https://phys.org/news/2017-11-james-webb-space-telescope-cryogenic.html James Webb Space Telescope completes final cryogenic testing November 20, 2017 by Eric Villard Please Register or Log in to view the hidden image! NASA's James Webb Space Telescope sits inside Chamber A at NASA's Johnson Space Center in Houston after having completed its cryogenic testing on Nov. 18, 2017. This marked the telescope's final cryogenic testing, and it ensured the observatory is ready for the frigid, airless environment of space. Credit: NASA/Chris Gunn The vault-like, 40-foot diameter, 40-ton door of Chamber A at NASA's Johnson Space Center in Houston was unsealed on November 18, signaling the end of cryogenic testing for NASA's James Webb Space Telescope. The historic chamber's massive door opening brings to a close about 100 days of testing for Webb, a significant milestone in the telescope's journey to the launch pad. The cryogenic vacuum test began when the chamber was sealed shut on July 10, 2017. Scientists and engineers at Johnson put Webb's optical telescope and integrated science instrument module (OTIS) through a series of tests designed to ensure the telescope functioned as expected in an extremely cold, airless environment akin to that of space. Read more at: https://phys.org/news/2017-11-james-webb-space-telescope-cryogenic.html#jCp Webb is expected to launch from Kourou, French Guiana, in the spring of 2019.