In the clean room atNASA's Goddard Space Flight Center in Greenbelt Maryland, a team ofengineers has unveiled the vast gold-covered primary mirror of thefuture James Webb Space Telescope (JWST). As the telescope waspainstakingly pieced together, the all-important mirror segments werecovered in a protective black sheaths to guard against scratches andan accumulation of dust.
Each of the18 20-kg (46-lb) mirrors that combine to form the 6.5-m(21-ft) mirror are comprised of alight but resilient metal known asberyllium, and coated in a thin layer of vaporizedgold. This same process wasfollowed in the design of the telescope's secondary mirror, which issupported by three lightweighthollow struts.
NASAhas anointed the JWST as the spiritual and scientific successor tothe Hubble Space Telescope, which recently celebrated its 26th year in orbit following its crisis-fraught early years. Hubble servesas both a marker for excellence for future space missions, as well asa reminder that a potentially phenomenally successful mission couldbe crippled before it even launched by a minor design defect.
Onceoperational, the JWST will be the largest reflecting telescope everto be sent into space.Inorder to launch so large a mirror, the telescope has been designed tofold up like a piece of high-tech origami inside the fairing of itslaunch vehicle.
Furthermore,each of the individual mirror segments has a number of motors fixedto the mounting, which will allow them to be manipulated to focusmore accurately on distant targets than would be the case if onesimply pointed the entire assembly toward it.
Combinethis with the sunshade, and you get a very ambitious design with alot of moving parts, and a whole lot that could go wrong. To reducethe chances of a failure, or a Hubble-like design defect, the mirrors are set to undergo a comprehensive regime of tests, alongsideother telescope components soon to to installed on the mirrorassembly.
TheJWST's powerful infrared capabilities will allow the orbital platformto undertake a vast array of observations. The more grandiose aspectsof its mission will involve capturing images and data on the oldestgalaxies and stars in creation as they existed 13.5 billion yearsago, soon after the creation of the universe. The telescope will alsobe tasked with observing distant exoplanets, as well as the celestialbodies populating our home Solar System.
Source:NASA