After 116 days of being subjected to extremely frigid temperatures like those in space, the heart of the James Webb Space Telescope, the Integrated Science Instrument Module (ISIM) and its sensitive instruments, emerged unscathed from the thermal vacuum chamber at NASA’s Goddard Space Flight Center.

A crane lifts the heart of the Webb Telescope from the thermal vacuum chamber. (NASA/Chris Gunn)

Teams of engineers and technicians have been on heart-monitoring duty around the clock since this complicated assembly was lowered into the chamber. The team used the massive thermal vacuum chamber called the Space Environment Simulator (SES) that duplicates the vacuum and extreme temperatures 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 the temperature simulating the space environment.

At any given time of day during the test, the control room held representatives from all four instrument teams. Each instrument has a test engineer, who makes sure the test is going well, and a data analyzer. Those teams are testing the hundreds of electrical connections and computer programs that give life to Webb's heart.