SpaceX Falcon 9 - EchoStar 23 - March 16, 2017 - DISCUSSION

[Ben the Space Brit]

I don't think that they 'explode' as much as break up as overheating causes parts of the structure to liquefy and aerodynamic stresses rip apart the rest of the structure.

[abaddon]

This isn't the first hot/destructive reentry they've performed and they haven't released that footage so don't expect anything this time, either.

It's only recently they've displayed the capability to show real-time video from the stage as it returns, well after the most recent destructive entry.  So it seems likely they will be able to get video.  There is no reason to think they will release it, though.

[Paul_G]

I don't think that they 'explode' as much as break up as overheating causes parts of the structure to liquefy and aerodynamic stresses rip apart the rest of the structure.

Remember the photos of more or less intact Chinese 1st stages coming down on villages down range. I was surprised at how much remained - I guess this highlights that stages that are essentially sub-orbital are not going fast enough to burn up, but will hit the ground at terminal velocity.

https://spaceflightnow.com/2015/01/04/photos-long-march-rocket-stage-falls-in-rural-china/

Paul

[AncientU]

I don't think that they 'explode' as much as break up as overheating causes parts of the structure to liquefy and aerodynamic stresses rip apart the rest of the structure.

It is a pressurized fuel mixture, though.
EM has used 'explode' which seems reasonable.

If overheating, then loss of Al structural strength is issue, causing hoop stresses to allow tankage to disassemble.

[ugordan]

It's only recently they've displayed the capability to show share real-time video from the stage as it returns

Fixed that for you. They had no problems with the reentry portion video going back to the first v1.1 flights while it's over the horizon, they just didn't decide to share it with us. Several webcasts gave hints of that in the back of the Hawthorne MCC screens. It was the landing part that was usually problematic which is obviously irrelevant for this particular flight as the regime that is likely to destroy the stage is the hot reentry.

[macpacheco]

I don't think that they 'explode' as much as break up as overheating causes parts of the structure to liquefy and aerodynamic stresses rip apart the rest of the structure.

It is a pressurized fuel mixture, though.
EM has used 'explode' which seems reasonable.

If overheating, then loss of Al structural strength is issue, causing hoop stresses to allow tankage to disassemble.

Consider the CRS-7 mishap. Although the booster was still heavily fueled and the 2nd stage fully fueled there wasn't an explosion, the stage just imploded/unzipped. Even with all of that RP1 and LOX dripping towards the exhaust of a still running rocket.
I think calling it an explosion is incorrect.
Besides on the way down after expending as much as possible of its fuel, whats left is a pittance in RP1 and LOX...
What indeed likely happen is at very high temps, Al and Al-Li metal burns. That's a more likely energy source than the fuel/oxidizer left.

[abaddon]

It's only recently they've displayed the capability to show share real-time video from the stage as it returns

Fixed that for you. They had no problems with the reentry portion video going back to the first v1.1 flights while it's over the horizon, they just didn't decide to share it with us. Several webcasts gave hints of that in the back of the Hawthorne MCC screens. It was the landing part that was usually problematic which is obviously irrelevant for this particular flight as the regime that is likely to destroy the stage is the hot reentry.

How many successful stage re-entrys did we see without getting on-board video until well after the fact?  Suddenly now, on the last two flights, they're showing on-board live broadcast reentry footage that they've supposedly had all along?  No way.  I am sure they had parts before, but nothing close to what they have shared on the last couple of flights.

In any case I agree with the main (?) point that it is extremely unlikely SpaceX will show us video from a stage destructively re-entering.  We'll have to [not] hope for that to come from a planned successful re-entry that goes awry.

[old_sellsword]

It's only recently they've displayed the capability to show share real-time video from the stage as it returns

Fixed that for you. They had no problems with the reentry portion video going back to the first v1.1 flights while it's over the horizon, they just didn't decide to share it with us. Several webcasts gave hints of that in the back of the Hawthorne MCC screens. It was the landing part that was usually problematic which is obviously irrelevant for this particular flight as the regime that is likely to destroy the stage is the hot reentry.

How many successful stage re-entrys did we see without getting on-board video until well after the fact?  Suddenly now, on the last two flights, they're showing on-board live broadcast reentry footage that they've supposedly had all along?  No way.  I am sure they had parts before, but nothing close to what they have shared on the last couple of flights.

Consider that the only full broadcasts of reentry have been an RTLS landing and a half-distance ASDS landing. I wouldn't be so sure that they get live descent video on a usual ASDS landing (~600 km downrange).

[ugordan]

Suddenly now, on the last two flights, they're showing on-board live broadcast reentry footage that they've supposedly had all along?  No way.

You're absolutely right and I apologize. What SpaceX employees see we also get to see, each and every time.

[wannamoonbase]

It's only recently they've displayed the capability to show share real-time video from the stage as it returns

Fixed that for you. They had no problems with the reentry portion video going back to the first v1.1 flights while it's over the horizon, they just didn't decide to share it with us. Several webcasts gave hints of that in the back of the Hawthorne MCC screens. It was the landing part that was usually problematic which is obviously irrelevant for this particular flight as the regime that is likely to destroy the stage is the hot reentry.

How many successful stage re-entrys did we see without getting on-board video until well after the fact?  Suddenly now, on the last two flights, they're showing on-board live broadcast reentry footage that they've supposedly had all along?  No way.  I am sure they had parts before, but nothing close to what they have shared on the last couple of flights.

In any case I agree with the main (?) point that it is extremely unlikely SpaceX will show us video from a stage destructively re-entering.  We'll have to [not] hope for that to come from a planned successful re-entry that goes awry.

I agree with Ugordan. It's been said 1000's of times, SpaceX is not NASA, they have no obligation to show the footage and a lot of the data.  Others have stated they have many more views and angles that aren't shared.

As for this flight, I'm interested in seeing the full up performance of the first stage.

[Comga]

Latest forecast attached. No change to launch conditions (60% GO) but delay day now 90% GO.

Edit: key statement is

Then cloud cover will begin diminishing, which will continue through the countdown and launch window.

With a long launch window hopefully there's time for cloud to clear

So we could see fueling start at 4:30 AM EDT?
Ugh!  This one I might miss......

[old_sellsword]

Latest forecast attached. No change to launch conditions (60% GO) but delay day now 90% GO.

Edit: key statement is

Then cloud cover will begin diminishing, which will continue through the countdown and launch window.

With a long launch window hopefully there's time for cloud to clear

So we could see fueling start at 4:30 AM EDT?
Ugh!  This one I might miss......

Not quite, the window closes at 4:04 AM EDT. So the latest fueling could start is around 3:00 AM EDT.

[Jim]

First view of the upgraded SMAB east bay? SpaceX picture.

[jpo234]

First view of the upgraded SMAB east bay?

SMAB = Space Mission Analysis Branch ?

[Folgers25]

SMAB= Solid Motor Assembly Building

That is a cool behind the scenes picture. What is the black sheet inside the faring for, protection?

[ugordan]

What is the black sheet inside the faring for, protection?

I'm pretty sure that's the outside of the fairing.

[Comga]

What is the black sheet inside the faring for, protection?

I'm pretty sure that's the outside of the fairing.

Agreed
I was looking for any signs of fairing recovery hardware, but it looks like the entire fairing, or fairing half, is shrouded in that black cloth or sheeting.

[Jim]

What is the black sheet inside the faring for, protection?

That is the fairing.  The frame is on the outside.

[old_sellsword]

What is the black sheet inside the faring for, protection?

That is the fairing.  The frame is on the outside.

But why does it have that black sheet over it?

[jpo234]

But why does it have that black sheet over it?

Protective cover for transportation? Similar to the tarp used to wrap the stages on the road?