Just over a week ago we got our very first look at images the James Webb Space Telescope was taking. The images are still far from the quality of scienfic images expected a few months from now, but now the previously messy array of light points has been organized and aligned according to mirror segment location.
The dots of starlight from HD 84406 that were previously rather randomly arrange have now been aligned into the iconic hexagonal array of the 18 mirrors of the James Webb Space Telescope.
This step, called Segment Image Identification, identified which mirror corresponded to which point of light and then adjusted the alignment into the corresponding position.
Clearly, each of these stars points of light is still a long way from producing deep-space images like we are used to with the Hubble, but the next two steps to work towards that are segment and global alignment. This will bring each of these 18 points of light, reflecting from each of the 18 primary mirrors and originating from the same source, into focus.
At that point, the teams can begin “image stacking,” where the 18 points are brought together to form a single point of light. NASA has an excellent visual representation of this from when James Webb sent back its first images, demonstrating how this alignment works:
This is still early in the deployment of the James Webb Space Telescope, which will gather images over the next decade or longer.
The joint project between NASA, the European Space Agency, and the Canadian Space Agency makes use of a much larger array of mirrors than Hubble, with improved light-gathering capabilities. Being out at L2, rather than low Earth orbit like Hubble, means it isn’t subject to objects like Starlink Satellites interfering with observations. These are just two of the many advantages James Webb Space Telescope has in its goal to enhance human understanding of the history of our universe.