This is an image of ice at the north pole of Mars.
Click on image for full size
STScI and NASA
The Environment of Mars in the Past
In the past, Mars was much different than it is today. Liquid water used to flow on the surface, as shown in this picture. Both the Earth and Mars should have been frozen in their early history because the sun was weak at first. But both planets show that water was flowing, which suggests that they both must have had lots of air in place to keep the surface warm. In this environment life may have once thrived.
The atmospheres on both planets came out of volcanoes. There were not many volcanoes on Mars, and those volcanoes were never very active. The Earth, on the other hand, has many active volcanoes.
The volcanic eruptions produce a lot of water. The water eventually falls to the ground or into the oceans. Mars is small, and cooled off very rapidly. Scientists estimate that water is absorbed into the ground and frozen like tundra in the Canadian northwest.
Compare this environment with Earth of the past.
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