The SLS Mess

Jason Davis has a good rundown on it, and the implications for Europa Clipper. I don’t know how he knows this, though:

Any other rocket besides SLS—including SpaceX’s upcoming Falcon Heavy—lacks the power to blast Clipper directly from Earth to Jupiter. A conventional rocket would rely on three gravity assists from Earth and one from Venus, increasing the transit time from about 2.7 years to 7.5 years.

How does he know that? Has he run the numbers, or is he just taking NASA’s word for it? He’s also not considering the possibility of New Glenn, New Armstrong, Vulcan/ACES with a distributed launch, or BFR, all of which could be ready by 2022.

12 thoughts on “The SLS Mess”

  1. I’m suspicious too, but it looks like it might be close? Musk claims that FH could reach Jupiter with a (“light” but not “fully loaded”) Dragon, dry mass of which is around 4,000kg, which is also roughly the weight of the “current concept” Europa Clipper in the only reference I could find. If that’s all true then FH might be an option, there’d just be little to no mass margin to spare.

      1. Interesting idea. A fully fueled Centaur masses just over 23 MT, and SpaceX claims Falcon Heavy’s maximum payload in fully expendable mode is 63.8 MT to LEO and 26.7 MT to GTO, so it could certainly loft the probe and a Centaur departure stage well beyond LEO. I wonder how that would compare with the SLS trajectory.

        To pull something like this off, SpaceX would have to develop an elongated fairing (their current 5.2 m fairing makes its 4.6 m ID available for only 6.6 m; ID reduces to 1.3 m at 11.4 m; the 3.05 m dia Centaur is 12.7 m long) and a stronger payload attach fitting (their heavy PAF is only good for 10.9 MT).

      2. Just how difficult would it be to integrate a Centaur into a Falcon Heavy?

        (Answer: More difficult and costly than I suspect, but hard to imagine it being as costly as an SLS flight is going to be, and available sooner.)

          1. How much of the Shuttle’s H2 infrastructure remains at 39A?

            In an ideal world FH/ACES but I would have to be benevolent Dictator in order for that to happen.

          2. I just finished reading Taming Liquid Hydrogen, and each time Centaur was mated to a different booster, it wasn’t treated as “just a payload”. You probably lived something different at Rockwell & Aerospace, so I’m all ears for your first hand accounts. Did you work on Centaur-G when you were at Rockwell?

  2. SLS Shows that NASA and the Beltway have learned the lesson of Apollo perfectly. Any program with realistic funding and a solid goal is in danger of succeeding and ending. “First Flight” can be 3-5 years out for the next 20 years and anyone that objects will be betraying the proud American Spirit that got us to the Moon. If they ever accidentally give it enough money to do something, some sort of expensive problem will be discovered.

  3. The Planetary Society article is a good one – some new bits I had not seen in public domain yet – but it omits one other aspect of the Clipper mission which illustrates the problems with SLS.

    Without the Clipper mission, SLS would have no launch of any kind between EM-1 and EM-2, the first crewed flight on SLS. The problem us that the Exploration Upper Stage only flies the first time on EM-2, as well. And that means the EUS will have had no test flight before that crewed flight. A crude equivalent might be launching Apollo 8 on an untested SIVB upper stage. And as one might imagine, the Astronaut Office is not happy about that prospect.

    Well, Europa Clipper would actually *solve* that problem, since it would provide a uncrewed flight (albeit an extremely expensive one) of the EUS before human beings take a ride on it. But that just raises the question of why the entire program is in this fix in the first place.

    1. This really emphasizes the problem that NASA has in being unable to fund testing that they would like to have and require of other launchers and also how the private sector can nearly eliminate that problem through commerce and making testing of future capabilities a part of current operations.

      The only way NASA can get more money is through the ideological battle for federal funds. A company just sells more products and services. It will be nice when our government and its agencies can just accept that commerce is a powerful force that when engaged properly, enables government to accomplish its desires with less cost and administrative/overhead bloat. That is unless the government’s desire is high costs and administrative/overhead bloat.

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