Next Generation Space Telescope

NASA’s next generation space telescope, the James Webb Space Telescope, is being displayed at the AAS annual meeting in Seattle, Washington. Despite the fact that the upcoming space telescope isn’t planned for launch until the mid 2013 the model currently on display is said to be a full scale mock up of the real thing.

James Webb Space Telescope (JWST) named after a former NASA Administrato, will have a large mirror, 6.5 meters (21.3 feet) in diameter and a sunshield the size of a tennis court. Since both the mirror and sunshade won’t fit onto the launch rocket fully open, thry will fold up and open only once JWST is in outer space. JWST will reside in an orbit about 1.5 million km (1 million miles) from the Earth.

NASA is currently developing several advanced technologies for the JWST including microshutters which will be used on the Near Infrared Spectrograph (NIRSpec) instrument of JWST. The NIRSpec is an instrument that will allow scientists to capture the spectra of more than 100 objects at once. Because the objects NIRSpec will be looking at are so far away and so faint, the instrument needs a way to block out the light of nearer bright objects. The microshutters were developed to help solve this problem. Each Microshutter is a tiny cell measuring 100 by 200 microns, or about the width of three to six human hairs. The microshutter cells have lids that open and close when a magnetic field is applied. Each cell can be controlled individually, allowing it to be opened or closed to view or block a portion of the sky. This adjustability is what allows the instrument to do spectroscopy on so many objects simultaneously.

Another important technology on the JWST is its lightweight cryogenic mirrors. Since a telescope’s sensitivity is directly related to the size of its mirror area that collects light the universe, the designers of the JWST tried to give the telescope the largest mirror size possible. Since a single very large mirror is complicated to make, expensive, usually heavy and can not fold to fit into the launch rocket JWST will have be made of up to 18 mirror segments that form a total area of 25 square-meters (almost 30 square yards) when they all come together. Each segment is made of beryllium, one of the lightest of all metals known to man. Beryllium has been used in other space telescopes and has worked well at the super-frigid temperatures of space in which the telescope will operate. The JWST impressive array will allow it to collect light approximately 9 times faster than the Hubble Space Telescope. The increased sensitivity will allow scientists to see back to when the first galaxies formed just after the Big Bang.

More on some of the new technologies planned for the JWST could be found on NASA’s website.
Image: A life-sized model of the JWST was recently on display at the AAS annual meeting in Seattle, Washington (Credit: NASA).