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NASA's full Artemis plan revealed: 37 launches and a lunar outpost
JF Mezei wrote on Wed, 22 May 2019
15:21:39 -0400: On 2019-05-21 22:42, Fred J. McCall wrote: You're a bit confused. There are five LaGrange points, not just one. https://space.stackexchange.com/ques...ear-halo-orbit Thanks. I take it this L2's advantage is that it gets closer to the moon from time to time, giving opportunities to have less beefier transfer/landers? It's covered in the cite I gave. From a requirements perspective, would the actuial lander (without transfer) be required to be able to rejoin the Gateway at any altitude, or only when it makes a low pass (since we're talking direst ascent) You've asked this before and it's been answered before. Neither the Lander Element nor the Transfer Element could reasonably be required to "be able to rejoin the Gateway at any altitude". I wish to God you would learn even a little bit about orbital mechanics. Think about what you're asking. I'm missing something in your thought process here because the preceding doesn't make sense. The Gateway is going to make its fast and low north to south orbital segment around the Moon about every six days. I was thinking in terms of a static distance between Gateway and Moon. If it varies, then this changes things. You need to take notes or something. This has been explained to you several times. At some point it ought to stick, Mayfly. Regardless, the same thing applies if the Gateway is in a fixed lunar orbit. Once a Transfer Element has dropped a Lander Element it is pretty much free to return to Gateway, drop more Lander Elements, and eventually still be available for the first Lander Element to meet with it. There is no requirement for a Transfer Element to 'loiter' once it drops a Lander Element. does that because we want the Lander Element to spend roughly a month on the surface. So they refuel it, mate with a new Lander, and 6 days later (12 from the first Lander) it repeats and deploys a second Lander. Another 12 days later and it deploys a third Lander. This time instead of returning to the Gateway, it waits around. The first Lander is 24 days into its mission. Does this limit where the various landers can land in order to ensure a lander can rejoin a transfer vehicle that is in the orbit that dropped off another lander ? No. If the lander has to wait X time to take off so it can rejoin the transfer element in orbit, does that make it harder to time it so that once joined, they are in good position to ascend to Gateway? No. I can see why direst ascent makes sense since you don't have to wait for the right time to launc to transfer element. But now your Lander Element would need sufficient grunt to get from Lunar surface into the appropriate NRHO to meet the Gateway. And you still have to wait for the right time to Launch to Gateway. Or you don't do that at all (remember, we're talking about L2 here), which is why I said there was something like a 20% 'cargo penalty' Just wanted to make sure I understood correctly. 20% is pretty significant, isn't it ? In terms of going to Mars and beyond, with that Gateway's L2 orbit have any advantage over an L1 orbit ? Yes. Shuttle couldn't get to the Gateway orbit even if it was still flying. Come on, I saw a documentary (Airplaine II) where the Shuttle ended up crash landing on the moon and couldn't stop in time and hit the control tower with Captn Kirk in it :-) Mayfly, there are times when your output could lead someone to believe that the preceding paragraph is about the level of your thinking. I used the shuttle since we have experience with the main ISS resupply vehicle being grounded for a long time. Nope. Main ISS resupply was always Progress. If Gateway needs to be refueled once a year, how many rockets can bring sufficient fuel mass to an L2 orbit? Is it only SLS? Anything that can get mass to that orbit can do the job. Gateway will use ion engines that are pretty stingy insofar as fuel use goes. It doesn't take huge amounts of thrust to maintain an L2 NRHO. Go read the cite I gave again. So no, it is not only (or probably even mainly) SLS that will be doing that job. So if this thing gets built, doesn't it prevent SLS from ever being cancelled? Perhaps until Falcon Super Heavy, New Armstrong, or other vehicles are flying, but not for the reason you're concerned with above. Other than that you would need (and throw away) a much larger and more capable Descent Element because now it needs the 'grunt' to get from NRHO to LLO in addition to what it needs to get from LLO to the surface. So you have Gateway, designed to support multiple missions to the moon, right? And an architecture that allows re-use of the Transfer element, right? Gateway is INTENDED to support both Lunar missions and deep space missions. Other than that, essentially correct. But if the landers ditch the descent stage when they ascend, won't they have to ship a new descent stages for every weekend camping trip to the moon? Seems to me like more than one resupply mission per year to Gateway. Again you're confused. First, shipping vehicles for Lunar missions out to Gateway is not 'resupply' any more than boosting up a new module for ISS is 'resupply'. Second, there will be multiple types of landers and each may (probably will) require it's own unique Elements. And weren't you the guy proposing to just use LEM, which leaves its descent stage on the Moon? If this project is to support only one mission to Moon, is this Gateway thing not only a waste of money, but also not providing any advantage to the logistics? If cows can fly, shouldn't you carry an umbrella? That question is the same form as yours, above. Start with a false conditional premise ("cows can fly") and then ask a question that assumes the premise is true. In your case, the falsehood is "this project is to support only one mission to Moon". Since that premise is false, your question is moot. -- "Some people get lost in thought because it's such unfamiliar territory." --G. Behn |
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NASA’s full Artemis plan revealed: 37 launches and a lunar outpost
I have a continuing suggestion. Put a ground robot station
on the Moon's surface below L2. The robots could be made more fault tolerant there, while they construct ultra-light solar sails. I am talking about multi-Kilometer sized sails. At L2 there is a vertical climb from ground, no Moon circling. I believe that robots with a ground construction base frame would be able to recover from faults easier than free fall. Free-fall sail oscillations would not exist also. |
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NASA?s full Artemis plan revealed: 37 launches and a lunar outpost
JF Mezei wrote on Wed, 22 May 2019
15:36:18 -0400: On 2019-05-21 23:08, Fred J. McCall wrote: Except it doesn't work that way. Try to buy an Intel 80486 processor. You can't. And that will apply to almost every part in the LEM blueprints. Since they need hardened CPUs and RAM, they'll use whatever is available on the market (usually older vintage) or special order some. Yes, they will, which means all the avionics (including heat dissipation, which affects structure) will be a clean sheet design. I am not advocating they use the same computers as on the 1960s LEM. I even mentioned they could run this on an iPhone if they wanted it. What you were advocating was, as usual, unclear, then. But for structures, I have to wonder why they wouldn't re-use the general design of the LEM, as ugly as it was since it fit the purpose. Probably because they don't want the limitations of that design. Why do you think Blue Origin didn't just do that for their Blue Moon lander? Are they so much stupider and so much more inexperienced than you? Somehow I just don't think so. But all your parts are going to be from new vendors using new assembly lines. You're going to have to certify everything as if it was a brand new vehicle. Yes, but re-using a design you know has worked well saves you on the design stage. Not really, no. Whatever you build needs to interface with boosters in a standard way and be of a size to fit inside the payload fairing of whatever rockets you plan on using to get it out to Gateway. You'd like to use modern alloys to build the thing. It needs to provide power and heat dissipation for all the electronics you stuff in it. You'd like to use modern, more efficient engines that use propellants that you can make in situ out of water ice. I could go on. Now lets see how the old LEM stacks up. It's too physically large to fit inside the payload fairing of anything other than SLS or Falcon Super Heavy. It relies on a docking adapter that doesn't exist anymore. It's battery powered and only has power for a 75 hour duration. It's made largely out of, well, tissue paper. Atmosphere is pure oxygen at 5 PSI or so. It uses old hypergolic engines fueled by Aerozine 50 and using dinitrogen tetroxide as the oxidizer. See what a poor fit that is for what we actually want to do? When totally new, you have to certify the design will work and then certify the hardware as built meets the design. When re-using an ecxisting design, you only have to certify the new hardware fits the design. You've never actually been exposed to engineering, have you? -- "Ignorance is preferable to error, and he is less remote from the truth who believes nothing than he who believes what is wrong." -- Thomas Jefferson |
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NASA's full Artemis plan revealed: 37 launches and a lunar outpost
JF Mezei wrote on Wed, 22 May 2019
16:34:48 -0400: On 2019-05-22 16:02, Fred J. McCall wrote: It's covered in the cite I gave. You explain the orbit, I asked if the orbit having periods where it is close to moon was the main advantage or if there are others. No, I didn't. I provided a cite which explained what an NRHO is and what the advantages are. Did you read all the papers it linked to? Did you understand it all? You've asked this before and it's been answered before. Neither the Lander Element nor the Transfer Element could reasonably be required to "be able to rejoin the Gateway at any altitude". I originally asked in a context where I thought Gateway would be in a lunar orbit. So I asked again, now that I know it is in L2 location. And when you originally asked I described the orbit (so you should have known what it was by now) and why your 'desirement' was not feasible or reasonable. Mayfly, is your long term memory defective or do you just not bother to read and understand the answers when you ask questions? be available for the first Lander Element to meet with it. There is no requirement for a Transfer Element to 'loiter' once it drops a Lander Element. Didn't you mention the transfer would have to wait for Gatway to again be close which happens every 6 days ? It doesn't have to 'loiter' WAITING FOR THE ASCENT ELEMENT TO COME BACK UP, YOU NINNY! Anything that can get mass to that orbit can do the job. Gateway will use ion engines that are pretty stingy insofar as fuel use goes. But Gateway will still need to be refueled so that it can refuel trasnfer element and landers, right? Right. And the long term goal is for that fuel to be produced on the Moon, not on Earth. The whole point of Gateway is a refueling station, isn't it? No. And weren't you the guy proposing to just use LEM, which leaves its descent stage on the Moon? Yes. I propose this in the context of a 2024 deadline where NASA is unable to deliver anything new in such time frames. Wrong. Landers and such will be commercial, not 'NASA delivered'. Blue Origin, for example, says that their Blue Moon lander can be ready for use by 2024. And in a context that this is a political one-off mission not some long term endeavour. Wrong. Pull your head out of your TDS asshole. ("cows can fly") and then ask a question that assumes the premise is true. In your case, the falsehood is "this project is to support only one mission to Moon". Since that premise is false, your question is moot. I asmed about missions to Mars. Does this Gateway provide any advantage. Yes, if you buy into NASA's architecture for this sort of thing. I answered that already. For Moon, I gave see resupply dicking when Grateway is "high", and Gateway launching landers to Moon when it is low. But for missions to Mars, is there any Advantage? Asked and answered. REPEATEDLY. The answer hasn't changed. Write it the **** own and stop asking. Also, assuming Gateway is to be built is wrong. With a goal of landing on Moon in 2024, all efforts will be amde to make it happen once. Only after, if funds aren't pulled, would they start thinking about a Gateway thing to support multiple missions. Again, pull your head out of your TDS ass. Your preceding paragraph is bull****. NASA has put forward a plan. You claim to have looked at it. It involves Gateway. -- "Ignorance is preferable to error, and he is less remote from the truth who believes nothing than he who believes what is wrong." -- Thomas Jefferson |
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NASA's full Artemis plan revealed: 37 launches and a lunar outpost
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NASA?s full Artemis plan revealed: 37 launches and a lunar outpost
On Thursday, May 23, 2019 at 12:11:18 AM UTC-4, Fred J. McCall wrote:
Now lets see how the old LEM stacks up. It's too physically large to fit inside the payload fairing of anything other than SLS or Falcon Super Heavy. It relies on a docking adapter that doesn't exist anymore. It's battery powered and only has power for a 75 hour duration. What is proposed for longer stays ... an APU, solar arrays? It's made largely out of, well, tissue paper. Atmosphere is pure oxygen at 5 PSI or so. It uses old hypergolic engines fueled by Aerozine 50 and using dinitrogen tetroxide as the oxidizer. The main advantage being non-cryogenic. What fuel and oxidizer would be superior for a LEM today? |
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NASA's full Artemis plan revealed: 37 launches and a lunar outpost
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NASA?s full Artemis plan revealed: 37 launches and a lunar outpost
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NASA?s full Artemis plan revealed: 37 launches and a lunar outpost
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