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Asked by anon-175384 to Alison, Alex, David, Ella, hayleypincott, Thomas on 12 Jun 2018. This question was also asked by anon-175407.
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Alison Hughes answered on 12 Jun 2018:
Wow, that is a difficult question, and I am not sure anyone can answer it. My best guess at an answer is a very philosophical answer. There was a time, about 4 BILLION years ago, when the air on earth did not contain oxygen, which we require to live. Actually, when oxygen first existed on earth, it was toxic to the creatures living there! But, the planet, and the creatures living on it, evolved and adapted to survive under these new conditions. This is why I believe there is life on mars, it is just that earth’s creatures could not survive on it. I also think that the universe is complicated far beyond our ability to understand (yet) and that there may be life on mars that is completely different to what we would call “life” on earth. Scientists on earth have defined what “life” actually means, which includes growth, reproduction, and metabolism (there are 7 characteristics of life according to scientists). However, this definition of life may be completely different on mars, so how do we really know what we are looking for when we are looking for life on mars?
I am sure this does not answer your question, but may give you some ideas to think about.
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David Mills answered on 19 Jun 2018:
As far as we know life forms everywhere there is water. Unfortunately we only have one data point – The Earth. It’s really not good science to make theories from one data point, but it’s all we can do for now…
Measurements taken on Mars by the robot probes there have found evidence of water and minerals on Mars, some of these look like minerals formed on earth by bacteria. We don’t know for sure if what we are seeing on Mars is evidence for life, or not. All we know is Mars once has seas or lakes and we know everywhere there is water on Earth there is life.
I’m not convinced there is life on Mars, I really hope there is. I’d love to see confirmation of it in my lifetime. I’d love to see how it differs from life on earth – it is cellular, does it have DNA, what does it eat? If there is life there I expect it’s just very very slowly growing bacteria type things.
One reason we haven’t found life there yet is we have literally only scratched the surface of the planet. There is life very deep on earth in rocks and deep sea, so perhaps any life on Mars moved deep into the planet when the seas and lakes vanished. We haven’t looked very far at all yet. Maybe one of the new probes on the way to Mars in the next few years will get lucky and find something alive, or even just a genuine fossil.
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Hayley Pincott answered on 20 Jun 2018:
We’ve been told that for life to exist we need water and there is evidence that there has been water on Mars at some point and this leads us to believe that it’s possible for there to have been life. As with Earth plants and animals have evolved over millions of years to adapt to their surroundings and this may have happened on Mars, life could well had evolved to adapt to the surrounding environment there. Our exploration of Mars is still in it’s early stages so a bit more time, loads more investigations and experiments then who knows what we will learn and find out?!
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Ella Mercer answered on 20 Jun 2018:
Scientists think that life on earth began with tiny organisms (creatures) living in the water and somehow we evolved from there! If that’s how life on earth started … maybe we just haven’t managed to find the life on Mars yet because they’re so small or we’re not looking in quite the right places. If life on earth started out with tiny creatures and now we have so many humans and animals … what do you think life on Mars might evolve to be like??
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Thomas Perriment answered on 20 Jun 2018:
Great question, I love questions like this. It’s so hard to know what we are looking for as we only have Earth as a reference point. It would be like trying to find life on other planets but only looking for humans – what if life elsewhere developed without the need for oxygen or carbon dioxide or even water? We could miss the signs entirely because we don’t know what we are looking for. I think that even though we haven’t found any life yet, perhaps we just haven’t yet found the evidence it would take to persuade us (such as trace fossils or biotic chemical alteration) – we might not even recognise what we already have as evidence! I’ve reviewed a lot of geology on the surface of mars, but nothing beneath the surface where there is a lot less high energy interference (wind, sandstorms, radiation…) which might destroy life or other evidence.
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