Scientists Design Mars Bricks

W I L L I A M S B U R G,  Va.,  Aug. 14 -- Ryan McGlothlin takes a sugar-like powder, stirs in a substance that resembles flour, pours the mixinto a mold and bakes it.

The end result is not a cake but a small, shiny, black bar designed to shield against radiation. The “sugar” really is polyethylene, and the “flour” is a gray topsoil.

McGlothlin, a chemistry major at the College of William andMary, and chemistry department chairman Richard Kiefer are usingthose ingredients to develop a material to make bricks that wouldprotect astronauts against radiation on Mars. They are working withaerospace researcher Sheila Thibeault at NASA Langley ResearchCenter in nearby Hampton.

“What we’re doing is the basic research, establishing that yes,you can do this,” Kiefer said. The work also could haveapplications on Earth, such as use in shields around nuclearreactors, he said.

Thinking Ahead

NASA hopes to put people on Mars within the next severaldecades. Because of the different orbits of Earth and Mars, thewindow of opportunity for travel between the two planets occursonly once every two years. That means that anyone traveling to Marswould have to stay there for a long time.

The prospect of an extended stay on Mars prompts a number ofconcerns, among them the health effects of galactic cosmicradiation, found nearly everywhere in space. The magnetic fieldsurrounding the Earth deflects the radiation, but Mars does nothave such a field.

Radiation can cause illness or even death, depending on thedosage and length of exposure. Therefore, astronauts will need amaterial they can use to build shelters and laboratories that alsowill shield against radiation.

The lighter the material is in terms of mass, the better itsshielding properties, and research has shown that liquid hydrogenis the best possible shield, Kiefer said. “But that’s a littleimpractical to take to Mars,” he said.

So the next best thing is a solid polymer, or chemical compound,that contains a lot of hydrogen. And polyethylene, a very cheapplastic from which plastic bags are made, has more hydrogen thanother polymers, said McGlothlin, 21, of Lebanon, Va.