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That is a very narrow-minded viewpoint I think. There is currently no comparable rocket system comparable to SLS even with all its warts. If it flies today, it'

That is a very narrow-minded viewpoint I think. There is currently no comparable rocket system comparable to SLS even with all its warts. If it flies today, it's the only operational Human rated heavy lift system. Starship is promising, but still a lot more speculative. Using the shuttle systems reduces the engineering risks. This means that SLS may be more expensive than something scratch-designed, but there is also a lot less insecurity in the schedule (though there was enough ...). I don't think there was a way for NASA to start the Artemis program sooner than with SLS. I don't think it's a good idea to entirely depend on SpaceX for heavy lift rockets or human rated space flight. I also don't understand your point about Orion not being able to go to the moon. Of course it "could" get as close to the moon as it wants. But it is basically a command and reentry module, not a lander. There are more potential missions for the Orion than for a combined lander and reentry module. So you'd have some kind of rendezvous in any case which also saves fuel.

panick21_ 4y ago
SLS was never needed for a moon program. I don't knew where people get this idea. You can use commercial rockets to go to LEO and stage of from there. I don't know why this is hard to understand. NASA knew this in 2011. > I don't think it's a good idea to entirely depend on SpaceX for heavy lift rockets or human rated space flight. They wouldn't have to. You have Crew Dragon and Starliner, both have potentially multiple rockets they could go on. > I also don't understand your point about Orion not being able to go to the moon. The point is that the Orion Service Module developed by ESA is seriously under-powered and NASA has to design around those constraints (and btw its an additional cost of SLS/Orion as this is paid for by NASA not ESA). Orion can't go into LLO and back.
deleted 4y ago
[deleted]
adastra22 4y ago
> There is currently no comparable rocket system comparable to SLS even with all its warts. If it flies today, it's the only operational Human rated heavy lift system. Starship is promising, but still a lot more speculative. It's human-rated only because NASA says it is. It has literally never flown. The NASA rules for human-rating its own internal-designed craft are way looser than the rules for human-rating commercial craft. SpaceX and Boeing had to jump through way more hoops to get their platforms human-rated by NASA. Artemis could just as easily be done by launching Orion + service module, and upper stage to LEO on separate Falcon Heavy launches, then launching crew on Dragon or Starliner. No starship required. It would be 3 launches, but with autonomous LEO rendezvous there would be no risk to the crew, for about 1/10th the cost (or alternatively, 5 missions a year instead of 1 every 2 years). This, btw, was NASA's plan before congress mandated the use of SLS! > Using the shuttle systems reduces the engineering risks. The extensive changes made for SLS and the fact that ~none of the original engineers were involved invalidates all that heritage. Or at least it would if NASA held the SLS program to the same standards as commercial industry. > This means that SLS may be more expensive than something scratch-designed, but there is also a lot less insecurity in the schedule (though there was enough ...). SLS has had more budget and timeline overruns than anything else out there. Even SpaceX's famously optimistic "Elon time" is not as bad as SLS's delays. > I don't think there was a way for NASA to start the Artemis program sooner than with SLS. Again, this was the plan before congress got in the way. I remember it vividly as I worked at NASA at the time. > I don't think it's a good idea to entirely depend on SpaceX for heavy lift rockets or human rated space flight. ULA would be happy to develop a super-heavy Vulcan. Or Rocket Lab. Or Relativity. etc. Do the same as COTS: fully fund two providers, and if one drops out then fund a 3rd. > I also don't understand your point about Orion not being able to go to the moon. Orion has insufficient fuel to enter circular LLO (like Apollo) and still get home. It's too heavy and under-powered compared with the Apollo Command and Service Modules.
- kiratp 4y ago
  > The NASA rules for human-rating its own internal-designed craft are way looser than the rules for human-rating commercial craft. SpaceX and Boeing had to jump through way more hoops to get their platforms human-rated by NASA. Can you share a couple of examples of this? Curious...
  - adastra22 4y ago
    The most obvious and glaring example is odds of loss of crew. NASA mandated that SpaceX and Boeing achieve an odds of loss-of-crew no higher than 1-in-270. Except no launch system in the history of NASA has ever had odds these good. The best was the Shuttle with on-paper odds of 1-in-100, but with two failures in 135 flown missions the actual odds were 1-in-67. The Apollo program lost one crew on Apollo 1, and very nearly lost Apollo 13. Gemini 8 also very nearly ended in loss of crew. 1-in-270 is an insanely high bar! I cannot find numbers for SLS, but I also cannot believe that it would be as good as SLS uses a fundamentally less safe rocket design than Falcon 9 or Atlas V. Which is actually a rather on-point observation: NASA human-rating certification is a lot of do-as-I-say,not-as-I-do hypocrisy. The commercial crew contractors had to actually demonstrate safety. NASA, on the other hand, asked Boeing, the prime contractor, to estimate odds of failure for various subsystems of SLS. Boeing wrote many reports explaining in detail why the odds of failure were within acceptable limits. NASA read these documents and said "okay, I believe you." And that is why the SLS is human-rated. This Quora answer does a decently good job of explaining the absurdity of the situation: https://www.quora.com/Why-will-SLS-be-man-rated-after-a-single-flight-whereas-SpaceX-and-ULA-had-to-go-through-so-many-qualifying-rocket-and-capsule-tests-It-doesnt-make-sense https://www.quora.com/Why-will-SLS-be-man-rated-after-a-sing... But also, let me introduce you to the magical concept of a 'waiver'. NASA has very strict rules for what are allowable risks in human spaceflight. If anything exceeds acceptable risk tolerances, the countdown stops or the mission aborts. UNLESS, you can get a 'waiver.' A waiver is a piece of paper that says NASA is free to ignore the identified problem! Cold Florida mornings leads to ice build up on the Shuttle overnight? Waiver! No need to wait until external temperatures are back within design limits. Foam insulation strike on the leading edge of the wing? Waiver! No need to image the impact point with ground-based radar. NASA, quite famously, gives out wavers like candy for its own launch systems. When I was at NASA (admittedly not on the human spaceflight side), whenever we encountered a problem the first question was always "alright, can we get a waiver?" The answer was usually yes for things in-house. But a commercial spaceflight provider? Good luck convincing NASA to give you a waiver for anything that isn't well and truly, quite obviously a procedural hiccup only.

panick21_ 4y ago

SLS was never needed for a moon program. I don't knew where people get this idea. You can use commercial rockets to go to LEO and stage of from there. I don't know why this is hard to understand. NASA knew this in 2011. > I don't think it's a good idea to entirely depend on SpaceX for heavy lift rockets or human rated space flight. They wouldn't have to. You have Crew Dragon and Starliner, both have potentially multiple rockets they could go on. > I also don't understand your point about Orion not being able to go to the moon. The point is that the Orion Service Module developed by ESA is seriously under-powered and NASA has to design around those constraints (and btw its an additional cost of SLS/Orion as this is paid for by NASA not ESA). Orion can't go into LLO and back.

deleted 4y ago

[deleted]

adastra22 4y ago

> There is currently no comparable rocket system comparable to SLS even with all its warts. If it flies today, it's the only operational Human rated heavy lift system. Starship is promising, but still a lot more speculative. It's human-rated only because NASA says it is. It has literally never flown. The NASA rules for human-rating its own internal-designed craft are way looser than the rules for human-rating commercial craft. SpaceX and Boeing had to jump through way more hoops to get their platforms human-rated by NASA. Artemis could just as easily be done by launching Orion + service module, and upper stage to LEO on separate Falcon Heavy launches, then launching crew on Dragon or Starliner. No starship required. It would be 3 launches, but with autonomous LEO rendezvous there would be no risk to the crew, for about 1/10th the cost (or alternatively, 5 missions a year instead of 1 every 2 years). This, btw, was NASA's plan before congress mandated the use of SLS! > Using the shuttle systems reduces the engineering risks. The extensive changes made for SLS and the fact that ~none of the original engineers were involved invalidates all that heritage. Or at least it would if NASA held the SLS program to the same standards as commercial industry. > This means that SLS may be more expensive than something scratch-designed, but there is also a lot less insecurity in the schedule (though there was enough ...). SLS has had more budget and timeline overruns than anything else out there. Even SpaceX's famously optimistic "Elon time" is not as bad as SLS's delays. > I don't think there was a way for NASA to start the Artemis program sooner than with SLS. Again, this was the plan before congress got in the way. I remember it vividly as I worked at NASA at the time. > I don't think it's a good idea to entirely depend on SpaceX for heavy lift rockets or human rated space flight. ULA would be happy to develop a super-heavy Vulcan. Or Rocket Lab. Or Relativity. etc. Do the same as COTS: fully fund two providers, and if one drops out then fund a 3rd. > I also don't understand your point about Orion not being able to go to the moon. Orion has insufficient fuel to enter circular LLO (like Apollo) and still get home. It's too heavy and under-powered compared with the Apollo Command and Service Modules.

kiratp 4y ago
> The NASA rules for human-rating its own internal-designed craft are way looser than the rules for human-rating commercial craft. SpaceX and Boeing had to jump through way more hoops to get their platforms human-rated by NASA. Can you share a couple of examples of this? Curious...
- adastra22 4y ago
  The most obvious and glaring example is odds of loss of crew. NASA mandated that SpaceX and Boeing achieve an odds of loss-of-crew no higher than 1-in-270. Except no launch system in the history of NASA has ever had odds these good. The best was the Shuttle with on-paper odds of 1-in-100, but with two failures in 135 flown missions the actual odds were 1-in-67. The Apollo program lost one crew on Apollo 1, and very nearly lost Apollo 13. Gemini 8 also very nearly ended in loss of crew. 1-in-270 is an insanely high bar! I cannot find numbers for SLS, but I also cannot believe that it would be as good as SLS uses a fundamentally less safe rocket design than Falcon 9 or Atlas V. Which is actually a rather on-point observation: NASA human-rating certification is a lot of do-as-I-say,not-as-I-do hypocrisy. The commercial crew contractors had to actually demonstrate safety. NASA, on the other hand, asked Boeing, the prime contractor, to estimate odds of failure for various subsystems of SLS. Boeing wrote many reports explaining in detail why the odds of failure were within acceptable limits. NASA read these documents and said "okay, I believe you." And that is why the SLS is human-rated. This Quora answer does a decently good job of explaining the absurdity of the situation: https://www.quora.com/Why-will-SLS-be-man-rated-after-a-single-flight-whereas-SpaceX-and-ULA-had-to-go-through-so-many-qualifying-rocket-and-capsule-tests-It-doesnt-make-sense https://www.quora.com/Why-will-SLS-be-man-rated-after-a-sing... But also, let me introduce you to the magical concept of a 'waiver'. NASA has very strict rules for what are allowable risks in human spaceflight. If anything exceeds acceptable risk tolerances, the countdown stops or the mission aborts. UNLESS, you can get a 'waiver.' A waiver is a piece of paper that says NASA is free to ignore the identified problem! Cold Florida mornings leads to ice build up on the Shuttle overnight? Waiver! No need to wait until external temperatures are back within design limits. Foam insulation strike on the leading edge of the wing? Waiver! No need to image the impact point with ground-based radar. NASA, quite famously, gives out wavers like candy for its own launch systems. When I was at NASA (admittedly not on the human spaceflight side), whenever we encountered a problem the first question was always "alright, can we get a waiver?" The answer was usually yes for things in-house. But a commercial spaceflight provider? Good luck convincing NASA to give you a waiver for anything that isn't well and truly, quite obviously a procedural hiccup only.