Well, this is something that doesn't come up much in the Star Wars movies: radiation is a huge threat to astronauts. NASA is looking at ways to prevent cancer.
Dr. David Alexander is head of the Rice Space Institute and says "radiation is a big deal and NASA is looking at a whole range of mitigation approaches."
Dr. Alexander says Earth protects us from space radiation.
"If you were to go live on Mars for the next hundred years -- or your family -- the radiation will change your DNA for you, but since we're hoping to bring these astronauts back within a relatively short time, you want them to come back as whole as possible."
Some have floated the idea of using so-called DNA drugs to protect astronauts.
Dr. Alexander says it's a serious consideration.
"The way that NASA works this risk is not so much will it'll kill you, but will it chop some years off your life; will it increase the risk you'll get a cancer earlier than you might have normally because you've been exposed."
So-called DNA drugs are probably decades away.