Ariane 5 launch of JWST
ESA and Arianespace said they are finalizing corrective actions to address a payload fairing separation issue sene on two Ariane 5 launches in 2020, setting up for a launch of JWST no earlier than November. Credit: ESA - D. Ducros

WASHINGTON — American and European officials acknowledged June 1 that the launch of the James Webb Space Telescope will likely slip from the end of October to at least mid-November because of delays linked to the Ariane 5.

At a European Space Agency briefing about the space telescope, representatives of the agency and Arianespace said they were finalizing reviews to correct a payload fairing problem found on two Ariane 5 launches last year that had grounded the rocket since August. Arianespace described the issue last month as “a less than fully nominal separation of the fairing” on those two launches.

“The origin of the problem has been found. Corrective actions have been taken,” Daniel de Chambure, acting head of Ariane 5 adaptations and future missions at ESA, said. “The qualification review has started, so we should be able to confirm all that within a few days or weeks.”

He did not elaborate on the problem or those corrective actions, beyond stating that the problem took place during separation of the payload fairing. Industry sources said in May that, on the two launches, the separation system imparted vibrations on the payload above acceptable limits, but did not damage the payloads.

The issue is not linked to a modification to the payload fairing required for JWST. Arianespace has been testing new vents on the fairing designed to reduce the pressure differential once the fairing is separated and thus reduce the loads on the spacecraft. “The issue of the modification of the venting system and the fairing anomaly are different,” de Chambure said.

The Ariane 5 is scheduled to make its next launch, the first since the August 2020 launch that had the payload fairing anomaly, in the second half of July, said Beatriz Romero, JWST project manager at Arianespace. That launch will be the first of two commercial Ariane 5 launches before the JWST launch.

At a May 11 media event, Greg Robinson, program director for JWST at NASA Headquarters, said that the JWST launch would take place about four months after the first of the two commercial Ariane 5 launches ahead of it. That would push the launch, currently scheduled for no earlier than Oct. 31, to at least the middle of November.

At the ESA briefing, Thomas Zurbuchen, NASA associate administrator for science, offered a similar schedule. Asked if a mid-November launch was likely, based on 10-week launch processing schedule that begins with JWST’s shipment from California to the launch site in French Guiana in late August, he said that timeframe is “approximately correct.”

“We want to be sure that we launch exactly when we’re ready, not a day earlier,” he said. “That is, when the spacecraft is ready and when the rocket and the fairing and everything is ready.”

Romero said several factors will go into setting a formal launch date, including the readiness of the rocket, the payload and the spaceport. “We are currently consolidating all of that information for the definition of the launch date,” she said. Arianespace has reserved a “launch period” for JWST that begins Oct. 31 and runs through early December.

An independent review commissioned by NASA of JWST in 2018, when technical problems with the telescope triggered another round of delays and cost increases, had recommended that NASA increase the oversight of the Ariane 5 to the same level as the agency does for missions launching on U.S. vehicles. While NASA did enhance its oversight, it fell short of the level recommended by that independent review.

Zurbuchen said that NASA has not had any problems getting information from its European partners on the status of the Ariane 5. “We’ve had all the information that we need. We’ve had in-depth technical discussions with all parties aligned with one goal, and that is to create mission success,” he said.

The briefing was primarily intended to preview the upcoming launch of JWST and the science that the observatory will perform once in space, emphasizing the roles that NASA’s partners, ESA and the Canadian Space Agency, play on the mission. Günther Hasinger, ESA director of science, estimated that Europe’s contributions to JWST, in the form of instruments and the Ariane 5 launch, to be about 700 million euros ($850 million), roughly the same as an ESA “M-class” science mission.

Gilles Leclerc, director general for space exploration at the Canadian Space Agency, said Canada’s contribution of an instrument and fine guidance sensors cost the agency about $200 million Canadian ($165 million) over 20 years. “This is an investment in discoveries of the universe,” he said.

NASA now estimates it will spend $8.8 billion on JWST through the spacecraft’s launch.

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...