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Cryogenics and Fluids Branch

Liquid Helium and Hybrid Systems

Goddard has had a series of programs with stored cryogen coolers. These have been of two types, superfluid helium dewars and solid cryogen coolers.

The first Goddard project to fly a superfluid helium dewar was the Cosmic Background Explorer (COBE). This large dewar was followed by the shuttle-based Superfluid Helium On-Orbit Transfer Experiment (SHOOT). Because the SHOOT dewars (2 dewars) flew on the shuttle, they were returned and are now being considered for re-flight.

Another on-going Goddard project, the X-Ray Spectrometer (XRS), is also using a superfliud helium dewar. This tiny dewar will reside inside a solid neon dewar. The total heat flux to the stored helium is only 0.8 milliwatts. In designing this dewar Goddard has pushed the design of helium dewars far beyond the previous limits. We have performed a series of studies on every conceivable heat input. As a result of these studies we are now convinced that it should be possible to build a small, light weight dewar that could fly on a small rocket such as the Pegasus.

Additional studies have been performed on "hybrid systems". These systems combine stored cryogen systems with either radiative coolers or mechanical coolers. An early version of XRS had a helium dewar/mechanical cooler system with an analytical lifetime in excess of 3 years. A study of a mission concept for the Space Infrared Telescope Facility (SIRTF) combined a helium dewar with a multi-stage radiative cooler to obtain a long lifetime with a light weight dewar. Hybrid systems can obtain very long lifetimes.

The most recent stored cryogen coolers flown on Goddard programs have been a solid argon cooler, built by Ball Aerospace, on the Broad Band X-Ray Telescope (BBXRT) and a solid neon cooler, built by Lockheed, Palo Alto, on the Cryogenic Limb Array Etalon Spectrometer (CLAES). The BBXRT was a shuttle attached payload and the CLAES was an instrument on the Upper Atmospheric Research Satellite. Two on-going Goddard projects are using solid cryogen coolers, the Near Infrared Camera and Multi-object Spectrometer (NICMOS), with a solid nitrogen cooler; and the Wide Field Infrared Explorer (WIRE), with a solid hydrogen cooler.

References , with some absracts.

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Curator: Mark O. Kimball
NASA Official: Eric A. Silk
Last Updated: 09/11/2014