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.
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.
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.
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.
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.
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.
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: