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08/06/1997 07:00:00

Caltech Question of the Week: Will Future Mars Colonies Utilize Local Martian Rocks and Soil for Building Materials?

Question of the Month Submitted through e-mail by Dave Cooley, Costa Mesa, California, and answered by Albert Yen, Caltech grad student in planetary science; and Peter Goldreich, professor of astrophysics and planetary physics.

Future colonies on Mars will maximize the use of in situ resources in order to minimize the supplies that need to be transported from Earth. Fuel, oxygen, and building materials can all be obtained from the Martian atmosphere and regolith (or loose bedrock). In fact, a lander will be launched to Mars in 2001 which will demonstrate the ability to produce propellant from the gases in the atmosphere.

Building materials for a sustained human presence on Mars will be derived from the rocks and soil. One of the basic uses of the regolith would be to cover the habitat to provide a radiation shield against high-energy solar particles. In more advanced stages of settlement, bricks could be made from soil by heating under pressure. Mortar and cement produced on Mars could be based on the sulfur that is found at the surface (about 3% by weight).

Iron and other metals are on Mars, but steel might not be necessary for construction purposes. Our best evidence is that there is little seismic activity or plate tectonics on Mars today, so it might be possible to dispense with the steel structural materials and build entirely with stone. We know that the latter material is in abundance, of course, because we have been seeing the graphic evidence every day since Pathfinder landed on July 4.

Building with stone might simplify things even more than we know: though Mars has iron, it might be hard to mine it for some reason or other. And since a major reason you would want to use metal in building is for protection against seismic activity, future Mars colonists might be able to build as most of the residents of Earth do now — with commonly available stone reasonably near the building site.