Halo Alpha
Halo Alpha

FUD Cryo

A cryo-chamber aboard the UNSC Forward Unto Dawn.

A cryo-chamber is a plastasteel[1] 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. Cryo-chambers are referred to as "the freezer" in slang,[2] named after a term often called freezer burn, which is a painful condition caused by frozen liquids damaging cells, organs, and joints. Another slang term for the chamber is "the Admiral's wife" because it is a "frosty bed."[3] Being put in cryo is also referred to as being "put on ice."[4]


During the active run of Corbulo Academy of Military Science, cadets would be placed in cryo-chambers in order to train for a high alert awakening.[5]

The most of the crew of the UNSC Spirit of Fire was put into cryosleep following their battle at a shield world.[6] 28 years later, the entirety of the crew would be woken up over Installation 00. For unknown reasons, many of the nameplates were not changed on the cryo-chambers of those who were deceased.[7]


John and a cryo engineer on the UNSC Pillar of Autumn.

Much of the crew would be in cryo-chambers at the start of the Battle of Installation 04. However, John-117 would be one of the last to wake. Following his awakening, he was given a quick physical examination by one of the cryo-engineers.[8]

After the Battle of Installation 00, the rear section of the UNSC Forward Unto Dawn with John 117 and Cortana was left to drift in space. Cortana sent out a distress signal, but it would be years before they reached UNSC space. As such, John went to cryo sleep until someone found them.[9] Almost 5 years later, a Covenant fleet boarded and ransacked the Forward Unto Dawn. Cortana woke John to a nearly frozen cryo-bay in order to fend off the attackers.[10]


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 UNSC Pillar of Autumn and later unhatched from the cryosleep chamber by Tech Chief Thom Shephard along with Tech Officer Sam Marcus.[8]


Cryo-chambers are monitored by the ship's AI, and the AI can awaken crew members at a moment's notice. The cryo-chamber's control computer is designed to change the dosage of necessary medications, or modulate the internal temperature, if an individual appears as though they might wake from cryonic sleep.[11] 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 tissue rapidly becomes damaged due to intracellular ice crystal formation, a condition commonly known as Freezer burn.[12] Contrary to normal protocol, however, at the Battle of Installation 04, John-117 emerges from the cryo-chamber completely fitted in his armor, using Spartan training to ignore the pain. His enhanced physiology presumably allows for a quick recovery from superficial pain and injury such as this.[13]

Placement in Ships[]


The Cryo-bay aboard the UNSC Spirit of Fire.

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. Spartan-058, after being severely injured during the fall of Reach, was placed in a cryo-chamber in the UNSC Pillar of Autumn. Prior to the ship's landing on Installation 04, her cryo-chamber was ejected, and she was picked up by John-117 at a later date.


H4 Campaign FUDCryo-chamber

A Mark VIII Cryo Chamber.

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.[14]


  • The Slipspace Field Pod is the Forerunner equivalent to the cryo-chamber.
  • While in cryo, humans don't age due to nearly halted metabolism. 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.[15]
  • Even though humans must enter a cryo-tube naked or risk being blistered when they emerge, Professor Ellen Anders entered her tube with her clothes on.
    • This was also done in Halo 4: Forward Unto Dawn, where the cadets must enter cryo-sleep to overcome the side effects through training. They use what appear to be special suits in order to remedy the freezer burn experienced under normal circumstances.
    • Master Chief also enters cryo-sleep in his suit in all appearances.
    • In the Halo Legends episode The Package, when John-117 locates Dr. Catherine Halsey in a cryo chamber, she is fully clothed. Yet when she awakens, she appears to have not suffered any effects of freezer burn such as any visible rashes or blisters, nor does she show any signs of pain or discomfort.
    • This is all likely done to avoid a higher age rating of the content, as nudity would give an age rating only suitable for adults.
  • In Halo: Combat Evolved, it is possible through a glitch to get back inside, and see John, headless.
  • A cryo-chamber is available as an avatar prop with the Halo 4 Limited Edition.
  • There is a Mega Bloks Edition set that is a UNSC Cryo Bay with John-117 and Cortana.
  • In Halo Reach, there is an Easter egg that allows the player to see Chief in a cryo-chamber. When the Pelican begins docking with the ship, either move the left analog stick to the right or hold right on the directional pad and the camera will shift to show Chief in the cryo-chamber.




  1. Halo: First Strike, page 150 ("John brushed off the frost buildup that clouded the top half of the cryotube, and revealed the green-armored figure sprawled behind the plastasteel shell.")
  2. Halo: The Fall of Reach, page 102
  3. Halo: The Cole Protocol, page 21
  4. Halo: The Cole Protocol, page 21
  5. Halo 4: Forward Unto Dawn
  6. Halo Wars - Level: Escape
  7. Halo Wars 2 - Level: The Signal
  8. 8.0 8.1 Halo: Combat Evolved - Level: The Pillar of Autumn
  9. Halo 3 - Level: Halo
  10. Halo 4 - Level: Dawn
  11. Halo: Contact Harvest, page 60 ("The cryo-computer observed a surge of activity in Avery’s brain-an effort to yank himself out of REM-and upped his dosage.")
  12. Halo: The Flood, page 20
  13. Halo: The Flood, page 21
  14. Halo Encyclopedia, page 216
  15. Halo: Contact Harvest, page 60