Falcon 9 Returns to Flight in Record Time

SpaceX’s launch of another set of Starlink satellites early this morning would be just another routine event except that it took place only two weeks after a Falcon 9 rocket failure. Companies typically take many months to analyze the cause of a failure and find and implement a fix. For SpaceX, the record-breaking number of launches they conduct and massive amounts of data they collect each time made it comparatively straightforward.

The Falcon 9 with 23 Starlink satellites lifted off at 1:45 am ET this morning from Kennedy Space Center’s Launch Complex 39A, which SpaceX leases from NASA.

Falcon 9 lifts off from pad 39A in Florida! pic.twitter.com/ozYLYUxCss

— SpaceX (@SpaceX) July 27, 2024

 

FALCON 9 RETURNS TO FLIGHT

This morning’s launch of 23 Starlink satellites, seen here transiting the Moon, was the first since a July 11 second stage anomaly during a Starlink mission from California grounded the Falcon fleet. In just 15 days, SpaceX identified and resolved the… pic.twitter.com/HMi0T365Bq

— John Kraus (@johnkrausphotos) July 27, 2024

It was SpaceX’s first launch since a July 11 failure of a Falcon 9 second stage that doomed 20 other Starlink satellites. They are part of thousands the company is launching for its satellite broadband Internet system.

The failure was the first since 2015 and only the second in the rocket’s history of 352 launches since June 2010. (This morning’s launch makes 353.) The first stage worked perfectly and returned to land on one of the company’s autonomous drone ships.

The second stage, also called the upper stage, fired correctly the first time, but reaching the intended orbit required a second burn. That time it failed.

During a news conference yesterday for the upcoming launch of NASA’s Crew-9 mission, also on a Falcon 9, SpaceX Director of Dragon Mission Management Sarah Walker said data quickly pointed to the problem — a crack in a “sense line” for a pressure sensor.

The crack was due to excessive vibrations because of a loose clamp and led to a liquid oxygen (LOX) leak in the upper stage engine. The first burn was OK, but by the time of the second burn 30 minutes later the ultra-cold LOX had caused excessive cooling of engine components, damaging them and preventing a restart. The upper stage nonetheless was able to complete automated sequences to release the satellites and passivate itself.  The orbit was too low for the satellites, however. Drag pulled them down into the atmosphere where they disintegrated.

Walker said the sense line was a second, redundant line added at the request of another customer for a particular launch, but the design change was left in place. The second line isn’t needed for most launches so the near-term solution is simply to remove it.

They made the change and tested it at their McGregor, TX rocket development facility “with enhanced qualification analysis and oversight by the FAA and involvement from the SpaceX investigation team,” according to a statement on the SpaceX website.

The FAA regulates commercial space launches and reentries and participated in SpaceX’s failure review to assess whether the failure posed a public safety risk.  On Thursday it determined there was no public safety risk and gave SpaceX permission to resume launches “while the overall investigation continues.”

Walker said there will be other fixes for the longer term, but did not elaborate.

She stressed the number of times they launch and the data they collect enabled them to quickly find the “root cause” of this failure. It was their 71st Falcon launch this year alone, a remarkable number. There were 96 in 2023 and the company is aiming for as many as 150 this year. No other rocket in the world has that cadence.

“SpaceX really feels strongly about testing like you fly and then also flying regularly so that we get a lot of flight heritage and history on our hardware and know how it works in every situation. So sometimes we need to fly a really unique mission for a customer that drives a necessary configuration change to the system, but the number of times we’re launching in a year, we want to take credit and have the data from every one of those previous launches to inform the next one and so that’s why we hold as tightly as we can to making every vehicle the same.”  Sarah Walker, SpaceX

She didn’t specify which customer required SpaceX to add the second sense line, but said it wasn’t NASA.

NASA Commercial Crew Program Manager Steve Stich pointed out that this failure would not affect a Crew Dragon launch to the International Space Station, like Crew-9, because they need only one upper stage burn. He also noted that the failure illustrates how even a small “innocuous” change can have a major impact and attention has to be paid to every detail.

NASA participated in the SpaceX failure review even though it was not a NASA mission. He praised SpaceX for going “above and beyond,” looking not only at the upper stage, but the first stage and the Dragon spacecraft to determine if there are any similar clamps or sense lines that might cause a problem. “We followed along and looked at all the data. In this case, because SpaceX did such an extraordinary job, we did not do any additional testing or analysis.”

Crew-9 is targeted for launch on August 18, although it could wait as long as early September depending on when Boeing’s Starliner departs ISS.

Walker also announced that SpaceX will soon stop using the ocean waters around Florida as the reentry point for Crew Dragon and Cargo Dragon. The splashdowns will return to the Pacific Coast in an effort to prevent the “trunks” of the spacecraft from landing on land. Jettisoned before reentry, the trunks are supposed to burn up in the atmosphere, but in several cases pieces have been recovered on land.  The change in reentry profile should prevent that. Walker added that it’ll take some time for SpaceX to reposition their recovery ships as they must go through the Panama Canal, but the plan is for all splashdowns to be off the coast of southern California beginning early next year.

In addition to Crew-9, SpaceX is planning two private astronaut Crew Dragon missions this year, Polaris Dawn and Axiom-4.