A major part of NASA’s nearly complete Nancy Grace Roman Space Telescope just passed a lengthy thermal test to ensure it will function properly in the space environment.

“This milestone tees us up to attach the flight solar array sun shield to the outer barrel assembly and deployable aperture cover, which we’ll begin this month,” said Jack Marshall, who leads integration and testing for these elements at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Then we’ll complete the remaining environmental tests for the flight assembly before moving on to connect Roman’s two major assemblies and run the full observatory through testing, and then we’ll be ready to launch.”

Prior to this thermal testing, technicians integrated Roman’s deployable aperture cover, a visor-like sunshade, into the outer barrel assembly, which will house the telescope and instruments, in January, then added test solar panels in March. They moved this whole structure into the Space Environment Simulator test chamber at NASA Goddard in April.