JWST in Kourou
The James Webb Space Telescope is now in a payload processing facility at the spaceport in Kourou, French Guiana, and on schedule for a launch Dec. 18. Credit: NASA/Chris Gunn

DUBAI, U.A.E. — The success of the most recent Ariane 5 launch has allowed preparations for the launch of NASA’s James Webb Space Telescope to move into the home stretch, officials said Oct. 27.

During a panel discussion at the 72nd International Astronautical Congress, representatives of NASA, the European Space Agency, Arianespace and other expressed confidence that the long-delayed giant space telescope will finally launch on Dec. 18.

That confidence is bolstered by the successful launch of the most recent Ariane 5 mission Oct. 23, placing into geostationary transfer orbit the SES-17 communications satellite for SES and the Syracuse 4A communications satellite for France’s military. The total payload mass of 10,264 kilograms was the heaviest for a geostationary orbit mission by any vehicle to date.

Stéphane Israël, chief executive of Arianespace, said on the panel that the final review of that launch was scheduled for Oct. 28. “It will be a very important milestone” allowing work to begin on the Ariane 5 launch of JWST, he said. The launch campaign for JWST will formally begin Nov. 6 for a Dec. 18 launch.

The spacecraft itself arrived in French Guiana Oct. 12, traveling by ship from Southern California. “The observatory is in the high bay in French Guiana,” beginning launch preparations, said Greg Robinson, JWST program director at NASA Headquarters. Fueling of the spacecraft will take place in about a month, after which it will be installed on the launch vehicle.

He said the team in French Guiana has had to deal with only minor issues associated with logistics, such as food and lodging, rather than technical issues with the spacecraft. Launch preparations have been running ahead of schedule, giving NASA some breathing room.

“We have a minimum of 11 days margin,” he said. “I have no concerns about margin. We’re in a really good state.” That margin will shrink once JWST is fueled and integrated with the Ariane 5, he added, but that is expected.

There’s also margin in launch vehicle preparations, Israël said. That includes accounting for two other launches at the spaceport ahead of JWST: a Vega launch of a cluster of French military smallsats in November and a Soyuz launch of two Galileo navigation satellites at the end of November. “We have margin, and we are very, very confident that we will be on time for the 18th of December.”

“We are in now the final, final mile heading towards this historical launch,” he said. “We feel the pressure, but it is a positive pressure for excellence, and we will deliver.”

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...