B-roll of NASA Goddard Space Flight Center's Space Environment Simulator - 1080p59.94
Video footage of the Space Environment Simulator (SES) at the NASA Goddard Space Flight Center.
The SES uses massive mechanical vacuum pumps augmented with cryopumps to ensure that the hard vacuum of space is simulated in the test chamber. The cryopumps use liquid nitrogen to condense remaining gases out of the chamber once the mechanical pumps have done their work. The two types of pumps work together to eliminate all but the tiniest trace of air in the chamber, down to about a billionth of Earth’s normal atmospheric pressure. To simulate the hot and cold extremes possible in space, the thermal vacuum chamber can reach temperatures in a 600-degree range from 302 F all the way down to -310 F. The cylindrical chamber is 40 feet tall and 27 feet wide.”
Engineers use the SES chamber to test the James Webb Space Telescope hardware using a helium shroud that allows temperatures ~ minus 387 F (40 K) and below!
The Helium shroud goes inside the SES and enables testing of Webb Telescope hardware and instruments to temperatures they’ll be operating at in space, which is about 40 Kelvin for all but JWST’s Mid-Infrared Instrument (MIRI) which has an additional cryo-cooler that gets it down to 6-7 Kelvin.