Following the successful placement of the James Webb Space Telescope in the Lagrangian point-of-the-Sun halo orbit, all instruments have now been successfully turned on to be ready for the first adjustment and illumination.
Following the arrival of the James Webb Space Telescope in its orbit around Lagrangian Point 2 on January 24, the mission team began the process of performing a series of critical steps: Turn on all the tools Scientifically, turning off the heaters as the first step in a long cooling process and finally receiving the first photons in the main camera, to enable the accurate alignment of the telescope, which will take several months.
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While the MIRI instrument and some telescope components were launched in the weeks after launch on December 25 , the mission team until a few days ago turned on the remaining three instruments, including the Near Infrared Camera (NIRCam) and the Spectrometer. Near Infrared (NIRSpec) and FGS / NIRISS.
Now that these tools are on, the next important step for the mission team is to turn off the heaters of the scientific tools. The heaters were necessary to keep the telescope’s optical structures warm and to prevent the risk of water and ice condensation. Now that the scientific instruments meet the set temperature standards, the team turns off the heaters so that the instruments can restart the cooling process to several months until the final temperature.
When the NIRCam reaches 120 K (approximately minus 153 degrees Celsius), the James Webb team is ready to begin the precise movement of the 18 main mirror sections to form an integrated surface. The team has chosen the star HD 84406 as the first target to start this process, and this will be the first object that NIRCam sees when light photons hit its illuminated detectors.
A very bright star that, although very bright to read after the mirror is in focus, makes it ideal for collecting engineering data during the web mirroring alignment period. This alignment process essentially creates an image of 18 random, blurred optical points. In the first few weeks of mirror alignment, the mission’s training team focuses on receiving starlight and makes microscopic and nanometer adjustments to the mirror sections.
Eventually a set of 18 blurred dots becomes a focused image of the star. Cooling of telescopes and instruments will continue next month, and near-infrared instruments will eventually reach temperatures of about 37 to 39 K (minus 234 to minus 236 degrees Celsius). Then in the following months the cryogenic cooling device “MIRI” cools the temperature to 6 K (about minus 267 degrees Celsius).
This week, James Webb also unveiled its powerful high-speed data transmission antenna, which, in addition to receiving commands, allows NASA to send large volumes of data to the telescope through the far-space network. Now that the observatory is fully deployed and in its final configuration, the antenna is located in the lower part of the telescope, which faces the ground, and opens out of the spacecraft bed where essential equipment such as electricity, altitude control and communications are located.
Like other parts of the spacecraft, the antenna was extensively tested on the ground before being ready for use in space. In December 2021 (December 1400) and only one day after the launch of the spacecraft, this antenna was opened as part of the spacecraft gimbal antenna . According to NASA, this antenna will be used a lot because it has to send at least 28.6 GB of scientific data to Earth from the Web Telescope twice a day. The data is sent through space and is collected by NASA’s Remote Space Network, which has three powerful antennas in different parts of the earth, so that at least one place can always connect to the web.
To make data transmission more efficient, the Web sends data over a portion of the electromagnetic spectrum called the Ka radio band, which NASA says provides a much higher data rate than the S band the Web has ever used for communications. The Ka band and high-gain antenna eventually allow the observatory to send all images and scientific data to Earth in full for analysis and exploration by astronomers around the world.
Cover photo: Graphic design of the James Webb Telescope
Credit: NASA
