Scientists shared the first unified image of James Webb after completing two more stages of the alignment process.
James Webb’s main mirror
The main mirror of the James Webb, consisting of 18 segments, has an area of 25 square meters, which is five times the area of the main mirror of the Hubble. The observatory is positioned as a replacement for the Hubble and Spitzer telescopes and will conduct observations in the near and mid-infrared range of the electromagnetic spectrum, being in a halo orbit around the second Lagrange point.
Initially, the telescope was supposed to go into space back in 2007, but the launch date was repeatedly postponed due to various difficulties. The cost of the project also grew steadily and eventually reached $10 billion. After the assembly was completed, the observatory underwent a number of tests for several years, both of the entire observatory as a whole and of its individual parts, including testing compatibility with the launch vehicle.
What will the telescope study?
The tasks for the telescope will be very different, it will observe objects in the early Universe, exoplanets and circumstellar disks, star formation regions, novae, and solar system objects.
James Webb will work in the red part of the visible range, as well as in the near and mid-infrared range. This allows it to better see many objects that were previously difficult to observe. For example, light from the first objects of the early Universe or planets with the temperature of the Earth, which are far from their stars. It is expected that it will be able to see such within a radius of up to 15 light-years from the Sun.
Engineers have completed two more steps of the alignment process of James Webb and showed a brand new unified image
For the pictures to be of high quality, the hexagons must be strictly in the same plane. No mechanical system for laying them out provided the desired degree of alignment on its own.
So, initially, the telescope took picture of the star HD 84406, located more than a quarter of a thousand light-years away, in the constellation Ursa Major.
Just like our Sun, this star is a yellow dwarf, that is, relatively bright, and at the same time isolated. By comparing 18 images taken with 18 mirror fragments, scientists began the long process to more accurately align each of the segments to bring the telescope to a fully functional state.
Engineers from the JWST team have already completed more stages from the seven-step process of aligning the main mirror. The additional alignment allowed the telescope to take the first images using all 18 mirror segments for the first time.
Scientists focused on the same target – HD 84406 – and the footage no longer includes 18 separate objects but one unified image. This week saw the team conclude two steps – Segment Alignment and Image Stacking. Now, experts will continue with the next step, which has been called – Coarse Phasing.
In the future, the quality of James Webb’s images will improve not only by aligning the mirrors but also by lowering the temperature of the main camera. The remaining part of the process will take several more weeks, and therefore is far from over.
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• Atkinson, N. (2022, February 25). Webb turns those 18 separate star images into a single unified star. next comes even better focus. Universe Today.
• Cameron, C. (2022, February 25). NASA gives a tantalizing preview of how the Webb Telescope Will See Stars. Inverse.
• Fisher, A. (2022, February 25). Webb Mirror Alignment continues successfully. NASA.
• Howell, E. (2022, February 25). James Webb Space Telescope is nearly halfway through its mirror alignment stages. Space.com.
• Kooser, A. (2022, February 25). James Webb Space Telescope delivers splendid star image as its mirrors align. CNET.