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Lunar Sample Return via Tether
Ian Stirling wrote in message ...
Charles F. Radley wrote: Vincent, Nice idea, but not original. Hoyt, Forward and Moravec have each proposed using tethers for lunar landing and sample return some years ago. It can be done even more cheaply than you propose. You do not even need any ion drive or propulsion at all actually. You can do it entirely with zero momentum exchange, you simply deposit payloads on to the lunar surface whose mass equals that of the samples you remove. Assuming a spherical moon. For non-spherical, non-ideal gravity moons, things get more interesting. Maybe. A lot of control can be gained by reeling the tethers in and out. A small propulsion system might help, but it is too early to say whether it is an essential component. Some analysis is needed. |
#13
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Lunar Sample Return via Tether
Ian Stirling wrote in message ...
Charles F. Radley wrote: Vincent, Nice idea, but not original. Hoyt, Forward and Moravec have each proposed using tethers for lunar landing and sample return some years ago. It can be done even more cheaply than you propose. You do not even need any ion drive or propulsion at all actually. You can do it entirely with zero momentum exchange, you simply deposit payloads on to the lunar surface whose mass equals that of the samples you remove. Assuming a spherical moon. For non-spherical, non-ideal gravity moons, things get more interesting. Maybe. A lot of control can be gained by reeling the tethers in and out. A small propulsion system might help, but it is too early to say whether it is an essential component. Some analysis is needed. |
#14
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Lunar Sample Return via Tether
In article ,
Vincent Cate wrote: You can do it entirely with zero momentum exchange, you simply deposit payloads on to the lunar surface whose mass equals that of the samples you remove. ...with the momentum from 1 Kg of xenon we can pick up 98 kps / 1.6 kps or about 61 Kg of regolith. If you simply deposited equal mass on the lunar surface you would only pick up 1 Kg for every 1 Kg you put down. So this way is cheaper for a probe on a sample return type mission. Yes and no and maybe. It uses less fuel, but that does not necessarily equate to "cheaper". The issue is not fuel cost -- xenon is one of the few fuels whose cost actually *is* comparable to LEO launch costs, but even so, that's a relatively minor issue here -- but hardware costs and complexity and reliability. -- MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer pointing, 10 Sept; first science, early Oct; all well. | |
#15
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Lunar Sample Return via Tether
In article ,
Vincent Cate wrote: You can do it entirely with zero momentum exchange, you simply deposit payloads on to the lunar surface whose mass equals that of the samples you remove. ...with the momentum from 1 Kg of xenon we can pick up 98 kps / 1.6 kps or about 61 Kg of regolith. If you simply deposited equal mass on the lunar surface you would only pick up 1 Kg for every 1 Kg you put down. So this way is cheaper for a probe on a sample return type mission. Yes and no and maybe. It uses less fuel, but that does not necessarily equate to "cheaper". The issue is not fuel cost -- xenon is one of the few fuels whose cost actually *is* comparable to LEO launch costs, but even so, that's a relatively minor issue here -- but hardware costs and complexity and reliability. -- MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer pointing, 10 Sept; first science, early Oct; all well. | |
#16
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Lunar Sample Return via Tether
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#17
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Lunar Sample Return via Tether
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#18
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Lunar Sample Return via Tether
(Henry Spencer) wrote in message ...
I *think* I have seen rotating tethers for orbital samplers mentioned before, but I'm unable to locate a specific reference. From: http://www.uah.edu/library/archives/...sinessBio.html ... "Tether-Assisted Planetoid Sampler" that would use a sampling penetrator on the end of rotating tether to obtain a sample from the surface of an airless planetoid (from comets and asteroids to Luna and Mercury) during a flyby trajectory and return it to the Earth, ... Our idea of orbiting for months and winching in sample after sample using a high ISP thruster is a little bit different from this single flyby idea. Though going from that to ours is not much of a leap. :-) Anyway, if you or anyone finds any references I am interested. -- Vince |
#19
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Lunar Sample Return via Tether
(Henry Spencer) wrote in message ...
I *think* I have seen rotating tethers for orbital samplers mentioned before, but I'm unable to locate a specific reference. From: http://www.uah.edu/library/archives/...sinessBio.html ... "Tether-Assisted Planetoid Sampler" that would use a sampling penetrator on the end of rotating tether to obtain a sample from the surface of an airless planetoid (from comets and asteroids to Luna and Mercury) during a flyby trajectory and return it to the Earth, ... Our idea of orbiting for months and winching in sample after sample using a high ISP thruster is a little bit different from this single flyby idea. Though going from that to ours is not much of a leap. :-) Anyway, if you or anyone finds any references I am interested. -- Vince |
#20
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Lunar Sample Return via Tether
I believe there is more money to make on hands-on space experience than
on the Moon rocks. It would be fun for the overweight Internet generation to control a low Earth orbit satellite and take pictures of a home town. It would be even more fun to do some real work. For example, the lunavator can deposit toy size, rock hunting excavators on the visible half of the Moon so that relatively cheap terrestrial microwave dishes can communicate directly with the excavators. The Internet users would control the excavators with a mouse. They would hunt for rocks and scratch graffiti on the Moon dust. A few years ago a businessman considered launching a remotely controlled lunar buggy and renting it for "virtual" joy riders. Whatever you do, keep in mind that novelty of such space hardware will wear off quickly unless the hardware can do new things that have not been done before. I would start with finding a massive piece of junk in low Earth orbit and attaching a 100 kg Zylon bolo to the junk. The bolo has internal wires which can be used as electrodynamic tethers and power supply for a remote manipulator riding on the bolo. The wires can make lots of electric power at night, and they can control the orbit of the junk/bolo satellite. Add a 200 kg sounding rocket, a few Hall thrusters, and you can use the bolo to launch your lunavator in 20 kg pieces assembled in space with another remote manipulator. When the lunavator is assembled, you have your own, dirt cheap, lunavator bolo relay, which is Earth-to-orbit, Earth-to-Moon, and Moon-to-Earth space transportation system. |
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