Today’s excitement came directly from the NASA livestream of the Mission Operations Center at Space Telescope Science Institute during the deployment of Webb’s secondary mirror. Webb Program Manager Bill Ochs exclaimed, “We have a telescope!” as the latching process was confirmed, and the secondary mirror was fully deployed.
This was a very big moment for Webb, but why? What did Bill Ochs mean when he said, “We have a telescope”?
Webb’s big beautiful 6.5-meter primary mirror, made up of the 18 gold hexagons, is useless without the smaller 0.74-meter secondary mirror. The primary mirror, concave in shape, focuses all the light it collects onto the secondary mirror. The secondary mirror then sends the light into the center of the telescope to Webb’s instruments. Without the secondary mirror, the light simply reflects out into space. See the illustration below:
Now that the secondary mirror is deployed, the light path from outer space into our instruments is complete, and we have a fully functional telescope!
Kudos for the hard work of all the teams at Space Telescope Science Institute and elsewhere who made today’s deployment possible.
One final big deployment is coming up (amidst several other smaller deployments): the unfolding of Webb’s primary mirror. Stay tuned…