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NASA installs key 'sunblock' shield on Roman Space Telescope

Technicians have successfully installed two sunshields onto NASA's Nancy Grace Roman Space Telescope's inner segment. Along with the observatory's Solar Array Sun Shield and Deployable Aperture Cover, the panels (together called the Lower Instrument Sun Shade) will play a critical role in keeping Roman's instruments cool and stable as the mission explores the infrared universe.

The team is on track to join Roman's outer and inner assemblies this fall to complete the full observatory, which can then undergo further prelaunch testing.

"This shield is like an extremely strong sunblock for Roman's sensitive instruments, protecting them from heat and light from the sun that would otherwise overwhelm our ability to detect faint signals from space," said Matthew Stephens, an aerospace engineer at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

The sunshade, which was designed and engineered at NASA Goddard, is essentially an extension of Roman's solar panels, except without solar cells. Each sunshade flap is roughly the size of a garage door—about 7 by 7 feet (2.1 by 2.1 meters)—and 3 inches (7.6 centimeters) thick.

"They're basically giant aluminum sandwiches, with metal sheets as thin as a credit card on the top and bottom and the central portion made up of a honeycomb structure," said Conrad Mason, an aerospace engineer at NASA Goddard.

This design makes the panels lightweight yet stiff, and the material helps limit heat transfer from the side facing the sun to the back––no small feat considering the front will be hot enough to boil water (up to 216 degrees Fahrenheit, or 102 degrees Celsius) while the back will be much colder than Antarctica's harshest winter (minus 211 Fahrenheit, or minus 135 Celsius). A specialized polymer film blanket will wrap around each panel to temper the heat, with 17 layers on the sun side and one on the shaded side.

The sunshade will be stowed and will gently deploy around an hour after launch.

"The deploying mechanisms have dampers that work like soft-close hinges for drawers or cabinets, so the panels won't slam open and rattle the observatory," Stephens said. "They each take about two minutes to move into their final positions. This is the very first system that Roman will deploy in space after the spacecraft separates from the launch vehicle."

Now completely assembled, Roman's inner segment is slated to undergo a 70-day thermal vacuum test next. Engineers and scientists will test the full functionality of the spacecraft, telescope, and instruments under simulated space conditions. Following the test, the sunshade will be temporarily removed while the team joins Roman's outer and inner assemblies, and then reattached to complete the observatory. The mission remains on track for launch no later than May 2027 with the team aiming for as early as fall 2026.