NASA reports that the James Webb Space Telescope has completed the first phase of alignment of scientific instruments. All instruments except one that has not yet cooled to operating temperature are tuned to receive focused reflection from all 18 segments of the main mirror. The previous rough focusing of the mirrors turned out to be so accurate that during the stage of adjusting the instruments, the secondary mirror was not even touched – this indicates the highest level of mission preparation.
The sixth stage of setting up the telescope’s scientific instruments is the sixth, according to NASA. At this stage, the focus is adjusted to the near-infrared camera (NIRCam), the precision guidance sensor (FGS), the slit-free near-infrared spectrometer (NIRISS) and the near-infrared spectrometer (NIRSpec). The latest scientific device, the Medium Infrared Camera (MIRI), continues to cool.
The MIRI operating temperature should drop to approximately 7 degrees above absolute zero. Passive systems do not achieve this, so the chamber is equipped with two circuits of active cooling. This is the only device on the telescope that requires forced cooling. MIRI is expected to cool for another two to three weeks, after which its focus will be adjusted.
The peculiarity of the James Webb telescope is that all four scientific instruments of the observatory work in parallel, but with different parts of the sky. The telescope can aim only at one specific part of the sky (object). Therefore, all scientific instruments will simultaneously receive light from the mirror without the ability to fine-tune the focus during operation. Precise focusing is performed when adjusting the devices – now or in the future, if such an operation is required.
After fine-tuning the focus of all devices and connecting them to the precision guidance system, the stage of testing the operation of each of the devices will begin, which will last all of May and part of June. The telescope will start its scientific work in late June or early July. The first targets of the telescope are still kept secret, but it is no secret that “James Webb” due to the high sensitivity in the near and middle infrared range expects to look back to the days of the young universe, when galaxies and stars were just beginning to form.
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