Originally Posted by Planetman
The James Webb Telescope will have to perform a myriad of procedures before it can become fully operational.
Timeline Of Events After Launch:
After launch, the telescope will deploy on its 30-day, million-mile journey out to the second Lagrange point (L2). This video shows the deployment procedure, timeline, and location of the satellite during deployment.
In the first hour:
The ride to space, solar array deployment, and “free flight.” The Ariane 5 launch vehicle will provide thrust for roughly 26 minutes after a morning liftoff from French Guiana. Moments after second stage engine cut-off, Webb will separate from the Ariane, which will trigger the solar array to deploy within minutes so that Webb can start making electricity from sunshine and stop draining its battery. Webb will quickly establish its ability to orient itself and “fly” in space.
In the first day:
Mid-course correction to L2. Ariane will have sent Webb on a direct route to L2, without first orbiting Earth. During the first day, we will execute the first and most important trajectory correction maneuver using small rocket engines aboard Webb itself. We will also release and deploy the high gain antenna to enable the highest available rates of data communication as early as practical.
In the first week:
Sunshield deployment. Shortly after we execute a second trajectory correction maneuver, we will start the sequence of major deployments, beginning with the fore and aft sunshield pallets. The next step is separation of the spacecraft bus and telescope by extending the telescoping tower between them. The tower will extend about 2 meters, and it is necessary at this point in the sequence so that the rest of the sunshield deployment can proceed. Next, the sunshield membranes will be unpinned and the telescoping sunshield midbooms will extend – first the port side and then the starboard side – pulling the membranes out with them. The last sunshield deployment step is tensioning of the membranes. In the meantime, other things like radiators will be released and deployed.
In the first month:
Telescope deployment, cooldown, instrument turn-on, and insertion into orbit around L2. During the second week after launch we will finish deploying the telescope structures by unfolding and latching the secondary mirror tripod and rotating and latching the two primary mirror wings. Note that the telescope and scientific instruments will start to cool rapidly in the shade of the sunshield, but it will take several weeks for them to cool all the way down and reach stable temperatures. This cooldown will be carefully controlled with strategically-placed electric heater strips so that everything shrinks carefully and so that water trapped inside parts of the observatory can escape as gas to the vacuum of space and not freeze as ice onto mirrors or detectors, which would degrade scientific performance. We will unlock all the primary mirror segments and the secondary mirror and verify that we can move them. Near the end of the first month, we will execute the last mid-course maneuver to insert into the optimum orbit around L2. During this time we will also power-up the scientific instrument systems. The remaining five months of commissioning will be all about aligning the optics and calibrating the scientific instruments.
In the second, third and fourth months:
Initial optics checkouts, and telescope alignment. Using the Fine Guidance Sensor, we will point Webb at a single bright star and demonstrate that the observatory can acquire and lock onto targets, and we will take data mainly with NIRCam. But because the primary mirror segments have yet to be aligned to work as a single mirror, there will be up to 18 distorted images of the same single target star. We will then embark on the long process of aligning all the telescope optics, beginning with identifying which primary mirror segment goes with which image by moving each segment one at a time and ending a few months later with all the segments aligned as one and the secondary mirror aligned optimally. Cooldown will effectively end and the cryocooler will start running at its lowest temperature and MIRI can start taking good data too.
In the fifth and sixth months:
Calibration and completion of commissioning. We will meticulously calibrate all of the scientific instruments’ many modes of operation while observing representative targets, and we will demonstrate the ability to track “moving” targets, which are nearby objects like asteroids, comets, moons, and planets in our own solar system. We will make “Early Release Observations,” to be revealed right after commissioning is over, that will showcase the capabilities of the observatory.
After six months:
“Science operations!” Webb will begin its science mission and start to conduct routine science operations.
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