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It doesn't work, not for Moon missions. It was never designed for Moon missions in the first place, the original plan was unspecified "deep space" missions wit

It doesn't work, not for Moon missions. It was never designed for Moon missions in the first place, the original plan was unspecified "deep space" missions without any clear plan of what it would actually be doing (because it's actual purpose is to keep money flowing to old Shuttle contractors.) Consequently, it can't do a Moon mission like the Saturn V could, it requires the idiotic nonsense that is the NHRO, which will endanger astronauts because it can't get Orion (which is a whole other can of pork) into a low lunar orbit. It also can't handle the lander, so now Artemis has to count on SpaceX and/or Blue Origin for that, which is probably what you're alluding to not working. But if those don't work, then neither does Artemis and then how can you say SLS works? Another problem with SLS is it's expensive AF and has a terrible launch cadence. Maybe you think that doesn't really matter, but it is for those reasons that NASA isn't going to test Orion again before putting astronauts on it. The last time they tested Orion, to verify the design and modelling, the heat shield started to come apart. But NASA can't do another test flight, because SLS sucks so hard, so instead they're going to fly Orion on an untested trajectory and trust their modeling to keep astronauts safe. Their same modeling which failed to predict Orion performance the first time. It's homicidally reckless. There is a real risk of this becoming yet another instance of NASA management's "go culture" getting people killed. Apollo 1, Challenger, Columbia, each time they say they've learned their lesson and will make changes to ensure it doesn't happen again, but either those changes are only superficial or they decay over time. We're now on the precipice of NASA management flying astronauts around the Moon with a heat shield which may quite possibly disintegrate during reentry, because SLS is too expensive for NASA to test it but NASA management wants to move forward anyway.

matthewdgreen 1y ago
We need to have a viable heavy rocket launch capability in the US at any given time, at very least just in case we detect an asteroid on a collision course. Right now that seems to fall entirely onto Falcon 9 (and Falcon Heavy), but the max payload weight even for Falcon Heavy seems much lower than the planned payload for SLS. Someday Starship may fix this, but we don't know if it will -- or if the final version will actually meet the planned specs.
- lupusreal 1y ago
  > We need to have a viable heavy rocket launch capability in the US at any given time Well we don't have that. SLS isn't it and never will be. The most SLS can be is a heavy lift rocket that can be used once every few years with a lot of upfront notice. Certainly not "launch capable" at "any given time".
  - matthewdgreen 1y ago
    I don’t think “at any given time” means we have an asteroid intercept mission sitting around on standby, although that’d be nice. I think it means “the capability exists and can be rushed to readiness over a series of weeks or months, at virtually unlimited cost.” Not sure that’s possible any other way. I would be fine with canceling SLS once good heavy lift alternatives are available, though.
SJC_Hacker 1y ago
> It doesn't work, not for Moon missions. It was never designed for Moon missions in the first place, the original plan was unspecified "deep space" missions without any clear plan of what it would actually be doing (because it's actual purpose is to keep money flowing to old Shuttle contractors.) Maybe I'm missing some details but I thought the entire purpose of first-stage rockets was to get a certain payload with certain max dimensions (what can fit inside a cylinder of a certain height and radius) to LEO, or the equivalent delta-V. At that point first stage is discarded anyway. So what exactly the payload is (beyond its dimensions) and you do with your payload after getting to LEO (or equiv delta V) that shouldn't really make a difference, and you can't blame the first stage (which SLS is) for that if it did its job. In the case of SLS, Block I can get 95 metric tons, Block I-B can get 105 tons and Block II 130 tons. The Falcon Heavy in comparison can only get max 64 tons to LEO, less if you want to recover boosters and the core to save money The real winner is the Saturn V which could get 140 tons to LEO. I know it was expensive per launch (about $1 billion in 2025 dollars) but given all the billions we've blown on trying to develop cheaper tech it seemed like we could have just stuck with what we know worked
- lupusreal 1y ago
  > "Maybe I'm missing some details but I thought the entire purpose of first-stage rockets was to get a certain payload with certain max dimensions (what can fit inside a cylinder of a certain height and radius) to LEO, or the equivalent delta-V. At that point first stage is discarded anyway. So what exactly the payload is (beyond its dimensions) and you do with your payload after getting to LEO (or equiv delta V) that shouldn't really make a difference," It makes a difference because if you're designing a rocket for a mission then you'll have a rocket that's as close to optimal for the mission, given mission requirements, timelines and budgets as you can reasonably get it. That's not SLS, the Moon mission wasn't planned when SLS was designed and instead SLS is optimized to reuse Shuttle hardware. Being stuck with a rocket that wasn't designed for the mission, as well as the political decision to use Orion, severely compromise the planning of Artemis. SLS lacks the power to get Orion into a proper lunar orbit, so instead they're going to use a highly elliptical NHRO lunar orbit with an orbital period of 7 days. This is extremely dangerous, it means that if there is any sort of emergency on the moon the astronauts may have to wait as long as a week to get back to Orion; which is probably a death sentence. It also means the lander has to be huge to make up for SLS's inadequacy, which means the Artemis program now relies on the success of Starship HLS and/or Blue Origin's HLS. This is going to delay Artemis and the entire reason this dependency exists is because Congress wanted a shuttle-derived rocket foremost, and then made the situation even worse by saddling it with their Boeing pork capsule. What it comes down to is SLS is a rocket that ""works"" but isn't actually good at anything and therefore never should have been built.

matthewdgreen 1y ago

We need to have a viable heavy rocket launch capability in the US at any given time, at very least just in case we detect an asteroid on a collision course. Right now that seems to fall entirely onto Falcon 9 (and Falcon Heavy), but the max payload weight even for Falcon Heavy seems much lower than the planned payload for SLS. Someday Starship may fix this, but we don't know if it will -- or if the final version will actually meet the planned specs.

lupusreal 1y ago
> We need to have a viable heavy rocket launch capability in the US at any given time Well we don't have that. SLS isn't it and never will be. The most SLS can be is a heavy lift rocket that can be used once every few years with a lot of upfront notice. Certainly not "launch capable" at "any given time".
- matthewdgreen 1y ago
  I don’t think “at any given time” means we have an asteroid intercept mission sitting around on standby, although that’d be nice. I think it means “the capability exists and can be rushed to readiness over a series of weeks or months, at virtually unlimited cost.” Not sure that’s possible any other way. I would be fine with canceling SLS once good heavy lift alternatives are available, though.

SJC_Hacker 1y ago

> It doesn't work, not for Moon missions. It was never designed for Moon missions in the first place, the original plan was unspecified "deep space" missions without any clear plan of what it would actually be doing (because it's actual purpose is to keep money flowing to old Shuttle contractors.) Maybe I'm missing some details but I thought the entire purpose of first-stage rockets was to get a certain payload with certain max dimensions (what can fit inside a cylinder of a certain height and radius) to LEO, or the equivalent delta-V. At that point first stage is discarded anyway. So what exactly the payload is (beyond its dimensions) and you do with your payload after getting to LEO (or equiv delta V) that shouldn't really make a difference, and you can't blame the first stage (which SLS is) for that if it did its job. In the case of SLS, Block I can get 95 metric tons, Block I-B can get 105 tons and Block II 130 tons. The Falcon Heavy in comparison can only get max 64 tons to LEO, less if you want to recover boosters and the core to save money The real winner is the Saturn V which could get 140 tons to LEO. I know it was expensive per launch (about $1 billion in 2025 dollars) but given all the billions we've blown on trying to develop cheaper tech it seemed like we could have just stuck with what we know worked

lupusreal 1y ago
> "Maybe I'm missing some details but I thought the entire purpose of first-stage rockets was to get a certain payload with certain max dimensions (what can fit inside a cylinder of a certain height and radius) to LEO, or the equivalent delta-V. At that point first stage is discarded anyway. So what exactly the payload is (beyond its dimensions) and you do with your payload after getting to LEO (or equiv delta V) that shouldn't really make a difference," It makes a difference because if you're designing a rocket for a mission then you'll have a rocket that's as close to optimal for the mission, given mission requirements, timelines and budgets as you can reasonably get it. That's not SLS, the Moon mission wasn't planned when SLS was designed and instead SLS is optimized to reuse Shuttle hardware. Being stuck with a rocket that wasn't designed for the mission, as well as the political decision to use Orion, severely compromise the planning of Artemis. SLS lacks the power to get Orion into a proper lunar orbit, so instead they're going to use a highly elliptical NHRO lunar orbit with an orbital period of 7 days. This is extremely dangerous, it means that if there is any sort of emergency on the moon the astronauts may have to wait as long as a week to get back to Orion; which is probably a death sentence. It also means the lander has to be huge to make up for SLS's inadequacy, which means the Artemis program now relies on the success of Starship HLS and/or Blue Origin's HLS. This is going to delay Artemis and the entire reason this dependency exists is because Congress wanted a shuttle-derived rocket foremost, and then made the situation even worse by saddling it with their Boeing pork capsule. What it comes down to is SLS is a rocket that ""works"" but isn't actually good at anything and therefore never should have been built.