Can People Go To Mars?

Once the risks are known, NASA can decide what kind of spaceship to build. It's possible that ordinary building materials like aluminium are good enough. If not, "we've already identified some alternatives," he says.

How about a spaceship made of plastic?

Bricks of reinforced polyethylene - Are these the building blocks of future spacecraft?

"Plastics are rich in hydrogen - an element that does a good job absorbing cosmic rays," explains Cucinotta. For instance, polyethylene, the same material garbage bags are made of, absorbs 20% more cosmic rays than aluminium A form of reinforced polyethylene developed at the Marshall Space Flight Centre. is 10 times stronger than aluminium, and lighter, too. This could become a material of choice for spaceship building, if it can be made cheaply enough. "Even if we don't build the whole spacecraft from plastic," notes Cucinotta, "we could still use it to shield key areas like crew quarters." Indeed, this is already done onboard the ISS.

If plastic isn't good enough then pure hydrogen might be required. Pound for pound, liquid hydrogen blocks cosmic rays 2.5 times better than aluminium does. Some advanced spacecraft designs call for big tanks of liquid hydrogen fuel, so "we could protect the crew from radiation by wrapping the fuel tank around their living space," speculates Cucinotta.

Can people go to Mars? Cucinotta believes so. But first, "we've got to figure out how much radiation our bodies can handle and what kind of spaceship we need to build." In labs around the country, the work has already begun.