• Friday, July 20, 2018

Atlas V rocket launches carrying multiple US military satellites

Discussion in 'Air Warfare' started by F-22Raptor, Apr 15, 2018.

  1. F-22Raptor

    F-22Raptor SENIOR MEMBER

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    A military communications satellite named CBAS, or Continuous Broadcast Augmenting SATCOM, is the forward payload in the Atlas 5’s upper shroud. A spacecraft named EAGLE, which contains several military experiments including a separating subsatellite named Mycroft, is in the aft position inside the Atlas 5 payload fairing.


     
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  2. Muhammad bin Hamid

    Muhammad bin Hamid FULL MEMBER

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    why not use spacex for this
     
  3. Dante80

    Dante80 FULL MEMBER

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    This is a DoD flight that belonged to the EELV block buy that ULA was awarded, which happened before SpaceX was certified for DoD payloads. Moreover, this is a reference mission in particular that the current SpaceX Falcon9 cannot service yet (direct GEO insertion).
     
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  4. Oldman1

    Oldman1 SENIOR MEMBER

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    Actually the current Falcon does have the ability to do so. And has done it in the past. If you look at the stats, they are similar between the two.

    Even with the success of Spacex and being way way cheaper, the Air Force still awards contracts to both sides. Perhaps because Spacex is booked full IMO.
     
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  5. Dante80

    Dante80 FULL MEMBER

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    Thanks for the insight. Some additional info.

    This was a obligatory vertical integration mission to service the EELV direct GEO reference orbit for the CBAS, Eagle and Mycroft payloads in AFSPC-11. Falcon 9 has never serviced a direct GEO insertion (they mainly work on the GTO-1800/1500 orbit, as well as super-synchronous GTO mission profiles). SpaceX has tested S2 long coast endurance (see GovSat-1 post-mission objectives, and the FH demo mission analysis) so as to validate and certify compatibility with the reference orbit for future launch contracts. It is theorized that F9 block5 will include said capability albeit still without vertical integration capacity (this has yet to come, and depends on additional changes to LC-39A that are designed but have yet to happen).

    Falcon 9 block3/4 (expendable) and Atlas V 551 do not have similar stats for high energy (LEO+3,150 m/s or higher) two phase missions. This stems from the fact that Falcon uses a kerolox S2 configuration that is optimized for LEO and/or GTO launches (as well as S1 re-usability). In contrast, the Atlas Centaur stage can leverage its very high efficiency/energy hydrolox propulsion to attain the additional Δv needed for said mission profiles as well as the long coast endurance that is mandatory for said missions (kerolox has RP-1 freezing problems that require additional work on the stage to rectify, this work has almost been completed).

    Now, with regards to DoD procurement policies. We are currently running the EELV 1a(x) FAR procurement phase, with both competitors bidding for new launch contracts inside it, and the DoD still being able to directly sole-source payloads to one vendor or the other outside the competition phase (see for example the sole-sourced OTV-5 mission SpaceX got for Boeing X-37B last year).

    SpaceX has indeed been bidding a lot lower on most of the contested contracts than ULA can, please have in mind though that launch service cost to DoD is not the sole qualifier for getting the contract. Booking and available launch slots is not an issue for SpaceX in this, since the contested contracts have to do with missions requiring long-lead items and payload-launcher integration studies, usually bringing the launch date multiple years after the contract is awarded. Thus, while SpaceX does have an impressive backlog, this doesn't really affect the DoD competitions (especially since SpaceX has done a pretty mind-boggling ramp up in their launch rate since 2017, and showing an impressive launch cadence).

    If you want to be cynical, you could say that the DoD is still awarding contracts to ULA that SpaceX can compete on so that ULA remains in the game and gets to certifying the Vulcan LV which will somewhat rectify the current big cost discrepancies between the competitors, on time for the EELV phase 2 procurement stage.

    Hope that helps, cheers..C:
     
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  6. Oldman1

    Oldman1 SENIOR MEMBER

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    Not sure what they mean on Spacex never serviced at direct GEO insertion.

    Still feel like they can still win most of the DoD contracts as time goes by, but as you pointed out the DoD still going to award some to ULA to keep them in the game. The X-37B, secret Zuma payload, a couple of NRO payloads are examples that could have been ULA's.

    https://www.bloomberg.com/news/arti...general-endorses-elon-musk-s-reusable-rockets

    The head of U.S. Air Force Space Command said he’s “completely committed” to launching future missions with recycled rockets like those championed by SpaceX’s Elon Musk as the military looks to drive down costs.



    It would be “absolutely foolish” not to begin using pre-flown rockets, which bring such significant savings that they’ll soon be commonplace for the entire industry, General John W. “Jay” Raymond said in an interview Monday at Bloomberg headquarters in New York.



    “The market’s going to go that way. We’d be dumb not to,” he said. “What we have to do is make sure we do it smartly.”



    Space Exploration Technologies Corp., founded by billionaire chief executive officer Musk, has employed rocket reusability as a way to lower launch costs and win a growing roster of customers. SpaceX reused its first Falcon 9 booster earlier this year and has since flown two more missions for commercial satellite operators with refurbished rockets.



    The Air Force won’t be able to use the recycled boosters until they’re certified for military use, a process that Raymond suggested may already be in the works.
     
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  7. Dante80

    Dante80 FULL MEMBER

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    A direct geostationary orbit insertion is a mission where the launch vehicle gets the payload (satellite) to its final orbit position, which is a geosynchronous circular orbit around 35,786 kilometres (22,236 mi) above the Earth's equator and following the direction of the Earth's rotation.

    It is a very difficult reference mission profile to serve, because your rocket has to do all the work in bringing the payload to its desired operational position. The upside is that your satellite can be a lot more compact and lighter, since it only carries fuel for station-keeping, not propelling itself to the operational orbit.

    SpaceX specializes is GTO, and super-synchronous GTO mission profiles. That is, Geostationary TRANSFER orbit profiles. In those missions, the rocket releases the payload to an elliptic orbit that has as little inclination as possible, and a apogee that matches its operational orbit altitude. Then, the sattelite uses its own propulsion system (liquid or electric propulsion) to bring the inclination to 0 degrees and circularize the orbit.

    To give an example. take a look at the Echostar 23 mission. SpaceX released the payload to a 179x35903x22.4 GTO orbit (that means, an orbit with a perigee of 179km, an apogee of 35,903km and an inclination of 22.4 degrees). Then, the sattelite engaged its liquid fuel propulsion engine and brought itself to a 35,786x35,786x0 (that means, an orbit with a perigee of 35,786km, an apogee of 35,786km and an inclination of 0 degrees) Geostationary orbit over the 45° West equator position.
     
    Last edited: Apr 15, 2018
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