While a little bit of heat is produced by radioactive decay, this is a very small world and that (heating) is pretty minor.

They're great images. They're what all of us were hoping for - better than some people were expecting.

Mars is the most habitable planet accessible to us. It's not extremely cold or hot. It's possible to imagine human colonies on Mars.

It isn't understood how that is happening.

The further away from Earth you get, the less plausible it is to talk about the similarities of life on Earth. It would be an independent origin of life that would be different from what we see here.

It could have implications for moons outside the solar system. It gives us lots to ponder in terms of physical science as far as the energies it takes to produce these (plumes).

Any place where there's liquid water, there's life.

It's great these images turned out well because a lot of things had to work right, including exactly how the spacecraft points and the stability. It turned out just right.

At this point we have an idea that water is probably abundant on Mars in the form of ice. It's not a matter of finding water on Mars but learning its importance in climate change ... and clearly it has been important to shaping the landscape.