Wednesday, July 15, 2020

SpaceX is Apparently Having Falcon 9 Problems

Back in June, SpaceX had scheduled the launch of the 10th Starlink satellite mission for the 22nd, a Monday.  That launch was delayed 24 hours until Tuesday, then Thursday and finally Friday.  On that Friday, they simply said,
“SpaceX is standing down from today's launch in order to allow additional time for pre-launch checkouts in advance of its tenth Starlink mission.  Falcon 9 and its payloads, 57 Starlink satellites and 2 satellites from BlackSky, a Spaceflight customer, remain healthy.  SpaceX teams are evaluating the next earliest launch opportunity and will announce a new target date once confirmed.”
The “next earliest launch opportunity” was last week, originally on Wednesday the 8th, but that one was scrubbed due to afternoon thunderstorms.  Launch was reset for Friday morning, but when I got up and set to watch, SpaceX said it was further delayed until Saturday the 11th.  That in turn was scrubbed with a shorter statement; the first sentence of the paragraph above.  

During the Wednesday scrub, they did something unusual that caught my eye.  The launch was scrubbed with 10 minutes left in the countdown, but they opted to run the countdown, fueling the vehicle completely and running lots of other operations until the T minus 1 minute mark (when the Falcon 9's computers take over things), “for data collection.”  I've never heard them say that; I've never heard anyone say that.

Something seems wrong.  The booster for this mission, B1051, was to fly its fifth mission, so since only one has completed five missions successfully, attention focuses on the first stage.  Along the way, I had heard that there was a static firing of B1051 but that they never specifically said it had passed.  It's hard to imagine them proceeding if it didn't pass, but not stating it passed is just another oddity that people are noticing.  Are they seeing something in the data during a countdown test that isn't normal but doesn't really mean a failure?  Are they seeing something fail then start working, or something that fails sometimes?

Then, Monday the 13th, SpaceX announced that the mission to launch a South Korean military satellite called ANASIS II set for No Earlier Than yesterday, July 14th, had also been delayed indefinitely to allow teams to inspect the Falcon 9 rocket’s upper stage and potentially replace hardware. Upper stage?  That's different.  Since the upper stages are always new, do both of these upper stages have a problem?  Or not necessarily even a problem, just something that “don't seem right?”

Whatever it was they wanted to look at, they seem to have regained confidence in it.  Spaceflight Now reported today that:
Airspace warning notices associated with the Falcon 9/Anasis 2 mission indicated SpaceX might reschedule the launch for Sunday, July 19, during a launch window opening at 5 p.m. EDT (2100 GMT).
That mission, by the way, will use the booster from the first manned Crew Demo mission on May 30th, B1058.  If that mission flies on Sunday, it will be 51 days from launch, through recovery, refurbishment, and relaunch.  The previous record is 62 days.  

There have been eight announced launch dates for the Starlink 10 mission; I don't know if they consider all eight to be scrubs, but until now they've been going pretty much like clockwork, whenever the mission is scheduled.  Maybe they scrub due to weather or some typical little problem, but they don't scrub eight times, spread over most of a month.
As of July 1st, SpaceX has completed 11 launches in 2020 and has at least another 16 within tentative launch targets in the second half of the year. To complete all 16, the company would have to average almost three launches per month for the rest of 2020, a cadence it’s only managed to sustain for two or so months at a time.
Starlink mission 10 still doesn't have an announced launch date and appears to be holding up several additional launches.  It would be interesting to learn what caused the eight launch delays. 

An “experienced” Falcon 9, apparently ready for a Starlink mission from Pad 39A at the Kennedy Space Center.  (Richard Angle/Richard Angle/NASASpaceflight photo)  I'd like to say it's B1051 and the Starlink 10 mission, but it's not identified that way at the source. 


  1. Wasn't the second stage flight for the latest GPS mission a first-of-a-kind for them? I wonder if there was something anomalous about it.

    1. I hadn't heard of anything unique to the second stage on that mission, and looking around for details doesn't show anything mentioned.

      The only thing that seemed unique was that the Air Force allowed them to recover the booster. The first time SpaceX launched a GPS sat for them, they were so afraid that recovering the booster would compromise the mission that they said "throw it out." Which still seems illogical.

      If you or anyone has any links about that upper stage, please send it on.

    2. I believe the Air Force reasoning was carrying extra fuel for the landing was a risk, albeit a small one. Once SpaceX had demonstrated landing a number of times the risk was reduced. And perhaps more importantly, IIRC SpaceX dumped a landing attempt because of a flight anomaly and abandoned the stage to complete the launch.

    3. I'll give them the benefit of the doubt that when SpaceX launched their first GPS satellite it was still unproven technology. Now that there have been over 50 Falcon 9 launches and they've missed very few recoveries since they refined the technology in '17, it's harder to argue against letting them land the booster.

      If the Teslarati website is correct (they usually are) the GPS III satellite weighs less than 2 metric tons and it's going to a medium altitude orbit. The Crew Demo mission lifted 12 metric tons, including two astronauts, and that booster was recovered.

      IIRC SpaceX dumped a landing attempt because of a flight anomaly and abandoned the stage to complete the launch. That was the first booster to fly five missions. The software noticed there was a loss of power from one engine and burned the stage long enough to make up for the loss of power. That ended up using enough more fuel to not be able make the landing and software guided the booster into the drink. As you all but said, it's a software feature, not a bug.

      SpaceX has always stated loudly that recovering the booster is a nice thing to have but getting the customer's payload to the right orbit is the first priority.

    4. D'oh! That was supposed to be "the GPS III satellite weighs less than 4 metric tons".

  2. This is the SpacefightNow article that talks about a revised flight profile:

    One change to the Falcon 9 rocket requested by the Space Force for the GPS SV03 mission is a gray band of thermal insulation on the launcher’s upper stage. The thermal layer will help maintain kerosene fuel at proper temperatures during a nearly one-hour coast phase between the first and second burns of the upper stage’s Merlin engine."

    There have been longer coasts for SpaceX second stages, so probably the need to do more checkout is unrelated to the GPS mission.

    1. Thanks! Good to know that. There was no mention of that on the Teslarati web site. I tend to think they're plugged in better than I am but maybe not.

      Since they seem to have scheduled the South Korean mission for Sunday at 5 PM, whatever it was they wanted to look at on the second stage must be fine. Still no word on the Starlink mission.