Is Webb at Its Final Temperature? This answer from NASA will surprise you
Article by: Andacs Robert Eugen, on 21 April 2022, at 11:12 am Los Angeles time
Let's get this straight with Webb's operating temperature: Webb has not yet reached its operating temperature, but it is close to reaching it.
NASA announced more than a week ago that Webb's infrared instrument, MIRI, has reached its operating temperature of 7 K (-447 degrees Fahrenheit, or -266 degrees Celsius).
According to the stages, MIRI will be checked by the coordinating team to make sure everything goes well, and Webb will be ready for the first observations starting this summer.
Why isn't Webb still at operating temperature?
Since the launch of Webb, NASA has announced that the process of aligning the mirrors and the rest that Webb has to perform in space will take several months.
As for the current stage, Webb still has to cool its mirrors, which must also reach an operating temperature.
Also, the material from which they are made matters in the cooling process.
The segments of the primary mirror and the secondary mirror are made of beryllium and covered with gold, according to NASA.
Beryllium takes a long time to cool or heat up due to the fact that it has a long thermal time constant.
Why were beryllium mirrors made?
It's simple, if they were made of glass or other materials, the cooling process can change their shape, but beryllium is different, the mirrors keep their shape, not affecting the alignment and cooling process.
At what temperature are the mirrors now?
According to NASA data, Webb's secondary and largest mirror reached 29.4 kelvins.
The rest of the mirrors (18 in number) have temperatures ranging from 34.4 kelvin to 54.5 kelvin.
Of the 18 mirrors, only 4 have temperatures above 50 kelvins, in ascending order: 52.6, 54.2, 54.4, and 54.5.
"These four mirror segments emit some mid-infrared light that reaches the MIRI detectors. Since all the mirror temperatures are now below 55 kelvins, it is expected that MIRI will be sensitive enough to perform its planned science, but any additional cooling of these mirrors will only enhance its performance," says NASA.
What temperature should they reach?
The Webb team wants the temperature of the mirrors to drop by another 0.5 to 2 kelvins.
Also, NASA answered the question:
"Is Webb at its final temperature? The answer is: almost!" said the space agency.