[meteorite-list] trips to the Moon (Moon bases and meteoriterecovery)
From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Tue, 28 Jun 2011 15:08:19 -0500 Message-ID: <AE1C95F3538F448F8F6233252F7ACECD_at_ATARIENGINE2> Just to cherry-pick one question: > Do we have any hard data on the approximate > rate of impacts on the lunar surface? Lunar seismic data should show the larger impacts, but the analysis is controversial. More recent (and more sophisticated) analysis shows more impacts than we once thought. But the simple physical reality is that meteoroids come from far away toward the Earth-Moon System. The collisional cross-section is influenced by the gravity field of the Earth-Moon System as the meteoroid approaches. Geometrically, the fall influx of the Moon should be about 1/16th of the Earth's, but gravitational focusing reduces that to 1/18th -- the Earth hogs the meteoroids. So, on a square-mile-basis, the Moon gets 12% fewer meteorites than the Earth. But those figures are for the top of the "atmosphere." On the Moon, the surface IS the top of the atmosphere! On the Earth, we know (roughly) the fall rate BENEATH the atmosphere, but not at the top of the atmosphere. Well, you say, meteorites that don't survive are converted to dust particles in ablative trails, so just determine how much dust gets from space to the Earth's surface. Easy. Seriously complicating that simple idea is the large amount of meteoric dust, as opposed to meteoritic dust. That is, material from meteor streams, which is mostly dust to begin with, so adds only a little to the lunar impact hazard. (There are larger pieces in meteor streams and monitoring the Moon for impacts during periodic showers always produces a few visible flashes from energetic events... but only a few.) The long-term dust influx preserved in the Earth's ocean sediments is about 25,000 tons per year. The total mass of meteorites arriving at the surface of the Earth is likely between 2000 and 3000 TONS per year. Or maybe 200 to 300 tons, depending on whether you favor 90% ablative loss or 99% ablative loss. That figure may astound, but it's clear that less than 1% of all meteorites that survive to the surface are recovered Based on these figures for the Earth, the Moon would get 1300 tons of dust and particles, 140 tons of which would be particles big enough to worry about. On a square-mile basis, the likelihood of a meteorite impact of some size bigger than dust is probably 8 to 12 times greater than the risk of being whacked on a square mile of the Earth. But the fact is that even that risk is tiny. Not just tiny, but tiny-tiny-tiny-tiny-tiny-tiny-tiny-tiny! Ten times super-tiny is still, well, TINY. Even if the risk were 100 times greater , it would still be tiny. Try an experiment. Put up a tray the size of a lunar hut in your yard, covered with a film that will exclude dust, leaves, twigs, that only a meteorite could puncture, and wait to collect a meteorite. When you do, divide the wait-time by 10 (or 100 if you like that better), and you have the risk of lunar meteorite impact, the mean wait time to an impact (at a minimum). And, because we worry about it, every room of every lunar base, lab, facility, shed, hut, homestead, outhouse, doghouse, cathouse, and -- oh, yeah -- spacesuit will have a HandiPak of Sticky Patches within arm's reach. Just get out your list of humans killed by being struck by a meteorite and increase their number by ten. (Where'd I put that list?) And this data would be for a planet with a billion or billions of humans (increasing the odds of being hit), so reduce that 10x number by 1000 or so. There won't be billions of people on the Moon for a while, trust me. It makes me want to go into the Meteorite Life Insurance business with a policy good for meteoric death on any planet. High benefit, low monthly premiums; just present the murderous meteorite to verify your claim... Sterling K. Webb ---------------------------------------------------------------------------- ----- Original Message ----- From: "Michael Gilmer" <meteoritemike at gmail.com> To: "Martin Altmann" <altmann at meteorite-martin.de> Cc: <meteorite-list at meteoritecentral.com> Sent: Tuesday, June 28, 2011 7:29 AM Subject: Re: [meteorite-list] trips to the Moon (Moon bases and meteoriterecovery) Hi Martin, I'm no expert, I only play one on the met-list. ;) But, meteoroids and micrometeoroids would arrive on a variety entry angles and velocities. Some at steeper angles and high speeds, others at shallow or oblique angles and lower speeds. ("lower" being relative) I agree that the more friable types of meteorite would be shattered or obliterated on contact with the lunar surface - probably into unrecognizable bits and destined to become part of the lunar regolith gumbo. Some robust meteorite types like irons, would probably survive as well. Imagine a large "crater maker" type of impactor, the energies involved would be enormous. There could well be shock and shock heating effects that would char or blacken the surviving shrapnel. Since the lunar surface is predominately one narrow palette of indigenous color, we can rule out easily detecting any meteorites at a glance that are of that same color range - white, light grey, medium grey, dark grey, But, higher contrast types should be more visible to the trained eye - pallasites, stony iron, iron, Martian (!?), some other achondrites. Or, mount a spectrometer to the exploration rover and look for reflectance feedback from the landscape that matches preset meteorite types. I don't know, it's a fanciful whimsy across a distant and bleak world, and it makes for good speculation. :) Best regards, MikeG PS - we can see the larger impacts on the Moon here from Earth, by chancing across a flash of light on the lunar surface. Do we have any hard data on the approximate rate of impacts on the lunar surface? Our Apollo astronauts were driving golf balls and tooling around in a rover, and did any of them witness or sense any nearby or even distant impacts while they were there? Just curious.... -- --------------------------------------------------------------------------------- Galactic Stone & Ironworks - Meteorites & Amber (Michael Gilmer) Website - http://www.galactic-stone.com Facebook - http://tinyurl.com/42h79my News Feed - http://www.galactic-stone.com/rss/126516 Twitter - http://twitter.com/galacticstone EOM - http://www.encyclopedia-of-meteorites.com/collection.aspx?id=1564 --------------------------------------------------------------------------------- On 6/28/11, Martin Altmann <altmann at meteorite-martin.de> wrote: > Hm Michael, > > question - if you haven't any atmosphere, which could slow down the > incoming > meteorids, > how many would survive the impact with cosmic velocities, such rocks > are > typically travelling with in the inner solar system, to such a degree, > that > they would lie there in nice sizes usually called "stones"? > (Hmmm and when I'll drive there around with my car, how could I spot > them, > if they haven't any fusion crust or a different color from > oxidation...) > And if they survived the impact, how long would they survive without > being > crunched, smashed, pulverized by other impacts? A little space > weathering we > have there, but else no weathering and no geological activities for 3 > billion years - but a permanent bombardment of small and large high > velocity > impacts - having hammered the complete lunar surface into a field of > debris > and dust. > And if you look at the Apollo rocks or into your lunar meteorites, > most of > them witness an extraordinary violent history. Shocked, mixed, full of > tiny > fragments of different rocks, glasses, resolified dust...ect. > On the other hand, iiif meteorites would survive all that on Moon, > why then the astronauts didn't stumble every step over a meteorite, if > they > had 3 billion years to assemble there and no weathering, making them > decaying? > > Would be my questions only (not knowledge). > > Martin > > > -----Urspr?ngliche Nachricht----- > Von: meteorite-list-bounces at meteoritecentral.com > [mailto:meteorite-list-bounces at meteoritecentral.com] Im Auftrag von > Michael > Gilmer > Gesendet: Dienstag, 28. Juni 2011 04:08 > An: James Beauchamp > Cc: Edwin Thompson; meteorite-list at meteoritecentral.com > Betreff: Re: [meteorite-list] trips to the Moon (Moon bases and > meteorite > recovery) > > Sorry for all of my typos - I meant to say : > > Well taken, and I agree. Part of their mission was to retrieve lunar > samples, but imagine how many meteorites could be found if a team was > put on to the lunar surface with the primary focus of finding > meteorites and ignoring native lunar materials. :) > > I'll stop posting now, I am having typing issues and developing > blabber mouth. LOL > > > On 6/27/11, Michael Gilmer <meteoritemike at gmail.com> wrote: >> Hi James, >> >> Well taken, and I agree. Part of their mission was to retrieve lunar >> samples, but how imagine meteorites could be found if a team was put >> on to the lunar surface with the primary focus of finding meteorites >> and ignoring native lunar materials. :) >> >> Maybe Acme H3 Industries, Inc, will have the spare room in their >> underground base to lease out space to a meteorite hunting team, and >> the necessary scientific equipment to use for the mission (modified >> rovers, infrastructure, etc). >> >> Heck, the mining teams might "unearth" (unlune?) buried meteorites >> from under layers of regolith. >> >> Best regards, >> >> MikeG >> >> -- >> > ---------------------------------------------------------------------------- > ----- >> Galactic Stone & Ironworks - Meteorites & Amber (Michael Gilmer) >> >> Website - http://www.galactic-stone.com >> Facebook - http://tinyurl.com/42h79my >> News Feed - http://www.galactic-stone.com/rss/126516 >> Twitter - http://twitter.com/galacticstone >> EOM - >> http://www.encyclopedia-of-meteorites.com/collection.aspx?id=1564 >> > ---------------------------------------------------------------------------- > ----- >> >> >> >> On 6/27/11, James Beauchamp <falcon99 at sbcglobal.net> wrote: >>> " The Apollo astronauts were not meteorite hunters, nor did they >>> have any >>> specific mission or training involving meteorites." >>> >>> Mike, I don't think that's quite correct. The Apollo crews were >>> well >>> versed >>> in the expected geology, and were looking for quite a diverse lot of >>> rocks. >>> They spent many months training with geologists. Certainly, Dr. >>> Schmitt >>> was no exception on Apollo 17. "From Earth to the Moon" episode 10 >>> was >>> an >>> excellent, even a bit romanticized focus on the geology focus. >>> I think the focus was (and should have been) more anti-meteorite. >>> We had >>> plenty of those. But we didn't have verified lunar samples - to >>> include >>> cores and other different types. We needed more of those to verify >>> the >>> origins of our companion, and very little time and resources on-hand >>> to >>> get >>> them. >>> Just my thoughts on the matter. Obviously, I fully admit I should >>> stay >>> in >>> my engineering corner, but couldn't help poking a little. :) >>> >>> >>> >>> >>> >>> --- On Mon, 6/27/11, Michael Gilmer <meteoritemike at gmail.com> wrote: >>> >>> From: Michael Gilmer <meteoritemike at gmail.com> >>> Subject: Re: [meteorite-list] trips to the Moon (Moon bases and >>> meteorite >>> recovery) >>> To: "Edwin Thompson" <etmeteorites at hotmail.com> >>> Cc: meteorite-list at meteoritecentral.com >>> Date: Monday, June 27, 2011, 7:43 PM >>> >>> Hi Edwin, Sterling, and List, >>> >>> I love a good science-fiction, science-fact, trip into speculation >>> land. It reminds me of the old pulp sci-fi novels from the 50's and >>> 60's that I have read, with rocketships and moon bases. >>> >>> Cosmic rays are not the only threat, there are also micro-meteorites >>> and meteorites. The Late Heavy Bombardment is long over, but there >>> is >>> still a lot of debris peppering the Earth and Moon on a regular >>> basis. >>> With no atmosphere, the lunar surface is basically naked to >>> incoming >>> impactors. A base facility on the lunar surface would be subject to >>> high-velocity impacts on a random basis. >>> >>> Now we can all imagine how the lunar surface is probably littered >>> with >>> plentiful meteorites. The Apollo astronauts were not meteorite >>> hunters, nor did they have any specific mission or training >>> involving >>> meteorites. The first meteorite recovery team to be stationed on >>> the >>> Moon would be the very first people to hunt the surface - the >>> opposite >>> of being "hunted out". The problem is the lethal environment >>> involved. It would be a death-trap full of meteorites if not >>> handled >>> properly. The Apollo astronauts could not stay out for the extended >>> periods necessary to walk a grid or do a meaningful amount of >>> searching for suspect rocks. Although we have made some >>> advancements >>> since then, the lunar surface is still the most hostile, alien, and >>> lethal environment that an Earthly meteorite hunter could imagine. >>> Our modern day meteornauts on the Moon would have to rely on radar, >>> remote rovers, and man-operated rovers. >>> >>> To have any permanent presence on the Moon, the surface would need a >>> warning system for incoming impactors. We can assume an >>> early-warning >>> detection system, partially automated, that consists of satellites >>> and >>> surface-based radars, telescopes, and other sensors. This warning >>> system would detect potential impactors that are large enough to >>> damage facilities or personnel. So, we could have a lunar rover that >>> could carry a small team of 2 individuals over a long distance with >>> a >>> meaningful duration (say, several hours, or even "overnight" in some >>> cases.). These individuals would be dispatched to retrieve >>> large/heavy meteorites that smaller unmanned rovers could not pick >>> up. >>> They could safely travel the surface (relatively speaking) and they >>> could be warned to evade/avoid a potentially deadly strike by the >>> warning system. They would still have to worry about the rare fluke >>> micro-meteorite or one that slips through the detection system, but >>> it >>> would be slightly better odds than a crap-shoot. >>> >>> The bulk of the searching and retrieval would be accomplished by >>> robust remote-operately rovers. These would be larger than the >>> current Mars rovers we know so well (thanks for the always reliable >>> updates Mr. Baalke!), but small enough to be produced on a low to >>> modest budget. Essentially it would be a "wander and grab" rover >>> with >>> a sophisticated optical system than can scan the lunar surface in >>> high >>> resolution and provide a "first person" view to the rover operator >>> who >>> is located miles away in an underground facility. It's main >>> attributes would be quickness (to cover larger amounts of real >>> estate >>> in a much shorter time span than today's rovers), keen eyes >>> (cameras), >>> and economy of travel (able to stay afield for extended periods of >>> time). >>> >>> The rover would also have a robotic arm and a collection bin than >>> can >>> be hermetically sealed. The operator would use the rover to locate >>> and retrieve all meteorites within the operating range of the rover. >>> Those meteorites which are too large, too heavy, or too numerous for >>> the rover to recover, would be assigned to a manned rover mission to >>> recover the specimens. >>> >>> I don't think there would be a lunar base built just to retrieve >>> meteorites. However, one can envision a scientific base that is an >>> all-purpose facility to house a number of teams that are based there >>> for extended periods of time and are rotated in and out. >>> Astronomers, >>> chemists, physicists, geologists....the potential uses for a lunar >>> surface facility would be many and varied, and meteorites could be >>> one >>> of those missions. >>> >>> Instead of ANSMET, we could have MOONMET - now who is going to apply >>> for the first expedition? >>> >>> Best regards, >>> >>> MikeG >>> >>> -- >>> > ---------------------------------------------------------------------------- > ----- >>> Galactic Stone & Ironworks - Meteorites & Amber (Michael Gilmer) >>> >>> Website - http://www.galactic-stone.com >>> Facebook - http://tinyurl.com/42h79my >>> News Feed - http://www.galactic-stone.com/rss/126516 >>> Twitter - http://twitter.com/galacticstone >>> EOM - >>> http://www.encyclopedia-of-meteorites.com/collection.aspx?id=1564 >>> > ---------------------------------------------------------------------------- > ----- >>> >>> >>> >>> On 6/27/11, Edwin Thompson <etmeteorites at hotmail.com> wrote: >>>> >>>> http://www.space.com/1111-private-moon-trips-forecast.html >>>> >>>> >>>> Dear fellow listers, for only 100 million dollars you can go to the >>>> moon >>>> and >>>> gather your own Lunar specimens. It could be a very profitable >>>> enterprise. >>>> But the rumor mill has it that China will be going to the Moon >>>> next. If >>>> you >>>> go there be sure to dodge those nasty cosmic rays. >>>> >>>> There is a society of brainiacs that has designed a substantial >>>> Moon >>>> base. >>>> Sadly that facility must be built beneath the Lunar surface in a >>>> volcanic >>>> cavern to shield the inhabitants from cosmic ray exposure. >>>> >>>> >>>> Cheers, E.T. >>>> ______________________________________________ >>>> Visit the Archives at >>>> http://www.meteoritecentral.com/mailing-list-archives.html >>>> Meteorite-list mailing list >>>> Meteorite-list at meteoritecentral.com >>>> http://six.pairlist.net/mailman/listinfo/meteorite-list >>>> >>> ______________________________________________ >>> Visit the Archives at >>> http://www.meteoritecentral.com/mailing-list-archives.html >>> Meteorite-list mailing list >>> Meteorite-list at meteoritecentral.com >>> http://six.pairlist.net/mailman/listinfo/meteorite-list >>> >> > > > -- > ---------------------------------------------------------------------------- > ----- > Galactic Stone & Ironworks - Meteorites & Amber (Michael Gilmer) > > Website - http://www.galactic-stone.com > Facebook - http://tinyurl.com/42h79my > News Feed - http://www.galactic-stone.com/rss/126516 > Twitter - http://twitter.com/galacticstone > EOM - > http://www.encyclopedia-of-meteorites.com/collection.aspx?id=1564 > ---------------------------------------------------------------------------- > ----- > ______________________________________________ > Visit the Archives at > http://www.meteoritecentral.com/mailing-list-archives.html > Meteorite-list mailing list > Meteorite-list at meteoritecentral.com > http://six.pairlist.net/mailman/listinfo/meteorite-list > > ______________________________________________ > Visit the Archives at > http://www.meteoritecentral.com/mailing-list-archives.html > Meteorite-list mailing list > Meteorite-list at meteoritecentral.com > http://six.pairlist.net/mailman/listinfo/meteorite-list > ______________________________________________ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list at meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-listReceived on Tue 28 Jun 2011 04:08:19 PM PDT |
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