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Our James Webb Space Telescope will be very cold during the hot Houston summer inside our Johnson Space Center’s historic Chamber A as it undergoes its final three months of testing in a cryogenic vacuum that mimics the cold temperatures of space. Chamber A will chill down to simulate a space environment of extreme cold -- around 37º Kelvin (-236ºC/-393ºF). In space, the telescope must be kept extremely cold, in order to be able to detect the infrared light from very faint, distant objects. To protect the telescope from external sources of light and heat (like the sun, Earth, and moon), as well as from heat emitted by the observatory, a five-layer, tennis court-sized sunshield acts like a parasol that provides shade. The sunshield separates the observatory into a warm, sun-facing side (reaching temperatures close to 400ºF) and a cold side (-185ºF). The sunshield blocks sunlight from interfering with the sensitive telescope instruments. The James Webb Space Telescope is the scientific successor to NASA's Hubble Space Telescope. It will be the most powerful space telescope ever built. Credits: NASA/Chris Gunn
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Rhea is a heavily-cratered, airless world, while Titan’s nitrogen-rich atmosphere is even thicker than Earth’s. This natural color image was taken in visible light by the Cassini spacecraft on Nov. 19, 2009, at a distance of approximately 713,300 miles (1,148,000 kilometers) from Rhea. After a nearly 20-year mission that overflowed with discoveries, the Cassini spacecraft ended its mission on Sept. 15, 2017. Credit: NASA/JPL-Caltech/Space Science Institute

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