About this ArticleM. Stiavelli (stiavelli[at]stsci.edu)
The commissioning of the NASA, ESA, CSA JWST continued to progress according to the mission plan. Earlier this year, after aligning the Optical Telescope Element for the Near Infrared Imager (NIRCam) [see Fig. 1], we then began multi-instrument alignment involving all instruments. The Mid-Infrared Instrument (MIRI), built by a consortium including US and European partners, was the last one to reach its operating temperature, which is colder than the other instruments. The MIRI detector operates at ~7 K thanks to the active cooling provided by a cryocooler. All instruments were checked out. The Near-Infrared Spectrometer (NIRSpec), provided by the European Space Agency, underwent testing of the Grating and Filter Wheels and observed stars as part of the multi-instrument alignment. Similarly, the Near Infrared Imager and Slitless Spectrograph (NIRISS), provided by the Canadian Space Agency, has been used to obtain images of stars to check its focus. The Fine Guidance Sensor (FGS), provided by the Canadian Space Agency, also provided focus information, as well as being regularly used to guide observations taken by the other instruments.
By April 28, 2022, NASA declared the telescope alignment was complete. Beautiful, crisp images are well focused after the seventh (final) stage of alignment [see Fig. 2]. Now, as of the writing of this article in May 2022, each instrument is being individually configured and tested, preparing for science operations this summer.
The main source of commissioning news is the blog, which is updated at least weekly.