In another instance of science-fiction becoming science-fact, NASA is currently researching how to cut costs for a manned mission to Mars by putting the crew in cryosleep.
Researchers at the NASA-funded SpaceWorks Enterprises are looking at ways to extend the amount of time a person could be placed in therapeutic torpor, which, up to this point, has only been used on critical care trauma patients in hospitals, but only for a maximum of a few days until the patient can receive the needed treatment. Therapeutic torpor reduces the body's metabolism and body temperature, and can happen naturally in the form of hypothermia.
By applying this same principle to space travel for longer periods of time, the cosmos could finally be at our fingertips. No longer would astronauts have to be awake for voyages that could takes months, years or even decades across the far reaches of space. It would also greatly reduce the cost and required size of space-faring vehicles, as crew members would be asleep for the majority of the mission.
It's a science-fiction staple that has been used for decades in everything from books to video games. Upcoming films like Interstellar will use the idea heavily, and it's been seen in other hallmarks of science fiction like Alien and more recently Avatar and Prometheus. In 2001: A Space Odyssey the crew of the Discovery are all in cryosleep on their way to Jupiter, leaving regular ship functions to the artificial intelligence HAL. That turns out to be not so great of an idea when HAL learns two crew members plan to disconnect him. He takes control of the shuttle and kills the crewmen unlucky enough to still be in cryosleep by turning off their life support functions.
NASA at least looks like it is trying to avoid that scenario. As an alternative to having the entire crew in stasis for prolonged periods of time, SpaceWorks suggests having one crewmate awake at a time for two to three days before going back into stasis for 14 days. By rotating the shifts, no one person is in stasis for long periods of time, and the crewmember that is awake could monitor the ship. You know, to protect from crazy computers attempting to hijack it.
Cryosleep could also come in handy in case something goes terribly wrong. At the end of video game Halo 3, main character Master Chief is adrift in space aboard a damaged ship, unable to return to Earth and unsure of his location. He sets up a distress beacon before hopping into cryosleep, where he would stay for years until eventually being found.
Staying in cryosleep for a few years is currently out of the question, as researchers haven't yet attempted to put a person in a cryogenic state for more than a week. A mission to Mars would require crew members to be placed in stasis for up to 180 days. But as technology continues to improve, who is to say people couldn't sleep for hundreds of years in a therapeutic torpor, only to wake up in a strange future? It happened to Cartman in the two-part South Park episode "Go God Go," when he put himself in the fridge so he wouldn't have to wait for the release of the Nintendo Wii. He oversleeps and finds himself in the atheistic future of the year 2546 by accident.
Okay sure, so maybe cryosleep has a lot of potential to go horribly, horribly wrong. But it sure does open up a world of possibilities, even if most of them are really bad ones.