Date: Tue, 18 Aug 92 05:12:29 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #123 To: Space Digest Readers Precedence: bulk Space Digest Tue, 18 Aug 92 Volume 15 : Issue 123 Today's Topics: 3He costs (was Re: He3 Power Source) Meteor Soaks Datona FL Welcome to the Space Digest!! Please send your messages to "space@isu.isunet.edu", and (un)subscription requests of the form "Subscribe Space " to one of these addresses: listserv@uga (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle (THENET), or space-REQUEST@isu.isunet.edu (Internet). ---------------------------------------------------------------------- Date: 18 Aug 92 07:30:44 GMT From: Bill Higgins-- Beam Jockey Subject: 3He costs (was Re: He3 Power Source) Newsgroups: sci.space In article <5488@ucsbcsl.ucsb.edu>, 3001crad@ucsbuxa.ucsb.edu (Charles Frank Radley) writes: >>From: sth0:05:28ipknot.mit.edu (Scott Hannahs) >>I think the energy cost of gettting >> to the moon, mining the 3He and bringing it back would be more than you >> can get out of the 3He. > - > Quick lesson in lunar economics :- > Transportation from the Moon would be by solar powered electromagnetic mass > driver. Operating costs essentially nil (except maintenance). > A modest one time capital cost will be incurred to launch and install the > small mass driver on Moon. After that, you can transport infinite > quantities of lunar material for virtaully zero cost. The finished product in this case is a very small amount of mass. Plow up a few football fields on the Moon to a depth of a few meters, and the helium-3 you extract might amount to a kilogram. A little bottle of it would fit inside one of your Heavy Boots. So you don't need anything as elaborate as a mass driver to deliver your helium home. Buy some Luna-16 clones from the Russians! Presumably, if you've got robots and people running bulldozers around the Moon and erecting solar furnaces and such, there are spacecraft returning from there on a fairly regular basis. Now, with all this infrastructure present, it makes sense to run other materials processing parasitically. For example, hydrogen is a byproduct of the helium-extraction process (it's embedded in the regolith particles too). Oxygen, silicon, aluminum, and other metals may be obtained from the soil if you want them badly enough. Many people have suggested that there is an extralunar market for these things-- SPS solar cells and structural materials, or a chemical-rocket economy serving OTVs, space stations, and Mars ferries are standard examples. If this is true (alas, these demands tend to fall apart when you look at them hard) then there may be a reason to build a mass driver or other transport system to move massive material around. The mass driver doesn't operate purely on electricity, though. Correct me if I'm wrong, but unless you're launching into orbits with very special characteristics, your payloads will need to have *some* kind of rocket motors and propellant aboard. So I can't believe the operating costs will be "essentially nil." > Extracting He-3 from lunar soil is cheap and simple - heat it up a > little, using solar mirrors. The cost of storing He-3 in its refined ^^^^ ^^ ^^^^^^^ > state is more expensive than handling lunar soil, so it might be cheaper to > launch lunar soil to Earth, rather than the He-3, despite the fact that the > mass of the soil is much higher, the cost of transporting it is very low. What? Is there some reason you can't just put the helium in a tank or a dewar? Charles, this assertion is incredible. Please explain. > It should be quite cheap to supply lunar He-3 to Earth for whatever > purpose. You need some pretty expensive equipment on the Moon. I would say the costs are in doubt. And if it's economical at all, it's because 3He is more precious than gold, possibly more precious than baseball cards, *and* a possible energy source. > Is there an easy way to store He other than cryogenci or gaseous ? EG can > it be soaked into something, say, Palladium or Lithium (like Hydrogen) ? Not that I know of. Disclaimer: Nearly all my experience is with Helium-4. Bill Higgins, Beam Jockey | The restaurant's architect Fermi National Accelerator Laboratory | said every effort had been Bitnet: HIGGINS@FNAL.BITNET | made to build McDonald's Internet: HIGGINS@FNAL.FNAL.GOV | 15th outlet in Italy SPAN/Hepnet: 43011::HIGGINS | in harmony with Pompeii. | --Reuters story in *Chicago | Sun-Times*, 18 June 92 ------------------------------ Date: 17 Aug 92 15:30:16 GMT From: Gary Coffman Subject: Meteor Soaks Datona FL Newsgroups: sci.space In article mwallis@clubzen.fidonet.org (Michael Wallis) writes: > >Excuse me, but what makes you think a 1 metre rock would "... be extremely >bright ..." or be "... as bright as the Sun ..."? A metre isn't very big >at all. My concern would be that something that small should create a wave >of (presumably) several feet in height. Also, an impact would create >multile waves, not a single wave, though the following ones would be >smaller. Is that the recorded pattern at Daytona? A meter isn't very large, but an ionized column of air one meter in diameter and 200 miles high *is* very large and potentially very bright. Remember that we're talking about an interplanetary object plunging to Earth. Meteors have impact velocities as high as 40 miles per second. If the 1 meter meteor was iron, it's impact would release kinetic energy equivalent to a 65 kiloton nuclear explosion. It's not like tossing a pebble into a pond. Gary ------------------------------ End of Space Digest Volume 15 : Issue 123 ------------------------------