SpaceX Falcon 9 v1.1 - Jason 3 - SLC-4E Vandenberg - Jan 17, 2016 - DISCUSSION

[OxCartMark]

Bad latch...baaadd..

Hope they get as much data as possible from it, although the problem might already be fixed in the next iteration.

IIRC, the F9 Full Thrust has strengthened and upgraded legs. This was the previous version of v1.1 because of contract stipulations.

The legs don't make it down until the last few seconds.  I just watched the Orbcomm 2 landing video (helicopter) and they were fully down 5 seconds before ground contact.  Perhaps the latch was good but the deployment was slow.  Or???

[Stan-1967]

A slightly different tone than after ORBCOMM2?

Jeff Bezos on Twitter: "Impressive launch and @SpaceX will soon make Falcon 9 landings routine – so good for space! Kudos SpaceX!"

Yeah, how boring. We're never going to see a SpaceX vs Blue Origin dance-off with this attitude.

A "dance off" is unbecoming two geniuses like Bezos and Musk.  I always have envisioned a death challenge, set it the flame trench of LC 39A.   The two sit down together to enjoy a nice unicorn steak, medium rare, with fava beans and a two ample goblets of  chianti, one of which is laced wit iocaine powder.   Have a coin toss to see who gets to pick which goblet they will drink from.

[meekGee]

Add Automated spacecraft drone buoys (ASDB). Measure incoming wave height and predict elevation of barge at landing.

Right. But even if you get a good prediction for the drone ship movements, it's nontrivial to exploit this in the landing algorithm in a reliable manner.

Very true, but it wouldn't hurt, and it is something which doesn't require large hardware changes (though reliable radio comm uplink to stage is, as you say, nontrivial). It's possible that no "solution" will be found by the landing algorithm, but at least it will likely be better than going in completely blind to the droneship's state.

Is there no radar to determine altitude on the stage in the moments leading to touch down? I find this hard to believe, and it would certainly be easier to integrate that into the algorithm than wave prediction updates from buoys.

I think there is radar. But you ideally need to know the full state of the barge, including pitch angle and its first time derivative.

Radar altimeters are small and cheap, you can have one in each leg.

However, I think you want to know the state of the barge from further away, so the correction is 50 seconds aways, not 5...

[NovaSilisko]

Party thread is thataway, people --->

[yg1968]

Been wondering when we would see a mechanical problem like this or a fairing, staging to spacecraft separation issue.

This is best case problem because the payload still made it.

The legs probably count among the least mission critical moving parts of the whole rocket. Their checks are certainly less extensive than anything required for the primary mission. If I was SpaceX I wouldn't throw too much oversight their way.

Haven't they updated the leg design recently? It's entirely probably they suspected an event of this nature would happen to a 1.1, or have prior data. It may have already been solved before we were aware of its existence.

Could the landing burns have caused damage to the latching mechanism?

[Marslauncher]

This goes to show that SpaceX have never (I believe) to date, failed from the same problem twice, they test and fly and then fly and test. If the leg latch out is confirmed via video as the issue then I highly doubt it will fail from this mode again.

We need another Musk email exchange, press conference or AMA to get some of these details.

Chris! Fire up the question machine generator!

John Cooke

[DecoLV]

Does Spx know actual condition yet? We're assuming orange balloon, but if the fire suppression helped at all...maybe octoweb survived? Any salvagable Merlins would be great silver lining!

[meekGee]

With the very tight timing between leg deploy and touchdown, I wonder if a slight lag in the deploy didn't result in touch down before leg lock.

[gin455res]

https://en.wikipedia.org/wiki/Semi-submersible

Is it possible to build a barge with submerged pontoons to avoid the effect of large swells?

The short answer that yes it's possible to build a floating recovery platform that is more isolated from surface wave action, but at a much higher cost than the converted cargo barges SpaceX is using.

But since we now have a lot of evidence [in the form of several very accurate and one near perfect landing attempt(s)], might it be worth making the investment? 

Before, it was a 'well, maybe it will work'. Let's buy a couple of '?beat up old barges'.

Isn't it now, a 'wow this looks fairly doable', and as such, worthy of a greater investment?

(but assuming it was only the leg lock-out failure that contributed to the crash, maybe this is academic and the sea-state is less critical. But Elon, also did make the aircraft carrier comparison. So it's hard to judge)

[punder]

With the very tight timing between leg deploy and touchdown, I wonder if a slight lag in the deploy didn't result in touch down before leg lock.

As with Falcon 1 flight 3, maybe just a timing issue.

[Rocket Science]

I was doing the updates and now catching up... So it was a "latch" fail to release or slow un-latch, late gear deploy and not down and locked?

[boog]

Maybe I'm the only one that remembers this, but wasn't a leg failing during the previous ASDS landing? I have a memory that one of the legs was folded back against itself in the moments before it exploded. Anyone else?

[yg1968]

Maybe I'm the only one that remembers this, but wasn't a leg failing during the previous ASDS landing? I have a memory that one of the legs was folded back against itself in the moments before it exploded. Anyone else?

Yes but but that was caused by a hard landing. Here, there was no hard landing according to Musk.

[RDoc]

The leg failed, but the underlying cause was a sticking valve on the engine swiveling system that cause wild overshooting during the approach so there was too much lateral velocity on touchdown.

[Dante80]

Maybe I'm the only one that remembers this, but wasn't a leg failing during the previous ASDS landing? I have a memory that one of the legs was folded back against itself in the moments before it exploded. Anyone else?

Yes, on CRS-6 a leg broke when the stage hit the barge too hard and at an angle. This was because of a valve problem (that made the engine behave more sluggish than planned at final approach).

This one was - reportedly - a soft landing, but with 3 secured legs instead of 4. The last one didn't latch into position (and thus folded when it reached the deck, since could not support the weight).

At least, thats the information we have at this point in time.

[boog]

Maybe I'm the only one that remembers this, but wasn't a leg failing during the previous ASDS landing? I have a memory that one of the legs was folded back against itself in the moments before it exploded. Anyone else?

Yes but but that was caused by a hard landing. Here, there was no hard landing according to Musk.

Id think once that leg was "locked" in place it would transfer the landing energy in to the booster core itself and sooner bend the side of the core at the attachment point than the leg bending back in on itself. But maybe that's just wishful thinking...

What Im suggesting is there must be an issue with the leg locking system itself (or the breaking tolerances of it) and we already had evidence for that before today. Maybe it has been fixed on the FT version.

[mb199]

Find some of this discussion silly,  talking about bigger boats and building platforms at sea. Simple solution is bring it back for a landing on land.  What Spacex proved again today is that can return the stage to the exact location.  In the future it will be easier to get a license to return the stage to land.

[mn]

Congratulations to spacex on a successful mission.

So is this the first F9 to launch on a T-0 published 30+ days out?

[yg1968]

Find some of this discussion silly,  talking about bigger boats and building platforms at sea. Simple solution is bring it back for a landing on land.  What Spacex proved again today is that can return the stage to the exact location.  In the future it will be easier to get a license to return the stage to land.

Some missions might still need the barge. The center core for FH will also need the barge for some missions.

[meekGee]

Maybe I'm the only one that remembers this, but wasn't a leg failing during the previous ASDS landing? I have a memory that one of the legs was folded back against itself in the moments before it exploded. Anyone else?

Yes but but that was caused by a hard landing. Here, there was no hard landing according to Musk.

Id think once that leg was "locked" in place it would transfer the landing energy in to the booster core itself and sooner bend the side of the core at the attachment point than the leg bending back in on itself. But maybe that's just wishful thinking...

I don't think any of the members are loaded in bending, so they should not fold over.  The sidewall can give, but there might be an internal truss there, connecting the four anchor points.