NASA’s James Webb Space Telescope blog reports that “The First Mid-Course Correction Burn ” was successfully accomplished at 00:50 UTC on 2021-12-26.
At 7:50 pm EST, Webb’s first mid-course correction burn began. It lasted 65 minutes and is now complete. This burn is one of two milestones that are time critical — the first was the solar array deployment, which happened shortly after launch.
This burn adjusts Webb’s trajectory toward the second Lagrange point, commonly known as L2. After launch, Webb needs to make its own mid-course thrust correction maneuvers to get to its orbit. This is by design: Webb received an intentional slight under-burn from the Ariane-5 that launched it into space, because it’s not possible to correct for overthrust. If Webb gets too much thrust, it can’t turn around to move back toward Earth because that would directly expose its telescope optics and structure to the Sun, overheating them and aborting the science mission before it can even begin.
Therefore, we ease up to the correct velocity in three stages, being careful never to deliver too much thrust — there will be three mid-course correction maneuvers in total.
After this burn, no key milestones are time critical, so the order, location, timing, and duration of deployments may change.
In Kiel, Germany, radio amateur Edgar Kaiser (DF2MZ) monitored the downlink telemetry signal from the spacecraft.
The waterfall plot shows the Doppler change in frequency as the burn progressed.