program or article about humans to Mars that mentions this. For some reason even astronomers and scientists hardly seem to give it any thought unless they are astrobiologists.

[robertinventor]

Here is a quora answer I did about: What is the probability of a significant asteroid impact event by 2100, to the best of our knowledge?

[robertinventor]

See also my answer to  If it were discovered that an asteroid was going to wipe humanity out, say in 2 months, how would the governments of the world respond? How would people respond? How would you? and to Is it okay to destroy the earth because it will any way be destroyed by sun/volcanoes/tectonic shifts/Earth axis wobble/geomagnetic shifts/galactic shifts/asteroids/meteors etc?, and to Why is it important to colonize Mars? and How feasible is Elon Musk's idea to establish a colony on Mars in the 2020s?

I've been discussing this a fair bit especially on quora via these answers to questions. 

[robertinventor]

First one link not working: http://www.quora.com/If-it-were-discovered-that-an-asteroid-was-going-to-wipe-humanity-out-say-in-2-months-how-would-the-governments-of-the-world-respond-How-would-people-respond-How-would-you?share=1

[Cath]

Even if we had the technology to terraform the surface of Mars enough for Earth life to survive there, you'd still be a silly billy to go walk-a-bouts due to the Suns radiation. Mars has no magnetic field (where as Earth does) to help prevent the dangerous radiation reaching the surface.

So even if we did manage to create a lovely warm outside Martian environment, you'd still be stuck in doors under the protection of a thick'ish water blanket or metallic blanket of some kind.

How long vegetation would last in such a radiation ridden environment I do not know.

Their are several reasons why we don't see surface life over there on Mars.

I think a lot of this apparent need to get there asap is I expect mostly due to how Humans are, a lot of people have fairly extreme egos, which need to be satisfied for one reason or another. Being the first, fame, being noticed, attention, etc etc.

I have no doubt that whoever was silly enough to go there (with no way back), would soon be changing their mind after the reality of the situation they have got themselves into hits them face on. There are better, less distressing/painful ways to die!

[robertinventor]

Yes human Martians would have to be troglodytes. I'm sure nobody would want to spend much time out of doors given that it's going to add significantly to your risk of getting cancer when young (not just towards the end of your life like smoking). We also don't know if it is possible to be healthy in Mars gravity.

Yes - most Earth vegetation wouldn't have a chance of handling the Mars surface. And greenhouses, even at a tenth of Earth atmospheric pressure, would need to withstand 1 ton per square meter of outwards pressure. You might as well build those in free space as the Mars atmosphere is a vacuum to all intents and purposes here.

There are some lichens however, polar and alpine, adapted to live in areas of permanent ice - that can in theory survive on the surface. Also some cyanobacteria (especially hardy green algae, Chroococcidiopsis). At least they have managed okay in the DLR Mars simulation experiments on the Earth. They survive by taking up the night time humidity which reaches 100% even in equatorial regions on Mars. And they have pigments that protect them against UV light so long as they are partially shaded -so they would tend to live in the cracks and shadows, or rock surfaces somewhat slanted away from the sun, or a mm or so below the surface of a rock or below surface of the soil.

The thing is - that the most Mars like places on Earth - such as the heart of the Atacama desert, and the McMurdo dry valleys also look totally lifeless from orbit. It's only when you look really closely, can drill below the surface of rocks, or sample inside salt pillars, or dig underground, that you find that there is life there. 

Also the life there is in small populations. So - the most habitable places on Mars are perhaps getting on for as habitable as the McMurdo dry valleys. Especially if for instance the "warm seasonal flows" pan out. Or the droplets of water on salt / ice interfaces. We also have halobacteria on the Earth - the ones that turn the Red Sea red - they also are good candidates, some of them, to survive on Mars in very salty droplets of water and mms thick temporary flows.

So, I think there is a chance of life on Mars, present day life. And also enough of a possibility of Earth life surviving there so we need to take care to protect it. But not any chance of growing food etc there except in pressurized greenhouses.

[Pig]

Surely the possibility of a large impact on Mars is almost as likely for that of Earth ?

[Jesterowl]

If we manage to install the mirrors and other such stuff to create a breathable atmosphere on Mars wont it just get stripped away again by the solar wind ?

[spartan45]

Just four days ago (18 March 2015) the Scientific American published details of a mystery dust cloud and aurora on Mars over pockets of magnetic field above areas of possibly permanently magnetised surface crust. This dust cloud, I first saw reported several days ago was at 250 km, but is now at up to 2,000 km above the surface of Mars, probably because of the recent extra strong solar winds. I wonder if the problem of solar radiation could be solved by settling under one of these local magnetic fields. I still think settlement on Mars anytime soon is a no go. 

[robertinventor]

Shaun, yes, indeed the probability of a large impact is several times larger for Mars than for Earth because it is closer to the asteroid belt.

Also because of its thin atmosphere, you have the danger of really small meteorites - which burn up in our atmosphere. On Mars they would hit the ground. So a significantly higher risk of damage to structures from meteorites on Mars for two reasons, more of them anyway, and very thin atmosphere.

So, as you say, it's a bit bizarre to go to Mars to get away from big asteroid impacts .

[robertinventor]

Jesterowl, yes,  whatever process stripped Mars atmosphere originally would presumably happen again for sure. They don't know quite how it lost its atmosphere, that's what Maven is studying. But it certainly had a thick enough atmosphere for liquid water for the floods and seas a few billion years ago.

In the plans for terraforming Mars then they acknowledge that it will lose its atmosphere again. It's a temporary terraforming for a few hundred thousand years or some such. Which I think myself also raises major ethical issues. Supposing that it was possible to terraform Mars with present day technology. And suppose that we could do it without creating some biological disaster on Mars or somehow losing the atmosphere or the water early on (e.g. what if the water just sinks into the ground - which is probably dry to  considerable depth?).

If we do find a way to terraform it somehow - is it ethical? Some time, could be a hundred thousand years, could be a few million years from now, some time in the future this will become a planet that used to have a flourishing ecosystem but is now losing its atmosphere. And it may quite well have residents that are intelligent like us - but what if they have lost our technical ability? It's a harder planet to survive on probably than Earth.

Then they could be in a situation where their planet is losing its atmosphere, and they can't do anything about it.

They are just like us, but separated from us by time, that's all. I think we have responsibility to those future inhabitants of Mars if we terraform it. If it is possible for us to do it at all, which I don't know. 

I'm not saying that's impossible to do, to make a self sustaining planet with atmosphere etc from Mars. But it seems quite a bit beyond our present capabilities also, just like terraforming itself. Especially because Mars is so much lighter. It needs three times as much atmosphere by weight as Earth for the same atmospheric pressure. Easier for the gases to leave it anyway. And no magnetic field added on top of that. 

Also it has no continental drift. That's what returns CO2 to the atmosphere for Earth and helped to get it out of the snowball phase and to regulate temperatures. So on Mars you'd need to create something else that would substitute for continental drift, to return CO2 to the atmosphere when it gets taken up into the oceans and formed into chalks etc by sea creatures. Otherwise it will gradually lose all its CO2. Which we only need small amounts of, but plants do need some. And as well as that of course there's the big problem of a buffer gas on Mars, as it has no nitrogen or hardly any as far as we know and a pure CO2 atmosphere is very poisonous to humans.

So again if you wanted to truly terraform it so it is breathable for humans - if that is possible at all - you have to figure out not just how to maintain oxygen levels but also to maintain levels of nitrogen or other buffer gas - and also to maintain CO2 levesls, high enough for plants, but not so high that they kill humans. 

Current level of CO2 is 0.04% in the Earth's atmosphere. I think most people don't realize how little we have. Raise that to a few percent and it begins to be dangerous for humans. At 7 - 10% it is lethal.

So you need a fine balance for the CO2, and need to maintain that for the foreseeable future, along with a buffer gas of nitrogen in large quantities. All this works automatically on the Earth. We've evolved to be able to live in this atmosphere also. But I think very improbable myself that a Mars atmosphere would naturally have the right percentages of the various gases for humans, even if engineered that way, for long. Unless some amazingly clever planetary eco-engineering is going on there.

[Cath]

They know they can't terraform Mars Robert, the physics over there really is quite wrong for large bodied life to survive on Mars.

The immediate worry is for the currently misguided who are extremely eager to get there for whatever reasons they may have. If they survive the long tightly enclosed journey (which will not be easy for them for various reasons), they will certainly run into serious problems on location, problems that they will have no way of surviving.

I guess you've just got to be the type who is willing (and currently with certainty) to sacrifice your life for whatever reasons you'd have for going there.

[robertinventor]

Cath, yes that's an issue. 

I think that is a major problem with Mars One - except that I don't think it could happen anyway - that there is no way those candidates, from their videos - can possibly truly understand how hostile Mars is for humans.

It's also I think a major problem with space tourism. I don't think that those who sign for e.g. Virgin Galactica can possibly realize what a risk they are taking. They are not the sort of people who would sign up to do base jumping off a cliff in Norway or the Alps. Even the Soyuz has had only of the order of 200 flights ever - I don't think you can say that going up in a Soyuz is anything like as safe as driving a car, say. It's like driving a new model of car that has an entirely novel engine and chassis design that has only had 200 test drives. As for Virgin Galactica, that's like driving  new model of car that's entirely novel in its design, e.g. able to drive over water - or a flying car - and only had two or three tests.

In case of Mars - then I would give perhaps even chances of them surviving as far as Mars orbit with present day technology, could crash on launch or have major issues of some sort with life support if it's not tested for years already closer to home. And obviously a high chance of crashing during landing on Mars, even with Elon Musk's idea if it works, surely at least as high a chance of crashing in the space shuttle before they discovered the issues that caused the two crashes.

So for instance, if Richard Branson or Elon Musk, wanted to attempt a human mission to Mars personally - well they are both people who are comfortable taking physical risks in extreme sports, so people like that are capable of doing journeys like that with an understanding of the risks. I see no problem with that, if they make such choices for themselves. 

If that was all - the main thing would be to make sure they do it willingly and in full understanding of what they are doing. I wouldn't object to anyone doing that in a flight, say, to Mercury, which is Category I, thought to be extremely unlikely to have any chance of hosting life (though there might be a tiny chance in the ice at its poles I suppose). Currently no precautions at all are required for missions to Mercury, even landers or crash landing.

The main thing with Mars, for me, is that it is Category III for planetary protection. I.e. we think there is a reasonable chance that Earth life could survive there and reproduce. For as long as it remains classified as category III, then I don't see how it can be possible at all to send humans to the surface consistent with planetary protection.

And the main issue there - first legally - is that all the space faring countries have signed an agrreement to prevent harmful contamination of the solar system. Where "harmful" is generally understood as including "harmful to experiments of other participating nation states".

So if say the US introduces Earth life to Mars - that would be extremely harmful to e.g. the scientific experiments of ESA such as ExoMars and its successors. From then on, instead of just checking for biosignatures and amino acids chiral imbalances and other very sensitive tests - you'd also always have to DNA sequence the life, and try to test to see if it originates on Earth or Mars. Hugely more complicated. And even then, if it's the DNA sequence of some microbe from the crashed human spaceship - well that's tens of thousands of species, and most of them would be unknown to science, never characterized, never observed in a microscope and certainly never sequenced. Because that's the current state of microbiology that about 99% of all microbes are completely unknown to science. With entire philae (same level as chordates, one step higher than creatures with backbones)  known only from a few DNA fragments. Indeed they are not yet sure how many philae of archaea there are.

And as well as that - it could make Mars microbes extinct before they are discovered - potentially.

So - to comply with the Outer Space Treaty - they have to make sure they can't introduce Earth life to Mars - at least until all the participating countries agree that the exploration phase is now over. I can't see the ESA for instance telling the US that they no longer need to study a biologically pristine Mars any time soon.

And the problem is that once you introduce a new life form to a planet - that's irreversible. We don't know any way of removing a microbe from Mars if it finds conditions there hospitable for it (some extremophile) and starts to reproduce widely. Once you have long lived spores in the dust and spread with the wind and in caves throughout Mars - there is no way we could ever remove that lifeform from Mars again.

So - that's the main issue with human colonists on Mars. I think they are also misguided myself, can't see how it can possibly work. But I wouldn't stand in the way of someone trying to realize their dream, however hopeless it seems to me - so l ong as 

• They understand the risks, truly understand them 
• Their mission doesn't curtail the freedom and vision and hopes of others

In the case of a human mission to Mars then their dream would curtail the hopes of all the astrobiologists who want to study Mars in its pristine state. That's like introducing new species to say Galapagos islands or some other place of special biological interest.

And more than that - would potentially irrevocably alter Mars itself. E.g. suppose later you want to terraform Mars, even that - well you might not be too happy to find the planet already seeded by aerobes or other microbes that might fight against the very processes you are trying to encourage - eat up oxygen produced, and eat the cyanobacteria you are using to try to terraform Mars.

Also whatever species you introduced, as rapidly evolving microbes, would not stay the same. In the Mars environment of high levels of cosmic radiation and UV light -and these are species that already have the ability to co-exist with humans in our habitats - they could evolve to be biologically hazardous to humans or to crops or plants (species often retain old capabilities when they evolve to become extremophiles in new conditions so they would be likely to keep their capability to survive in huma habitats). And as  well as that if there is life on Mars and it is biologically related to Earth life, then through Gene Transfer Agents, the introduced life would swap fragments of DNA with the Mars life, which archaea especially do very readily. So you end up with new lifeforms that are part Earth and part Mars in their DNA. 

We just know far too little to seed Mars with Earth life intentionally. And to do it by accident is an irreversible change in Mars. And all the space faring nations have signed the OST which prohibits this and participate in the COSPAR which works out the details of how to prevent biological contamination of Mars and other places in the solar system.

[Ags]

I know the USA and other nations have signed agreements to avoid contaminating Mars and elsewhere with Earth life but... bacteria have proved repeatedly that they are smarter than us.