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SLS never made sense. Too big, too expensive, too low flight rate. These all problems contribute to each other. Also, large solid rockets are very troublesome

SLS never made sense. Too big, too expensive, too low flight rate. These all problems contribute to each other. Also, large solid rockets are very troublesome. They can not be fueled on the pad, so they are heavy and dangerous from casting to stacking to launch. There will never be a high launch rate reusable rocket with solids.

bryanlarsen 6y ago
Big was the whole point, people decided we needed the capability to send large masses beyond Earth orbit in a single launch. Anything smaller would mean "giving up" on human spaceflight to the moon or Mars. Doing it in a single launch is silly, but that thinking was widespread at the time. And a low flight rate was also a given. Delta IV Heavy only files about once every 18 months, there's insignificant demand for anything even bigger. That was why NASA decided they had to do this themselves, because it would be insane for any commercial company to build a rocket without a market. And expensive was also part of the plan, you can't spread enough pork to make it unkillable if it isn't expensive. Big, expensive, low flight rate. Those weren't problems, they were requirements.
- Gravityloss 6y ago
  I think you misunderstood what I said. I understand that NASA thought it needed the vehicle. However I'm saying it did not in fact need it for any missions. (The idea for docking in earth orbit at the start of a mission is not new.) Very different thing, and you actually demonstrate those points. Everything starts with the misplaced thought that it needs to be so big. Not actually required. Probably correct thought that it needs to be NASA-made since it wouldn't make sense commercially, but this is a consequence of misplaced thought 1. Expensive to spend pork. Again, not needed for the mission, if something more sensible was chosen in the first place. There could have been a capsule flying on Atlas V for many years already. The ESAS study just had all kind of really bad assumptions that made Ares happen instead.
  - bryanlarsen 6y ago
    Yes, bad assumptions led to a bad result. Some of those bad assumptions made sense 10 years ago. Some of them didn't. I was far too generous to Congress by only talking about the former and not mentioning the latter. Multi-launch for large beyond-Earth missions made much more sense 10 years ago than a big rocket. Heck, multi-launch probably made more sense in the 60's than Apollo, if it wouldn't have been for that 1969 hard deadline.
    - wongarsu 6y ago
      Multi-launch was considered for the Apollo program, but was ruled out because it had higher technical risk than just scaling up the rocket and making the payload extra light. If we didn't have the hard 1969 deadline we would likely have gone with the multi-launch option back then. It's an interesting alternate reality to imagine: we might have had a more interesting moon program that had the ability to naturally scale to larger and larger missions, instead of repeating basically the same thing until the public gets bored and cancels it.
      - Gravityloss 6y ago
        Yeah, first orbital docking was done 1966 on Gemini 8. The architecture for Apollo was decided much earlier already (it did include the lunar orbit rendezvous and docking which was indeed risky). We now have 54 years of repeated low earth orbit dockings so maybe the architecture designs could start taking that into account. Even SpaceX is planning on doing orbital refueling.
      - garaetjjte 6y ago
        There were plans for more interesting moon missions under Apollo Applications Program, cancelled because of budget cuts. (and what was left was botched as Skylab)
- pfdietz 6y ago
  > Big was the whole point Big was political. It was a requirement added because SLS could provide it, not because it was needed. It was there to stop the order-of-magnitude cheaper per pound smaller launchers from being proposed instead. Part of all this was strong arm twisting from the politicians involved to stop all work on in-space propellant transfer and propellant depots (because with them, you might as well launch lots of smaller cheaper launchers to carry up the propellant.)
- blackrock 6y ago
  Can they launch multiple satellites on the same rocket?
pfdietz 6y ago
Right. I will go further: if SLS is the best that could be done, then human space activities themselves would make no sense. SLS is a solution to no real problem beyond "how do we deliver $$$ to the appropriate pork consumers?" If you believe humanity has a future in space, then you must believe it's possible to do much better than SLS. So do that, not waste time on a pointless and hideously expensive diversion.

bryanlarsen 6y ago

Big was the whole point, people decided we needed the capability to send large masses beyond Earth orbit in a single launch. Anything smaller would mean "giving up" on human spaceflight to the moon or Mars. Doing it in a single launch is silly, but that thinking was widespread at the time. And a low flight rate was also a given. Delta IV Heavy only files about once every 18 months, there's insignificant demand for anything even bigger. That was why NASA decided they had to do this themselves, because it would be insane for any commercial company to build a rocket without a market. And expensive was also part of the plan, you can't spread enough pork to make it unkillable if it isn't expensive. Big, expensive, low flight rate. Those weren't problems, they were requirements.

Gravityloss 6y ago
I think you misunderstood what I said. I understand that NASA thought it needed the vehicle. However I'm saying it did not in fact need it for any missions. (The idea for docking in earth orbit at the start of a mission is not new.) Very different thing, and you actually demonstrate those points. Everything starts with the misplaced thought that it needs to be so big. Not actually required. Probably correct thought that it needs to be NASA-made since it wouldn't make sense commercially, but this is a consequence of misplaced thought 1. Expensive to spend pork. Again, not needed for the mission, if something more sensible was chosen in the first place. There could have been a capsule flying on Atlas V for many years already. The ESAS study just had all kind of really bad assumptions that made Ares happen instead.
- bryanlarsen 6y ago
  Yes, bad assumptions led to a bad result. Some of those bad assumptions made sense 10 years ago. Some of them didn't. I was far too generous to Congress by only talking about the former and not mentioning the latter. Multi-launch for large beyond-Earth missions made much more sense 10 years ago than a big rocket. Heck, multi-launch probably made more sense in the 60's than Apollo, if it wouldn't have been for that 1969 hard deadline.
  - wongarsu 6y ago
    Multi-launch was considered for the Apollo program, but was ruled out because it had higher technical risk than just scaling up the rocket and making the payload extra light. If we didn't have the hard 1969 deadline we would likely have gone with the multi-launch option back then. It's an interesting alternate reality to imagine: we might have had a more interesting moon program that had the ability to naturally scale to larger and larger missions, instead of repeating basically the same thing until the public gets bored and cancels it.
    - Gravityloss 6y ago
      Yeah, first orbital docking was done 1966 on Gemini 8. The architecture for Apollo was decided much earlier already (it did include the lunar orbit rendezvous and docking which was indeed risky). We now have 54 years of repeated low earth orbit dockings so maybe the architecture designs could start taking that into account. Even SpaceX is planning on doing orbital refueling.
    - garaetjjte 6y ago
      There were plans for more interesting moon missions under Apollo Applications Program, cancelled because of budget cuts. (and what was left was botched as Skylab)
pfdietz 6y ago
> Big was the whole point Big was political. It was a requirement added because SLS could provide it, not because it was needed. It was there to stop the order-of-magnitude cheaper per pound smaller launchers from being proposed instead. Part of all this was strong arm twisting from the politicians involved to stop all work on in-space propellant transfer and propellant depots (because with them, you might as well launch lots of smaller cheaper launchers to carry up the propellant.)
blackrock 6y ago
Can they launch multiple satellites on the same rocket?

pfdietz 6y ago

Right. I will go further: if SLS is the best that could be done, then human space activities themselves would make no sense. SLS is a solution to no real problem beyond "how do we deliver $$$ to the appropriate pork consumers?" If you believe humanity has a future in space, then you must believe it's possible to do much better than SLS. So do that, not waste time on a pointless and hideously expensive diversion.