ULA pinpoints cause of Delta launch abort, reschedules launch

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ULA has identified the cause of the launch abort of its Delta 4 Heavy rocket on August 29th, and has now aiming for a launch no earlier than September 18th.

A torn diaphragm in one of three pressure regulators at Cape Canaveral Air Force Station’s Launch Complex 37 caused the computer-controlled scrub just three seconds before liftoff on Aug. 29, ULA CEO Tory Bruno said via Twitter on Wednesday. The engines briefly lit on fire, but the rocket remained firmly on the pad.

“Torn diaphragm (in the regulator), which can occur over time,” Bruno said. “Verifying the condition of the other two regulators. We will replace or rebuild as needed, re-test, and then resume towards launch.” [emphasis mine]

The highlighted words illustrate the less than stellar old space rocket design that the Delta 4 Heavy represents, and that ULA is perpetuating as long as it uses this rocket. Rather than redesign so that these torn diaphragms will no longer be a problem, it appears they will simply make sure this design is tested and works, for this launch. Thus, this issue has the possibility of reappearing in a future launch.

Wouldn’t it be better to upgrade and eliminate such a problem, for good, once it is identified? That appears to be SpaceX’s strategy, and the consequence is that their rockets and spacecraft get increasingly more reliable with time.

Anyway, if ULA’s schedule holds, it means there will be two launches at Cape Canaveral in less than 24 hours, as SpaceX is aiming for another Starlink launch the day earlier.


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  • Rose

    Only four Delta IV Heavy flights are planned after this NROL-44 mission:
    * December 2020: NROL-82 from Vandenberg
    * 2022: NROL-91 from Vandenberg
    * 2022: NROL-68 from Canaveral
    * 2023: NROL-70 from Canaveral
    … and then the Delta IV model will be retired, having flown 16 times.

    It will be interesting to see how many times the Falcon Heavy flies before it is retired.
    Upcoming Falcon Heavy flights:
    * 28 February 2021: USSF-44, a direct insertion (!) geostationary mission for a classified payload, expected to land the two side boosters on droneships and expend the center core. Until recently this fourth flight of the Falcon Heavy had been expected to fly late this year.
    * Spring 2021: USSF-52, another classified geo mission.
    * 2021: ViaSat-3 geostationary telecom satellite for Viasat Inc.
    * July 2022: Psyche probe for NASA, to explore the ~200+ km metal asteroid 16 Psyche in the asteroid belt.

  • Rose observes:

    “… and then the Delta IV model will be retired, having flown 16 times.
    It will be interesting to see how many times the Falcon Heavy flies before it is retired.”

    If the over/under is 16, I’ll go with the over.

  • Blair Ivey: I wouldn’t make that bet. It isn’t that I don’t think the Falcon Heavy could easily outdo the Delta 4 Heavy, it’s that it will likely get replaced by Starship/Super Heavy before it gets to 16 flights.

  • Rose

    Missing from my list is:
    * Q4 2022: USSF-67. This is SpaceX’s first flight under the NSSL Phase 2 launch service contract, and while mission details have not been made public, most observers expect it to be the first Falcon Heavy mission with vertical payload integration, utilizing a new Mobile Service Tower (MST) at LC-39A.

    I wouldn’t know where to place my bet on the longevity of Falcon Heavy. Starship development progress is exciting to watch, but it is such an ambitious project, with heat shielded movable aero-control surfaces capable of surviving higher energy return trajectories than the Shuttle and on-orbit refueling, both required for direct insertion geo missions. And would the Starship be expended for escape trajectory missions such as Psyche?

    Just as I expect to see single stick F9 missions launching astronauts for a good while after Starship is operational, I think there may be an extended role for FH as well. Enough so for two mission per year through 2027? I don’t know.

  • Jimbo

    It sounds like the diaphragm was in the ground systems equipment not in the rocket itself.

    If that is the case it is more of a equipment maintenance and inspection issue.

    A piece of equipment will have parts that wear and fail. Depending on the consequences and costs of failure a company will weigh the inspection and testing frequency costs/benefits, part replacement costs/benefits, and costs/benefits of design improvement. And based on that they can make some improvements or accept the risk.

    As a thought experiment: If a scrubbed launch costs $500,000 and diaphragms cost $100,000 a piece and you can’t inspect it without breaking it and you have 3 of them in service, and you have never scrubbed for a broken diaphragm, how much do you invest when you only need to launch 3 more times?

  • Jimbo,

    That’s the impression I got also, but wouldn’t the ground systems be specific to the rocket itself, ie the hold down clamps ?
    Don’t know just asking.

  • Rose

    SLC-37B supported single stick Delta IV launches (until their retirement) and Delta IV Heavy launches, and while much of the ground support equipment would be shared between the two vehicles, some of it would be specific to the Heavy. The last time this pad was used was August 2019, with the final launch of a single stick Delta IV. The last time a Heavy was launched there was August 2018, with the Parker Solar Probe.

    It will be interesting to see how well SpaceX does reactivating SLC-4E at Vandenberg. Their last launch there was June 2019, and they have a Falcon 9 scheduled to launch Sentinel-6A (an ocean observing satellite) there in November 2020.

  • Edward

    Rose asked: “And would the Starship be expended for escape trajectory missions such as Psyche?

    Not necessarily. The Starship can carry 100 tonnes, which allows for a small upper propulsion stage to take care of any delta-v that the Starship cannot impart to the spacecraft while retaining enough delta-v for Starship to return to Earth.

    Once there are refueling stations near the Moon (high lunar orbit, L1, L4, or L5), then Starship may be able to get a heavy payload well on its way and then go to a refueling station for the return fuel. At 100 tonne capacity, Starship may not be needed to take a probe out of low Earth orbit (LEO), so Starship may only be needed for basic LEO launch of the probe and upper stage, which does the rest of the work to escape velocity.

    Having a 100 tonne capacity allows for a lot of mission flexibility, and if the price is as low as expected, a lot of missions become affordable.

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