After 25 years and over 10 billion US dollars, on Christmas Day 2021, the James Webb Space Telescope (JWST) was finally launched into space by a European Ariane 5 rocket. With its 6.5-metre primary mirror and its tennis-court-sized sunshield, Webb had to be folded up to fit in the rocket's fairing, only to be deployed step by step in the first two weeks of its mission (see box, 'Unfolding the telescope', on p36). However, the successor to the Hubble Space Telescope won't take its first images of the Universe before late June or early July 2022, which begs the question - why?
It seems like an excessively long wait, especially since JWST arrived in its final orbit on 24 January. A total of three mid-course correction manoeuvres successfully placed the huge space telescope in a slow looping orbit around the second Lagrange point (L2), a stable gravitational point some 1.5 million kilometres behind Earth as seen from the Sun. "But a lot more needs to be done before we can start science operations," says Mark McCaughrean, the Senior Advisor for Science and Exploration at ESA (the European Space Agency), NASA's main partner in the programme.
For one, the telescope and its sensitive instruments, which left the French Guianalaunch platform at tropical temperatures, have to cool down to 230°C below zero.
Denne historien er fra March 2022-utgaven av BBC Sky at Night Magazine.
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Denne historien er fra March 2022-utgaven av BBC Sky at Night Magazine.
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