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)