In the Hollywood thriller "Gravity," screenwriters concocted a frightening space scenario. Two NASA astronauts on a spacewalk, portrayed by Sandra Bullock and George Clooney, find themselves stranded in the emptiness of space, after their spacecraft is wrecked by debris from a satellite destroyed by a missile.
While that particular dilemma was fictional, it resonated powerfully with movie audiences, because those of us who grew up watching the triumphs and tragedies of the Space Age know that being an astronaut is dangerous work. We've heard about the deaths of the three Apollo astronauts during a launching pad test exercise in 1967, the six who lost their lives when the space shuttle Challenger disintegrated 73 seconds after liftoff in 1986, and the seven who were killed when the Columbia shuttle broke up during re-entry in 2003 [source: Airsafe.com].
But while leaving Earth and returning to it are both risky business, the time that astronauts spend in the airless, cold and highly irradiated void of space is fraught with ever-present lethal peril, too. Space is so dangerous, in fact, that it's amazing that only three humans—a trio of Soviet cosmonauts on a 1971 mission—have actually perished there. Here are 10 of the ways in which the cosmos is unforgiving of our inherent frailties.