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#12
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In article , Rupert
Goodwins wrote: If I wanted to actually *plan* to steal it, then it would be very easy to make a small fake to leave in its place; I doubted that anyone would notice for a very long time. Certainly the most recent thief didn't notice. If you see a 'Moon rock' advertised on e-bay that looks exactly like a broken shard of a coffee mug, you know where it came from. -- David M. Palmer (formerly @clark.net, @ematic.com) |
#13
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Hi All,
I was just wondering, we have a 10~20 gram stone worth 5 million. Surely someone could design a robot to go to the moon and pick up 20 kilo of rock (pebbles, dirt, etc. it probably wouldn't matter). Assuming that the value of the rocks would decrease in value as much as 90% due to the fact that they would be on the open market, 20 kilo of rocks could be worth as much as 500 million dollars. One should be able to build and launch a probe for that much. Terry "Robert Pearlman" wrote in message om... LooseChanj wrote in message news: Where in the world did they get the "$5 million" figure from? $5 million was the asking price by a Miami businessman whose Honduran moon rock was allegedly smuggled into the U.S. and was subsequently confiscated when he tried to sell it to undercover agents: http://www.collectspace.com/news/news-062902a.html -- Robert Pearlman, Editor collectSPACE - The Source for Space History & Artifacts http://www.collectspace.com/ |
#15
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![]() Terry Goodrich wrote: I was just wondering, we have a 10~20 gram stone worth 5 million. Surely someone could design a robot to go to the moon and pick up 20 kilo of rock (pebbles, dirt, etc. it probably wouldn't matter). Assuming that the value of the rocks would decrease in value as much as 90% due to the fact that they would be on the open market, 20 kilo of rocks could be worth as much as 500 million dollars. One should be able to build and launch a probe for that much. I now have a sneaking suspicion about that Chinese lunar sample return mission.... :-) Pat |
#16
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In article ,
Terry Goodrich wrote: Let's see, a Soyuz booster around $30 million or so... The old Luna sample-return missions maxed out the Proton -- in fact, they needed Proton performance enhancements and reduction of safety margins -- to return a few hundred grams of sample. Yeah, the hardware was pretty crude stuff and we could do better, but it's a demanding mission, and trying to squeeze maximum payload out of a mass-limited system will get expensive fast. This leaves the descent and ascent module along with recovery systems and guidance system, which I have no clue on cost. They are, alas, the key systems. It's a propulsion-intensive mission, and needs precision guidance en route and for landing, and at least a minimum of guidance for the return trip. Hmm, 20kg payload. Perhaps: 5kg of packaging, 10kg heatshield, 5kg parachutes, 5kg main structure, 5kg misc. subsystems. That's 50kg at reentry. 5kg of electronics, 5kg midcourse maneuvering, 5kg power and misc. gives 65kg payload for the ascent stage. 5kg engines, 5kg controls, 5kg tanks and general structure, with the payload handling guidance, gives 80kg dry mass for a pretty light ascent stage. Assuming unimpressive pressure-fed propulsion, mass ratio is going to be 3 or so, giving lunar liftoff mass of 250kg. 25kg of cameras and sample handling etc., 25kg engines, 10kg controls, 50kg tanks and general structure (including structural bracing for the ascent stage so it can be lightweight), 15kg of landing guidance sensors, 25kg RCS and maneuvering, 25kg power and misc. subsystems, 25kg legs and shock absorbers, gives a landed mass without main propellants of 450kg. Surveyor landed about 30% of its launch mass. With similar descent propulsion performance, we need 1500kg at post-TLI separation. Add 100kg for general margin, and we are right at the limit of what a Molniya (Soyuz with an injection stage) can inject to a lunar trajectory. Almost all of those numbers are wild guesses. Some of them I think I could beat. But there are probably things I've forgotten, and I might also have been optimistic here and there. At this by-guess-and-by-golly level, 100kg margin out of 1600kg is uncomfortably small. I'd say we're marginal here for a Molniya launch; it could easily need something bigger. How much all this will cost is unclear. Not very much of the hardware is available off the shelf. Much will depend on how confident you want to be that the first one will work. Surveyor (less ambitious mission, but also using a lower technological base) cost maybe $3G in today's dollars, and that is the sort of number you'd be looking at for business-as-usual development with a reasonable chance of first-attempt success. What could be done with a leaner development philosophy... is unclear. The cheap-satellite community hasn't done landers or major propulsion much, so we lack calibration data. Moreover, for something this novel, there's going to be a considerable debugging period. That is to say, with a low-cost approach, the first few attempts probably won't work. Wild guess, assuming sweet-talking the Russians into a steep discount for a bulk buy of Molniya launches, *and* assuming it doesn't threaten too badly to outgrow Molniya, *AND* assuming upper management that will bite its lip and keep quiet when attempt after attempt fails, $250-300M gets you ten attempts of which two or three should be full successes. -- MOST launched 30 June; science observations running | Henry Spencer since Oct; first surprises seen; papers pending. | |
#17
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![]() Henry Spencer wrote: They are, alas, the key systems. It's a propulsion-intensive mission, and needs precision guidance en route and for landing, and at least a minimum of guidance for the return trip. Hmm, 20kg payload. Perhaps: 5kg of packaging, 10kg heatshield, 5kg parachutes, 5kg main structure, 5kg misc. subsystems. That's 50kg at reentry. 5kg of electronics, 5kg midcourse maneuvering, 5kg power and misc. gives 65kg payload for the ascent stage. 5kg engines, 5kg controls, 5kg tanks and general structure, with the payload handling guidance, gives 80kg dry mass for a pretty light ascent stage. Assuming unimpressive pressure-fed propulsion, mass ratio is going to be 3 or so, giving lunar liftoff mass of 250kg. The Soviet sample return missions had no midcourse correction ability; the return stage was launched toward the zenith of the Lunar heavens over where the lander was positioned, and gravity did all the rest to get it back to mother Russia. The landing sites had to be precise to allow this to work, and in fact a specific launch time from Earth meant a specific landing site on the Moon- badly limiting the areas that could be sampled. The ascent stage carried just gyro stabilization systems that kept its ascent vertical and accelerometers to permit motor shutdown at the correct velocity for its return trip Earthwards. I think this gets discussed in "Challenge To Apollo". The mathematician who came up with the idea for this mission trajectory was very well thought of in the U.S.S.R.; AFAIK, the U.S. never developed this idea independently. Pat |
#18
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In article ,
Pat Flannery wrote: The Soviet sample return missions had no midcourse correction ability; the return stage was launched toward the zenith of the Lunar heavens over where the lander was positioned, and gravity did all the rest to get it back to mother Russia... Yep. Too much of a single-point design for my taste, especially given modern electronics. Full guidance and a capability for small midcourse corrections just isn't that big a deal any more. -- MOST launched 30 June; science observations running | Henry Spencer since Oct; first surprises seen; papers pending. | |
#19
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#20
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In article ,
says... (Henry Spencer) wrote in message ... The old Luna sample-return missions maxed out the Proton -- in fact, they needed Proton performance enhancements and reduction of safety margins -- to return a few hundred grams of sample. Yeah, the hardware was pretty crude stuff and we could do better, but it's a demanding mission, and trying to squeeze maximum payload out of a mass-limited system will get expensive fast. If you use an ion-drive to get to lunar orbit and back and a tether to collect samples, you don't need to be so mass-limited in your design and you could bring back much more lunar mass. The difficulty of having the end of the tether pickup some samples seems much less than having a couple more rocket stages. An easy mass margin design should be much easier on R&D money. A Falcon-V would be plenty of LEO launch capacity. Yes, you would still need to plan on some failures. Having a few backup winch/tether/scoop modules seems easy. Even loosing all your tether lift ability after lifting only 1/10th of your expected 10,000 Kg would still have you well ahead of the non-tether design. So if your goal is to make a profit returning lunar samples, using a tether to pickup samples from orbit seems a less demanding mission that will return far more product. I think you're *really* underestimating the difficulty of designing and building a tether that can hold up to the conditions it would encounter, as well as the difficulty in operating a scoop at the end of such a tether on what are predominantly rolling and hummocky terrains. Remember, our one and only attempt to deploy a long tether in LEO met with failure and near-disaster. I'm aware that the conditions in lunar orbit are different than in LEO, but still, it seems to me that until we demonstrate something as simple as deploying a 20km tether in LEO, we're talking out of our asses when speaking of 100km tethers pulling up lunar materials from orbit. I'd really like to see a materials engineer chime in on this one... Doug |
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