The first image we've seen from the James Webb Space Telescope has been released by NASA, but don't get too excited just yet.
The image, which NASA published online on Friday, shows the star HD 84406 as seen from each of Webb's 18 primary mirror segments. At the moment, those segments are not in alignment with each other, so the image effectively shows a single star from 18 different angles.
The challenge is to align each mirror segment so that the star it sees perfectly aligns with the star as seen from the other mirrors – essentially, aligning the mirrors until 18 stars become a single, perfectly overlapping image.
The instrument used to image the star, the Near Infrared Camera (NIRCam), is one of four light collecting instruments on the Webb telescope, and the test image serves two purposes.
First, it confirms that light is passing through the entire telescope to the NIRCam sensor, which shows that the telescope actually works. Second, it provides the starting point for the telescope alignment.
As the telescope cools down, we'll hopefully get more images throughout the process as NASA works to aligned each mirror segment in nanometer increments, a process that is expected to take a few months.
Analysis: it's working!
While the first image we've gotten from Webb might not look like much, it's a really big deal. First, it shows the challenge ahead of having to line up each mirror correctly to get the actual images we're looking forward to getting in a few months time.
But most importantly, it shows that light is passing through the entire instrument as it should. While there are three more sensors that need to be tested in the weeks ahead, once the mirrors are aligned, Webb will at least be able to give us much clearer images than we've ever gotten in the near infrared spectrum, which will in itself be a huge boost for astronomy.
"The entire Webb team is ecstatic at how well the first steps of taking images and aligning the telescope are proceeding," Marcia Rieke, principal investigator for the NIRCam instrument and regents professor of astronomy, University of Arizona, said in the NASA update. "We were so happy to see that light makes its way into NIRCam."
While the more sensitive, deeper infrared spectrum instruments are what really make Webb the important astronomical tool that we hope it will be, knowing that light is making it to the instruments is exciting news indeed.
