Webb Telescope Video Provides a View of Vacuum Chamber Test

The Integrated Science Instrument Module, which is the heart of the Webb Telescope, is placed into the Space Environment Simulator at NASA's Goddard Space Flight Center for cryogenic testing. Image Credit: NASA's Goddard Space Flight Center.

Inside NASA's Goddard Space Flight Center in Greenbelt, Md., sits a massive thermal vacuum chamber called the Space Environment Simulator, or SES, that duplicates the vacuum and extreme temperatures of space. A new video shows how engineers use the chamber to test equipment that will fly aboard NASA's James Webb Space Telescope.

The giant SES is used to create both the temperature and hard vacuum of space. This 40-foot-tall, 27-foot-diameter cylindrical chamber eliminates the tiniest trace of air with vacuum pumps and uses liquid nitrogen and even colder liquid helium to drop temperatures to simulate those that exist in space.

The video shows engineers moving and lowering the heart of the James Webb Space Telescope, the Integrated Science Instrument Module (ISIM), into the SES. Afterward they sealed the chamber, evacuated all the air using vacuum pumps and then flowed liquid nitrogen and cold gaseous helium through plumbing within the SES to reduce the temperature inside down to as low as -423 F(-253 C or 20 kelvins).

The ISIM is the element of the Webb that contains all four of its scientific instruments. The ISIM is being tested to verify that it will operate as designed once it is in space, before it is integrated with other elements of Webb. For this particular test, known as "Cryo-Vac 1 - Risk Reduction," only two of the instruments are included: the Fine Guidance Sensor and Near Infrared Imaging Slitless Spectrograph (FGS/NIRISS) and the Mid-Infrared Instrument (MIRI). During the months-long test, the ISIM itself will cool to around -387 F (-233 C or 40 kelvins), which is the temperature that it will operate at in space. The objective of this test is to exercise all the testing systems and procedures and to check initial ISIM performance before final verification testing of the entire flight ISIM with all four of the scientific instruments installed.

FGS/NIRISS was provided by the Canadian Space Agency.

MIRI was built by a European consortium together with NASA's Jet Propulsion Laboratory
in Pasadena, Calif. It took eight years to design, build and test. MIRI was the first of Webb''s four instruments to be delivered to NASA for integration into the observatory. Webb is an international project led by NASA with its partners the European Space Agency and the Canadian Space Agency.

The video is available for download from http://svs.gsfc.nasa.gov/vis/a010000/a011300/a011360/index.html.

For more information about NASA's James Webb Space Telescope, visit:
www.nasa.gov/webb or www.jwst.nasa.gov

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