The James Webb Space Telescope, which launched on December 25, 2021, goes through a cooling process until it reaches the right temperature to operate at full capacity. A new statement posted on the official NASA website explains this part of the mission a little more.
According to the US space agency, the instrument known as “MIRI” (short for “Middle Infrared Instrument”) should operate at a temperature between -239.15 degrees Celsius (Celsius) and -234.15 degrees Celsius. However, its optical detectors – essentially, the “eyes” of a telescope that would be able to see the light – would have to be much cooler than that. This is where the “cooled radiator” comes in.
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“For the past two weeks, the cooler has been circulating cooled helium through the MIRI optical line, which will allow us to cool it down to -258.15 degrees Celsius. Soon, the cryogenics will face their toughest days of mission,” said Konstantin Benanen and Brett Naylor, cooling specialists at NASA’s Jet Propulsion Laboratory. (JPL-Caltech), by turning on the cryogenic valves, it will redirect the helium and force it to constrict the flow.“As the gas expands as it exits the restriction, it will become colder, bringing the operating temperature of the MIRI detectors below -266.15°C.”
In fact, at any temperature higher than this, the photodetectors will be effectively “blind”. Since they are tuned to operate at mid-infrared frequencies, there is no other option for them to operate. For this reason, the MIRI is installed outside the metal grille where the telescope’s lenses are also located – incredibly heated by absorbing sunlight, but in this way the instrument is thermally insulated.
“Cooling this instrument is one of Webb’s last big challenges before our team can truly relax, and getting past that point is a very important step in this challenge,” said Alistair Glass and Macarena Garcia-Marin, both MIRI calibration experts, when the time is right, the coolant will be It extracted nearly all of the heat from 100 kg of MIRI metal, the remnants of the orbital day of its launch.
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