The James Webb Space Telescope (JWST) is advancing through its intricate deployment in space. On Monday, January 3, mission controllers began tensioning its enormous five-layer sunshield—a tennis court-sized, ultra-reflective shield engineered to keep the observatory at optimal low temperatures.
Launched on Christmas Day, JWST is optimized for infrared observations, perfect for studying the early universe. Detecting faint thermal signals from distant objects requires shielding it from stray heat sources.
Positioned at the L2 Lagrange point, 1.5 million kilometers from Earth away from the Sun, the telescope features a 22 m by 11 m sunshield composed of five ultra-thin, highly reflective layers. Engineers confirm this setup will maintain the primary mirror at around -223 °C.
The sunshield is a cornerstone of the mission, making its deployment a high-stakes process. Any misstep could jeopardize over two decades of development. That Monday, controllers successfully tensioned the first layer of the sunshield.
The process started two days late due to two minor issues identified Sunday during checks of JWST's power subsystem.
One involved six motors for sunshield tensioning, which ran slightly warmer than expected from sunlight exposure. Engineers reoriented the observatory to shade them, completing the maneuver Sunday.
The second was reduced output from the solar arrays, affecting power supply. Powered by five panels, a preset maximum duty cycle in a grid regulator limited voltage, forcing greater reliance on the backup battery. The team, anticipating this post-launch adjustment, implemented it ahead of schedule.
These challenges were largely anticipated as JWST adapts to space. If all proceeds as planned, remaining sunshield layers will deploy by Wednesday, January 5, followed by mirror alignment.
