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> NASA built a working engine in the 70s. Kind of. No NTR has ever been flown and tested in space. The program achieved many milestones and got pretty far into

• XorNot 2y ago
  > The real lunacy is simply not being mission-driven. Okay but why does the mission exist? People keep going "the mission is go to to the moon". Is it? Why are we doing that? How much do the "proven technologies" cost? Are they reusable? The answer of course, is that the mission is not "go to the moon". It's "go to the moon and establish permanent, long term scientific research operations with a view to using that experience to send crewed missions to Mars and other deep-space destinations". And in that box then, one might look at how the long term storage and handling of hydrazine has worked out in enclosed environments on Earth - like submarines as torpedo propellant - and concluded that the longer and more frequently you use it, the more likely you get to a vehicle loss due to the intrinsic hazards.
  • qayxc 2y ago
    > Okay but why does the mission exist? Politics. > People keep going "the mission is go to to the moon". Is it? Why are we doing that? Again, politics. The US has to assert dominance in space and cannot allow parties like China to one-up them. It's also a great way for political leadership to score points with the public. A more rational approach for establishing a permanent human presence on the moon would have included a thorough requirement analysis like Apollo did. Just FYI, SpaceX to this day (i.e. less than 12 months before the initially planned first landing!) don't even known how many tanker launches are required... > How much do the "proven technologies" cost? Less than developing a set of radically new systems from scratch - if done correctly (i.e. no cost-plus contracts). Some ideas, just for pondering: * Falcon 9 is a reliable, proven, and partly reusable system. Its capabilities are sufficient to put crew and cargo into LEO * FH is a proven and partly reusable system. Its capabilities are sufficient even for Lunar missions. * Designing a mission around these existing capabilities would eliminate the risk of developing two completely new rockets (SLS and Super Heavy/"Starship") while allowing for testing vital equipment basically from day one (i.e. autonomous docking with fuel tanks, long term fuel storage in orbit, etc.) > Are they reusable? There's no reason why a moon lander and transfer vehicles shouldn't be reusable. This is not a question of the engines or fuel used. Just a side note: the "Lunar Starship" isn't going to be reused either on its first missions. This is a medium to long term goal that hinges on quite a few factors (like the feasibility of long-term cryogenic storage in space). > one might look at how the long term storage and handling of hydrazine has worked out in enclosed environments on Earth First of all, the environments are not the same - i.e. no unprotected humans will ever be around the fuel tanks or perform hazardous activities like smoking near them or operate valves. Secondly, in stark contrast to cryogenic fuels, we actually do have plenty of data points for long term use and storage of non-cryogenic fuels in space. Most satellites used hydrazine or its derivatives for station keeping and manoeuvring in deep space missions for decades. This is nothing new whatsoever. On the other hand no one has ever successfully performed a vehicle to vehicle fuel transfer in space, let alone cryogenic fuel or long term storage of said fuels in space. This is new territory that doesn't even have all of its physics fully understood.
    • XorNot 2y ago
      > Politics. You're saying "we need to be mission focused". If the mission is "politics", then hey, you're right - turn on the money faucet we're doing Apollo again. Developing new technology, doing science, whatever - all not actually happening. Of course...if it's not politics, then maybe the new technology is the point? That a mission where you don't fundamentally improve how you're doing it would in fact be the only waste of money, because it's just the same pointless thing all over again.
      • qayxc 2y ago
        When I say mission, I specifically mean the mission in the form of Artemis, not a permanent human presence on the Moon. The latter doesn't require three brand new rocket systems, especially not a Shuttle derived one. SLS was created to keep job in the states that had STS facilities and needed Shuttle tech to justify their continued existence. SpaceX HLS was just as questionable. Competitors presented realistic timelines and budgets, while a single person at NASA on her own decided to exploit the power vacuum after an administration change to award the only contract to SpaceX only to be hired by them shortly after. The mission is not to develop a rocket that can deploy StarLink 2.0 satellites or supposedly take people to Mars. The mission is also NOT to keep engineers who worked on Shuttle employed. That's the issue and that's the problem with Artemis. As far as new technology is concerned - you focus on tech required for the mission: new and more capable space suits (in the works), a more capable vehicle (Orion), reliable long term power delivery (NASA's KiloPower reactors), a logistics hub (Lunar gateway), communication systems (relay satellites), new surface capabilities (contract signed with JAXA), etc. If you really want to achieve a goal, like giving NASA some new focus and establish a permanent presence on the Moon, you take the lessons from the past and improve upon them. A shoestring budget, a needlessly expensive new launch system that only exists to keep jobs and reliance on high risk new technologies without proper justification aren't it.
• nordsieck 2y ago
  > The real lunacy is simply not being mission-driven. A true mission driven design would have used a simple, reliable option using proven and existing technology. Like non-cryogenic fuel for example. Are you talking about the lander? Because IMO, the lander it the least objectionable part of the whole thing. Congress, in their infinite wisdom, decided that the lander budget would be $3 B - about 1 year's worth of development costs of Orion + SLS, systems which have been in development for over a decade. The moon rover got more money than that. Any system that's going to squeeze into that constraint is going to need to be economically optimized and a bit... creative.
  • qayxc 2y ago
    > Are you talking about the lander? I'm talking about the entirety of Artemis. SLS was basically a job-saving programme initiated by Congress to appease senators that feared job losses in their respective states after the Shuttle programme was axed. Alternative designs that would use fuel storage in space and space tugs could've worked without an expensive new rocket. > IMO, the lander it the least objectionable part of the whole thing Then we have a disagreement :) The HLS requires the following in order work: * the development of a rapidly reusable, radically new rocket system with new engines that haven't been flight tested before; alternative options could've used existing systems * development of long term in-orbit cryogenic fuel storage - something that has never been tried before * development of safe and reliable cryogenic fuel transfer between vehicles in orbit - again, a capability that has never been demonstrated before * a lander with a single point of failure for exiting/entering the vehicle (on account of its ridiculous height) * a lander that relies on turbo-pump driven bi-propellant engines for ascend - something so risky that Apollo-era engineers didn't even consider it * a lander with a mass of around 100 tons for 2 crew initially - horrible weight to payload ratio, as this mass has to be launched from the surface * several (actual number unknown as of now, but certainly more than 4) required refuelling launches In conclusion we have 4 mission critical technologies that have never been demonstrated before, yet need to work flawlessly. We also have added risk due to the use of turbo-pump driven bi-propellant cryogenic fuel and the requirement of a 30+ metre crane for accessing the vehicle. I cannot comment on the stability during landing and ascend or the risks involved with dust and rocks from the exhaust plume on the moon. As far as the economics go, yeah, I agree that with such tight budget a mission like that is very challenging to say the least. Low-balling the cost, exaggerating the timeline and hiring the person who on her own decided to hand out the contract throws a bad light on the issue, though.