Another Delay for Webb, But This Time it’s Because of the Rocket, Not the Telescope

Officials from NASA and ESA this acknowledged the launch of the James Webb Space Telescope will very likely be delayed from the end of October to at least mid-November, 2021. As we reported last month, the usually reliable Ariane 5 has experienced problems on two previous launches where unexpected vehicle accelerations occurred when the fairing separated from the rocket. The fairing is the nose cone used to protect a spacecraft payload during launch and acceleration through Earth’s atmosphere.

“Indeed, there was an anomaly which has been mentioned recently in the media,” said Daniel de Chambure, acting head of Ariane 5 adaptations, during a media briefing on JWST. “The origin of the problem has been found; corrective actions have been taken.”

De Chambure added they are currently conducting the last tests and a qualification review has started “so we should be able to confirm all that in a few days or weeks. This should not jeopardize in any way the launch of James Webb,” he said.

Jeopardize, hopefully not. But delay, yes.

The officials in the briefing, including NASA’s Thomas Zurbuchen, NASA’s associate administrator for the Science Mission Directorate, were noncommittal about how long the delay may actually be.

The officials confirmed the telescope will be shipped to ESA’s launch site in Kourou, French Guiana in late August. From the start of shipping, it will take 10 weeks until the telescope will be ready to launch, with 55 days from its arrival to load the telescope on the rocket. When a member of the media worked out the timeline as leading to a launch no earlier than mid-November, Zurbuchen said that assessment is “approximately correct. I don’t really have anything else to add.”  

He did add, however, that Arianespace and ESA has been transparent with information in the past ten months about the possible delays.

“We’ve had all the information that we need,” Zurbuchen said. We’ve had in-depth technical discussions with all parties aligned with one goal, and that is to create mission success.”

The James Webb Space Telescope inside a cleanroom at NASA’s Johnson Space Center in Houston. Credit: NASA/JSC

While the recent anomalies occurred during the past two Ariane 5 launches, the payloads were successfully placed in orbit, however. There are two Ariane launches on the manifest before the JWST launch, and those launches are now expected no earlier than June and August 2021, respectively.

While the JWST project has a well-known and well-documented history of significant schedule delays and project cost increases, recently the project has completed significant technical milestones, such as successfully completing the final set of acoustics and vibration testing in October 2020, and performing sunshield deployment exercises in December 2020. This spring, the primary mirror was opened for the last time on Earth before packing up the telescope for launch.

Nancy Atkinson

Nancy has been with Universe Today since 2004, and has published over 6,000 articles on space exploration, astronomy, science and technology. She is the author of two books: "Eight Years to the Moon: the History of the Apollo Missions," (2019) which shares the stories of 60 engineers and scientists who worked behind the scenes to make landing on the Moon possible; and "Incredible Stories from Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos" (2016) tells the stories of those who work on NASA's robotic missions to explore the Solar System and beyond. Follow Nancy on Twitter at and and Instagram at and

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