The Kennedy Space Center Gaseous Nitrogen Freezer (GN2) is a double-middeck-locker replacement facility designed to provide a cryogenic preservation environment for experiment samples onboard the space shuttle and the International Space Station.Facility Manager(s)
Kennedy Space Center, Space Life Sciences Laboratory, Cape Canaveral, FL, United States
Bionetics Corporation, Cape Canaveral, FL, United States
National Aeronautics and Space Administration (NASA)Expeditions Assigned
0Previous ISS Missions
The Kennedy Space Center Gaseous Nitrogen Freezer (GN2) was used on STS-87, STS-95, and STS-111.
The aluminum outer tank of the Kennedy Space Center Gaseous Nitrogen Freezer (GN2) houses an internal tank containing the absorbent material used to hold the gaseous nitrogen. The absorbent material is CAB-O-SIL TS-720, manufactured by Cabot Corporation. CAB-O-SIL TS-720 is a hydrophilic (it has a strong affinity for water) fumed silica whose surface has been rendered hydrophobic (it has little affinity for water) through treatment with a silicone fluid. The absorbent material is appropriately contained with cotton cloth. The CAB-O-SIL is insulated with a combination foil, molecular sieve, and palladin oxide getter. The insulation material is sealed between the outside tank and the inner tank. The freezer's outer dimensions are 14.5 in. in diameter and 19.0 in. in height.
The sample area inside the internal tank can hold up to four cylinders 6.0 in. long and 3.7 in. in outer diameter. In addition, one of the freezer compartments will be filled preflight with an insert of the same absorbent material to increase the thermal mass of the system. The additional insert is wrapped with cotton cloth to contain any particulate.
Quick disconnects are added to the freezer lid to allow for ease of use. The ladles containing the biological samples in the freezer are tethered to the external body pf the freezer via insulated wire. The freezer lid is stowed in a foam insert. The lid's quick-disconnect pin is tethered to the lid to prevent it from floating away. The gaseous nitrogen is held in the absorbent material by a vacuum and the insulation material. The freezer has a valve that ensures the integrity of the vacuum container. The total volume of liquid nitrogen when full is 6.5 L. The static evaporation rate of the unit is about 0.3 L/day. Depending on the flight configuration and use scenario, the GN2 can hold temperatures at approximately -196 °C for between 21 and 35 days.
The GN2 is a passive facility which provides access for crew interaction for removal and insertion of biological samples in microgravity.