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Aerospace Technology Facilities

NASA's Largest Cryoshroud Installed in World's Largest Vacuum Chamber

An 80-ft-long by 40-ft-wide by 23-ft-high cryoshroud was installed inside the Space Power Facility (SPF) to support space station thermal vacuum testing. The Space Station Program required a facility where the thermal conditions of space could be duplicated for three ground tests:

Deployment of the photovoltaic module radiator
Deployment of the thermal control system radiator
Mission simulation test of the photovoltaic module

The cryoshroud simulates the radiative coldness of space by surrounding a test article (75 ft 3 15 ft) with black-painted cold panels chilled by flowing -250 deg.F gaseous nitrogen through tubes attached to them.

The Space Power Facility at Plum Brook Station near Sandusky, Ohio, contains the largest vacuum chamber in the world--a 100-ft diameter by 75-ft-high cylinder topped by a 50-ft hemispherical dome (125-ft centerline height). SPF simulates a space environment over a wide range of thermal and vacuum conditions to test advanced propulsion and space power systems. SPF was chosen for these space station tests because of its unique size. No other vacuum chamber has the 75-ft-long by 35-ft-wide floor area required for the space station tests.

photograph

Cryoshroud for thermal vacuum testing at SPF.

The cryoshroud was successfully operated during a series of checkout tests in August 1994. Its primary requirement was to produce a uniform cold soak temperature below -200 deg.F to approximate the cold sink temperatures of low Earth orbit. During the test 97% of all the thermocouples produced readouts below -230 deg.F and all the thermocouples read below -220 deg.F, exceeding the requirements.

The unique qualities of the cryoshroud include

Its physical size of 80 ft long by 40 ft wide by 23 ft high. No cryoshroud is as long and still has the same width.
A cold floor that can move on rail tracks in and out of the chamber--allowing test article and support hardware buildup outside the chamber, where large cranes are available
The ability to provide a uniform soak temperature ranging from -230 to 85 deg.F
The ability to be removed or reinstalled, depending on the thermal requirements of individual test programs. Setup time is estimated to be 4 weeks, and removal and storage takes 2 weeks.
Ten individually controlled zones where coolant flow rate can be adjusted to produce a more uniform cold soak condition

The cryoshroud was provided by Process Systems International, Inc., of Westborough, Massachusetts.

Lewis contact: Henry J. Speier, (216) 977-7420
Headquarters program office: OSF

Last updated 1995

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