The chamber is cooled with a cascade 2.2hp hermetic refrigeration system and heated with electrical resistance elements.

Test items are loaded by crane onto the payload cart, which is rolled into the chamber on a rail system. The payload cart includes plumbing for auxiliary heating and cooling via a thermal conditioning unit, and heaters for increased transition rates. The payload cart can support loads up to 3,000 lbs.

The chamber door remains open while thermocouples are installed on the test item inside the chamber. A temperature controlled baseplate may be provided for high thermal dissipation.

Chamber evacuation is provided by a blower and rotary vane mechanical pump, while high vacuum is achieved using two cryopumps and one turbomolecular pump. Shroud temperature conditioning is accomplished by a recirculating GN₂ thermal system or being flooded with LN₂.

The test item is installed in the chamber and connected to an external power source and data acquisition equipment via an access port.

After ambient functional checks are completed, electrical heaters warm, and a cascade refrigeration system cools the air stream. A separate cooling unit provides dehumidification, and an electrically heated vapor generator provides humidification.

The preferred procedure is to operate the chamber with a hot cycled before decreasing the temperature below +4°C (+39°F). A dry nitrogen purge system regulates humidity in the chamber to prevent frost build-up on the test item.

Five integral gloves are provided in the front of the chamber for "glovebox" type testing of mechanisms, etc.

The test item is installed in the chamber and connected to an external power source and data acquisition equipment via an access port.

After ambient functional checks are completed, electrical heaters warm, and a cascade refrigeration system cools the air stream. A separate cooling unit provides dehumidification, and an electrically heated vapor generator provides humidification.

The preferred procedure is to operate the chamber with a hot cycled before decreasing the temperature below +4°C (+39°F). A dry nitrogen purge system regulates humidity in the chamber to prevent frost build-up on the test item.

Two integral gloves are provided in the front of the chamber for "glovebox" type testing of mechanisms, etc.

The test item is mounted on the portable payload cart which is positioned at the chamber door. An overhead rail is also available for mounting purposes.

The payload is instrumented with thermocouples and rolled into the chamber. Ground support equipment cabling is connected through the penetration plates and ambient functional checks are performed.

Chamber evacuation is provided by a rotary piston mechanical pump and an oil diffusion pump. Rapid pump down can also be performed. A sliding gate main valve allows chamber access while the pumping systems are established.

With the chamber dome rolled back, the overhead crane is used to lower the payload onto the support fixture.

Once installed, the payload is instrumented and connected to the ground support equipment via feedthroughs.

Access to the chamber is through a clean tent. The use of cleanroom procedures and the wearing of clean garments are required when working in the chamber.

Initial chamber evacuation is provided by two rotary piston mechanical pumps and two blowers, with three closed cycle cryopumps and one turbomolecular pump for high vacuum pumping. Each cryopump is isolated from the chamber by a sliding gate main valve to allow off-line cool down and regeneration.

The test item is mounted on the portable payload cart which is positioned at the chamber door. An overhead rail is also available for mounting purposes.

After instrumenting the payload with thermocouples, it is rolled into the chamber. Ground support equipment cabling is connected through the penetration plates and ambient functional checks are performed.

After the test article is instrumented with thermocouples and placed in the chamber, ground support equipment cabling is connected through the penetration plates, and ambient functional checks are performed.

Placing the test article on a baseplate or suspending it from the overhead rail are acceptable mounting methods.

Chamber evacuation is provided by rotary piston mechanical pumps and an oil diffusion pump. A main valve allows test set up while the pumping system is being established.

After the test article is instrumented with thermocouples and installed in the chamber, it is connected to the ground support equipment and data acquisition system via electrical feedthroughs.

After roughing down the chamber with the mechanical pump, ultimate pressure is achieved with the cryopump. A main valve allows test set up while the pumping system is being established.

After the test article is instrumented with thermocouples and placed in the chamber, ground support equipment cabling is connected through penetration plates and ambient functional checks are performed.

After roughing down the chamber with the rotary piston mechanical pump, ultimate pressure is achieved with the turbomolecular pump.

After the test article is instrumented with thermocouples and installed in the chamber, it is connected to the ground support equipment and data acquisition system via electrical feedthroughs.

After roughing down the chamber with the mechanical pump, ultimate pressure is achieved with the cryopump. A main valve allows test set up while the pumping system is being established.

The chamber includes doors on opposite ends of the chamber to improve accessibility to payloads.

After the test article is instrumented with thermocouples and installed in the chamber, it is connected to the ground support equipment and data acquisition system via electrical feedthroughs.

After roughing down the chamber with the mechanical pump, ultimate pressure is achieved with the cryopump. A main valve allows test set up while the pumping system is being established.

The test article is loaded onto the payload table or internal fixturing with the chamber dome rolled back. Often, special fixturing is required.

An external clean air supply provides fresh air to the chamber during pre-test activities.

Entry to instrument the payload with thermocouples, connect ground support equipment cabling, and install hardware is through a cleanroom airshower at the personnel door. Wearing of clean room garments is required.

Scaffolding may be erected to provide access to the payload. An area adjacent to the main facility control console is reserved for the experimenter's ground support equipment. Ambient functional checks are normally performed.

Payloads are typically installed on the 10’ diameter payload table in the center of the chamber, while ground support equipment (GSE) rests on the bottom shroud or optional personnel grates, when installed. Verify that your test article and/or GSE can be supported with a Code 549 Space Simulation Test Engineer during the planning phase.

During temperature cycling, soak periods are observed for functional checks as specified in the test plan. A computer data terminal is provided with packaged software routines for temperature monitoring.

Chamber evacuation is provided by eight rotary piston mechanical pumps with Roots blowers, and eight cryopumps. Two turbomolecular pumps are available to pump the lighter gases to achieve ultra-low pressures.

Thermal control is provided by an aluminum tube-in-sheet cylindrical shroud with both liquid nitrogen and gaseous nitrogen operational modes. The dome and bottom shrouds are also connected to the thermal skids. The payload table includes tubing, which can also be connected to the shroud thermal system, controlled independently by a thermal conditioning unit, or flooded with LN₂.

Resistance heater arrays, with external power supplies or gaseous nitrogen panels, are available for special thermal requirements. A thermoelectric quartz crystal microbalance (TQCM) and residual gas analyzer (RGA) provide both quantitative and qualitative monitoring of molecular contamination and gaseous constituents within the chamber. A helium refrigeration system can be used to cool auxiliary shrouds or cryopanels to temperatures as low as -253°C (20°K).

Vacuum compatible cameras are available for monitoring the test article.