The James Webb Space Telescope (JWST) has reached a crucial phase in the alignment of its mirrors. Images from this process have shown that everything is working even better than expected, and the telescope’s operators say that its performance will be able to meet or even exceed the goals that were originally set for it.
JWST peers into the cosmos with the help of 18 gold-plated hexagonal mirrors. For it to work properly, all of these mirrors have to be aligned with extraordinary precision – within nanometers – so that they act as one. When the observatory sent back its first images in February, the mirrors weren’t yet aligned and the images were blurry. Now, although the alignment process isn’t quite complete, the image is crystal clear.
“This is as sharp an image as you can get from a telescope of this size,” said JWST scientist Marshall Perrin at the Space Telescope Science Institute in Maryland during a 16 March press conference. It is the highest resolution infrared image ever taken from space. The picture itself shows a bright star called 2MASS J17554042+6551277. If the alignment hadn’t been precise enough, there would be multiple copies of the star in the image, but it shows that the mirrors are now all working together to create a single image of a star flanked by distant galaxies.
“The telescope performance so far is everything that we dared hope,” said JWST scientist Jane Rigby at NASA’s Goddard Space Flight Center in Maryland during the press conference. There are a few more alignment steps before the observatory can take its first science images, which are expected in June or July. This image of a single star is only the beginning. Once JWST begins taking science images, it should help unravel some of the universe’s biggest mysteries, from exoplanet habitability to dark energy.
How the James Webb telescope will rewrite the story of the universe
IN EARLY October, a cargo ship steered to starboard, leaving the Atlantic Ocean off the east coast of South America and entering the muddy waters of the Korou river. It was the final phase of the voyage and no effort had been spared to protect the prized item on board. It was housed inside a specially designed case to keep it safe from the pitch and roll of the waves. The river had been dredged to ensure the ship didn’t get stuck in the shallows. Even the exact date of the voyage had been kept secret, to avoid the attention of pirates.
The precious cargo was the James Webb Space Telescope, perhaps the most hotly anticipated scientific instrument ever. Known as the JWST, the telescope has been more than 25 years in the making and its launch has been delayed countless times. But it has now completed its voyage to the launch site in French Guiana and, if all goes smoothly, it will finally leave Earth in late December. “I still haven’t wrapped my head around it,” says Torsten Böker, deputy project scientist for the JWST at the European Space Agency (ESA). “It seems a little, bit unreal.”
Unreal not only because it has often looked like the telescope might never take off, but also because this device is designed to be a time machine that will help us see back to the enigmatic era of the universe’s first stars, which we know precious little about. Unreal, too, …
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