Webb Has Almost Reached its Final, Coldest Temperature

The James Webb Space Telescope (JWST) was launched from the French Guiana launch site on December 25, 2021. The observing mission should begin in about a month.

NASA has been cooling off its instruments to make sure they are ready for their mission. The mirrors are left to cool down after they have reached that point.

MIRI is using a closed-cycle gaseous-helium cryocooler to keep its temperature down. The telescope's mirrors and other instruments are being cooled down without any help. Their temperature is lowered when heat is thrown into space.

The secondary mirror is at the end of the support structure. It is far away from the heat sources of the telescope's instruments. The 18 primary mirror segments are almost completely cooled. Their temperatures range from 34.4 to 54.5 kelvins. The team operating the telescope would like to see them cool down.

Why is this necessary? The part of the spectrum that will be seen by the JWST is the part of the spectrum that is visible in the visible light. If the telescope's instruments are kept below a certain temperature, the heat from the telescope's instruments will cause it to be unable to see the objects it is trying to observe.

The near- and mid-infrared part of the spectrum will be observed by the James Webb Space Telescope. The light's wavelength tends to bounce off of dust particles, preventing it from reaching a telescope here on Earth or even a space based observatory. The ability to get past many more obstacles than visible light allows us to capture images that would otherwise not be possible.

Some of the first stars to form, brown dwarfs, and black holes are some of the objects that will be imaged by the JWST. The light from those objects in the early universe has redshifted and will be able to be seen by the James Webb Space Telescope, giving us a better view of this time period and hopefully answering many questions about how our universe works.

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The artist's conception shows NASA's James Webb Space Telescope, which will provide more information about previously detected exoplanets. Next- generation space telescopes are expected to build on what they discover. Credit: NASA.