The James Webb Space Telescope (JWST) has already caused some spine-chilling moments this year when it deployed its tennis-court-sized multi-layered sunshield and flipped out its 18-segment, 20-foot primary mirror earlier this year.

By then, relief at the success of this impressive technological challenge had already been great, and nervous tension had given way to anticipation of the first images from space.

In January, however, the JWST scientists initially urged patience.

"The first images are going to be ugly, fuzzy, we're going to see 18 small images scattered across the sky," James Webb project scientist Jane Rigby said at a press conference at the time.

After all, the 18 mirror segments were initially not aligned in such a way that their individual images would produce a common image.

The initial phase in the operation of the space telescope was therefore initially devoted to focusing the mirror.

Sibylle Anderl

Editor in the feuilleton, responsible for the "Nature and Science" department.

  • Follow I follow

The first announced 'ugly' image was taken in early February using the near-infrared NIRCam of the star HD 84406 in the constellation of the Big Dipper and was presented to the public on February 11th.

NIRCam was chosen from the four observation instruments on board JWST because the camera images a particularly large area of ​​the sky and contains components that were specially developed for this mirror focusing process.

In addition, unlike the other instruments on board, it could be operated before the telescope was fully cooled.

Preparation for summer observations

A lot has happened since the observation of the star HD 84406, which started the seven-step mirror alignment process, as can be seen in the latest image released by NASA from the JWST.

Visible on it is the bright star 2MASS J17554042+6551277, about 2000 light-years distant, which was the primary target of the observation to check the mirror alignment.

In fact, the image no longer provides any indication that it was originally created from the superimposition of images from 18 mirror segments.

These are now also working in a vertical direction in such a coordinated manner that they have actually become one large telescope.

An impressive demonstration of the extraordinary functionality of the telescope is not only provided by the star itself, but also by what can be seen in its background: a large number of distant galaxies can be discovered there, some billions of light years away.

"The resolution of James Webb is the highest ever achieved by a space telescope in the infrared," reported project scientist Scott Acton in the course of the release of the image, "all our expectations have been exceeded." In fact, with the completion of the fifth step of the alignment phase, the "Fine Phasings”, it can be summarized that the JWST at least meets the target specifications or even works better than predicted with regard to all optical parameters tested so far.

The two remaining steps in the alignment process now concern the observations made with the three remaining instruments on board James Webb.

The next six weeks are planned for this.

As with NIRCam, the necessary corrections must be calculated from the observation data using a complicated mathematical process.

After that, small errors that still exist will be corrected again by the beginning of May at the latest.

The first scientific data should then be published in the summer.