Answer 1:
Interesting question! I’m afraid that I can’t
answer the first part of the question– if Mars
ever had life on it, in fact, I don’t think that
anyone in the world can answer that question
yet. NASA has a rover (sort of a little car with
science tools) called Curiosity on the surface
of Mars right now. One of the big parts of the
Curiosity mission is look for signs of life on
Mars, but not all of the results have come in
just yet. You should check out the NASA website
on the rover
click here to see – it’s very
interesting!
Many people think that is possible that Mars
had life at one time because it had liquid water
at the surface in the past (liquid water is
necessary for “life” as we understand it on
Earth). That brings me to the next part of your
question…
Mars doesn’t have liquid water at its
surface today (because it is too cold and the
pressure is too low), but it almost certainly
did in the past. We know this because there are
certain landscape features on Mars’ surface that
can only form from liquid water. For example,
there are channels or valleys that get carved
out by flowing water in rivers and streams. The
water is all gone but the valleys are still
there.
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