James Webb Space Telescope: How, When and Why Its Launch

Rehearsals and training at the Space Telescope Science Institute are essential to ensure that the assembly process runs smoothly and that any unexpected anomalies can be addressed. NASA / STScI, CC BY

After the tests, the rehearsals. The telescope will be controlled remotely by commands sent over a radio link. But because the telescope will be so far away – it takes six seconds for a signal to go one way – there is no real-time control. So for three years my team and I have been going to Space Telescope Science Institute in Baltimore and perform rehearsal missions on a simulator covering everything from launch to routine science operations. The team has even practiced handling the potential problems that the test organizers throw at us and nicely call “anomalies”.

Some alignment required

The Webb team will continue to rehearse and practice until the launch date in December, but our job is far from over once Webb is folded up and loaded into the rocket.

We have to wait 35 days after launch for parts to cool before starting alignment. Once the mirror is deployed, NIRCam will capture high resolution image sequences of the individual mirror segments. The telescope team will analyze the images and have the motors adjust the segments in steps measured in billionths of a meter. Once the motors have put the mirrors in place, we will confirm that the telescope alignment is perfect. This task is so critical that there are two identical copies of NIRCam on board – if one fails, the other can take over the alignment job.

This alignment and verification process is expected to take six months. When complete, Webb will begin collecting data. After 20 years of work, astronomers will finally have a telescope capable of scanning the most distant and far reaches of the universe.


This story was originally published with The conversation. Read the original here.

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