So Hubble’s Retiring: What next? NASAs prolific Hubble Space Telescope will soon celebrate the 23rd anniversary of its launch, but time is ticking down on this beloved and iconic symbol of space-based astronomy. Launched into orbit on April 24, 1990, Hubble very nearly became a national embarrassment. A defective mirror and fuzzy pictures beamed back to Earth made its debut less than stellar. But a 1993 repair mission corrected the flaw, and soon after, stunning images were being relayed home. Several more repair missions have made the telescope about a hundred times better. But it is unlikely that Hubble, which orbits about 300 miles (480 kilometers) above the Earth, will be serviced again in the future. If left untouched, the telescope would eventually start to tumble toward Earth. NASA is already paving the way for a successor to the aging space observatory. Pegged as the next great space telescope, construction on the $8 billion James Webb Space Telescope is underway. With its ability to travel farther into the universe and use its infrared eyes to cut through the clutter and see things beyond the range of visible light, there are high expectations for the discoveries that the Webb telescope could yield. After all, its got some big shoes to fill. The James Webb Space Telescope (sometimes called JWST, also NGST or the Next Generation Space Telescope) is a large, infrared-optimized space telescope. Webb will find the first galaxies that formed in the early Universe, connecting the Big Bang to our own Milky Way Galaxy. Webb will peer through dusty clouds to see stars forming planetary systems, connecting the Milky Way to our own Solar System. Webbs instruments will be designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range. Webb will have a large mirror, 6.5 meters (21.3 feet) in diameter and a sunshield the size of a tennis court. It has a planned mass about half of Hubble, but its primary mirror (a gold-coated beryllium reflector) has a collecting area about five times larger (25 m2 vs. 4.5 m2). The JWST is oriented towards near-infrared astronomy, but can also see orange and red visible light as well as the mid infrared region, depending on the instrument. The combination of these features will give JWST unprecedented resolution and sensitivity from long-wavelength visible to the mid-infrared, enabling its two main scientific goals – studying the birth and evolution of galaxies, and the formation of stars and planets. Both the mirror and sunshade wont fit onto a rocket fully open, so both will fold up and open once Webb is in outer space. Webb will reside in an orbit about 1.5 million km (1 million miles) from the Earth. The JWSTs primary scientific mission has four main components: to search for light from the first stars and galaxies that formed in the Universe after the Big Bang, to study the formation and evolution of galaxies, to understand the formation of stars and planetary systems and to study the origins of life. All of these jobs can be done more effectively by analyzing near-infrared light rather than light in the visible part of the spectrum. For this reason the JWSTs instruments will not measure visible or ultraviolet light like the Hubble Telescope, but will have a much greater capacity to collect infrared light. In planning since 1996, the project represents an international collaboration of about 17 countries led by NASA, and with significant contributions from the European Space Agency and the Canadian Space Agency. It is named after James E. Webb, the second administrator of NASA, who played an integral role in the Apollo program. The observatory is currently scheduled to be launched by an Ariane 5 from Guiana Space Centre Kourou, French Guiana into an L2 orbit with a launch mass of approximately 6.2 tonnes (6.1 long tons; 6.8 short tons). After a commissioning period of approximately six months the observatory will begin the science mission which is expected to last a minimum of five years. The potential for extension of the science mission beyond this period exists and the observatory is being designed accordingly. It is slated for an October 2018 launch date. So it’s quite clear that with Hubble’s successor, we’ll be able to see farther ahead in space, and deeper back in time. Universe, here we come!
Posted on: Wed, 16 Oct 2013 09:34:44 +0000
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