Life exists in many extreme environments on the Earth, places where we would have never thought to find life before. Finding life in these extreme places on Earth helps to guide us on where we may find similar types of life on other planets.

There are many places on the Earth where life exists in pitch dark, freezing cold or stinging acidic environments. No matter what the environment though, one thing is always present - water.

What does that mean for our search for life on other planets? We need to look for water!

Possibilities include: Ancient river and lake beds on Mars, Martian polar caps, under the icy crust of Europa, and planets around other stars