Mercury Landers |
Mercury Landers |
Nov 26 2005, 06:14 PM
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#31
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Member Group: Members Posts: 903 Joined: 30-January 05 Member No.: 162 |
Just throwing out some ideas, may be helpful in the long run.
The amazing trajectory Messenger is taking to Mercury would be reversible, wouldn't it? I'm thinking an orbiter/lander could be sent to Mercury (granted this part is going to be heavy) to study the planet, and the lander could collect some surface samples and put them into orbit around Mercury. A retreiver craft could be sent to collect the samples and then return to earth via a reversed version of the Messenger flight plan. The key to making this work is that you set it up so that as much of the delta v as possible is provided by gravity assists from Earth, Venus, and Mercury for all the spacecraft involved in the mission. Also, To expand on some of the ideas posted in this thread, could a kevlar net orbiting Mercury (tethered to a shielded orbiter) 'snag' debris from a plume generated from an impactor craft? This might be a 'cheap and dirty' way of retrieving materials from the surface of Mercury as part of mission to return them to earth. |
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Nov 26 2005, 06:30 PM
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#32
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Senior Member Group: Members Posts: 2488 Joined: 17-April 05 From: Glasgow, Scotland, UK Member No.: 239 |
QUOTE (tasp @ Nov 26 2005, 07:14 PM) Just throwing out some ideas, may be helpful in the long run. The amazing trajectory Messenger is taking to Mercury would be reversible, wouldn't it? I'm thinking an orbiter/lander could be sent to Mercury (granted this part is going to be heavy) to study the planet, and the lander could collect some surface samples and put them into orbit around Mercury. A retreiver craft could be sent to collect the samples and then return to earth via a reversed version of the Messenger flight plan. The key to making this work is that you set it up so that as much of the delta v as possible is provided by gravity assists from Earth, Venus, and Mercury for all the spacecraft involved in the mission. Also, To expand on some of the ideas posted in this thread, could a kevlar net orbiting Mercury (tethered to a shielded orbiter) 'snag' debris from a plume generated from an impactor craft? This might be a 'cheap and dirty' way of retrieving materials from the surface of Mercury as part of mission to return them to earth. The killer with Mercury landings - not counting the interplanetary stuff, where perhaps there might be *reverse* slingshots to be had with some clever planning - is that as it's an airless body you're limited to rocket-based descents. Add the cost of transporting your fuel for ascent and there are some quite rapid diminishing returns! Of course, if there's ice at the poles, in-situ fuel might be an option - otherwise, the 'smash and grab' mission seems about the only game in town! Bob Shaw -------------------- Remember: Time Flies like the wind - but Fruit Flies like bananas!
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Guest_BruceMoomaw_* |
Nov 26 2005, 09:13 PM
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#33
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There was, I've heard (though I haven't confirmed it), a smash-and-grab Mercury sampling mission once proposed for Discovery. Meanwhile, the ESA has actually done the preliminary design for a full-fledged Mercury landing and sample return -- although they also did so for Venus, which may give you some idea of how politically realistic the plan is. I'm convinced that, given their cost, it will be a long time before we see a landing and sample-return mission from any large world that doesn't have possible biological evidence -- that is, Mars and (in the longer run, if previous landers turn up something interesting) Europa.
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Nov 27 2005, 04:42 PM
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#34
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Member Group: Members Posts: 688 Joined: 20-April 05 From: Sweden Member No.: 273 |
QUOTE (Bob Shaw @ Nov 26 2005, 08:30 PM) The killer with Mercury landings - not counting the interplanetary stuff, where perhaps there might be *reverse* slingshots to be had with some clever planning - is that as it's an airless body you're limited to rocket-based descents. Add the cost of transporting your fuel for ascent and there are some quite rapid diminishing returns! Of course, if there's ice at the poles, in-situ fuel might be an option - otherwise, the 'smash and grab' mission seems about the only game in town! Bob Shaw The best and fastest way to acquire Mercury samples is almost certainly to search for meteorites here on Earth. I'm reminded of an old saying in paleontological circles: "The best place to find unknown fossil species is in museum drawers". tty |
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Nov 27 2005, 08:43 PM
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#35
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Senior Member Group: Members Posts: 1870 Joined: 20-February 05 Member No.: 174 |
Two or three years ago, there was some reporting on an odd meteorite that had distinctive isotope patterns and chemistry. There was some speculation it was Mercury ejecta, but that interpretation didn't seem strongly favored. I don't recall it's name/designation. I've heard no further discussion of it, and have wondered what the status on it is. Meteoritical Society meeting abstracts may have contained something but I haven't broused them extensively.
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Nov 27 2005, 09:20 PM
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#36
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Member Group: Members Posts: 270 Joined: 29-December 04 From: NLA0: Member No.: 133 |
QUOTE (tty @ Nov 27 2005, 05:42 PM) The best and fastest way to acquire Mercury samples is almost certainly to search for meteorites here on Earth. But that wouldn't be as interesting. The great thing about a sample return mission is that you can select the rocks that you'll be researching. There are a lot of Martian meteorites, but we would learn at lot more if we could get our hands on some Meridiani Planum sedimentary rocks. -------------------- PDP, VAX and Alpha fanatic ; HP-Compaq is the Satan! ; Let us pray daily while facing Maynard! ; Life starts at 150 km/h ;
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Nov 28 2005, 01:55 AM
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#37
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
I can't find the reference to the Mercury smash-and-grab sample return either, although I had found it on the web a couple of years ago. It was a real "outsider" proposal, conceived from someone not really working in space exploration, IIRC, and I don't know if it was an official Discovery proposal or not -- yet it is a solid idea. Certainly this kind of sample return is not as useful scientifically as having a rover move around and delicately select a geologist's wishlist, but what this kind of mission lacks in benefit, it makes up for in cost savings.
NWA 011 is the name of the meteorite that was speculated upon as being mercurean in origin. Here are some discussions of the item's origin, however, that don't even mention the word "Mercury", FWIW: http://web.utk.edu/~lataylor/pub-list/Floss-1153.pdf http://www.lpi.usra.edu/meetings/lpsc2004/pdf/1094.pdf http://aaa.wustl.edu/Work/pub_files/northwestafrica011.html There can only be so many rocky parent bodies in our solar system's past/present that were large enough to exhibit major radiogenic heating, and Mercury is one of them. Perhaps we'll end up with an exhaustive list one day and identify the Mercury meteorites by elimination. But we're not close to that day... A smash-and-grab sample return would not only have its own value, but would also possibly clinch the identification of Mercury meteorites in our possession. In terms of delta-v, we more or less need a solar orbit that has aphelion at 1 AU and perihelion at 0.48 AU -- that is more delta-v than a Venus/Mars lander, but then the craft would essentially be an Earth lander without instruments. It would be highly desirable to perform remote sensing of the impact site, a la Deep Impact -- the instruments should perhaps be mainly contained on the impactor, since instruments on the return craft wouldn't have any use after the impact while flying back to Earth. |
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Guest_BruceMoomaw_* |
Nov 28 2005, 02:11 AM
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#38
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Keep in mind that this thing will fly past Mercury at damn high speed, and thus its sample grains may be largely melted. However, since a comparably high-speed flyby of Europa is considered scientifically worthwhile, I presume one of Mercury is too.
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May 30 2006, 06:15 PM
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#39
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Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
In this 1971 book, Beyond the Moon: Future Explorations in Interplanetary Space
by C. B. Colby, there is a chart of then future planetary missions: http://sun3.lib.uci.edu/~jsisson/beyond.htm For Mercury, they indicate an orbiter for 1982. Was there ever an actual plan to orbit Mercury in the early 1980s? Of course the chart also declares a manned lunar base in 1978 and manned expeditions to Venus and Mars in 1982 and 1981, respectively. -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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Guest_BruceMoomaw_* |
May 31 2006, 05:45 AM
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#40
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NASA never -- and I mean never -- put any Mercury orbiter anywhere in even the also-ran listings of its desired future planetary missions, until Chen-Wan Yen, in the late 1980s, came up with the complex but workable kind of multiple gravity-assist flyby setup that Messenger is now using. Until then it was thought to be far too expensive and complex for what (to quote Ken Croswell in 1991) "isn't a sexy planet." Indeed, I didn't hear a peep about Mercury as a possible high-priority target until the Discovery Program AOs started.
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