Health Risks With the right spaceship, astronauts can get to Mars. Surviving the long trip is another issue. T ey’ll face many health risks in space. One danger is radiation from the sun and
cosmic rays. T is form of energy can harm a human body. Large doses of it can cause cancer or even kill people. Earth’s atmosphere protects people from most radiation. T ere’s no atmosphere in space, though. So astronauts need something else to protect them. T e materials used today to build spaceships
and spacesuits block some radiation. T ey don’t block all of it, though. T at’s okay for today’s astronauts. T ey don’t spend a long time in space. T e Mars astronauts will. So engineers are trying to invent new materials that will do a better job blocking radiation.
Getting Weak Astronauts also oſt en suff er from weak muscles and brittle bones. On Earth, human bodies stay strong thanks to gravity. T is force pulls on us and gives us weight. It exercises our muscles and bones. T ere’s no gravity in space, so bones and
muscles don’t get a workout. Without use, they start to weaken. A special exercise machine could help solve
this problem. T e machine makes astronauts feel like they are pushing against gravity. T at may help build muscle. It may not be enough to protect bones, though. So scientists also are studying a new medicine that slows bone loss.
Getting Along Mars astronauts need to be physically strong. T ey also need to be mentally strong. T at’s because they’ll be cooped up in a small place for a long time. T ey might get bored. T ey might miss Earth and their families. T ey might become depressed. T ey might argue. No matter how they’re feeling, they must
work together. If something goes wrong, it’ll be hard to call for help. A message from Mars could take 20 minutes to reach Earth. So the astronauts will need to rely on one another to survive. It’ll take a special group of people to work and live together far from home.
GRAVITY is a force that pulls objects toward each other. Its strength depends on the objects’ mass, or amount of matter. Mars is smaller than Earth, so has less mass. As a result, its gravity is about a third of what it is on Earth.
The surface of Mars, as seen by the rover, Spirit.
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