PAGE 09
Aligned &
2022 WINTER EDITION
JWST progresses ever closer towar
By Jodi
We are one step closer to unravelling the mysteries of the universe with the James Webb Space Telescopes’ penultimate phase of commissioning completed. The multi-phase commissioning process for this freshly launched galactic eye in the sky officially started the second of blast off from the launch pad of the Kourou space port in French Guiana on Christmas day 2021. The first phase of spacecraft launch and deployment ran smoothly with no reported issues during the unfurling process. The tennis court sized sun shield was unfolded over a period of a week bringing the final steps of the deployment to a close on January 8th. The next crucial phase was to cool down the onboard instruments ready for mirror and scientific instrument commissioning operations to begin. This phase saw the Gaseous Helium Cryocooler chill down the science instruments to -266◦C, a temperature below the freezing point of nitrogen. This incredibly low temperature will help optimise the detection of the faint heat signatures from infrared light with limited interference from onboard generated electronic heat. Astonishingly according to NASA the JWST is so sensitive to infrared light, it would be able to detect even the slightest heat of a bumblebee at the distance of the moon. Surprisingly the 18 hexagonal gold coated beryllium mirrors stretching 6.5 meters in diameter took a while longer than the instruments to cool down. This was mostly due to the fact beryllium has a long thermal time constant at cryogenic temperatures, meaning this particular material takes a long time to cool down and heat up. The operational target temperature for the mirrors is below - 223◦C. By February the telescope was optimally cooled and the 3 month, 7 stage instrument and mirror alignment process could begin. This has been the most exciting instalment in the JWST story so far.
Image Credit: NASA GSFC/CIL/Adriana Manrique Gutierrez
