“After today’s successful launch of Crew-9, Falcon 9’s second stage was disposed in the ocean as planned, but experienced an off-nominal deorbit burn. As a result, the second stage safely landed in the ocean, but outside of the targeted area.
We will resume launching after we better understand root cause.”
"So where did the Crew-9 second stage come down? Here is the ground track of Crew-9 based on the TLE (orange) and the planned stage 2 deorbit area (white rectangle)"
"The most likely failure mode that still results in reentry is a slight underburn (less delta-V, higher resulting perigee). If you underburn too much the perigee will be too high for reentry to occur. So you expect the entry to be further along the orange line but not by too much"
"Here is the ground track showing the planned reentry area at bottom left. My analysis suggests that an off nominal deorbit that still ends up with stage reentry will impact on the orange line somewhere between the end of the white rectangle and the equator"
"Of course one can imagine weirder scenarios, where the stage points stably in the wrong direction during the burn and ends up in a high apogee arc splashing down further downrange, but it's unlikely."
"More possible is an overburn (failure of the engine to shut down) resulting in early reentry nearer (but still safely south of) New Zealand. But I think an underburn is more likely. Hopefully we'll hear more."
"NASA's Steve Stich announces New Dragon Contingency: New for Crew-8 and Crew-9, in the event of all 4 parachutes failing to deploy, SpaceX can use the SuperDracos launch abort system to perform a soft-splashdown."
"SpaceX's Bill Gerstenmaier says that this capability has been flown before, however this is just the first time it is being flown on a NASA mission. He confirms it allows Dragon to fire the SuperDracos "at the very end" to provide a "tolerable landing" for the crew."
"SpaceX's Sarah Walker says that this SuperDraco splashdown capability first flew on the Crew-7 mission (August 2023). However, it was deactivated due to a dodgy GPS sensor."
We will resume launching after we better understand root cause.”
"So where did the Crew-9 second stage come down?
Here is the ground track of Crew-9 based on the TLE (orange) and the planned stage 2 deorbit area (white rectangle)"
"Here is the ground track showing the planned reentry area at bottom left. My analysis suggests that an off nominal deorbit that still ends up with stage reentry will impact on the orange line somewhere between the end of the white rectangle and the equator"
New for Crew-8 and Crew-9, in the event of all 4 parachutes failing to deploy, SpaceX can use the SuperDracos launch abort system to perform a soft-splashdown."
NASA mission.
He confirms it allows Dragon to fire the SuperDracos "at the very end" to provide a "tolerable landing" for the crew."