A crisp image of a bright star shows the James Webb Space Telescope's complex, segmented mirror is functioning flawlessly, NASA announced last week. After launching the $10 billion Webb in December 2021, engineers have spent weeks delicately tweaking the position and curvature of each of the mirror's 18 segments (which had been folded up during launch) until they behaved as a single, 6.5-meter reflector. Operators tested the mirror by using Webb's Near Infrared Camera to observe a star in the Ursa Major constellation 2000 light-years away. "Performance is everything we dared hope," says Webb operations scientist Jane Rigby-and a sign that NASA's gamble on Webb's design, a first for any space telescope, is paying off. Operators will next test the mirror's alignment with the telescope's three other observational instruments. The science campaign is expected to begin in July after the instruments are calibrated.
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