Software patch planned to fix Ariane 6 upper stage issue

PARIS — European officials say a software change should fix a problem that occurred during Ariane 6’s inaugural launch in July that prevented the rocket’s upper stage from completing its final maneuver.

The Ariane 6 Task Team, which includes the European Space Agency, the French space agency CNES, ArianeGroup and Arianespace, said in a joint statement on September 16 that a review of data collected during the inaugural launch on July 9 showed “no obstacles” to a second mission, currently scheduled for later this year.

This inaugural launch was not ideal, however, because the upper stage’s Vinci engine failed to reignite for a final burn that would have deorbited the stage. The stage’s auxiliary power unit (APU) failed to ignite during the long landing phase, preventing the Vinci engine from firing its final burn at the end of the mission, leaving the stage in low Earth orbit.

In its statement, the task force said one temperature measurement exceeded the limit, which caused the APU to shut down. Engineers will implement a software change to adjust APU cooling “to improve ignition conditions and resolve the identified anomaly.”

This will not require any changes to the vehicle hardware itself. The software change will be implemented before the next launch of Ariane 6, the French military reconnaissance satellite CSO-3, Stéphane Israël, CEO of Arianespace, said during a Sept. 16 briefing organized as part of World Space Business Week here.

“We could do a second flight without fixing it,” he said, because the mission does not require multiple Vinci engine firings to put the satellite in the planned orbit. “But we want to deorbit the second stage on that second flight, and to deorbit the upper stage, we have to fix what happened.”

He added that the software change needed to fix the problem should be “fairly easy” to implement. The task force statement mentioned “a few unexpected behaviors” during the inaugural launch but did not elaborate on those issues or any changes needed for the second launch.

Israël said Arianespace still plans to conduct a second Ariane 6 launch by the end of the year, a few weeks after the Vega C rocket’s return to flight, which is currently planned for late November or early December, even with the APU software change. “We’ll see if we can meet that goal in the coming weeks and months,” he said of the timeline.

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