OUR ancestors made their first homes in caves. Now it looks like the first humans on Mars will do the same.
An analysis of Martian geography suggests where to look for the right kind of caves. “At least two regions, the Tharsis rise and the Elysium rise, contain volcanic features which may be suitable locations for caves,” says lead author Kaj Williams of NASA’s Ames Research Center in Mountain View, California.
What’s more, the analysis suggests that caves in these regions will contain a ready supply of water, in the form of ice.
Lava tubes are the most likely form of cave that we could occupy on Mars. These tunnel-like caves were created when ancient lava flows solidified at the surface, while lava inside drained away.
The existence of ice in these caves has been suggested before, but Williams and colleagues have taken the idea one step further by using a computer model to find out exactly how ice might build up inside them. They also looked at how long it might last. The team represented their cave as a box 10 metres square by 8 metres high, with a single small opening to the atmosphere in the roof.
They found that during the Martian day, warm, buoyant air would not enter the cool cave, saving the ice from melting. At night, as the outside air cooled, it would sink into the cave and bring in water vapour that condensed as frost onto the already icy walls. The model showed that the ice would be stable, lasting for up to 100,000 years (Icarus, DOI: 10.1016/j.icarus.2010.03.039).