NASA is gearing up to launch a pretty big telescope that will search for the universe's furthest galaxies, study the formation of stars, and look for the chemistry of life in other star systems. This is, of course, the James Webb Space Telescope, or JWST. Recently, segments of its huge mirror underwent a brutal but vital cryogenics test in preparation for work in space.
JWST will have a 6.5-meter primary mirror, built to reflect infrared light into its suite of instruments. Although ground-based telescopes have been sporting 8- and 10-meter mirrors for some time, space telescopes tend to come in smaller packages. The Hubble Space Telescope's primary mirror, for example, is 2.4 meters across, and just look at the wonders of the universe that has opened up for us.
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This large mirror will need to withstand the extreme cold of being in space, but that is a boon for infrared astronomy. Whereas really hot objects like stars give off plenty of visible light, "warm" objects -- such as planets, people, and telescope mirrors -- emit infrared radiation. A cold mirror and chilly instruments make an infrared telescope much more sensitive to the faint infrared light coming to it from distant astronomical sources.
The 6 of 18 mirror segments were cooled to -415 Fahrenheit (-248 Celsius, or 25 Kelvin). When cooled, the tiny surface deviations will be measured, and the mirrors will be polished to account for those deviations. Eventually, the polished beryllium surfaces will receive a thin coating of gold, hence the characteristic yellow sheen in models.
The telescope will launch no sooner than 2014, but astronomers are already excited about the new insights that they are sure to glean with this new instrument.
Image: Full-scale model of the James Webb Space Telescope at Goddard Space Flight Center with telescope team in 2005. Credit: NASA
Tags: NASA, Space Technology, Space Telescopes
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