Author Topic: SpaceX Falcon Heavy - STP-2 mission - 39A, Cape Canaveral - Mid 2015  (Read 41411 times)

Online LouScheffer

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Wow, this looks like a complicated mission. Two primary spacecraft inserted into different orbits (one LEO, one 12,000 km) and a ton of secondaries. Looks like every spare spacecraft the USAF could think of...
From the document:

Insertion Orbit #1

Deliver the IPS to a circular orbit with an orbital altitude of 720 km and an orbital inclination of 24. Deploy only the COSMIC-2 payload set, up to six APLs (TBR), and actuate up to eight P-PODs (TBR).

Insertion Orbit #2

Deliver the IPS (with remaining payloads) to the elliptical orbit with a perigee of 6,000 km, apogee of 12,000 km, and an orbital inclination of 45. Deploy the DSX payload followed by remaining APLs and actuate remaining P-PODs. After deployment of these payloads, the LV shall enter a coast phase of [3 hours threshold, 5 hours objective]. After the coast phase, the LV shall execute an upper stage restart with a minimum duration of 5 seconds (TBR).

This looks like at least 5 burns of the second stage to me, over many hours.  #1, get into orbit with a 720 km apogee, 24 inclination.  #2, circularize at 720, release first payload.  #3, Next equator crossing, boost to a 6000 km perigee.  Coast until apogee, #4, boost to a 12000x6000 orbit and change plane to 45.  Wait the required 3 hours for the final stage restart (#5).

I'm not an orbital mechanics guy, but you might get less delta-v by doing the last plane change at the 12,000 km apogee, rather than including it as part of burn #4.  That would be yet another burn, and a few more hours.

The Russian missions to GTO from their high latitude Proton launches are the only other ones I can think of with this many restarts, and they've had reliability problems over the years.   It's a lot of successive events, all of which must go right, and no alternatives....

Offline Jim

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At the time the type was officially announced, it was implied very strongly that DoD or USAF had urged SpaceX to proceed with Falcon Heavy more quickly than they had initially planned.  I wonder if STP-2 was the mission that they had in mind, even then?
I don't think this specific mission was on their minds, I think they pushed SpaceX to accelerate FH because F1v1 wasn't meeting their requirements in general. DoD's high valure payloads are big and may be getting bigger.

Huh?  Unwarranted speculation.  This is just a  mission made up to test the FH.  There is no pushing from the DOD either.  The onus is on Spacex to provide the vehicle, the DOD was not looking for another one.

Offline padrat

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It's a wonderful opportunity for Spacex, but they need to execute.  It might seem like it's a long way off in 2015, but it's really not that far off for a vehicle that has not flown yet.

and from a pad whose construction has not been started.
I will trust Chris that this confirms that SpaceX will launch the FH from the East coast using LC-40. 
This will be interesting.

Yep, the plan is to have a Falcon Heavy hanger and ramp, clocked 90 degrees (could be 180, but the Cape guys say 90) from the Falcon 9 Hanger and ramp. Other options include 39A - I just made Jim frown ;D -or a new pad.....if they don't need it, they don't need it.

Was pretty specific in the presser too: "The DSCOVR mission will be launched aboard a Falcon 9 and is currently slated for late 2014, while STP-2 will be launched aboard the Falcon Heavy and is targeted for mid-2015. Both are expected to launch from Space Launch Complex 40 at Cape Canaveral Air Force Station, Florida.".
All I'm saying is that I'm hearing decisions for the Heavy pad havent been finalized yet. 39A would be nice but so far it comes with a lot of red tape, which I'm sure Spacex would like to avoid....
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Offline kevin-rf

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Well, sounds like SpaceX will have it's hands full managing the boil off. Hats off if they pull off this Hat Trick.
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Offline avollhar

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This looks like at least 5 burns of the second stage to me, over many hours.  #1, get into orbit with a 720 km apogee, 24 inclination.  #2, circularize at 720, release first payload.  #3, Next equator crossing, boost to a 6000 km perigee.  Coast until apogee, #4, boost to a 12000x6000 orbit and change plane to 45.  Wait the required 3 hours for the final stage restart (#5).

I'm not an orbital mechanics guy, but you might get less delta-v by doing the last plane change at the 12,000 km apogee, rather than including it as part of burn #4.  That would be yet another burn, and a few more hours.


I am no orbital mechanics guy either, but had to do some math a few years ago. Indeed, changing planes is most efficient with lowest orbital velocity: high apogee, low perigee.

Therefore my best guess is:

- Launch into 720x250km transfer orbit 24 deg inclination. The 4.5 deg difference to KSC latitude could be included already.
- Burn 1: 720x720km, 24 deg incl.
- Burn 2: 720x12000km, 24 deg incl.
- Burn 3: 720x12000km, plane change to 45 deg incl.
- Burn 4: 6000x12000km, 45 deg incl.
- Burn 5: as required by contract

I don't think there is a way around separating Burn 2/3. But 3/4 could be possibly joined as they both happen at apogee.

As others noted: a hell of a launch sequence..

Offline mlindner

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I'm personally wondering about those cubesat P-PODs. My lab here has several nanosats in the pipeline that could be ready for launch in roughly that timeframe. Would be really cool to be on this launch. Only 1 of 3 planned is currently manifested.
« Last Edit: 12/06/2012 02:23 PM by mlindner »

Offline baldusi

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I'm personally wondering about those cubesat P-PODs. My lab here has several nanosats in the pipeline that could be ready for launch in roughly that timeframe. Would be really cool to be on this launch. Only 1 of 3 planned is currently manifested.
I always joked that you could launch 25k cubesats on a Falcon Heavy for 6000USD/cubesat. Jokes aside, I don't know what sort of cubesat could use a 24deg 720km circular orbit, or a 45deg x 12.000km x 6.000km. But if somebody can use it there's that 5.000kg of ballast to fill.
And it will test some very exiting ESPA technology.

Online LouScheffer

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This looks like at least 5 burns of the second stage to me, over many hours.  #1, get into orbit with a 720 km apogee, 24 inclination.  #2, circularize at 720, release first payload.  #3, Next equator crossing, boost to a 6000 km perigee.  Coast until apogee, #4, boost to a 12000x6000 orbit and change plane to 45.  Wait the required 3 hours for the final stage restart (#5).

I'm not an orbital mechanics guy, but you might get less delta-v by doing the last plane change at the 12,000 km apogee, rather than including it as part of burn #4.  That would be yet another burn, and a few more hours.


[...] Indeed, changing planes is most efficient with lowest orbital velocity: high apogee, low perigee.   Therefore my best guess is:

- Launch into 720x250km transfer orbit 24 deg inclination. The 4.5 deg difference to KSC latitude could be included already.
- Burn 1: 720x720km, 24 deg incl.
- Burn 2: 720x12000km, 24 deg incl.
- Burn 3: 720x12000km, plane change to 45 deg incl.
- Burn 4: 6000x12000km, 45 deg incl.
- Burn 5: as required by contract

I don't think there is a way around separating Burn 2/3. But 3/4 could be possibly joined as they both happen at apogee.
Burns 3/4 in your sequence would definitely be combined, thanks to the triangle inequality (The vector sum of two vectors is shorter than the sum of the lengths of the two vectors, unless they are colinear, which does not apply here.)  Whether the saving from the plane change with the lower perigee outweighs the orbital-raising benefit of doing each burn at the highest velocity is not obvious, at least to me.

I suspect the true solution is to do some of the plane change at each relevant firing. Due to the sin/cos relation, you can get a sideways delta-v of 10% of the maneuver total by giving up only 0.5% in the main direction.  So you'd pick up some of the plane change on the 750 circ->750x6000, some on the 750x6000->6000x12000, and the remainder (if any) at apogee.  I'm sure that someone at SpaceX has worked this out in detail already, to make sure they have enough delta-v.

Offline Halidon

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At the time the type was officially announced, it was implied very strongly that DoD or USAF had urged SpaceX to proceed with Falcon Heavy more quickly than they had initially planned.  I wonder if STP-2 was the mission that they had in mind, even then?
I don't think this specific mission was on their minds, I think they pushed SpaceX to accelerate FH because F1v1 wasn't meeting their requirements in general. DoD's high valure payloads are big and may be getting bigger.

Huh?  Unwarranted speculation.  This is just a  mission made up to test the FH.  There is no pushing from the DOD either.  The onus is on Spacex to provide the vehicle, the DOD was not looking for another one.
You're misunderstanding me. I'm not saying SecDef called up Elon and said "build be a Heavy," I'm saying Falcon 9, at least V1, wasn't meeting requirements for the payloads DoD puts on EELVs.

DoD may not have been looking for another vehicle, but they are definitely looking to reduce costs. IF SpaceX can deliver lower costs with a reliable vehicle they'll get payloads.

Offline Antares

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Sounds like a 3 burn mission to me.
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Offline FinalFrontier

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Well between this, specualtion that FH might be the vehicle for GSC, ongoing CRS, ongoing CCDEV, and ongoing investigation into the engine one failure on the last flight, spacex sure has their hands full right now.

Really pulling for them to pull all this off.
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Offline ugordan

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Sounds like a 3 burn mission to me.

How do you get from 720x720 to 6000x12000 in one burn, because there is this final requirement for the insertion orbit #2 which accounts for an additional burn: After the coast phase, the LV shall execute an upper stage restart with a minimum duration of 5 seconds (TBR).?

Online Robotbeat

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Sounds like a 3 burn mission to me.

How do you get from 720x720 to 6000x12000 in one burn, because there is this final requirement for the insertion orbit #2 which accounts for an additional burn: After the coast phase, the LV shall execute an upper stage restart with a minimum duration of 5 seconds (TBR).?
Agreed, I immediately thought it sounded more like a 4-burn mission.
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Offline oldAtlas_Eguy

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The launch of NET August 2015 is probably prior to the Intelsat launch making this one the test launch for the East coast of FH.

Offline cleonard

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Sounds like a 3 burn mission to me.

Launch into  720x720km, 24 deg incl.
Restart 1: Increase altitude to 720x12000km, 24 deg incl.
Restart 2: Increase altitude to 6000x12000 and plane change to 45 deg
Restart 3: as required by contract

How do you get from 720x720 to 6000x12000 in one burn, because there is this final requirement for the insertion orbit #2 which accounts for an additional burn: After the coast phase, the LV shall execute an upper stage restart with a minimum duration of 5 seconds (TBR).?
Agreed, I immediately thought it sounded more like a 4-burn mission.

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