SpaceX Prepared for 'Most Difficult Launch Ever' - STP-2 FH launch

[Nikxice]

Leaving an unsteerable center engine still thrusting, and presumably not perfectly centered, so it began to veer away.

Curious as to why the center engine doesn't gimbal (unsteerable?) after the two outer engines shutdown. At low speed and altitude the grid fins have pretty much lost control authority. SpaceX doesn't leave imprecision to chance, so maybe there's more to the story?

 

[Brass Guy]

Curious as to why the center engine doesn't gimbal (unsteerable?) after the two outer engines shutdown. At low speed and altitude the grid fins have pretty much lost control authority. SpaceX doesn't leave imprecision to chance, so maybe there's more to the story?

I assumed this

3-engine landing burn, center engine not steering but the outer two steering

meant the center engine was not steering but was supposed to.

 

[Electroman]

How does the booster identify where the center of the Drone ship platform is? is there a radio transponder or gizmo that is used, or is it all GPS coordinates?

 

[Sparky]

First of the Cosmic2 satellites just deployed. Five to go. You can see it pulling away at the top of the screen.

Thanks for those pics! That's my gear on those sats (primary instrument) and also have payload on Deep Space Atomic Clock (not the clock).

First. If seeing a night-time FH launch/landing is not on bucket list, I highly recommend adding. Ridiculously impressive, from the supernova bright lift-off, to the booster landings punctuated like exclamation points with 4 rapid sonic booms just as they touch down. Holy S***!!!! was all I could think of.

I was in a VIP spot with one of my kids. SpaceX had a party zone with DJ and families etc. Swamp in the front and Saturn V at your back with 30 meters of lawn in between. Lots of gator warning signs, nightclub lighting and Village People music. Off in the distance, between palm trees, a rocket all lit up. It was a surreal scene at 2am, one fat clown shy of a Fellini film .

Spacecraft are doing well so far. My stuff won't be turned on for a few days.

 

[Cosmacelf]

How does the booster identify where the center of the Drone ship platform is? is there a radio transponder or gizmo that is used, or is it all GPS coordinates?

It’s gotta be a gizmo. GPS is too inaccurate. Any gizmo experts out there to comment on how a gizmo works?

 

[SMAlset]

Thanks for those pics! That's my gear on those sats (primary instrument) and also have payload on Deep Space Atomic Clock (not the clock).

First. If seeing a night-time FH launch/landing is not on bucket list, I highly recommend adding. Ridiculously impressive, from the supernova bright lift-off, to the booster landings punctuated like exclamation points with 4 rapid sonic booms just as they touch down. Holy S***!!!! was all I could think of.

I was in a VIP spot with one of my kids. SpaceX had a party zone with DJ and families etc. Swamp in the front and Saturn V at your back with 30 meters of lawn in between. Lots of gator warning signs, nightclub lighting and Village People music. Off in the distance, between palm trees, a rocket all lit up. It was a surreal scene at 2am, one fat clown shy of a Fellini film .

Spacecraft are doing well so far. My stuff won't be turned on for a few days.

How extra special of a launch then this was for you! And sounds like a cool in-person thing to experience. Unfortunately we're on the other coast but we were driving close to Vandenberg (hoping to see the launch there in time) when we saw a F9 launch take off and could clearly see the boosters as it lifted upwards. The FH with all those booster engines has got to be intense seeing in person where you get the visual and assume feel the vibration from them. Sure your kid will remember that night years later. It was too bad the launch got pushed back 3 hours though as that precluded a lot of people from staying up to watch it.

So are you able to monitor anything at all until then? And curious why the equipment doesn't get turned on after being deployed. Is it to give the solar panels a chance to power up and if so couldn't the battery be charged ahead of time? Clearly a non-technical person here. Guess your celebration moment is still coming. Hope everything gets up and running. Thanks for sharing.

 

[bmah]

It’s gotta be a gizmo. GPS is too inaccurate. Any gizmo experts out there to comment on how a gizmo works?

I thought the gizmo involved radar reflective paint, at least for landing zones. Not sure for the drone ships.

Bruce.

 

[bxr140]

It’s gotta be a gizmo. GPS is too inaccurate. Any gizmo experts out there to comment on how a gizmo works?

I would guess that GPS is the primary instrument, likely with basic gyros providing rate feedback for the control system. All COTS parts, not bespoke gizmos.

GPS/GLONASS/BeiDou receivers are commonplace in LEO sats (which are moving at many km/hr). The slow velocity of a falling fairing--especially at unlocked accuracy--would be more than enough to get plenty accurate knowledge.

 

[ecarfan]

Curious as to why the center engine doesn't gimbal (unsteerable?) after the two outer engines shutdown. At low speed and altitude the grid fins have pretty much lost control authority. SpaceX doesn't leave imprecision to chance, so maybe there's more to the story?

See post upthread by @Grendal, here is what he said:
——————————————————————-
Answer of what went wrong with the center core:
Elon Musk on Twitter
Elon: High entry force & heat breached engine bay & center engine TVC failed

TVC = Thrust Vector Control = Engine Gimbal
———————————————————————-

The center engine does gimbal, but the mechanism failed because of the extra hot re-entry.