The preliminary design of NASA's James Webb Space Telescope sunshield has reached a major milestone. The five-layer shield is the size of a tennis court and is composed of specially coated reflective membranes and a support structure. It is designed to block solar heat to keep the telescope's instruments operating at cryogenic temperatures.
The Webb telescope will feature a mirror that is 21.3 feet in diameter. Because of the large size of the mirror and sunshield, the telescope will be folded to fit into a rocket and will be opened once in space. The telescope will reside in an orbit that is approximately 1 million miles from the Earth and used to explore distant galaxies as well as nearby planets and stars at the near- and mid-infrared wavelengths.
With the preliminary design review of the sunshield now complete, the work on the detailed engineering design of the instrument will now progress toward the scheduled launch in 2013. Northrop Grumman Corporation's space technology sector, prime contractor for the telescope, built the sunshield under a design and development contract from NASA's Goddard Space Flight Center, Greenbelt, Maryland.