Question: is there life on the moon or mars???

Paul Roche answered on 13 Jun 2010:

This is quite similar to another question about “is there life on other planets”, so I’ll repeat a bit of that answer here: “There are several places where we think liquid water exists (under the surface on Mars, and below the icy surfaces of some of the moons of Jupiter, like Europa, Ganymede and Callisto, and also the moon Titan that orbits Saturn), and that is one of the vital keys to life (as far as we know, from our experience with life on Earth – but maybe we don’t know as much about life as we think we do).

So we look for liquid water as our best indication of places where life might exist – the Moon is very cold and has no atmosphere, but we do now think that there is ice (so frozen water) in some regions of the surface (particularly in deep, dark craters near the poles, where sunlight never gets). But as the Moon has no atmosphere, any life that might exist there would have to be incredibly tough, to survive the constant bombardment od radiation and tiny meteorites that hits the lunar surface. So I think it is unlikely that we’ll find any life on the Moon.

Mars is a very different place, with a think carbon dioxide atmosphere and clear evidence that liquid water used to flow over the surface – we see evidence for rivers, oceans and other features that look just like ares of the Earth where water has once flowed. But this was probably several billion years ago, so maybe there was once microbial life on Mars, but it either died (when most of the atmosphere
evaporated over time) or went underground – so maybe there is life on Mars right now, living under the surface where we think there is liquid water (just like we find on Earth), and where it is warmer than on the surface (which is typically 40 degrees below freezing, and sometimes much colder than that!).

So if you want my opinion, I think there isn’t anything on the Moon, but Mars is a possible – so future space missions will be looking for evidence of fossils (not dinosaur-like stuff, but evidence of bacteria etc.) on Mars, to see if anything did evolve there in the early period when Mars was more like Earth (warmer and wetter).

Life is pretty tough, and seems to exist (on Earth) wherever it can find liquid water – although mostly it’s slimy bacterial stuff…