SpaceX Falcon 9 FT - ORBCOMM-2 - Dec. 21, 2015 (Return To Flight) DISCUSSION

[RonM]

Kim Keller has stated here that since the S1 engines were observed to continue to fire right through the RUD of S2, that the FTS was never activated, because the first thing the FTS does is shut down the engines.  Since the engines were observed to continue to fire right up to the point where S1 came apart, he concluded that the FTS never activated.  Since Kim is one of the stalwart pros here, I tend to believe him.

Yup, that's plenty good enough for me. Now that you mention it, I do recall that discussion. So outside a direct contradiction from SpaceX, I think that is settled.

Now I have heard that there are break-wires between the stages that are supposed to trigger the FTS. So, should have the FTS fired? Is this a secondary failure that no one is talking about, or is the first stage supposed to ignore a disintegrated second stage?

That depends on how the break-wires work. Is it loss of communications with the second stage avionics or a physical break between the stages? If the latter, then maybe there was enough of the second stage still attach to pass a continuity check.

[guckyfan]

That depends on how the break-wires work. Is it loss of communications with the second stage avionics or a physical break between the stages? If the latter, then maybe there was enough of the second stage still attach to pass a continuity check.

I think there was a "failure" of imagination. Nobody anticipated failure of the second stage while the first stage was still firing nominally. So there was no code to react to it even if the first stage avionics was aware of what was happening.

Just the same as with Dragon. It had not been anticipated and no software coded for Cargo Dragon surviving a breakup of the vehicle so it could not trigger the parachutes that would have saved it.

[PreferToLurk]

If musk has another press conference following the official determination of cause, I hope this is a question that gets asked.  I would love for Musk to clarify what the first stage was doing and "thinking" as the second stage ceased to exist, and if they have programmed in new contingencies to the first stage avionics should something like this happen again.

[Kabloona]

If musk has another press conference following the official determination of cause, I hope this is a question that gets asked.  I would love for Musk to clarify what the first stage was doing and "thinking" as the second stage ceased to exist, and if they have programmed in new contingencies to the first stage avionics should something like this happen again.

Reprogram the first stage to do what? The thing kept flying like a champ even as S2 was disintegrating, and the guidance system looked rock solid. You want the vehicle to keep flying no matter what, until FTS command is issued. It did. Hard to improve on that.

[guckyfan]

Reprogram the first stage to do what? The thing kept flying like a champ even as S2 was disintegrating, and the guidance system looked rock solid. Hard to improve on that.

Reprogram to stop accelerating and putting the escaping Dragon in danger as is supposed to happen in crewed flight.

[Kabloona]

Reprogram the first stage to do what? The thing kept flying like a champ even as S2 was disintegrating, and the guidance system looked rock solid. Hard to improve on that.

Reprogram to stop accelerating and putting the escaping Dragon in danger as is supposed to happen in crewed flight.

PreferToLurk was talking about "something like this happening again," which I took to mean on uncrewed cargo flights. On CRS-7, stage 1 did exactly what it was supposed to do, keep flying as long as safely possible.

You're talking about launch abort software that will be active when crewed Dragon comes on line, which I agree would hopefully behave differently.

Meanwhile, I fail to see the need to "program new contingencies" on S1 for cargo flights. Evidently cargo Dragon will get a software change for chute deployment in case of premature separation. Seems to me that's all they need to do for now.

[Nomadd]

Reprogram the first stage to do what? The thing kept flying like a champ even as S2 was disintegrating, and the guidance system looked rock solid. Hard to improve on that.

Reprogram to stop accelerating and putting the escaping Dragon in danger as is supposed to happen in crewed flight.

PreferToLurk was talking about "something like this happening again," which I took to mean on uncrewed cargo flights. On CRS-7, stage 1 did exactly what it was supposed to do, keep flying as long as safely possible.

You're talking about launch abort software that will be active when crewed Dragon comes on line, which I agree would hopefully behave differently.

Meanwhile, I fail to see the need to "program new contingencies" on S1 for cargo flights. Evidently cargo Dragon will get a software change for chute deployment in case of premature separation. Seems to me that's all they need to do for now.

If they're modifying the software to let Dragon use parachutes in a similar unmanned failure,  I'd expect they'll be treating it just like crewed flights and shutting down the 1st stage to give the capsule a better chance. It would seem simpler and more in their philosophy to make software as similar as possible on crewed and uncrewed Dragon flights.

[PreferToLurk]

If musk has another press conference following the official determination of cause, I hope this is a question that gets asked.  I would love for Musk to clarify what the first stage was doing and "thinking" as the second stage ceased to exist, and if they have programmed in new contingencies to the first stage avionics should something like this happen again.

Reprogram the first stage to do what? The thing kept flying like a champ even as S2 was disintegrating, and the guidance system looked rock solid. You want the vehicle to keep flying no matter what, until FTS command is issued. It did. Hard to improve on that.

IMHO, It should have triggered FTS once stage 2 stopped existing.  Or at least shut down engines as guckyfan suggests.  I think it is a reasonable question to ask if SpaceX was happy with how the first stage reacted to the failure.  No one has asked that question yet, and I don't think the answer is blindingly obvious.

[guckyfan]

I think it is entirely possible that they had not thought of this contingency and would not have programmed for it in their manrated version. They will now, for sure. Has it ever happened before that a second stage disintegrates during nominal first stage performance?

Edit: I don't think they would FTS and produce a fiery cloud near the escaping Dragon if it is not necessary to protect people elsewhere. Even if Dragon is designed for escaping that cloud.

[Karloss12]

I'm sure deploying the dragon parachutes in the event of failure (and in the process saving the expensive on board cargo) was something that SpaceX was fully aware of and wanted.

However with stretched resources it would have been on a non essential risk/loss to-do list.  It's a pity failure occurred before they were able to do it.

With limited resources their efforts have been all about getting cargo into orbit rather than recovering them in the event of failure.

I think the same goes for FTS.  They have a button that they can press at any time.  The resources aren't there to do anything more complex for cargo FTS at this stage.  Crew flights are of course a different story.

[matthewkantar]

Is it time to start some sort of a pool to guess at the announced/actual return to flight date?

Enjoy, Matthew.

[NX-0]

Is it time to start some sort of a pool to guess at the announced/actual return to flight date?

Good point. "End of September" is six weeks away.

[rcoppola]

Is it time to start some sort of a pool to guess at the announced/actual return to flight date?

Enjoy, Matthew.

Well, if you did and wanted the best chance of being correct, I'd suggest joining L2.

[Steven Pietrobon]

Has it ever happened before that a second stage disintegrates during nominal first stage performance?

Yes. First flight of Atlas Centaur.

[Karloss12]

Is it time to start some sort of a pool to guess at the announced/actual return to flight date?

Enjoy, Matthew.

I think that the bolt failure issue could be rectified for a launch at the end of September

However I bet that SpaceX are reviewing their entire philosophy to QA, which will result in the discovery of other needed improvements.

I'm tentatively guestimating a Novemberish launch.  Maybe even into the new year.  I'm optimistic that they will really iron out a good few failure scenarios with the QA review that they will be going through.

[NovaSilisko]

Has it ever happened before that a second stage disintegrates during nominal first stage performance?

Yes. First flight of Atlas Centaur.

Now that was a bit eerily similar, especially with the large dark object falling away early on, just like Dragon in the F9 footage.

[Chris Bergin]

The idea is to build an article for early next week. In fact, I've already started drafting, but I have to give a lot of people a chance to respond and people don't exactly answer phones and say "Oh yeah, what do you want to know!" when it surrounds a failure......idea is to focus on RTF, however.

Safe to say you can probably rule out September.....

[Encelade]

I guess all security protocols are reviewed/changed, not only the "bad bolt" business.
The next launch must be flawless. They won't rush it.

[Helodriver]

Has it ever happened before that a second stage disintegrates during nominal first stage performance?

Yes. First flight of Atlas Centaur.

Now that was a bit eerily similar, especially with the large dark object falling away early on, just like Dragon in the F9 footage.

Good color footage of the end of that Atlas Centaur flight was used in the finale of the 1982 experimental film Koyaanisqatsi. Great view of the LR-105 sustainer engine twirling and burning as it plunges back to Earth.  A lot more flame surrounded that failure than the CRS-7 blast, perhaps due to the lower altitude deflagration. Clip is linked, beginning after a few moments of Saturn V ignition

[Jim]

I guess all security protocols are reviewed/changed,

Why?