I think every science fiction writer has a cryo (aka “human popsicle“) story sitting around somewhere, even if it’s just in the back of their head. It’s one of those tropes that keeps coming back, just like the alien invasion, the robot apocalypse, and the Adam and Eve plot.
The basic concept is pretty simple, even if the technology is a bit more complex: a human or animal undergoes rapid freezing in order to put themselves into stasis for an extended period of time. Months, years, or even centuries later, someone thaws and resuscitates them so that they wake up in a completely different time and place.
There are a lot of good reasons why going into cryo makes sense in a science fiction universe. One of the more common ones is that the characters are colonists on a mission to an alien star, and their spaceship doesn’t have a faster-than-light drive. Rather than go through all the trouble of building a generation ship, the designers instead built a series of cryo chambers to put the colonists into stasis for an extended period of time. It might take centuries or millennia for the ship to reach its destination, but when it does, the colonists wake up as if it’s just been a long, dreamless night.
In The Worthing Saga, Orson Scott Card has a somewhat unusual rationale behind the prevalence of cryo in his universe (though they call it “hot sleep,” and it’s induced by a drug called soma). Only the rich can afford the technology, and the imperial overlords very carefully regulate the use of it so that there’s a clear hierarchy based on who goes under for the longest amount at a time. It’s a way for the citizens to achieve a simulated form of immortality, by skipping five or ten years every year or two of their lives.
In the Halo video game series, the UNSC uses cryo as a way to preserve their greatest military assets, the Spartans, for the times when they’re needed. The first game in the series starts when John-117, aka the Master Chief, is awakened just as the starship Pillar of Autumn crash lands on a mysterious alien structure. Like something from an old Norse legend, the third game ends when the Master Chief seals himself into the cryo chamber of a derelict starship, telling the AI Cortana “wake me when you need me.” (highlight to view spoilers).
So why are cryo stories so prevalent in science fiction? For one thing, they’ve been floating around in our cultural subconscious a lot longer than the genre has been in existence–just think of Sleeping Beauty or Rip Van Winkle. For another thing, the science is not that far-fetched. Certain animals can be revived after extended periods of frozen stasis, and according to the New York Times, it’s happened at least once with a human being. Science fiction has a long history of turning fiction into fact (for example, Arthur C. Clarke and communication satellites), so perhaps it’s only a matter of time before human cryotech becomes a reality.
I’m definitely a fan of this trope in my own writing. Genesis Earth has a chapter with a rather horrific cryothaw scene, which I later spun off into a short piece titled “From the Ice Incarnate.” I haven’t played with it much in my latest books, but in Heart of the Nebula which I hope to publish later this year, the cryotech plays a very important role in the plot. And if I ever write a prequel to my Gaia Nova series showing how that universe got started, it will feature a cryo colonization story. The main premise of that series is that a group of human colonists fled 21st century Earth and went into cryo to colonize a distant corner of the galaxy, but when they woke up, they couldn’t find Earth anymore, so it became something of an ancient holy legend (which is a major driver for Desert Stars).