It hasn't been done deliberately, but it could have happened accidentally. We do a lot to try to prevent it from happening, and all the spacecraft are carefully sterilised. Hopefully this has worked, but the aim all along was a less than 0.1% chance of contaminating Mars in the exploration phase, not complete certainty as that's impossible.
There have been a number of crashes especially e.g. the Mars Climate Orbiter, the one that crashed due to mix-up of metric and imperial units, not sterilized for the surface. So perhaps the chance is higher than 0.1% but because Mars is so hostile, seems pretty likely that we haven't introduced life there yet.
It used to be thought impossible for life to survive on Mars, but that has changed, now there is thought to be a chance it could survive in micro-habitats just a few millimeters thin. Also some lichens from the Arctic it seems might be able to survive even on the surface in Mars, just using moisture from the air - it gets to 100% humidity briefly in morning and evening when frosts from. The micro-habitats work rather similarly, they form around deliquescing salts that take up moisture from the atmosphere at times of high humidity. With just the right mixture of salts, then the habitat might be one that life could use.
So, maybe it could happen. For now scientists are really keen to keep Mars free of Earth life so they can study it in its pristine state. Especially, there may be answers to many questions about the origins of life on Mars, because it was so Earth like when it formed, and for a few hundred million years before it lost its atmosphere and got colder. With no continental drift, and the cold, and some salts and clays able to preserve organics, it may be an ideal place to study the origins of life - or indeed, if life didn't arise there - what happens on a planet like Earth if life does not arise on it. Both ways, want to keep it pristine at least during this exploration phase.
Later on then maybe we could introduce life to Mars. But if so, would be a careful sequence probably using the process of Ecopoesis. The idea is to try to reproduce what happened on Earth but speeded up a lot. So to early on for instance, you have cyanobacteria able to create oxygen, at that point you don't want other micro-organisms that eat your cyanobacteria and take the oxygen out of the air, want to keep those away as long as you can.
Mars seems a really hard place to terraform for many reasons, and it might never be possible. For various reasons the big cycles of nature would need to work differently on Mars, especially, the CO2 in the atmosphere on Earth is maintained by the volcanoes long term, on Mars there is no continental drift, and so not much to keep the CO2 in the atmosphere if we find a way to create a thick atmosphere. So some other CO2 cycle needs to be established on Mars.
Are ideas for ways to do it, but will be a different cycle from the one on Earth. It all has to be carefully done. You don't want to create an ecosystem on Mars that will just run out of air a few thousand years from now, that would be unethical surely for whatever beings live there in the future.
It might be possible to get to the point where you can grow plants there but not have much by way of oxygen in the atmosphere. But whatever we do, the terraforming might be much harder if we introduce other micro-organisms accidentally first.
We might also accidentally introduce micro-organisms that contaminate the water supplies on Mars or otherwise make it hazardous for humans.
So it is something to do with great care. Personally I'm not sure we have the understanding and wisdom to deliberately introduce life to Mars or anywhere else quite yet.
Perhaps once we have experience of creating large self contained ecosystems in space colonies, and have perhaps been able to study life processes on exoplanets around other stars, we might have a better idea of the range of possibilities and whether it is possible or wise to terraform Mars.
Can Human Explorers Keep Mars Clean, For Science?
How Valuable is Pristine Mars for Humanity
Might there be Microbes on the Surface of Mars?
Asteroid Resources Could Create Space Habs For Trillions; Land Area Of A Thousand Earths
There have been a number of crashes especially e.g. the Mars Climate Orbiter, the one that crashed due to mix-up of metric and imperial units, not sterilized for the surface. So perhaps the chance is higher than 0.1% but because Mars is so hostile, seems pretty likely that we haven't introduced life there yet.
It used to be thought impossible for life to survive on Mars, but that has changed, now there is thought to be a chance it could survive in micro-habitats just a few millimeters thin. Also some lichens from the Arctic it seems might be able to survive even on the surface in Mars, just using moisture from the air - it gets to 100% humidity briefly in morning and evening when frosts from. The micro-habitats work rather similarly, they form around deliquescing salts that take up moisture from the atmosphere at times of high humidity. With just the right mixture of salts, then the habitat might be one that life could use.
So, maybe it could happen. For now scientists are really keen to keep Mars free of Earth life so they can study it in its pristine state. Especially, there may be answers to many questions about the origins of life on Mars, because it was so Earth like when it formed, and for a few hundred million years before it lost its atmosphere and got colder. With no continental drift, and the cold, and some salts and clays able to preserve organics, it may be an ideal place to study the origins of life - or indeed, if life didn't arise there - what happens on a planet like Earth if life does not arise on it. Both ways, want to keep it pristine at least during this exploration phase.
Later on then maybe we could introduce life to Mars. But if so, would be a careful sequence probably using the process of Ecopoesis. The idea is to try to reproduce what happened on Earth but speeded up a lot. So to early on for instance, you have cyanobacteria able to create oxygen, at that point you don't want other micro-organisms that eat your cyanobacteria and take the oxygen out of the air, want to keep those away as long as you can.
Mars seems a really hard place to terraform for many reasons, and it might never be possible. For various reasons the big cycles of nature would need to work differently on Mars, especially, the CO2 in the atmosphere on Earth is maintained by the volcanoes long term, on Mars there is no continental drift, and so not much to keep the CO2 in the atmosphere if we find a way to create a thick atmosphere. So some other CO2 cycle needs to be established on Mars.
Are ideas for ways to do it, but will be a different cycle from the one on Earth. It all has to be carefully done. You don't want to create an ecosystem on Mars that will just run out of air a few thousand years from now, that would be unethical surely for whatever beings live there in the future.
It might be possible to get to the point where you can grow plants there but not have much by way of oxygen in the atmosphere. But whatever we do, the terraforming might be much harder if we introduce other micro-organisms accidentally first.
We might also accidentally introduce micro-organisms that contaminate the water supplies on Mars or otherwise make it hazardous for humans.
So it is something to do with great care. Personally I'm not sure we have the understanding and wisdom to deliberately introduce life to Mars or anywhere else quite yet.
Perhaps once we have experience of creating large self contained ecosystems in space colonies, and have perhaps been able to study life processes on exoplanets around other stars, we might have a better idea of the range of possibilities and whether it is possible or wise to terraform Mars.
Find out more
Can Human Explorers Keep Mars Clean, For Science?
How Valuable is Pristine Mars for Humanity
Might there be Microbes on the Surface of Mars?
Asteroid Resources Could Create Space Habs For Trillions; Land Area Of A Thousand Earths
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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