The Elon Musk-backed company completed three successful blast-offs of its Starlink satellites from 27 to 28 July at both Cape Canaveral in Florida and Vandenberg in California.
It comes after SpaceX suffered its first failure in more than 300 successful attempts earlier this month when a Starlink launch broke up.
The incident involved a problem with the second-stage engine, which failed to reignite and instead deployed the payloads into a “lower than intended” orbit.
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After a short investigation, SpaceX revealed on 25 July that the problem was caused by a liquid oxygen leak within the insulation around the upper-stage engine.
“The cause of the leak was identified as a crack in a sense line for a pressure sensor attached to the vehicle’s oxygen system,” it said.
“This line cracked due to fatigue caused by high loading from engine vibration and looseness in the clamp that normally constrains the line.
“Despite the leak, the second stage engine continued to operate through the duration of its first burn, and completed its engine shutdown, where it entered the coast phase of the mission in the intended elliptical parking orbit.
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“A second burn of the upper stage engine was planned to circularise the orbit ahead of satellite deployment. However, the liquid oxygen leak on the upper stage led to the excessive cooling of engine components, most importantly those associated with delivery of ignition fluid to the engine.
“As a result, the engine experienced a hard start rather than a controlled burn, which damaged the engine hardware and caused the upper stage to subsequently lose attitude control.
“Even so, the second stage continued to operate as designed, deploying the Starlink satellites and successfully completing stage passivation, a process of venting down stored energy on the stage, which occurs at the conclusion of every Falcon mission.”
SpaceX was able to make contact with 10 of the satellites but revealed they were in an “enormously high-drag environment” that meant they were unable to be saved.
As a short-term fix, engineers are now removing the failed sense line and sensor on the second-stage engine to enable blast-offs to continue.
NASA’s commercial crew program manager, Steve Stich, praised the company for being “very transparent” with its investigation and said the incident showed that even small elements on a rocket can have major impacts.
“It was a small change that you would think would be innocuous,” he said. “It’s a good lesson learned for all of us in human spaceflight, and spaceflight in general, that small changes matter.”
Adam Thorn
Adam is a journalist who has worked for more than 40 prestigious media brands in the UK and Australia. Since 2005, his varied career has included stints as a reporter, copy editor, feature writer and editor for publications as diverse as Fleet Street newspaper The Sunday Times, fashion bible Jones, media and marketing website Mumbrella as well as lifestyle magazines such as GQ, Woman’s Weekly, Men’s Health and Loaded. He joined Momentum Media in early 2020 and currently writes for Australian Aviation and World of Aviation.
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