SpaceX FH: STP-2 : LC-39A : June 25, 2019 - DISCUSSION

[Draggendrop]

https://twitter.com/SpaceX/status/1143439449230938112

It has been great to have this webcast up the full time so far.

2nd stage hanging in there...

[eeergo]

I believe the Airforce would want to preserve the first reused hardware ever flown on a DoD mission instead of reusing it; therefore, it’s more likely imo that the side boosters are put on display at the Cape than reused for a future mission.

I disagree, although it is certainly more probable the side boosters will see further missions as single first stages for F9's. However, it does not change the fact that the F9/FH system is now mostly reusable (bar 2nd stage, a pity IMO) or, in the case of FH, has demonstrated it can be made up of mostly reused elements, even if they're not necessarily coming from a previous FH flight.

[Star One]

[They caught the fairing!]

Had they succeeded in avoiding that last-second issue with the center core, this launch would have meant the world's most powerful rocket in service to be recovered for reuse! Extraordinary every time I stop to reflect about it.

None of this rocket is getting reused, the next launch is a classified mission for the airforce in over a years time and will require a clean sheet booster.

Is that an NRO mission?

AFSC-152 for the Airforce Space Command, it’s a direct to GEO mission.

Thank you. Beyond the first three launches I hadn’t seen anything much about further FH launches.

[ugordan]

Look to me that the first stage started to spin wildly on the leftmost monitor.  Guessing one of the Grid fines did not deploy and went wild.

Doubtful, IMO. If your theory was correct, then it would never have made it as close to landing as it did.

  Understand.  Just a guess based on this video.

That would be the ground IR camera view that was tracking the returning boosters, not onboard core stage video.

[ugordan]

Some weird lighting effect!

Thrusters firing to settle propellant.

[Draggendrop]

https://twitter.com/AdamGlambert304/status/1143460605963231232

[alang]

Some weird lighting effect!

Thrusters firing to settle propellant.

https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=48325.0;attach=1566541;image

Are you certain it's just ullage?
I understand that there is an MVac chill down prior to first ignition. Does that chill down happen prior to later ignition s as well? If so then what happens to the propellant used for cooling?

[ugordan]

Some weird lighting effect!

Thrusters firing to settle propellant.

https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=48325.0;attach=1566541;image

Are you certain it's just ullage?

Yes, it was 4 separate pulses of GN2

I understand that there is an MVac chill down prior to first ignition. Does that chill down happen prior to later ignition s as well? If so then what happens to the propellant used for cooling?

Yes, prior to any ignition. That GOX/LOX is dumped overboard during chilldown but it looks visually different than this and it's continuous venting for a while.

[Steven Pietrobon]

AFSC-152 for the Airforce Space Command, it’s a direct to GEO mission.

Its AFSPC 52 in September 2020.

https://forum.nasaspaceflight.com/index.php?topic=45886.0

[ugordan]

Hard to tell, but did all 4 legs deploy properly? I could see it aborting if a leg didn't come down and lock.

We're going to have to see. Could be a throttle issue, could be legs, could be a sensor issue. Most likely cause is the hot entry, but I don't think we are going to hear anything more until Elon tweets

If it wasn't a deliberate evasive burn due to too much vertical velocity (it didn't really look to me that it was going to lawn-dart OCISLY, though), I'm wondering if it was a center engine gimbal failure.

[Steven Pietrobon]

Congratulations to SpaceX and USAF for the successful launch!

Some screen grabs I missed. I couldn't get any more grabs from earlier in the flight because the YouTube link now starts at T+1:36:52.

Fairing separation.

Nice infrared view of booster just before the landing burn.

Another shot of the booster landings.

[ZachS09]

Looking at the drone ship camera showing the center core, it looks like while it was divebombing towards the water, the oxidizer cut out right before impact.

If it's not the oxidizer, then the fuel must have run out at that time.

Compare that to the Eutelsat/ABS F2 landing failure.

[envy887]

Hard to tell, but did all 4 legs deploy properly? I could see it aborting if a leg didn't come down and lock.

We're going to have to see. Could be a throttle issue, could be legs, could be a sensor issue. Most likely cause is the hot entry, but I don't think we are going to hear anything more until Elon tweets

If it wasn't a deliberate evasive burn due to too much vertical velocity (it didn't really look to me that it was going to lawn-dart OCISLY, though), I'm wondering if it was a center engine gimbal failure.

Agreed. Looks to me like a TVC issue resulting in the tip-over. Since it was lined up correctly in the first place, maybe it throttled up on purpose to get away from OCISLY.

[Alexphysics]

Is SpaceX still putting tail numbers on each booster? Is soot obscuring them or am I looking in the wrong place?

They're little numbers below the grid fins.  I haven't seen a picture from today that is clear enough to read them.

The answer to this is on L2

Also, for the next FH mission (the AFSPC 52) I would expect double side booster droneship landing and center core expended, pretty much what they initially planned for this mission before dropping the second stage deorbit burn.

[codav]

Is SpaceX still putting tail numbers on each booster? Is soot obscuring them or am I looking in the wrong place?

They're little numbers below the grid fins.  I haven't seen a picture from today that is clear enough to read them.

The answer to this is on L2

Also, for the next FH mission (the AFSPC 52) I would expect double side booster droneship landing and center core expended, pretty much what they initially planned for this mission before dropping the second stage deorbit burn.

I'm not sure if the booster numbers really are L2-only content, even if the many beautiful high-res photos there certainly are. The side booster positions were assigned identical to the Arabsat-6A mission, with B1052 on the west side on the pad (facing the FSS) and B0153 on the east.

Regarding AFSPC-52, the target transfer orbit (185x35188km with a 27° inclination) is nearly the same as Arabsat-6A and the satellite even weighs a bit less, so I'd expect a very similar flight profile.

[Prettz]

Also, for the next FH mission (the AFSPC 52) I would expect double side booster droneship landing and center core expended, pretty much what they initially planned for this mission before dropping the second stage deorbit burn.

Had this been discussed publicly before? I might have just forgotten seeing it, but I didn't remember this mission being planned to expend the center. (Obviously, this is not a very searchable question)

[meekGee]

Is SpaceX still putting tail numbers on each booster? Is soot obscuring them or am I looking in the wrong place?

They're little numbers below the grid fins.  I haven't seen a picture from today that is clear enough to read them.

The answer to this is on L2

Also, for the next FH mission (the AFSPC 52) I would expect double side booster droneship landing and center core expended, pretty much what they initially planned for this mission before dropping the second stage deorbit burn.

I'm not sure if the booster numbers really are L2-only content, even if the many beautiful high-res photos there certainly are. The side booster positions were assigned identical to the Arabsat-6A mission, with B1052 on the west side on the pad (facing the FSS) and B0153 on the east.

Regarding AFSPC-52, the target transfer orbit (185x35188km with a 27° inclination) is nearly the same as Arabsat-6A and the satellite even weighs a bit less, so I'd expect a very similar flight profile.

Also, for the next FH mission (the AFSPC 52) I would expect double side booster droneship landing and center core expended, pretty much what they initially planned for this mission before dropping the second stage deorbit burn.

Had this been discussed publicly before? I might have just forgotten seeing it, but I didn't remember this mission being planned to expend the center. (Obviously, this is not a very searchable question)

And double droneship landing?

[Draggendrop]

https://twitter.com/NOAASatellites/status/1143520496660746240

[ZachS09]

Is SpaceX still putting tail numbers on each booster? Is soot obscuring them or am I looking in the wrong place?

They're little numbers below the grid fins.  I haven't seen a picture from today that is clear enough to read them.

The answer to this is on L2

Also, for the next FH mission (the AFSPC 52) I would expect double side booster droneship landing and center core expended, pretty much what they initially planned for this mission before dropping the second stage deorbit burn.

I'm not sure if the booster numbers really are L2-only content, even if the many beautiful high-res photos there certainly are. The side booster positions were assigned identical to the Arabsat-6A mission, with B1052 on the west side on the pad (facing the FSS) and B0153 on the east.

Regarding AFSPC-52, the target transfer orbit (185x35188km with a 27° inclination) is nearly the same as Arabsat-6A and the satellite even weighs a bit less, so I'd expect a very similar flight profile.

Also, for the next FH mission (the AFSPC 52) I would expect double side booster drone ship landing and center core expended, pretty much what they initially planned for this mission before dropping the second stage deorbit burn.

Had this been discussed publicly before? I might have just forgotten seeing it, but I didn't remember this mission being planned to expend the center. (Obviously, this is not a very searchable question)

And double drone ship landing?

That's if they get "A Shortfall Of Gravitas" ready for that mission.

[meekGee]

Is SpaceX still putting tail numbers on each booster? Is soot obscuring them or am I looking in the wrong place?

They're little numbers below the grid fins.  I haven't seen a picture from today that is clear enough to read them.

The answer to this is on L2

Also, for the next FH mission (the AFSPC 52) I would expect double side booster droneship landing and center core expended, pretty much what they initially planned for this mission before dropping the second stage deorbit burn.

I'm not sure if the booster numbers really are L2-only content, even if the many beautiful high-res photos there certainly are. The side booster positions were assigned identical to the Arabsat-6A mission, with B1052 on the west side on the pad (facing the FSS) and B0153 on the east.

Regarding AFSPC-52, the target transfer orbit (185x35188km with a 27° inclination) is nearly the same as Arabsat-6A and the satellite even weighs a bit less, so I'd expect a very similar flight profile.

Also, for the next FH mission (the AFSPC 52) I would expect double side booster drone ship landing and center core expended, pretty much what they initially planned for this mission before dropping the second stage deorbit burn.

Had this been discussed publicly before? I might have just forgotten seeing it, but I didn't remember this mission being planned to expend the center. (Obviously, this is not a very searchable question)

And double drone ship landing?

That's if they get "A Shortfall Of Gravitas" ready for that mission.

Yeah, but it could not have been planned for this mission