SpaceX F9 : Starlink v1.0 L19 : CCSFS SLC-40 : 15/16 Feb 2021 (0359 UTC)

[electricdawn]

Nothing important to say, so I will just leave this:

Space is still hard. Sometimes we tend to forget this with SpaceX. We're now almost taking successful booster landings for granted. Which noone ever would've thought possible only five years ago.

[rsnellenberger]

The entry burn itself (pre-shutdown) never looked right -- there's always a very clear and symmetric 1-engine/3-engine/1-engine pattern in the plume that seemed to be missing this time. If a turbopump or the thrust chamber (like CRS-1) failed, it could have damaged the boattail enough to create enough asymmetric drag that the grid-fins couldn't overcome due to insufficient authority or running out of hydraulic fluid.  The light we saw from the recovery ship might have been a normal center engine (but off-target) landing that RUD when it hit the water.

[russianhalo117]

The entry burn itself (pre-shutdown) never looked right -- there's always a very clear and symmetric 1-engine/3-engine/1-engine pattern in the plume that seemed to be missing this time. If a turbopump or the thrust chamber (like CRS-1) failed, it could have damaged the boattail enough to create enough asymmetric drag that the grid-fins couldn't overcome due to insufficient authority or running out of hydraulic fluid.  The light we saw from the recovery ship might have been a normal center engine (but off-target) landing that RUD when it hit the water.

At 21.6km AMSL the grid fins do not have primary control authority and could not help in this phase of flight.

[cpushack]

The entry burn itself (pre-shutdown) never looked right -- there's always a very clear and symmetric 1-engine/3-engine/1-engine pattern in the plume that seemed to be missing this time. If a turbopump or the thrust chamber (like CRS-1) failed, it could have damaged the boattail enough to create enough asymmetric drag that the grid-fins couldn't overcome due to insufficient authority or running out of hydraulic fluid.  The light we saw from the recovery ship might have been a normal center engine (but off-target) landing that RUD when it hit the water.

At 21.6km AMSL the grid fins do not have primary control authority and could not help in this phase of flight.

I think the poster meant that because of the engine damage the asymmetry would have made it more work for the grid fins later in the flight (from the then non symmetric drag not the reentry firing earlier).

[rsnellenberger]

The entry burn itself (pre-shutdown) never looked right -- there's always a very clear and symmetric 1-engine/3-engine/1-engine pattern in the plume that seemed to be missing this time. If a turbopump or the thrust chamber (like CRS-1) failed, it could have damaged the boattail enough to create enough asymmetric drag that the grid-fins couldn't overcome due to insufficient authority or running out of hydraulic fluid.  The light we saw from the recovery ship might have been a normal center engine (but off-target) landing that RUD when it hit the water.

At 21.6km AMSL the grid fins do not have primary control authority and could not help in this phase of flight.

I think the poster meant that because of the engine damage the asymmetry would have made it more work for the grid fins later in the flight (from the then non symmetric drag not the reentry firing earlier).

Yes, that's what I meant - since the booster is still supersonic after the entry burn, any drag from damage wouldn't be a factor until the "tail shock" dissipates at a lower velocity and altitude... (still speculating of course).

In any event - any turbopump or thrust chamber issue, even on a well-used engine, will probably put a hold on flights for the near term.  It might also justify trying to recover some of the boattail debris for evidence if the telemetry isn't pretty conclusive.

[FutureSpaceTourist]

twitter.com/spacexfleet/status/1361785484436000772

I've analyzed the progress of Ms. Tree using data from @MarineTraffic.

The fairing catcher ship spent ~3 hours (from around T+4 hours) stopped in a 7 km area approx halfway between OCISLY and the fairing recovery site. Ms. Tree then continued onwards towards Port Canaveral.

https://twitter.com/spacexfleet/status/1361785840981200905

Not drawing any particular conclusion from that at all. Just something curious to note.

The ships will be back at Port Canaveral soon.

[Herb Schaltegger]

The entry burn itself (pre-shutdown) never looked right -- there's always a very clear and symmetric 1-engine/3-engine/1-engine pattern in the plume that seemed to be missing this time. If a turbopump or the thrust chamber (like CRS-1) failed, it could have damaged the boattail enough to create enough asymmetric drag that the grid-fins couldn't overcome due to insufficient authority or running out of hydraulic fluid.  The light we saw from the recovery ship might have been a normal center engine (but off-target) landing that RUD when it hit the water.

At 21.6km AMSL the grid fins do not have primary control authority and could not help in this phase of flight.

I think the poster meant that because of the engine damage the asymmetry would have made it more work for the grid fins later in the flight (from the then non symmetric drag not the reentry firing earlier).

Yes, that's what I meant - since the booster is still supersonic after the entry burn, any drag from damage wouldn't be a factor until the "tail shock" dissipates at a lower velocity and altitude... (still speculating of course).

In any event - any turbopump or thrust chamber issue, even on a well-used engine, will probably put a hold on flights for the near term.  It might also justify trying to recover some of the boattail debris for evidence if the telemetry isn't pretty conclusive.

If there was significant aft-end damage, it's conceivable that the supersonic flow would create overlapping, non-symmetrical shockwaves; that could cause localized heating and hot-spots on the booster as well as thoroughly bolloxing up the guidance algorithms.

That said, in the absence of evidence to the contrary, and in light of Occam's Razor, I prefer a more prosaic explanation. Engine failure during the entry burn (evidenced by the seemingly-anomalous telemetry compared to prior Starlink entries), which resulted in descent to the lower atmosphere both faster and out of the expected trajectory corridor. Guidance compensated as much as possible but, unable to get an IIP over the barge with confidence, ditched in the sea. Heck, it may not have even been close - in the pitch dark sea, the landing burn would probably glow as we see in the video from a few miles away. Had this been a daylight landing, we might not even have seen the landing burn at all.

Until Elon tweets something different, or further info comes to light from reliable sources, this is my personal theory and I'm sticking with it.

[Vettedrmr]

Heck, it may not have even been close - in the pitch dark sea, the landing burn would probably glow as we see in the video from a few miles away. Had this been a daylight landing, we might not even have seen the landing burn at all.

Assuming the final, bright flare was impact, and the 2nd, more significant movement of the gulls was when the sound got to the barge (~11 seconds), that's roughly 2 miles away. 

I agree with your final assertion; now we wait and see.  I do find it interesting that L17 already has a tentative launch date of 2/19.  Don't know if that's just a placeholder or they already have a decent idea of what happened.

Have a good one,
Mike

[mn]

Musk is often quick with a cause when the reason is clear from telemetry.

The fact that he hasn't tweeted anything could indicate that the cause is not immediately clear from telemetry.

[Herb Schaltegger]

Musk is often quick with a cause when the reason is clear from telemetry.

The fact that he hasn't tweeted anything could indicate that the cause is not immediately clear from telemetry.

Or the cause is ITAR-related, or competition-sensitive for high-reuse flights, or ...

Heck, he's the father of a toddler with a beautiful young partner. Maybe he's entitled to a day or two not answering questions from randos on Twitter.

[Tommyboy]

Musk is often quick with a cause when the reason is clear from telemetry.

The fact that he hasn't tweeted anything could indicate that the cause is not immediately clear from telemetry.

Or the cause is ITAR-related, or competition-sensitive for high-reuse flights, or ...

Heck, he's the father of a toddler with a beautiful young partner. Maybe he's entitled to a day or two not answering questions from randos on Twitter.

I've also heard from reputable sources that Elon also has some side gigs besides SpaceX, that might also take up some of his time.

[AndrewRG10]

Heck, he's the father of a toddler with a beautiful young partner. Maybe he's entitled to a day or two not answering questions from randos on Twitter.

That's a fair statement if he hadn't been on Twitter talking about dogecoin and Giga Texas being covered in snow.
Also gotta remember that it took weeks for Elon to mention B1056 landing failure and explain what happened. And it's been 11 months since B1048 failed and we don't know exactly what went wrong to cause the landing failure. So it might be a while before we know what happened.

[Lars-J]

Heck, he's the father of a toddler with a beautiful young partner. Maybe he's entitled to a day or two not answering questions from randos on Twitter.

That's a fair statement if he hadn't been on Twitter talking about dogecoin and Giga Texas being covered in snow.

Just because someone was on twitter once at some point yesterday does NOT mean that can be expected to be a 24/7 news source.

[mn]

Musk is often quick with a cause when the reason is clear from telemetry.

The fact that he hasn't tweeted anything could indicate that the cause is not immediately clear from telemetry.

Or the cause is ITAR-related, or competition-sensitive for high-reuse flights, or ...

Heck, he's the father of a toddler with a beautiful young partner. Maybe he's entitled to a day or two not answering questions from randos on Twitter.

Musk is often quick with a cause when the reason is clear from telemetry.

The fact that he hasn't tweeted anything could indicate that the cause is not immediately clear from telemetry.

Or the cause is ITAR-related, or competition-sensitive for high-reuse flights, or ...

Heck, he's the father of a toddler with a beautiful young partner. Maybe he's entitled to a day or two not answering questions from randos on Twitter.

I've also heard from reputable sources that Elon also has some side gigs besides SpaceX, that might also take up some of his time.

I have heard from reputable sources that all of these things have been true for the longest time and yet they have not prevented him from tweeting failure causes very soon after the event in the past. (not always but often enough)

[Herb Schaltegger]

Heck, he's the father of a toddler with a beautiful young partner. Maybe he's entitled to a day or two not answering questions from randos on Twitter.

That's a fair statement if he hadn't been on Twitter talking about dogecoin and Giga Texas being covered in snow.
Also gotta remember that it took weeks for Elon to mention B1056 landing failure and explain what happened. And it's been 11 months since B1048 failed and we don't know exactly what went wrong to cause the landing failure. So it might be a while before we know what happened.

Some people don't seem to get it: Elon Musk doesn't owe anyone not on his Board of Directors and not a customer or FAA Office of Commercial Space Transportation regulator a single $DEITY-damned thing about root cause for loss of a booster. The space-fan community has gotten used to his relative transparency and lack of appreciable filters, but that has clearly spoiled some people.

[Lars-J]

People seem to be getting a bit spoiled with regards to Elon tweets....

 - Elon has in the past on occasion tweeted out likely or known failure causes quickly, BUT he is under no obligation to do so, don't be greedy
 - Elon not tweeting does not indicate whether or not SpaceX knows the cause

[Jansen]

Things are getting a bit heated.

Let’s just all agree that it sucks we’ve lost another booster, and it’d be great if we got some information from SpaceX or Elon since we’re all space geeks at heart. ❤️ 🚀

[mn]

People seem to be getting a bit spoiled with regards to Elon tweets....

 - Elon has in the past on occasion tweeted out likely or known failure causes quickly, BUT he is under no obligation to do so, don't be greedy
 - Elon not tweeting does not indicate whether or not SpaceX knows the cause

Heck, he's the father of a toddler with a beautiful young partner. Maybe he's entitled to a day or two not answering questions from randos on Twitter.

That's a fair statement if he hadn't been on Twitter talking about dogecoin and Giga Texas being covered in snow.
Also gotta remember that it took weeks for Elon to mention B1056 landing failure and explain what happened. And it's been 11 months since B1048 failed and we don't know exactly what went wrong to cause the landing failure. So it might be a while before we know what happened.

Some people don't seem to get it: Elon Musk doesn't owe anyone not on his Board of Directors and not a customer or FAA Office of Commercial Space Transportation regulator a single $DEITY-damned thing about root cause for loss of a booster. The space-fan community has gotten used to his relative transparency and lack of appreciable filters, but that has clearly spoiled some people.

I did not suggest in any way shape or form that Elon owes anyone anything.

I was just suggesting that we might infer something based on his tweets or lack thereof. Just because he doesn't owe anyone anything doesn't preclude us from inferring things from his actions based on previous patterns.

[cscott]

I think the scheduling of the next launch is a much more reliable indicator of known-cause than Elon's tweets or lack thereof.

Anyway.

Herb's computation of ~2 miles (~3km) isn't totally inconsistent with the boat tracking, which showed them lingering about 7km away.  For a ~1 significant digit estimate it's all right.

[CJ]

I may well be wrong, but the plume pattern of the entry burn did not look right to me, nor did the after-burn flames many here noted.

This got me to wondering (as many here have said before me); engine failure? However, we did see a flare for the landing burn. So, maybe center engine failed for the entry burn, and the FCS diverted the booster but is set to command a relight, because why wouldn't it be? (Might learn something, and no reason not to). 

Or, what if it's one of the two other engines used for the entry burn? The F9 may not have the capability of restoring its trajectory if the entry burn comes up short, and would overshoot. (if we knew the heading of the ASDS, this would be a significant clue. Anyone happen to know?)

I also wonder what the SpaceX commentators were hearing and seeing, because their tone, post entry burn startup, seemed to me to change a lot, as if they were expecting bad news. Would anyone happen to know what sort of realtime info they'd have access to?

Edit to add; the post-entry-burn flaring seems (to me) to be trailing off to the right side only. It makes me wonder if the F9 was, at that point, significantly angled away from the velocity vector, or tumbling.