SpaceX F9 : Hera (asteroid mission) : CCSFS SLC-40 : 7 October 2024 (14:52 UTC)

[Steven Pietrobon]

Just finished watching the SpaceX webcast and was surprised to see two video leaks of the second stage tank at T+1:05:48 and T+1:06:28! I suspect the radiation environment might have caused a computer glitch which allowed the video to leak through. After the second leak, SpaceX stopped the video from the second stage until just before spacecraft separation, where the leak was apparently fixed.

Anyway, we see four large COPV helium tanks with one of the tanks having COMMERCIAL written on top of the tank. Not sure what that is supposed to mean. There appears to be vapour surrounding the helium tanks. Flick between the two images to see the vapour moving. This could be caused by the super cold helium tanks causing the gaseous oxygen in the tank to condense, like water vapour in air. The tank appears to have quite a bit of LOX left. We can see the filter structure in the centre quite clearly. Compared to five years ago, the white tank does not appear to be present.

[LouScheffer]

My guess would be that this was not accidental, but upon a request from the propulsion engineers to see exactly how much LOX was left in the tank.  Since this launch was on the first day of the window, after the final burn, there should be nothing left except performance reserves (otherwise the window would be longer). 

The second stage holds about 75,000 kg of LOX.  If reserves are 1%, that's 750 kg, well under a cubic meter.  Without doing the calculation, I'd expect that to fill the downcomer with maybe a little pool at the center of the common dome.  I suspect this is what they were looking at.

I also suspect that if showing this was a mistake, it was human error and not a computer glitch.  Likely they meant to shut the public video off, *then* take the LOX pictures.  But somehow the timeline got scrambled, and we got a peek.

[LouScheffer]

"Nominal burn 2"

For you interplanterary orbit transfer specialists:  Is the velocity drop from 43K kmph to 38K kmph in about 8 minutes expected and nominal?

Don't know about the time scale, but the velocity is expected to drop by a lot over the next few days.  This launch had a C3 of about 32 km²/sec².  That's the square of the velocity at infinity, after the Earth's gravity has finished its work of slowing the spacecraft down.  So you'd expect this speed to drop to 5.65 km/sec (20.4 kmph) over the next few days.  But it drops more and more slowly as the spacecraft gets further from Earth, until it settles out at the final value.

Bottom line:  SpaceX said at some point "Nominal trajectory", so the drop in speed is an aspect of that trajectory, and quite expected.

[Brigantine]

video leaks of the second stage tank

Possible connection to a fix for the Crew-9 2nd stage over-burn

The leak was fixed in both figurative and literal sense!

[Steven Pietrobon]

My guess would be that this was not accidental, but upon a request from the propulsion engineers to see exactly how much LOX was left in the tank.

Video of the second stage tank is always broadcast to the ground, interleaved with views of the engine and payload. However, SpaceX does not want to the public to see the tank views, so cuts them off and shows the orbit animation instead. These leaks happened quite a lot in the early days of Falcon 9, but its been awhile since the last leak.

[GWR64]

My guess would be that this was not accidental, but upon a request from the propulsion engineers to see exactly how much LOX was left in the tank.  Since this launch was on the first day of the window, after the final burn, there should be nothing left except performance reserves (otherwise the window would be longer). 

The second stage holds about 75,000 kg of LOX.  If reserves are 1%, that's 750 kg, well under a cubic meter.  Without doing the calculation, I'd expect that to fill the downcomer with maybe a little pool at the center of the common dome.  I suspect this is what they were looking at.

I also suspect that if showing this was a mistake, it was human error and not a computer glitch.  Likely they meant to shut the public video off, *then* take the LOX pictures.  But somehow the timeline got scrambled, and we got a peek.

But wouldn't pictures be more interesting towards the end of the engine burn? Like at the Starlink launch shown.
In the pictures from the Hera launch, the upper stage is without propulsion, so the oxygen floats around weightless
or sticks to the tank's internal components.

[FutureSpaceTourist]

https://twitter.com/spaceoffshore/status/1845098679302029649

SpaceX recovery ship Doug makes a triumphant post-Milton return to Port Canaveral with both fairing halves from the Hera mission.

Can you spot the marks where the decal artwork on the fairing half was scorched away on re-entry? nsf.live/spacecoast

[realnouns]

Although Doug destination was identified as Port Canaveral, it looked to be headed northeast towards the LZ.  Go Cosmos looks to be headed south toward PC.  Go Cosmos departed Port of Charleston on Sep 17 @ 6:59am ET

Doug returned to PC on Sep 20 @ 7:00am ET

Doug departed PC on Oct 4 @ 11:46am ET

Doug returned to PC on Oct 12 @ 9:36am ET