A Martian Ocean?

A new study bringing together data from various platforms suggests ancient Mars had a huge ocean. That idea has been around for years, but such proposals had been based on smaller projects. The new study takes a broader perspective and suggests that over three billion years ago an ocean of water existed in Mars' northern hemisphere. Researchers say the ocean covered more than a third of the planet's surface, and that the water cycle on early Mars seems to have been basically the same as the one that still exists on Earth.

The question, of course, becomes: What happened to all the water? There seems to be a substantial amount of water under the surface, and more frozen in the polar ice caps, especially in the northern cap, so all the water didn't go away. Still, the climate radically changed on Mars, whereas the basic natural systems on Earth either maintained or reasserted themselves. One factor involved may be simple size. Earth has enough mass, and therefore gravity, to keep its atmosphere and water from leaking away into space while Mars does not.

Of course, the presence of a large ocean of water on early Mars for any length of time inevitably leads to the possibility that life may have developed there. If it did, and if the Martian climate changed slowly enough to allow biological evolution to do its thing, life may still exist in niche environments on Mars.