Sleeper Ship

A sleeper ship is a hypothetical type of manned spaceship in which most or all of the crew spends the journey in some form of hibernation or suspended animation. There is currently no known technology that allows for long-term suspended animation of humans.

The most common role of sleeper ships in fiction is for interstellar travel, usually at sub-light speed. Travel times for such journeys could reach into the hundreds or thousands of years, making some form of life extension such as suspended animation necessary for the original crew to live to see their destination. Suspended animation is also required on ships which cannot be used as generation ships, for whatever reason.

Freezing the astronauts would probably involve whole body vitrification, and they would most likely be frozen at 145 Kelvin to reduce the risk of fracturing.

Suspended animation can also be useful to reduce the consumption of life support system resources by crew members who are not needed during the trip (and also to an author as a plot device), and for this reason sleeper ships sometimes also make an appearance in the context of purely interplanetary travel.