Webb Is On Its Way!

The James Webb Space Telescope is safely in space, powered on and communicating with ground controllers.

Webb continues in coast phase, and is now oriented correctly with respect to the Sun. The six reaction wheels of the spacecraft’s attitude control system have been powered on, and they are now responsible for keeping the spacecraft pointing in the right direction – so that its massive sunshield, which is the size of a tennis court and which will deploy over the course of the next week – will be able to keep the telescope protected from solar radiation and heat.

Webb is on its way to L2. Our next big milestone is this evening, when we conduct the first Mid-Course Correction burn.

Follow all of Webb’s upcoming milestones here.

Upper Stage Separation

The Ariane 5 upper stage brought the James Webb Space Telescope up to a speed of approximately 22 thousand miles per hour – headed for its final orbit around the second Lagrange point, commonly known as L2.

The upper stage engine has now cut off and the spacecraft has separated. An extra battery on the upper stage provided power for a boost after release of the telescope, distancing it from Webb.

Webb is now flying on its own in coast phase.

Main Stage Separation

After exhausting all its fuel and bringing Webb to speeds of approximately 16 thousand miles per hour, the main stage engine of the Ariane 5 has shut down and been jettisoned. The upper stage engine has ignited. It will burn for approximately 16 minutes, beginning Webb on its journey to its final orbit around the second Lagrange point, commonly known as L2, a point on the opposite side of Earth from the Sun,  directly on a path towards L2 on which it will continue for four weeks.

The Ariane 5 upper stage will now begin a special rolling maneuver to protect Webb from solar radiation after fairing separation. It will continue this maneuver until Webb is released from the upper stage, planned within the next 20 minutes.

Webb Telemetry Received

Telemetry from the James Webb Space Telescope has successfully been received at the Jupiter Control Center at Europe’s Spaceport in French Guiana.

A little more than two minutes after launch, the two solid rocket boosters on the Ariane 5 separated from the vehicle and then fell back into the ocean. Next, the fairing — which was modified with additional venting ports to allow for smooth depressurization of the fairing from ground pressure to vacuum during the flight—was jettisoned, exposing Webb to space for the first time. The S-Band Transmitter has now been powered on and is confirmed as transmitting telemetry.

Lift off!

The boosters have ignited, and we have liftoff!  The Ariane 5 launcher carrying NASA’s James Webb Space Telescope launched into space at 7:20 am EST from Europe’s Spaceport in French Guiana.

Webb Mission Moving to Automated Countdown Activities

Webb has completed internal checks. All ground stations and the spacecraft are go for launch. Spacecraft and launch engineers at the Jupiter Control Center at Europe’s Spaceport in French Guiana and at the Mission Operations Center at the Space Telescope Science Institute in Baltimore, Maryland, have confirmed that Webb is on internal battery and is in its final launch configuration.

At seven minutes before launch, computers will initiate all Ariane 5 automatic countdown activities. The Ariane 5 will launch unless computers detect an issue, ground controllers initiate a stop, or the Webb team requests a hold due to a concern.

During liftoff the two solid propellant boosters — known as EAPs, from the French Etage d’Acceleration à Poudre – ignite and, along with the main stage engine, power the Ariane 5 up and away from the pad. The EAP boosters are the largest solid rocket boosters ever produced by European industry, providing roughly 92% of the total thrust at liftoff.

Launch teams monitor the countdown to the launch of Arianespace’s Ariane 5 rocket carrying NASA’s James Webb Space Telescope, Saturday, Dec. 25, 2021, in the Jupiter Center at the Guiana Space Center 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)

Ariane 5 Fueling is Complete

Fueling for both the main and upper stages of the Ariane 5 rocket is now complete.

In preparation for launch scheduled for no earlier than 7:20 am EST (9:20 am GFT). The cryogenic arms attached to the Ariane 5 are now supplying top-up fuel until liftoff. All systems are being continually measured to monitor the readiness of Ariane 5 to launch and the condition of its precious cargo.

We Are Go For Launch!

Webb has been confirmed as being go for launch, and the countdown clock was started!  With weather reports looking favorable, the team authorized fueling of the Ariane 5, which began at 3 am EST.

Arianespace will measure winds at high altitude with the help of balloons to ensure absolute safety for the launch. Meanwhile the team continues to monitor Webb which is kept in a stable condition in the fairing. The team is monitoring temperatures, relative humidity, and cleanliness of the air entering the fairing – critical parameters to keep Webb cool, dry, and clean before liftoff.

Our broadcast of launch will begin at 6 am and can be watched on nasa.gov/live.  You can also follow along on the NASA app, and on social with the hashtag #unfoldtheuniverse.

Launch teams wearing Santa hats monitor the Webb telescope countdown from a control room.
Launch teams monitor the countdown to the launch of Arianespace’s Ariane 5 rocket carrying NASA’s James Webb Space Telescope, Saturday, Dec. 25, 2021, in the Jupiter Center at the Guiana Space Center 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)

Key Milestones After Liftoff

Both immediately after launch and over the following weeks, the James Webb Space telescope will pass through numerous milestones on its journey of approximately 1 million miles to its final orbit around the second Lagrange point, commonly known as L2.

NASA has a detailed plan to deploy the Webb Space Telescope over a roughly two-week period. For details on any particular milestone – or to get updates on how far along Webb is in the process – please read about the deployments here. You may also watch a visualization.

The process involves hundreds of individual deployments. It is not an automatic, hands-off sequence; it is human-controlled. This means that the order, location, timing, and duration of deployments may change. However, the default order and approximate timing is as follows:

First hour:
Liftoff
~9 minutes: main stage separation
~27 minutes: upper stage separation
~33 minutes: solar array deployed

First Day
~12.5 hours: Midcourse correction burn (MCC1a)
~1 day: Release and motion test of the gimbaled antenna assembly

.  . . and on
2 days: Midcourse correction burn (MCC1 b)
3 days: Forward sunshield pallet deployment
3 days: Aft sunshield pallet deployment
4 days: Deployable tower assembly
5 days: Aft momentum flap
5 days: Sunshield covers release
6 days: Sunshield port mid-boom and sunshield starboard mid-boom
7 days: Sunshield layer tensioning begins
8 days: Sunshield layer tensioning complete
10 days: Secondary mirror deployment begins and is completed
11 days: Aft Deployed Instrument Radiator
12 days: Port primary mirror wing deployment begins and is completed
13 days: Starboard primary mirror wing deployment begins and is completed
13 days: Webb is fully deployed
15-24 days: Individual mirror segment movements
29 days: Midcourse correction burn (MCC2)/L2 insertion burn
29.5 days: Orbit insertion complete