Webb will have a 6.5-meter-diameter primary mirror, which would give it a significant larger collecting area than the mirrors available on the current generation of space telescopes. Hubble's mirror is a much smaller 2.4 meters in diameter and its corresponding collecting area is 4.5 square meters, giving Webb around 7 times more collecting area! Webb will have significantly larger field of view than the NICMOS camera on Hubble (covering more than about 15 times the area) and significantly better spatial resolution than is available with the infrared Spitzer Space Telescope.
1ST HOUR: Starting at liftoff, the Ariane rocket will provide thrust for a little over 8 minutes. Webb will separate from the Ariane V launch vehicle a half hour after launch and we will deploy the solar array immediately afterward. We will also release several systems that were locked for launch.
1ST DAY: Two hours after launch we will deploy the high gain antenna. About ten and a half hours after launch, JWST will pass the Moon's orbit, nearly a quarter of the way to L2. Twelve hours after launch there will be the first trajectory correction maneuver by small rocket engines aboard JWST itself.
1ST WEEK: The second trajectory correction maneuver will take place at 2.5 days after launch. We will start the sequence of major deployment just after that. The first deployments are the fore and aft sunshield pallets, followed by the release of remaining sub-system launch locks. The next deployment is the telescope in which the telescope and the spacecraft bus move apart from each other by about 2 meters when the deployable tower assembly extends. The full sunshield deployment with unfolding and tensioning of the membranes can then be initiated. At 6 days we deploy the secondary mirror, followed by the side wings of the primary mirror.
1ST MONTH: As the telescope cools down in the shade of the deployed sunshield, we will turn on the warm electronics and initialize the flight software. At the end of the first month, we will do the mid-course correction that ensures that Webb will achieve its final orbit around L2. Although the telescope cools to near its operating temperature, the Integrated Science Instrument Module (ISIM) is warmed with electric heaters to prevent condensation on the instruments as residual water trapped in the materials making up the observatory escapes to the vacuum of space.
2ND MONTH: At 33 days after launch we will turn on and operate the Fine Guidance Sensor, then NIRCam and NIRSpec. The first NIRCam image will be of a crowded star field to make sure that light gets through the telescope into the instruments. Since the primary mirror segments will not yet be aligned, the picture will still be out of focus. At 44 days after launch we will begin the process of adjusting the primary mirror segments, first identifying each mirror segment with its image of a star in the camera. We will also focus the secondary mirror.
3RD MONTH: From 60 to 90 days after launch we will align the primary mirror segments so that they can work together as a single optical surface. We will also turn on and operate the MIRI. By the end of the third month we will be able to take the first science-quality images. Also by this time, Webb will complete its initial orbit around L2.
4TH – 6TH MONTHS: At about 85 days after launch we will have completed the optimization of the telescope image in the NIRCam. Over the next month and a half we will optimize the image for the other instruments. We will test and calibrate all of the instrument capabilities by observing representative science targets.
AFTER 6 MONTHS: Webb will begin its science mission and start to conduct routine science operations.
This illustration of the Webb telescope captures the telescope's "hot side" beneath the sunshield, where Webb's ambient-temperature equipment, like its solar panel, antennae, computer, gyroscopes, and navigational jets are kept.
These are two Hubble images of the "Pillars of Creation" in the Eagle Nebula. The left image captures a visible light view, showing an opaque cloud of gas and dust. On the right, near-infrared light penetrates much of the gas and dust, revealing stars behind the nebula and hidden away inside the pillars.