SpaceX Falcon 9 : GovSat-1 (SES-16) : Jan 31. 2018 - Discussion

[John Alan]

So... do they go looking for any booster they soft land in the water, just in case? Or are they close enough in the ships to see the explosions or lack thereof?

My guess is they are done soft landing stages... all done on that...
You may have noticed the side boosters on the FH used a new 1-3-1 RTLS landing burn Tuesday...
My guess is they have made GovSat's landing burn the standard going forward... for all landings... 
Saves Prop... and Govsat proved it worked... so it's standard now... my opinion... 

[speedevil]

So... do they go looking for any booster they soft land in the water, just in case? Or are they close enough in the ships to see the explosions or lack thereof?

There are high bandwidth telemetry feeds that need line-of-sight to receive them, and recover all the expected data.
This is done from a boat, which happens to be in position to see any impact too, and gain a little extra info, as well as recover any floating debris - it is usual for the helium tanks to float, for example. The fairing may also in some cases come down moderately close and be fishable out in bits.

[Pete]

Wouldn't it still have had oxygen in the lox tank? I can't guess how explosive the RP1 and oxygen mixture would have been, I guess it depends on whether or not the lox was vented after touchdown. Anyway, what's the chance of setting it off with just a few explosive shells? Of course with those guns, it's hard to fire just a few rounds. And under the circumstances, what pilot would stop at just a few?

Actually oxygen and RP1 is not explosive at all, just very very very flammable.
But within an hour of landing in the water, that booster would have had not one drop of LOX remaining in it, the rate of heat absorption from warm ocean water through aluminum shell would be orders of magnitudes higher than heat absorption through the same skin in vacuum, or even in air (where it develops a nice insulating jacket of frost)

The problem is that if it retains significant pressure in the oxygen tank, it could pop with significant force if it does fail, and if it does *not* retain significant pressure in the tank, then it has very poor structural integrity as the falcon derives a lot of its structural strength from internal pressure. Lose-lose situation.
The falcon 9 first stage is not designed to be towed around in the ocean.

[georgegassaway]

My take on the financial cost for the USAF to sink it, is it may have been a wash, so to speak. Plenty of training missions, flying all the time. Usually with fake bombs/missiles, but also live sometimes. Live fire exercises often over the same fixed target ranges. 

This time, a unique opportunity to take out a ship-sized target at sea (albeit a relatively skinny ratio for a lot of ships). 

I mean, for a planned practice mission to take out a real target at sea, would involve the cost to tow it out, and whatever the value of the target might be (whether built-for-purpose targets. Or  ship hulks that do have a scrap metal value that is lost - if they even still sink old ships just for practice), and likely other costs. So they were presented with a “free target” to practice destroying, a unique real mission which also was  necessary and served a useful purpose in carrying it out.

[vanoord]

Agree with that.

The chance of a 'free' target to take out in a live-fire exercise was probably welcomed.

What will be interesting will be whether or not SpaceX try to 'soft land' any more cores - if they do so, presumably it will be in the knowledge that the USAF would be willing to finish them off if they do survive again.

[StuffOfInterest]

What will be interesting will be whether or not SpaceX try to 'soft land' any more cores - if they do so, presumably it will be in the knowledge that the USAF would be willing to finish them off if they do survive again.

SpaceX may also decide to add in a scuttling option to the stage.  Should really be just some valves that can be opened to flood the tank hooked to a receiver and an independent power source.

[vanoord]

SpaceX may also decide to add in a scuttling option to the stage.  Should really be just some valves that can be opened to flood the tank hooked to a receiver and an independent power source.

The trouble with that is that it's not required for missions; and that it introduces a possible failure mode (however remotely unlikely).

As long as there's the option to finish a stage off with remotely delivered ordnance, there's no effect on the probabilities of launch success.

[sevenperforce]

SpaceX may also decide to add in a scuttling option to the stage.  Should really be just some valves that can be opened to flood the tank hooked to a receiver and an independent power source.

The trouble with that is that it's not required for missions; and that it introduces a possible failure mode (however remotely unlikely).

As long as there's the option to finish a stage off with remotely delivered ordnance, there's no effect on the probabilities of launch success.

"Remotely Delivered Ordnance" is a euphemism for "airstrike" on a level with "Rapid Unplanned Disassembly".

[abaddon]

What will be interesting will be whether or not SpaceX try to 'soft land' any more cores

The easy answer is they can practice soft landing at an offset, say 100 feet up.  They still can practice hitting that spot, and there's no chance the stage survives the fall after engine cut-off.

[biosehnsucht]

Alternatively, just don't disable AFTS and instead program it to activate before splashdown.

[Kansan52]

A high powered rifle or two on the support ship from now on if another scuttling is required.

[QuantumG]

A high powered rifle or two on the support ship from now on if another scuttling is required.

Never trust engineers with firearms - especially Californians

[QuantumG]

No... what you have here is an amateur who reports an anonymous source without waiting for confirmation vs a professional who waits for confirmation and is now reporting the denial.

One would hope that the amateur will go back to his anonymous source and ask wtf, but I doubt he will.

[saliva_sweet]

One would hope that the amateur will go back to his anonymous source and ask wtf, but I doubt he will.

There were two: Mike Killian and Chris Gerbhart. I'd hope to see clarification from both, as both appear to be reputable. Amateur or not.

[HMXHMX]

A high powered rifle or two on the support ship from now on if another scuttling is required.

It worked to ‘remotely vent’ an early Viking at White Sands.

[QuantumG]

One would hope that the amateur will go back to his anonymous source and ask wtf, but I doubt he will.

There were two: Mike Killian and Chris Gerbhart. I'd hope to see clarification from both, as both appear to be reputable. Amateur or not.

Chris G can answer here for himself

That's one of the risks of getting information from anonymous sources, they tend to say stuff like "that's what I heard".

[ZachS09]

https://twitter.com/EmreKelly/status/962089727871643649

Full SpaceX statement on #GovSat1: “While the Falcon 9 first stage for the GovSat-1 mission was expendable, it initially survived splashdown in the Atlantic Ocean. However, the stage broke apart before we could complete an unplanned recovery effort for this mission.”

I wonder what caused the breakup. It could be excessive saltwater corrosion to the point where the COPVs overreacted.

[eeergo]

I wonder what caused the breakup. It could be excessive saltwater corrosion to the point where the COPVs overreacted.

Likely just mechanical fatigue from bobbing in the waves for a prolonged period of time, maybe exacerbated by slowly flooding compartments unevenly adding weight to some parts of the stage. COPVs should be pretty inert mechanically.

Note AmericaSpace is insistently reporting it was intentionally destroyed (as opposed to "broken apart", which suggests a natural cause), not by the USAF but by a private demolition contractor. Not that I attach any particular credibility to this based on their previous track record.

[AC in NC]

SpaceX may also decide to add in a scuttling option to the stage.  Should really be just some valves that can be opened to flood the tank hooked to a receiver and an independent power source.

Automatic Float Termination System

[CJ]

https://twitter.com/EmreKelly/status/962089727871643649

Full SpaceX statement on #GovSat1: “While the Falcon 9 first stage for the GovSat-1 mission was expendable, it initially survived splashdown in the Atlantic Ocean. However, the stage broke apart before we could complete an unplanned recovery effort for this mission.”

I wonder what caused the breakup. It could be excessive saltwater corrosion to the point where the COPVs overreacted.

An exacerbating factor may well be structural damage incurred during splashdown and subsequent toppling.