Yes, both. And Mars is a connected planet, with a global weather system including its dust storms which would protect microbes from UV light. And UV light is blocked just by ashadow or a microbe is shielded in a tiny crack in a grain of dust. So, you can't rely on it to keep the microbes away from the rest of Mars. So, if there are surface habitats, I think it's hard to see how realistically you could have humans on Mars without contaminating the entire planet eventually. Human occupied spacecraft could also crash, e.g. a mistimed or too long or too short insertion burn leading to a crash into the higher latitude "special regions". So - I don't see myself how the astrobioloogists in COSPAR will be able to pass a human landing on Mars as consistent with planetary proteciton on current understanding - although the planetary protection officer in the US and others have said they think it is possible. Just don't see it myself, will be interested to see what the plans are if they think they have a way to do it safely without greatly increasing risk of contamination over robotic missions.
There's a lot of focus on the effect of human health. And - that is possible - though not adapted to Earth life, Earth life is also not going to be adapted to recognize it as a threat. That's a concern about synthetic life made in the laboratory here on Earth, so also for Mars life.
But there are many other ways it could be harmful. To prospective colonists - invade their greenhouses for instance and kill the plants, or make the soil unusable as a result of byproducts they create when they grow. Or allergens for humans. Or chemicals that resemble Earth amino acids but not identical and misincorporated when eaten in food, causing tangle diseases like Alzheimers. Or could just be altogether better at metabolizing and photosynthesizing than Earth life. Just by a tiny amount.
And unless it is totally one way, could have microbes harmless on Mars but harmful to essential species on Earth. Example, some form of photosynthetic lifeform that outcompetes Earth algae in the oceans, and produces chemicals hazardous to Earth life. Or that is harmful to any of the many species of plants, animals, microbes etc that humans rely on. Etc etc.
And quarantine can't protect against this -can't put all the Earth's species into the quarantine facilities to test them, and effects could also "switch on" like grashoppers becoming locusts, due to some stimulus or other not replicated in the facility. Or there can be incubation periods, for some human diseases, e.g. leprosy, incubation period can be decades.
The only solution I think is to keep Earth life far away from Mars life (or any other extraterrestrial life e.g. Europa, or Enceladus) and vice versa, and to study in situ. If we do a sample return, to return to telerobotically operated facilities in high Earth orbit, say above GEO, humans go nowhere near. Or sterilize everything returned to Earth. Until we know for sure.
We get tons of meteorites from Mars on Earth every century. But most probably come from uninhabited regions of Mars, the proposed habitats there are mostly fragile -salt deposits and such like. Most Mars life, maybe all, would be unable to make the transit in a meteorite - fastest 100 years in extreme cold, hard vacuum + cosmic radiation, unable to revive - some lifeforms could survive that but many probably not. And they come from meteorite hits on Mars every one or two million years, it's not like there's a constant stream of meteorites hitting Mars every year and sending material our way, most of the hits don't create any material at escape velocity.
So, we have to take care here, both ways. Could be as Sagan said that Mars life is completely harmless to humans. Perhaps you can eat kilograms of it with no ill effect, and perhaps it has no effect at all on our ecosystems. But until we know, we can't take such a risk with a billion lives, nor can we say it is safe for human colonists.
So, I think that surely we won't return life from Mars to Earth unless totally sure we can do it safely. At the time of Apollo, then they could publish their intended precautions on the day of the launch to the Moon. But nowadays you couldn't do that. If NASA do go ahead with their plan for sample return, it will be subject to intense international scrutiny, and there will be at least ten years spent passing new laws to permit it (that's an estimate by Margaret Race of SETI), during which it will need to be subject to world wide public debate and new international laws needed as well as the US ones. And the COSPAR astrobiologists - international organization again - would need to okay all the proposals too.
And similarly for humans on Mars, it would all have to be okayed after careful study of plans by expert astrobiologists and others, and not just from NASA, but internationally.
I have many articles on this topic in my Science20 blog
Will NASA's Sample Return Answer Mars Life Questions? Need For Comparison With In Situ Search
Mars Sample Return - Legal Issues and Need for International Public Debate
Need For Caution For An Early Mars Sample Return - Opinion Piece
There's a lot of focus on the effect of human health. And - that is possible - though not adapted to Earth life, Earth life is also not going to be adapted to recognize it as a threat. That's a concern about synthetic life made in the laboratory here on Earth, so also for Mars life.
But there are many other ways it could be harmful. To prospective colonists - invade their greenhouses for instance and kill the plants, or make the soil unusable as a result of byproducts they create when they grow. Or allergens for humans. Or chemicals that resemble Earth amino acids but not identical and misincorporated when eaten in food, causing tangle diseases like Alzheimers. Or could just be altogether better at metabolizing and photosynthesizing than Earth life. Just by a tiny amount.
And unless it is totally one way, could have microbes harmless on Mars but harmful to essential species on Earth. Example, some form of photosynthetic lifeform that outcompetes Earth algae in the oceans, and produces chemicals hazardous to Earth life. Or that is harmful to any of the many species of plants, animals, microbes etc that humans rely on. Etc etc.
And quarantine can't protect against this -can't put all the Earth's species into the quarantine facilities to test them, and effects could also "switch on" like grashoppers becoming locusts, due to some stimulus or other not replicated in the facility. Or there can be incubation periods, for some human diseases, e.g. leprosy, incubation period can be decades.
The only solution I think is to keep Earth life far away from Mars life (or any other extraterrestrial life e.g. Europa, or Enceladus) and vice versa, and to study in situ. If we do a sample return, to return to telerobotically operated facilities in high Earth orbit, say above GEO, humans go nowhere near. Or sterilize everything returned to Earth. Until we know for sure.
We get tons of meteorites from Mars on Earth every century. But most probably come from uninhabited regions of Mars, the proposed habitats there are mostly fragile -salt deposits and such like. Most Mars life, maybe all, would be unable to make the transit in a meteorite - fastest 100 years in extreme cold, hard vacuum + cosmic radiation, unable to revive - some lifeforms could survive that but many probably not. And they come from meteorite hits on Mars every one or two million years, it's not like there's a constant stream of meteorites hitting Mars every year and sending material our way, most of the hits don't create any material at escape velocity.
So, we have to take care here, both ways. Could be as Sagan said that Mars life is completely harmless to humans. Perhaps you can eat kilograms of it with no ill effect, and perhaps it has no effect at all on our ecosystems. But until we know, we can't take such a risk with a billion lives, nor can we say it is safe for human colonists.
So, I think that surely we won't return life from Mars to Earth unless totally sure we can do it safely. At the time of Apollo, then they could publish their intended precautions on the day of the launch to the Moon. But nowadays you couldn't do that. If NASA do go ahead with their plan for sample return, it will be subject to intense international scrutiny, and there will be at least ten years spent passing new laws to permit it (that's an estimate by Margaret Race of SETI), during which it will need to be subject to world wide public debate and new international laws needed as well as the US ones. And the COSPAR astrobiologists - international organization again - would need to okay all the proposals too.
And similarly for humans on Mars, it would all have to be okayed after careful study of plans by expert astrobiologists and others, and not just from NASA, but internationally.
I have many articles on this topic in my Science20 blog
Will NASA's Sample Return Answer Mars Life Questions? Need For Comparison With In Situ Search
Mars Sample Return - Legal Issues and Need for International Public Debate
Need For Caution For An Early Mars Sample Return - Opinion Piece
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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