Space travel

by Michele Regenold

The possibilities are thrilling.

Humans have circled the earth and walked on the moon. So where to next? Mars.

Sending humans to Mars will be challenging, in part because it’s so far away. This is no quick 3- or 4-day jaunt to the moon. The astronauts going to Mars will have to travel about 100 million miles round trip. That’s a whole year inside a space craft, 6 months each way, plus up to 2 years on Mars itself.

Learning from the International Space Station

Astronauts stationed on the International Space Station (ISS) are getting some sense of what such a lengthy voyage may be like—at least in terms of time spent in space. Their assignments on the ISS are for 6 months at a time.

The ISS is also helping NASA answer a number of questions about a long space journey, like what happens to food and medicine that’s been in space for several months. Food seems to lose some of its nutritional value. When astronauts’ blood and urine were tested after returning to Earth, “markers of nutritional status didn’t match expected levels of nutrients in space foods,” says Dr. Scott Smith, head of Johnson Space Center’s Nutritional Biochemistry Laboratory. Other researchers discovered that some of the medicines had lost their potency.

Scientists don’t know why this loss of potency happens. They speculate that space radiation may be the culprit. Particles of space radiation that collide with molecules in food and medicine may damage them. Will food and medicines have to be kept in specially shielded areas?

A current experiment on board the ISS is testing 3 identical sets of food and medicine. One set will return to Earth after 6 months, one after 12 months, and one after 18 months. Researchers hope to learn the rate at which food and medicine lose potency.

Protecting astronauts from space radiation

If you spend too much time in the sun, those UV rays can damage your skin. And that’s with the protection of Earth’s atmosphere between you and the sun. In space, of course, there’s no atmosphere to filter the power of those rays. Plus, space radiation is a combination of protons from solar flares, gamma rays from black holes, and cosmic rays from exploding stars.

Galactic cosmic rays (GCRs) are the biggest threat to astronauts going to Mars. NASA compares these dangerous rays to miniature cannon balls that blast through people’s skin, ripping DNA molecules to shreds.
 
The problem with all of this radiation is that it damages cells in the body, and ultimately, people can develop cancer.

Astronauts are exposed to space radiation whenever they travel in space, but their exposure will be greater when they make the long trip to Mars. Earth won’t be nearby to act as a partial block.

NASA’s Space Radiation Laboratory is working to figure out how much damage GCRs will cause. Using simulated GCRs, they expose cells and tissue from mammals to particle beams. By 2015 they’ll have a much better idea of the risks to astronauts. Once scientists and engineers know the risks, a spaceship can be built.

Building a ship to Mars

If the Mars ship is built of aluminum, about half the space radiation that hits it will be absorbed by the aluminum skin. Aluminum is light and strong, and many aircraft and spacecraft are made of it—so it’s familiar.

But other materials may work better for a ship to Mars. Like plastic.

According to NASA, plastics like the kinds in kitchen garbage bags are rich in hydrogen, and hydrogen absorbs GCRs pretty well. The garbage bag plastic, polyethylene, absorbs 20% more GCRs than aluminum. The Marshall Space Flight Center has developed a reinforced polyethylene that’s 10 times stronger than aluminum.

Even if a whole ship isn’t built of a special plastic, it could be used to shield crew quarters, says Frank Cucinotta from NASA’s Space Radiation Health Project.

Researchers are working hard to answer all sorts of questions about what it will take to get humans safely to Mars.

About the jobs

According to NASA's website, “NASA is more than astronauts. We are scientists, engineers, computer programmers, personnel specialists, accountants, writers, maintenance workers and many, many other kinds of people.”

To learn more about jobs at NASA, see http://www.nasajobs.nasa.gov/.

To learn about opportunities for students at NASA, see http://www.nasajobs.nasa.gov/studentopps/employment/programs.htm.