Webb’s team continues to make progress in aligning the observatory’s mirrors. The engineers completed the first stage of this process, called “CT definition”. The resulting image shows that the team moved each of Webb’s 18 primary mirror segments to bring 18 unfocused copies of a single star into a striped hexagonal formation.
With the image array completed, the team has now begun the second phase of the alignment: “Fragment Alignment”. During this phase, the team will correct the large positioning errors of the mirror segments and update the secondary mirror’s alignment, making each individual point of starlight more focused. When the “general alignment” is complete, the team will begin the third stage, called “image stacking,” which will bring 18 light spots on top of each other.
“We orient the clip points into this array so that they have the same relative positions as the physical mirrors,” said Matthew Lallo, systems scientist and director of the Telescopes Branch at the Space Telescope Science Institute. “During general alignment and image stacking, this familiar arrangement gives the wavefront team an intuitive and natural way to visualize changes in clip points in the context of the entire primary mirror. We can now actually watch the primary mirror slowly form into its exact, intended shape!”
James Webb Space Telescope uses a process called wavefront sensing and control to perfect its vision in orbit. This animation illustrates that process. Credit: NASA’s Goddard Space Flight Center
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