James Webb Space Telescope powers on its instruments in Ground Segment Test

NASA’s upcoming James Webb Space Telescope has run into its share of problems during its development process, but now it has reached a milestone with the completion of the “Ground Segment Test.”

This test involved sending commands to power on the scientific instruments aboard the James Webb for the first time, ensuring that ground control personnel at NASA will be able to control the telescope once it is in orbit.

“This was the first time we have done this with both the actual Webb flight hardware and ground system,” Amanda Arvai, deputy division head of mission operations at the Space Telescope Science Institute (STScI) in Maryland said in a statement.

“We’ve performed pieces of this test as the observatory was being assembled, but this is the first ever, and fully successful, end-to-end operation of the observatory and ground segment. This is a big milestone for the project, and very rewarding to see Webb working as expected.”

Now that the observatory has been completely assembled, Webb teams are running full observatory level tests to ensure it is prepared for the rigors of liftoff.
Now that the observatory has been completely assembled, Webb teams are running full observatory level tests to ensure it is prepared for the rigors of liftoff. NASA/Chris Gunn

The test required over 100 people, most working remotely, and took four days. It consisted of turning on, moving, and operating the telescope’s four instruments: The Near-Infrared Camera, the Near-Infrared Spectrograph, the Mid-Infrared Instrument, and the Fine Guidance Sensor/Near InfraRed Imager and Slitless Spectrograph.

“This was also the first time we’ve demonstrated the complete cycle for conducting observations with the observatory’s science instruments,” Arvai said.

“This cycle starts with the creation of an observation plan by the ground system which is uplinked to the observatory by the Flight Operations Team. Webb’s science instruments then performed the observations and the data was transmitted back to the Mission Operations Center in Baltimore, where the science was processed and distributed to scientists.”

The engineers wanted to simulate the communications conditions of the telescope being in space and being controlled from the ground, so they sent the commands via NASA’s Deep Space Network. Once the telescope is in orbit, commands will be relayed using the network which has locations in California, Spain, and Australia to ensure that communication with space-based instruments can continue as the Earth rotates.

Testing of the James Webb will continue with acoustic and sine-vibration testing which simulate the challenging conditions of a launch, and the launch itself is scheduled for October 31, 2021.

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