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The Lunacy of Artemis

idlewords.com

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Re: The Lunacy of Artemis

#101

Post by idlewords »

dotnet00 wrote: post #100
pclmulqdq wrote: post #95

Earlier quoted context omitted.

"Demonstrated" is a strong word given what we all saw. I'm not sure there has been any document released that they actually proved that they successfully did a propellant transfer.

Last month NASA stated at a meeting that SpaceX had successful propellant transfer: https://spacenews.com/spacex-making-progress-on-starship-in-... "On Flight 3, they did an intertank transfer of cryogens, which was successful by all accounts," It has admittedly been a weirdly quiet confirmation though, coming from a NASA official rather than from the usual sources (Elon/Gwynne/SpaceX official X).

NASA always adds the caveat that analysis of the data is still ongoing. Something weird is going on with that demo.

Re: The Lunacy of Artemis

#102

Post by XorNot »

qayxc wrote: post #41
fallingknife wrote: post #3

The real lunacy is using chemical rockets instead of nuclear thermal once the ship is in orbit. That could reduce the fuel requirements for an Earth - Moon transfer by 4x. And this isn't some sci-fi tech. NASA built a working engine in the 70s.

> 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 development, but was cancelled 50 years ago due to budget constraints. It's always the last 10% that are the hardest in engineering and while NASA (as well as the Soviet Union) got 90% there, it would still have taken a few years (maybe just two) of further de…

> 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.

Re: The Lunacy of Artemis

#103

Post by carapace »

hi_hi wrote: post #78

Out of interest, what do people think is going to happen once humans can semi-reliably get to the moon? I don't often see this part talked about. I read lots about the astronomical (thank you!) cost and effort of getting there, often framed in a way that makes the whole endeavour appear pointless and dumb. Will they just potter about for a few days, grab a handful of rocks, take some jaunty selfies, have a cup of tea…

Fly.

On Luna a human being can fly. You need wings and a large air-filled cave and then you can fly like a bird.

https://en.wikipedia.org/wiki/The_Menace_from_Earth

That alone would surely be worth the price of admission?

Also, it's the gateway to the rest of the Solar system, galaxy, and Universe.

Re: The Lunacy of Artemis

#104

Post by iamthirsty »

dotancohen wrote: post #50
idlewords wrote: post #34

Earlier quoted context omitted.

Note that the first reason you give is tautological.

Possibly, but it's not unique to SLS. People were jesting twenty years ago about the purpose of the Space Shuttle being just a vehicle to get to and from the ISS. And the purpose of the ISS? So that the Space Shuttle would have somewhere to go.

> And the purpose of the ISS? So that the Space Shuttle would have somewhere to go.

I don’t think this is accurate. ISS was conceived almost 10 years after the Shuttle started launching, and the U.S. obviously had space station ambitions even before the Shuttle was on the drawing board (Skylab).

Additionally the Soviets did the exact same, with Mir being launched prior to the Buran’s first test flight — heck Salyut 1 was launched in 1971.

Re: The Lunacy of Artemis

#105

Post by idlewords »

iamthirsty wrote: post #104
dotancohen wrote: post #50

Earlier quoted context omitted.

Possibly, but it's not unique to SLS. People were jesting twenty years ago about the purpose of the Space Shuttle being just a vehicle to get to and from the ISS. And the purpose of the ISS? So that the Space Shuttle would have somewhere to go.

> And the purpose of the ISS? So that the Space Shuttle would have somewhere to go. I don’t think this is accurate. ISS was conceived almost 10 years after the Shuttle started launching, and the U.S. obviously had space station ambitions even before the Shuttle was on the drawing board (Skylab). Additionally the Soviets did the exact same, with Mir being launched prior to the Buran’s first test flight — heck Salyut 1…

It's true for the post-Challenger Shuttle, which really didn't have a credible job to perform except for ISS assembly.

Re: The Lunacy of Artemis

#106

Post by jessriedel »

idlewords wrote: post #77
jessriedel wrote: post #74

Earlier quoted context omitted.

The cryogenic aspect seems much more distinct than whether it's rocket-to-rocket or rocket-to-ISS.

No, they're both pretty significant. In the ISS case you have propellant mass moving around that's just a tiny fraction of the total system mass, while in the rocket case a sizable portion of the total mass gets shifted. Moreover, in refueling ISS you can use something like a flexible bladder and pressure differential to simplify the job of moving liquid from container A into container B. But in the rocket-to-rocket…

The lack of bladder seems directly driven by the cryogenic temp. Whats stopping you from using large (or many) bladders for warm fuels?

I don’t see the hard problem of “hunting” for fuel in a rigid container. Yes you need ullage, but how is this worse than what you need typically to feed an engine?

Re: The Lunacy of Artemis

#107

Post by idlewords »

bnralt wrote: post #82

> What NASA is doing is like an office worker blowing half their salary on lottery tickets while putting the other half in a pension fund. If the lottery money comes through, then there was really no need for the pension fund. But without the lottery win, there’s not enough money in the pension account to retire on. The two strategies don't make sense together. I don't think this analogy works, and it reflects a bigg…

Personally, I agree with you that the whole program is useless. The point I'm trying to make with this analogy is that the effort is internally incoherent even if you grant the premise that moon landings and building Gateway are desirable outcomes.

Re: The Lunacy of Artemis

#108

Post by Tao3300 »

pengaru wrote: post #86
Tao3300 wrote: post #31

Earlier quoted context omitted.

Yeah, I watched it. I can hear it both ways. I don't know his mind or lack thereof, only that he hasn't necessarily spoken wrongly in that phrase I could see governmental types having a colloquial use of the word at times like these that doesn't mean "it's always in the literal absence of light".

> Yeah, I watched it. I can hear it both ways. I don't know his mind or lack thereof, only that he hasn't necessarily spoken wrongly in that phrase What line do I have to stand in to receive some of your overflowing charity?

I had a really good breakfast today.

Re: The Lunacy of Artemis

#109

Post by grecy »

xt00 wrote: post #15

I think we all can understand the situation here unless people are really dense.. the Artemis program was setup at a time when the private space companies were still very new. SpaceX will soon be quite close to technically doing the entire mission themselves without Artemis at all. SpaceX took the money from NASA to help fund their Starship development and probably for other reasons as well. Net result is that by the…

You are confusing the issue here.

Imagine a world where Space X does not exist - never did.

Even still, Artemis is a terribly designed rocket that costs gobs more than Saturn V and performs much less.

Would you be happy buying something today that costs more than it did in 1970 and performs worse?

It doesn't matter what else is going on in the world, Artemis is shit.

Re: The Lunacy of Artemis

#110

Post by idlewords »

jessriedel wrote: post #106
idlewords wrote: post #77

Earlier quoted context omitted.

No, they're both pretty significant. In the ISS case you have propellant mass moving around that's just a tiny fraction of the total system mass, while in the rocket case a sizable portion of the total mass gets shifted. Moreover, in refueling ISS you can use something like a flexible bladder and pressure differential to simplify the job of moving liquid from container A into container B. But in the rocket-to-rocket…

The lack of bladder seems directly driven by the cryogenic temp. Whats stopping you from using large (or many) bladders for warm fuels? I don’t see the hard problem of “hunting” for fuel in a rigid container. Yes you need ullage, but how is this worse than what you need typically to feed an engine?

I'll defer to people who know more about rocket design about why you couldn't have a huge stretchy bladder holding RP-1 (for example) in a rocket stage.

The problem with hunting is that a liquid/gas system forms a bunch of weird intermixed 3D blobs in microgravity. You either need to accelerate the docked rockets (so the liquids pool at one end) or you need some apparatus to separate liquid and gas in microgravity. Both are hard to do.

Engines never have to worry about the microgravity case, there are always ullage motors or some other mechanism to accelerate the rocket before engine ignition so that fluid and gas separate.

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