Cryo chamber

A cryo-chamber is a plastasteel chamber that allows all of a starship's non-essential personnel to be cryonically frozen for long periods of time. An example of its use would be during prolonged Slipspace jumps. They are basically large metal pods with form-fitting gel beds where the personnel are frozen until they are needed. An example of this is John-117, who was stored in a cryo-chamber aboard the ship and later unhatched from the cryosleep chamber by Tech Chief Thom Shephard along with Tech Officer Sam Marcus.

Known models of the cryo-chamber include the Mark VII Personal Suspension Unit, manufactured by Jakubaitis Standard Systems. It was widely disliked by UNSC personnel because of its inferior moisture balancing; this resulted in dry, itchy skin for a day or more after awakening, known as "cryo-itch". It was later replaced by the Mark VIII Cryogenic Suspension Chamber, although many older craft still use the Mark VII.

Technical specifications
The cryo-chambers are usually stored in their own areas of the ship. Each cryo-chamber will hold an individual for as long as necessary, provided they use a Bronchial Surfactant, and can be ejected prior to an emergency landing, thus saving some crew from harm to be recovered later. Some pods feature slow-impulse thrusters for limited maneuvering in the event of ejection. Often a person may be placed in cryo in order to save them from succumbing to grievous injuries, such as in the case of Linda-058, who was placed in a cryo-chamber after being severely injured during the Fall of Reach, and successfully revived later despite being previously declared clinically dead.

Cryo-chambers are monitored by the Ship's AI, and the AI can awaken crew members at a moment's notice. Cryo-computer is designed to change the pharmaceuticals dosage if a individual appears as though they might wake from cryogenic sleep. Cryo wake-up protocols demand that crew check each other to make sure everyone revives from cryo all right. There is usually a medical pod in cryogenics bays for emergency resuscitation situations. People are almost always stored in cryo-pods naked, as covered skin generally reacts badly to the cryo process, leaving skin raw and blistered. However Spartans often go into their cryo-chambers fully armored, using their conditioning and training to ignore the pain.

It is unknown whether the Covenant has a similar technology, but it is likely considering the vast distances of interstellar space their ships may need to travel. Even though Covenant ships are much faster than UNSC ships, Slipspace travel is still not instantaneous.

Trivia

 * Cryo-chambers are referred to as "the freezer" in slang, named after a term often called freezer burn which is a pain in joints and muscles caused by the cryo sleep pharmaceuticals trapped in muscles and joints. Another slang term for the chamber is "the Admiral's wife" because it is a "frosty bed." Being put in cryo is also referred to as being "put on ice."
 * The Slipspace Field Pod is the Forerunner equivalent to the Cryo-chamber. The Covenant has no known long term stasis devices like the Cryo-chamber that have been directly observed, but some ships have been observed with tube-like objects that some think might be a Covenant Cryo-chamber.
 * While in cryo, humans don't age. Individuals in cryo tubes are given a steady supply of pharmaceuticals that control the frequency and duration of cryo-sleep cycles along with influencing the content of their dreams.
 * Even though humans must enter a cryo-tube naked or risk being blistered when they emerge, Professor Ellen Anders in Halo Wars and Dr. Catherine Halsey in The Package both entered their tubes fully clothed. These were cases of artistic license, however, since showing nudity would force up both the game's and the short film's rating.
 * In Halo: Combat Evolved, it is possible through a glitch to get back inside the tube, and see the Chief, headless.

List of appearances

 * Halo: Combat Evolved
 * Halo 3
 * Halo Wars
 * Halo: Reach
 * Halo 4
 * Halo: The Fall of Reach
 * Halo: The Flood
 * Halo: First Strike
 * Halo: Contact Harvest
 * Halo: The Cole Protocol
 * Halo: Evolutions - Essential Tales of the Halo Universe
 * Dirt
 * Halo: Blood Line
 * Halo: Fall of Reach
 * Boot Camp
 * Invasion
 * Halo Legends
 * Origins
 * The Package
 * Halo 4: Forward Unto Dawn