Did you know that if you were to throw a bucket of water onto the surface of Mars, the water would immediately boil off into the atmosphere?! We know that the average temperature of Mars is roughly -80 degrees F. Knowing this, you might be wondering If Mars is so cold, how can water boil on the planet’s surface? Water boils on the surface of Mars because, “the atmospheric pressure on Mars is very low compared to that of Earth, which means that water boils at much lower temperature than it does on Earth”. So, because of minimal atmospheric pressure, water cannot stay on the surface of Mars. This is not to say that water doesn’t exist on Mars. According to NASA, beneath a region of the desolate plains on Mars, there is a frozen lake that contains about as much water as Lake Superior!
Liquid water may be a problem, but I think I read that there could be ice at the poles and trapped in the permafrost too.