Challenge: To conduct deep space testing for its new James Webb Space Telescope (JWST), NASA needed to upgrade its historic Chamber A at the Johnson Space Center that was famously used to test Apollo space craft. The JWST is a large infrared telescope with a 6.5m primary mirror set to launch in 2018 to replace the Hubble Telescope. Testing the JWST required the massive 45 foot diameter x 65 ft high chamber to reach and hold temperatures of 30K (-405 °F). Never before had this been a been attempted for this large of a chamber.
Solution: To develop this unprecedented Gaseous Helium (GHe) shroud system, NASA and its primary contractor, Jacobs, turned to Dynavac- the expert in thermal cryogenic engineering and manufacturing. Dynavac fabricated and installed both LN2 (80 K) and gaseous helium cooled (20 K) shrouds. The helium gas generated from the helium refrigeration system passes through extruded tubing to create the thermal environment. The interior shroud system, fabricated from aluminum sheet and I beams, was constructed from panels approximately 12 ft wide and 40 ft long. These had to be painted on one side with special high optical absorptivity/emissivity black paint.
Extensive engineering analysis by Dynavac was required for placement and welding of the tubing onto the aluminum sheet to ensure compliance with operating and thermal performance specifications.The resulting system is one of the largest GHe shrouds ever constructed and includes exterior panels that operate under liquid nitrogen conditions (-196C), and helium shroud of the inner chamber that operates at 30 K (-405F).
In all, Dynavac designed, manufactured and installed 70 cryogenic shroud panels in Chamber A. Because of stringent NASA requirements for performance and safety, the project required substantial efforts in planning, scheduling, reporting, and certification of materials and procedures. In fact, NASA applied many of the same test and documentation specifications used for manned space flight. All shroud components were produced and tested in the company’s 50,000 sq. ft. facility in Hingham, Massachusetts.
Dynavac is one of the few companies in the world that can handle such multi-year, large-scale space simulation projects and we look forward to providing NASA with continued support for the James Webb Space Telescope program. Check out these NASA Chamber A shroud upgrade and retrofit process videos and visit the JSWST project website to keep up with the latest news.