The Webb telescope is now fully assembled

The last delicate operation in the unfurling of the James Webb Space Telescope was successfully carried out when the two side mirrors were unfolded so that the large 6.5m concave mirror is now complete. This was the last final phase of the telescope assembly, as shown in this simulation.

A few days ago, the secondary mirror (the little mirror that faces the big golden mirror) was unfolded and the support structure for it was successfully locked into place.

The 2.4-foot-wide (0.74 meters) secondary mirror sits attached to a tripod opposite the main mirror. Its task is to concentrate the light collected by the gold-coated main mirror into an opening at the main mirror’s center. Through this opening, the light reaches the third mirror, which reflects it to the telescope’s instruments.

The confirmation that the mirror was in place arrived at about 11:30 a.m. EST (1630 GMT). The operators then took another 30 minutes to lock the tripod in place with several latches to ensure it will remain stable for the duration of Webb’s at least ten-year scientific mission. 

“This is unbelievable. We are now at a point where we’re about 600,000 miles [1 million kilometers] from Earth, and we actually have a telescope,” Bill Ochs, the James Webb Space Telescope project manager at NASA’s Goddard Space Flight Center in Greenbelt,  Maryland, said in the webstream. “So congratulations to everybody.”

“Once it’s latched, it’s complete and we do not ever come back and adjust this again,” added Webb’s deputy commissioning manager Julie van Campen, also of NASA Goddard. 

The next major step that was completed on January 6th was the unpacking of a radiator at the back of the telescope that will remove heat from the scientific instruments.

On Thursday (Jan. 6), the operators will unpack a radiator on the back of the telescope, designed to remove heat from the scientific instruments. They will then move on to assembling the main 21-foot (6.4 m) mirror, which due to its size also had to be folded for launch.

The telescope won’t be ready for science until this summer. It will take more than 100 days for Webb to cool down to its operational temperature of minus 400 degrees Fahrenheit (minus 235 degrees Celsius). Only in such extreme cold will the telescope be able to detect the faintest infrared signals from the most distant stars and galaxies.

The telescope now heads to its final location at the second Lagrange point and should arrive towards the end of the month and then there will be a period of about six months of various things that need to be done and components tested before it starts sending back images of the very early universe and exoplanets.

We have to now hope that the mirror does not have any curvature problems the way that Hubble had and that the electronics also work correctly so that we get the images we hope for.

You can keep up to date with the developments here.


  1. moarscienceplz says

    “We have to now hope that the mirror does not have any curvature problems the way that Hubble had and that the electronics also work correctly so that we get the images we hope for.”
    Mirror curvature should not be a problem. It was a problem for Hubble because it is a one-piece mirror. The segments of the Webb mirror are individually movable, and I believe they also can flex each segment to tweak its curvature.
    Also, it just feels like this is a different NASA from the one that effed up Hubble AND made a Space Shuttle that turned out to be so unreliable AND badly damaged Skylab during its launch, AND crashed a Mars orbiter because they confused English and Metric measurements. Since those days we have had several highly successful Mars rovers and the Pluto flyby was spectacular. Every step of the unfolding of Webb has worked without a hitch, and they announced that the initial rocket lauch went so close to ideal, that they believe they will have more fuel available to extend Webb’s mission longer than they had initially dared to project. I wonder if this improved NASA might be due to the fact that they now have more scientists and engineers that are not white men?

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