Nasa’s James Webb Space Telescope has sent back its first images.
The blurry image appears to show 18 different blobs of starlight – though they are actually all the same star, shaken up because the pieces of mirror in the telescope are not yet properly aligned.
(Nasa)
As such, the image is not only a major milestone in the rollout of a telescope that could one day reveal the ancient history of the universe and search for habitable alien planets.
It is also an important part of the alignment and focusing of the telescope, since engineers will use it to properly setup its view of the universe so that it can start that research.
Over the next month or so, Nasa’s engineers will adjust the telescope so that those 18 dots merge into one.
“The entire Webb team is ecstatic at how well the first steps of taking images and aligning the telescope are proceeding. We were so happy to see that light makes its way into NIRCam,” said Marcia Rieke, principal investigator for the NIRCam instrument and regents professor of astronomy, University of Arizona.
The $10 billion Webb telescope launched on Christmas day after years of delays and decades of development, and spent the next month traveling 1.5 million kilometers to its operational orbit. It was a busy month for the big telescope, which slowly and careful deployed its mirrors and solar panels that had been folded, origami like, for launch aboard an Ariane 5 rocket.
Webb reached Lagrangian Point 2, a region of space where the gravity of the Earth and Sun cancel out, allowing Webb to orbit the Sun while always keeping Earth at its back, on 24 January. Ground operators then began the commissioning phase for the big telescope, beginning with aligning the 18 beryllium mirror segments that make up Webb’s 6.5 metre primary mirror, the large diameter mirror ever flown in space.
To begin the alignment process, operators pointed Webb at 156 points in the sky where they predicted they could image a single star, an area of sky roughly the same size as the full Moon. The telescope took more than 1,500 images over more than 24 hours, stitching them together into a huge, 2 billion pixel image.
“Taking so much data right on the first day required all of Webb’s science operations and data processing systems here on Earth working smoothly with the observatory in space right from the start,” said Marshall Perrin, deputy telescope scientist for Webb and astronomer at the Space Telescope Science Institute, in Baltimore, which operates Webb and the Hubble Space Telescope. “And we found light from all 18 segments very near the center early in that search! This is a great starting point for mirror alignment.”
Completely aligning all of Webb’s mirror segments so that they produce a single image of a distant star could take another week or more, and even then the alignment process is not complete. The current alignment only takes one instrument — NIRCam — into account. Operators will also need to ensure the telescope produces a perfectly aligned and focused image for Webb’s three additional instruments, the Mid-Infrared Instrument (MIRI), Near-Infrared Spectrograph (NIRSpec), and the Near-Infrared Imager and Slitless Spectrograph/Fine Guidance Sensor (NIRISS/FGS).
After Webb’s optics are completely aligned, the telescope’s instruments will be calibrated and checked, a process that could take months. It will likely be sometime in mid-summer before Webb can begin making scientific observations.
