Experts from the James Webb Mission Support Team (JWST) reported the successful cooling to operating temperature of the telescope’s most sensitive instrument, the MIRI Medium Infrared Camera. This means that the observatory is one step closer to the beginning of its scientific program.
How to see the light of the first stars
Why do you need to cool JWST tools? The fact is that the telescope is designed to conduct observations in the infrared range. It makes it possible to observe celestial bodies with extremely large redshifts. These are stars and galaxies that are located at such great distances from the Earth that the wavelength of light emitted by them has increased so much that it has turned into infrared radiation.
But in order to capture the infrared radiation of such extremely distant objects, JWST instruments must be reliably protected from any heat sources. To do this, the telescope has the largest sunscreen in history. After successful deployment, it was able to cool the telescope to -183 °C, which is enough to maintain the normal operation of three of the telescope’s four scientific instruments.
James Webb’s most sensitive tool
However, JWST’s fourth scientific instrument, the MIRI camera, has such a high sensitivity that its operating temperature should not exceed -267 °C. One sunscreen is not enough to cool it to such a low value. Therefore, engineers have equipped MIRI with a cryocooler that uses liquid helium. In several successive steps, they activated the device and first cooled the chamber to -258 °C and then to -267 °C.
The successful cooling of MIRI was an important milestone for the project. At present, the mission’s specialists can fully focus their efforts on calibrating the camera and testing it and other telescope instruments. These works are expected to be completed by June, after which JWST will begin implementing its rather intensive research program.
