• Question: how possible is it that we find life on mars or water and if so what implictions would that have on science at the moment?

    Asked by wrigb012 to Kristian, Tim, Zachary on 21 Nov 2013.
    • Photo: Zachary Williamson

      Zachary Williamson answered on 21 Nov 2013:

      We’ve already found water on Mars, in tiny amounts under the soil and in quite large amounts in frozen chunks at the poles.

      If we find life, the implications are quite profound. For life on Mars to exist, it has to life in the harshest of climates. No oxygen, no atmosphere, very little heat. If life can survive in these climates, it opens up the possibility of life elsewhere in our solar system. Further afield, it means that the probability of life existing outside our solar system is considerable.

      There are good reasons to think there might be some sort of life. There are types of bacteria on Earth called extremophiles: they can live in habitats we thought were completely lifeless.

      A good example is a type of bacteria that doesn’t rely on sunlight for its food. Directly or indirectly, we all rely on the Sun as our energy source. Either as a plant converting sunlight into energy, or as an animal eating that plant, or as an animal eating the animal that eats the plant!

      But this bacteria we discovered gets its food by processing hydrogen sulphide produced by undersea vents at the bottom of our ocean. If life can exist in these conditions, it’s not a huge logical leap to think that it might exist on Mars.

    • Photo: Tim Hollowood

      Tim Hollowood answered on 21 Nov 2013:

      It would be truly astounding if we found life on Mars. That would show that the processes that lead to life are not so improbable. This would mean that there would be much higher probabilities of having life on nearby stars. So finding life on Mars would be a huge moment for mankind.

    • Photo: Kristian Harder

      Kristian Harder answered on 21 Nov 2013:

      Well, Tim and Zachary have explained it already. We have found water on Mars already (even though it’s frozen and a lot less than it seems to have been a few billion years ago, when Mars is said to have had oceans, really). And it is definitely possible for life to exist on Mars, because the conditions are not very different from some places here on Earth where life, even though only very simple life forms such as bacteria, thrives perfectly well. Real big life forms such as little green men don’t seem to exist on Mars, though, otherwise we would have probably seen some traces of them on some of the many many detailed photos we have taken from Mars. (It’s like using Google Earth: how much do you have to zoom in to figure out that there is life on Earth? Just close enough to see roads, bridges, dams, mining activity and so on. It’s quite easy to see.)

      So, what’s left for *me* to tell you then? Well, maybe that we also need to try to *avoid* finding life on Mars. More specifically, we should avoid finding life *from Earth* on Mars. I am not saying we shouldn’t send astronauts over to Mars at some point. What I mean is that life is very persistent. Some people even speculate that life was brought to Earth on meteorites. It is quite amazing, but organic molecules could indeed survive traveling through space and then entering the Earth’s atmosphere riding on a shooting star. In the same way, our space probes and robotic explorers could carry microbes from Earth to other planets. And that would be a bad thing for several reasons. First of all, it would be very embarrassing to discover life on another planet, only to find out later on that it looks suspiciously like the good old flu virus from back home. 😉 Secondly, if there really *is* life on other planets, introducing organisms from Earth to them could do some serious harm. What may be a completely harmless bacterium for us could potentially destroy or modify life elsewhere. We must not risk that, and NASA and ESA and whoever else is shooting planetary exploration probes into space these days are aware of these issues and try to make sure all equipment sent up there is perfectly sterile.

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