The Webb Space Telescope has passed a critical milestone in its commissioning phase, as mission controllers fully aligned the observatory’s primary imager.
Before we get into the details of today’s announcement, take a moment to bask in the glory of this new Webb image. The star is called 2MASS J17554042+6551277, and mission controllers have been using it to align the space telescope’s 18 hexagonal mirrors. But just look at it — look at how sharp it looks. And check out all those galaxies in the background. Unreal, especially considering it’s just a “test” image.
“This is the future from now on — whatever we see will be in the deep field,” said Jane Rigby, Webb operations project scientist, at NASA press conference held earlier today. “The only way for us to make this image any sharper would be to make a bigger mirror,” she added.
Rigby and her colleagues gathered to discuss a major milestone in the alignment process, the end of the fine phasing stage on March 11. The telescope’s primary imager — the Near-Infrared Camera — is fully aligned, and all 18 segments are now working as a single infrared eye that scientists will use to gaze upon the cosmos. More alignments are required, including work with the Near-Infrared Spectrograph, the Mid-Infrared Instrument, the Near InfraRed Imager, and the Slitless Spectrograph, but Webb is already blowing everyone away with its performance.
“This is one of the most magnificent days in my career at NASA,” Thomas Zurbuchen, associate administrator for science, said at the press conference. “Today we can announce that the optics will perform according to expectations, if not better.”
Webb’s 6.5-metre mirror had to be folded up for launch and then aligned to precision at the nanometre scale. Plenty of work remains, such as the cooling of the telescope, further instrument preparations, and those aforementioned alignments, but Webb is on track to enter into its science phase in July. At that stage, the commissioning team will turn the telescope over to the science community and view the infrared universe at resolutions not seen before, according to Zurbuchen. He said the team is nearing the top of the mountain, “but the sleepless nights are now behind us.”
During the press conference, I asked the panel if any critical points of failure remain or if there’s still potential for things to go off the rails. Rigby echoed the comments made by Zurbuchen, saying the heavy lifting has ended, and “now if things don’t work” it will only result in the “partial degradation of science.” That said, the telescope’s temperature is something she’s still looking into, as Webb continues to cool down. Marshall Perrin, Webb deputy telescope scientist, chimed in, saying some subsystems might not work at some point, “but we have lots of redundancy in electrical systems” and “we’re in very good shape.”
Lee Feinberg, Webb optical telescope element manager, said the optical performance of the telescope is absolutely phenomenal and “is good if not better than our most optimistic predictions.” The success of the mission so far shows that “we’ve pioneered a new way to build space telescopes,” an achievement that “will be of benefit to the next generation.” For Perrin, the biggest surprise was how closely the performance of Webb matched models and predictions on the ground. The images are focused together as “finely as the laws of physics will allow” for a telescope of this size, he said.
The star in the new Webb image was “plucked from obscurity,” said Rigby, a “nice boring star with the right amount of brightness.” The image was captured in infrared and then applied through a red filter to optimise visual contrast. As for the spiky appearance of the star, that’s the result of diffraction.
Marshall said the team is “almost exactly on schedule.” Rigby said they’re on track to meet the “very demanding scientific requirements” of the mission, but they’ve refrained from collecting any science data. Rigby said more than 1,000 proposals were submitted by astronomers requesting access to Webb, with only the “best ones” being picked, adding that the first batch of targets have been selected but not disclosed to the public. She said the first cycle of science will see the telescope peer back in time a few million years after the Big Bang, and that closer targets, such as the moons of Jupiter and Saturn and the Trojan Asteroids, will also be studied by Webb at some future point.
Launched on December 25, 2021, the $US10 ($14) billion Webb telescope is a joint mission of NASA, the European Space Agency, and the Canadian Space Agency. The telescope finally made it to space after many years of delays, and it’s now apparently working beyond expectations. Webb will provide a new lens for studying the oldest stars and galaxies, the atmospheres of distant exoplanets, and other celestial phenomena.