Two down, one to go

A busy day even for SpaceX. 

The Crew-13 mission to the ISS went off on schedule, and apparently completely "by the book." While completely clouded out and unable to see or even hear a thing during the mission (11:10AM and for another eight to ten minutes), we watched it all on YouTube, through the Booster return to LZ-40 there on CCSFS. Within the last hour, Crew Dragon "Grace" docked with the ISS and the crew should have entered the ISS by now. 

The Transporter 18 mission from Vandenberg was during our grocery shopping run so we didn't watch that one live, but on YouTube when we got back and put everything away. Another one completely by the book, with every call during ascent on the expected time and flawless. The booster also successfully landed. I'll confess to boredom while watching the 130 satellites on the rideshare mission get deployed.

You will probably recall that Crew-13 was supposed to launch on September 12 but was grounded due to a leak in the Dragon capsule, specifically in the oxidizer system. In the intervening weeks, I've never come across an explanation of the problem and the fix SpaceX implemented. Until today. 

The launch was delayed from mid-September to replace a balky valve in the Dragon spacecraft’s propulsion system, a task that involved cutting into a propellant line inside the ship to swap out a faulty component. 

Bill Gerstenmaier, SpaceX’s vice president of build and flight reliability, pointed to the valve replacement inside the Dragon spacecraft as evidence of SpaceX’s commitment to fulfilling its contract with NASA. I think it's also evidence of SpaceX being extremely good at what they do. 

NASA announced a postponement for the Crew-13 launch in late August to give ground teams time to resolve an oxidizer leak inside Dragon’s propulsion system detected during launch preparations at Cape Canaveral. SpaceX traced the leak to a valve. The spacecraft was already loaded with nitrogen tetroxide, or NTO, the volatile, toxic oxidizer used by Dragon’s control thrusters in combination with hydrazine fuel.

Teams devised an unprecedented bit of spaceship surgery to replace the valve without draining the propellant and disassembling the spacecraft, steps that would have triggered a much longer delay. The fix involved cutting into the propellant line, removing and replacing the valve, then welding the line together again. It was the first time SpaceX has performed such a repair with a fully assembled Dragon spacecraft loaded with propellant.

“We looked at the plans, all of the data coming out of that, the welds, the leak, everything looks great,” said Dana Weigel, NASA’s program manager for the International Space Station. [We’re] really happy with how that repair was done.”
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SpaceX’s preference to cut out the valve in place, rather than take a longer stand-down, kept the Crew-13 mission on track to arrive at the space station in time to replace Crew-12, which will return to Earth in mid-October after eight months in orbit.

The Crew Dragon spacecraft was inside SpaceX’s fueling and hazardous processing facility, known as Area 59, at Cape Canaveral Space Force Station, not at the company’s usual maintenance hangar a few miles away.

Because the Oxidizer tank was full of Nitrogen Tetroxide, a very reactive compound (which is why they use it, after all), Gerstenmaier said, “We had to get special permission from the [Space Force’s Eastern] Test Range to do these activities, to do ‘hot work’ with nitrogen tetroxide on the vehicle.” (I'll note that instead of NTO, some of you might prefer something closer to the standard chemical notation of N₂O₄ over NTO, as I do).

As for the third launch of the day, tonight's Falcon Heavy mission at 11:53 PM, at the moment I'm planning to watch this one online. We're still under the cloud cover we've been under all day and the forecast looks to be much like for the Crew-13 launch today. About a 60% chance of acceptable weather. 

A SpaceX Falcon Heavy rocket launches with NASA’S Nancy Grace Roman Space Telescope from Launch Complex 39A, just over a month ago, Aug. 30, 2026. Same vehicle on the same launch complex as tonight. (Image credit: NASA/Joel Kowsky)