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Congress

Upper Stage Engine Amnesia in Alabama

By Keith Cowing
NASA Watch
March 10, 2016
Filed under , , ,
Upper Stage Engine Amnesia in Alabama

Statement by Sen. Shelby on NASA FY 2017 Budget Request
“Surprisingly, NASA has not proposed a single dollar for the development of an upper stage engine that is absolutely necessary for a crewed mission that is only seven years away.”
Keith’s note: Of course Shelby forgets that $1.2 billion NASA spent on the J-2X for use on Ares V and SLS upper stages – much of it was spent in Alabama. That engine was subsequently mothballed because NASA had no idea what it was doing. But Shelby paid their bills anyway.
Overview: J-2X Engine, NASA
“J-2X is a highly efficient and versatile advanced rocket engine with the ideal thrust and performance characteristics to power the upper stage of NASA’s Space Launch System, a new heavy-lift launch vehicle capable of missions beyond low-Earth orbit. Fueled by liquid oxygen and liquid hydrogen, the J-2X builds on heritage designs but relies on nearly a half-century of NASA spaceflight experience and technological and manufacturing advances to deliver up to 294,000 pounds of thrust, powering exploration to new destinations in our solar system.”
NASA Has No Clear Use for the J-2X That It Once Needed, earlier post

NASA Watch founder, Explorers Club Fellow, ex-NASA, Away Teams, Journalist, Space & Astrobiology, Lapsed climber.

36 responses to “Upper Stage Engine Amnesia in Alabama”

  1. Tim Blaxland says:
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    Isn’t the Exploration Upper Stage proposed to be powered by the RL-10 now? It’s been around for donkey’s years, including in the deeply throttleable Common Extensible Cryogenic Engine variant. Also, the BE-3 is in development (independent, but NASA could still consider it I guess). How many cryogenic upper stage engines does Shelby want? #JourneyDownTheBottomlessMoneyPit

  2. Nathan Rogers says:
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    But why isn’t this being used? Even if it is overpowered for the job it’s got to be cheaper than designing something new again

    • spacegaucho says:
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      As many as it takes for full employment at MSFC.

    • Patrick Bane says:
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      And it’s a great engine, developed from the ground up and tested as per design.

    • Zed_WEASEL says:
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      The J-2X is tailored as the Ares-1 upper stage engine. More thrust less ISP. Performance when compare to competitors (RL-10C, BE-3U & the XCOR XR-8H21) is inferior and the J-2X a lot more costly never mind additional cost reopening the manufacturing line for low rate production.

      If you need to get a lot of mass to LEO than the J-2X is your engine.

  3. Tritium3H says:
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    In all seriousness, what EXACTLY is the primary Earth departure / Mars Departure engine that NASA is planning on using for any manned Martian mission? Do we have an engine that can be re-lit after being in deep space for 8 or more months, with sufficient power to return an orbiting Mars crew vehicle back to Earth? Is there anything even in active development by NASA? I am not talking about SpaceX or Blue Origin or other commercial companies…I am talking specifically about NASA, here.

    What unique challenges are posed in ensuring the successful ignition, reliable thrust and performance, for a chemical rocket that has been in zero-G vacuum and exposed to deep space radiation environment for months (maybe years). How is the propellant stored? What about the main turbo pumps? Not to mention all the other critical mechanical sub-systems that need to function after an extended period of dormancy in the incredibly challenging environment of deep space.

    I mean, I am sure all these things have been considered…but perhaps some of the more knowledgeable forum members could reply with some information and specifics. This is a legit question. Thanks in advance.

    • EtOH says:
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      Long term propellant storage necessitates hypergolic fuel. The engine for the Orion service module is the AJ10, of shuttle origin. I don’t know how long it is certified to operate without maintenance, but weeks at the very least, and since there isn’t really much degradation of bulk components like engines in deep space, I imagine much longer. There are many examples of (much smaller) hypergolic engines lasting for 100’s of cycles over periods of a decade +. Unless they go solar electric, I imagine they will continue using the AJ10, with maybe a little study into long-term hibernation.

      • Jeff2Space says:
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        I disagree.

        ULA claims they have the technology for long term LOX/LH2 storage. If NASA would fund a commercial LEO fuel depot demonstrator (preferably with two different companies flying two different designs), we could not only eliminate this as a (perceived) program risk, we could open up the possibility of a better launch/departure architecture in general. If the departure stage doubled as a launch stage, and was refueled in LEO, the size of the launch vehicle and/or number of launches required for the actual mission hardware can be reduced.

        • EtOH says:
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          Agreed. I was trying to specifically address the return engine question.

          • Daniel Woodard says:
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            Hall effect thrusters have come a long way since the 60’s with many comsats using only electrical thrusters. I think we can reasonably say that the thrust available with nuclear-electric propulsion is limited only by the amount of electrical power that can be produced. If higher thrust is needed RF heating is available. Nuclear thermal could in theory produce higher thrust but at the cost of a lower Isp. Also, nuclear-thermal Isp is determined by molecular mass, so for maximum performance you would still need to carry LH2.

          • fcrary says:
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            I’m one of the few fans of nuclear electric rockets, but I can’t make that work. I think nuclear thermal will always give higher thrust. The output power from any rocket is the thrust times the exhaust velocity ( Isp times g, if you like those units.) Even is you dial an electric thruster down to the specific impulse of a thermal rocket, you would still be limited by the power output of the reactor. Worse, you have the inefficiency and mass required to convert thermal power to electric.

            A few more pedantic notes:

            Nuclear thermal more-or-less requires hydrogen. There aren’t any viable fluids with a mass between 2 and 16 AMU, and once you get to 16, you might as well use a chemical rocket.

            Most satellites, at least American ones, use Kaufman, not Hall effect thrusters (from the XIPS/NSTAR/NEXT line). To the user, there isn’t much of a difference, but it’s more than the difference between an Otto and Diesel engine under a car’s hood. The Russians and Europeans tend to use Hall effect.

        • Tritium3H says:
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          Again, playing the part of a “wet blanket”, I would question the applicability/suitability of claims that the technology exists. I mean, one could say that our country has the technology for developing a Nuclear Thermal rocket engine suitable for the transfer vehicle required in a manned Mars mission. The same goes for VASIMR. However, both are predicated on a low weight, high power density nuclear reactor which has NEVER been built. Yes, the ground-work has been laid, and even promising, prototype reactors have been demonstrated. But NOTHING actually exists. The same goes for a hypothetical space-based LOX/LH2 storage facility. If an “Apollo-like” crash program was started, on any of these systems, tomorrow…we might have the necessary pieces of the puzzle flight-tested and ready in 7-10 years.

          However, let’s put aside the question of the propulsion system(s) for the moment. What about the actual environmental and Life support systems necessary for the habitation module(s) required. Think of all the systems and sub-systems that have to not only be designed, and tested, but integrated into a complete and functional infrastructure. Again, bits and pieces either exist, or are in prototype-phase development. But major issues remain, and nothing has been flight-tested, much less approved for a 1-1/2 to 2 year duration mission.

          Finally, since an “Apollo-like” crash program is never going to happen, DOUBLE whatever previous time-frames have been suggested.

          My argument being, we are not going to see a manned Mars mission (with landing and exploration) before the decade of the 2040’s. More than likely, it will not happen until 2050 or later.

          • Daniel Woodard says:
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            The US actually launched a nuclear reactor in 1965. It is still in orbit. We haven’t done it since.
            https://en.wikipedia.org/wi…. I also feel the zeroing out of technology development was unfortunate as this activity has the potential for producing practical benefits for America.

          • fcrary says:
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            Strictly speaking, SNAP-10A doesn’t count. The comment was about nuclear thermal rockets, not nuclear electric. That means an open loop, hydrogen coolant. SNAP-10A was a closed-loop, NaK cooled pile.

          • Jeff2Space says:
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            LOX/LH2 storage is not as complicated as nuclear propulsion. ULA has been flying (and tweaking the design of) Centaur for decades. ULA truly does have the experience necessary to complete the R&D for a LEO fuel depot. What the engineers need is the funding to fly one or two prototype fuel depots to prove the concept. But just as ULA’s management and parent companies were content to keep flying the EELVs unchanged as long as they could, they weren’t going to fund development of LEO fuel depots on their own dime.

      • Tritium3H says:
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        Does the AJ10 have the necessary thrust and Isp specifications to perform the Delta-V necessary for Earth departure/Trans-Mars Injection, Mars Orbital Insertion, and Trans-Earth injection of a vehicle with the expected mass necessary for a long duration, crewed Mars mission? Has any studies been done on a representative manned mission, using existing manned-rated rocket engines?? I am not talking about some notional engine that exists only on paper…I am talking about actual flight-ready engines, requiring only the minimum of adaptation/modifications. Again, I don’t know the answer…this is a serious question.

        • EtOH says:
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          Perhaps I should have clarified. I was specifically adressing the question of engines that can operate in deep space. The TMI would almost certainly be done with some sort of hydrogen upper stage like the EUS. The AJ10 is man rated and slated for use on Orion, it has plenty of thrust but like all hypergolic engines it has limited Isp. This means more fuel for the return trip. Other propulsion options are VASIMIR or some sort of cryocooled liquid propellent, but these all require considerable development.

          As for the readiness of the insertion TMI stage, the RL10 engine is very well known, been around since the 60s, so it should only take NASA 7 or 8 years to finish developing the EUS.

          • Tritium3H says:
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            Hi EtOH,
            Understood. Thank you for your response and answers, and we are in agreement. I am kind of playing “devil’s advocate”, here…or perhaps, the proverbial “wet blanket”. Unless I am mistaken, the EUS, in and of itself, is not sufficient for a manned mission to Mars. The RL10 engine, used in a cluster, might be the basis for the primary engines used in some notional Earth-Mars transfer vehicle…but unless I am very much mistaken, there really is nothing under active development, as a total, combined system, that fits the bill. I mean, sure there are bits and pieces of existing hardware and technology that could be adapted and used for a hypothetical crewed Mars exploration system. However, since there is no actual plan (except in large brush-strokes), there are no defined engineering specifications.

          • EtOH says:
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            Yeah, while there are answers to your questions, they aren’t all that compelling. In short there is existing propulsion hardware for much of the #pathtomars plan, it’s just all shuttle-era (or earlier). When Obama proposed following the flexible path plan, the two primary investments were to be COTS/CC and technology development. The former took a lot of heat but it’s the latter that got really axed. So the only new propulsion tech in the pipeline is SEP, and NASA is left patching a mars program out of shuttle parts. With the help of SEP, the EUS might be sufficient for a mars mission if you split the mission up into a lot of pieces that get sent to mars separately, but I agree with Jeff2Space that fuel depots would have been a more flexible and capable option.

          • Michael Spencer says:
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            Thanks for this discussion. I don’t think I realized just how much fuel would be required for TMI (and coming back).

          • Daniel Woodard says:
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            I assume Mars orbital insertin would be hypergolic since it would be several months after Earth departure?

          • EtOH says:
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            Yup. There are certainly ways to do it with ion propulsion but then the transfer takes much longer.

          • fcrary says:
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            You could use liquid hydrogen for the Mars orbital injection burn. It would require active cooling or extra hydrogen (for boil-off cooling) during the cruise phase. I personally don’t like that option, and I’ve seen estimates that it isn’t mass-effective. But I wouldn’t automatically call it a bad idea. If someone did the numbers, for a particular mission configuration, I might change my mind.

          • EtOH says:
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            I’m not really opposed to cryogenics for these spacecraft, the necessary tech would also be useful for fuel depots, but it doesn’t seem to be the path they are currently pursuing (unless I’ve missed something).

          • fcrary says:
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            Honestly, I am unable to figure out what path “they” are currently pursuing. Without knowing that, all I can say is what technology could be useful for possible paths. And, perhaps, which technologies aren’t useful for any option I can imagine.

            I think that is a key issue. Given a known and fixed plan, people can get to work on the required technology. It does not have to be the best plan, or my favorite one. But until the plan is in place, everyone is just spinning their wheels and talking about poorly-constrained and poorly-posed problems.

      • muomega0 says:
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        Hypergolics for the trips to deep space is the just plain silly. Cryogenic engines have restarted many times and offer superior ISP which rules in deep space, significantly reducing mass launched from LEO, significantly reducing costs. Spend the cash to raise the TRLs huge reward with little risk.

        • EtOH says:
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          Note that Tritium’s question was explicitly about existing or clearly planned propulsion systems. Silly or not, until long-term cryogenic storage gets developed, hypergolic engines are what we’ve got.

          • fcrary says:
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            Strictly speaking, you mean _efficient_ long-term, cryogenic storage. There are inefficient, BF&I (brute force and ignorance) solutions available today. But that isn’t good enough for this application.

    • Ben Russell-Gough says:
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      I don’t know if there has been any official word but most of the announcements on the Exploration Upper Stage (EUS) that I’ve seen seem to assume a 4 x RL-10C cluster. Personally, I would have liked 4 x MB-60 but no-one asked me so… 😉

      • Zed_WEASEL says:
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        The MB-60 is not in consideration for the EUS. It’s been mothballed like the J-2X.

        AFAIK the RL-10C-3 is the planned engines on the unfunded EUS. There is a stockpile of RL-10B engines to convert from. IIRC Boeing ordered over 50 units for the EELV program before the ULA shotgun marriage.

    • muomega0 says:
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      Congress refuses to authorize funding that would displace the expendable status quo. With a gas station, one can reduce the LV size, increase the flight rate, and reduce costs by cutting production lines. NASA spends 8B+ on ISS, SLS/Orion, leaving much less than 1B for technology.

      A few years ago, the word ‘depot’ was not even included in the detailed, multiple page road maps. The word ‘reuse’ does not appear in the EUS requirements for either the LV or for a common element, e.g. the engine to another portion of the architecture (its all expendable).

      Rather than a depot centric, special interests now push ‘distributed launch’, where a few LVs launch at about the same time to conduct a mission (an expendable tanker topping off the expendable transfer stage) that may extend the duration to a few weeks rather than a few hours–but that’s all one needs to head to the moon for 6 day lunar sorties and continuously build expendable hardware…get to reuse, Mars, asteroids, ‘later’.

      The cold vacuum environment actually provides benefits while presenting other challenges. A key technology is to pressurize with the propellant’s gas; otherwise one must additionally provide these purge and pressurization tanks. A second is to separate the liquid and gas, which takes either a very small g level or static device.

  4. Ben Russell-Gough says:
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    If NASA were confident that J-2X were ideal for the SLS upper stage, I doubt that it would have been mothballed. Maybe they know something about it that didn’t reach the public domain? It can’t be cost; at a flight rate of about 2 every three years, every SLS will be practically a bespoke one-off (with the associated high costs) anyway!

  5. Jeff2Space says:
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    Papers from ULA which talk about fuel depots which depend heavily on their 50 years of Centaur experience:

    http://www.ulalaunch.com/up

    http://www.ulalaunch.com/up

    http://www.ulalaunch.com/up