This afternoon, the Webb team successfully extended the observatory’s Deployable Tower Assembly (DTA), creating critical distance between the two halves of the spacecraft.
The DTA extended about 48 inches (1.22 meters), putting room between the upper section of the observatory, which houses the mirrors and scientific instruments, and the spacecraft bus, which holds the electronics and propulsion systems. This creates enough distance to allow the sensitive mirrors and instruments to cool down to the necessary temperatures to detect infrared light. This gap will also provide room for the sunshield membranes to fully unfold.
Engineers perform the final deployment test of the James Webb Space Telescope’s Deployable Tower Assembly in June 2021 at Northrop Grumman Space Park in Redondo Beach, California. Credit: NASA’s Goddard Space Flight Center
The deployment took more than six and a half hours, as engineers activated release devices and configured heaters, software, and electronics, before commanding the DTA itself to extend. The movement of the DTA, which looks like a large, black pipe, is driven by a motor. The team began the deployment at approximately 9:45 a.m. EST and completed it at approximately 4:24 p.m. EST.
This step furthers the team’s progress in deploying Webb’s sunshield – a human-controlled, multi-day process that will continue with the release of aft momentum flap and the sunshield covers.
Shortly after 9:00 a.m. EST today, engineering teams began the process of extending Webb’s Deployable Tower Assembly (DTA). When deployed, the DTA will create space between the spacecraft and the telescope, to allow for better thermal isolation and provide room for the sunshield to deploy.
This deployment is expected to take six or more hours. It is a human-controlled process that provides the team with the flexibility to pause, assess the data, and make adjustments as needed.
After a successful launch of NASA’s James Webb Space Telescope Dec. 25, and completion of two mid-course correction maneuvers, the Webb team has analyzed its initial trajectory and determined the observatory should have enough propellant to allow support of science operations in orbit for significantly more than a 10-year science lifetime. (The minimum baseline for the mission is five years.)
The analysis shows that less propellant than originally planned for is needed to correct Webb’s trajectory toward its final orbit around the second Lagrange point known as L2, a point of gravitational balance on the far side of Earth away from the Sun. Consequently, Webb will have much more than the baseline estimate of propellant – though many factors could ultimately affect Webb’s duration of operation.
Webb has rocket propellant onboard not only for midcourse correction and insertion into orbit around L2, but also for necessary functions during the life of the mission, including “station keeping” maneuvers – small thruster burns to adjust Webb’s orbit — as well as what’s known as momentum management, which maintains Webb’s orientation in space.
Arianespace’s Ariane 5 rocket launches with NASA’s James Webb Space Telescope onboard, Saturday, Dec. 25, 2021, from the ELA-3 Launch Zone of Europe’s Spaceport at the Guiana Space Centre in Kourou, French Guiana. The James Webb Space Telescope (sometimes called JWST or Webb) is a large infrared telescope with a 21.3 foot (6.5 meter) primary mirror. The observatory will study every phase of cosmic history—from within our solar system to the most distant observable galaxies in the early universe. Photo Credit: (NASA/Bill Ingalls)
The extra propellant is largely due to the precision of the Arianespace Ariane 5 launch, which exceeded the requirements needed to put Webb on the right path, as well as the precision of the first mid-course correction maneuver – a relatively small, 65-minute burn after launch that added approximately 45 mph (20 meters/sec) to the observatory’s speed. A second correction maneuver occurred on Dec. 27, adding around 6.3 mph (2.8 meters/sec) to the speed.
The accuracy of the launch trajectory had another result: the timing of the solar array deployment. That deployment was executed automatically after separation from the Ariane 5 based on a stored command to deploy either when Webb reached a certain attitude toward the Sun ideal for capturing sunlight to power the observatory – or automatically at 33 minutes after launch. Because Webb was already in the correct attitude after separation from the Ariane 5 second stage, the solar array was able to deploy about a minute and a half after separation, approximately 29 minutes after launch.
From here on, all deployments are human-controlled so deployment timing – or even their order — may change. Explore what’s planned here.