In a message dated 3/27/2001 9:53:00 PM Alaskan Standard Time, [EMAIL PROTECTED] writes: > Here's something to chew on. As you know, I've been intrigued by the prospect > of mining ice and water on Europa, but had a lot of trouble figuring out how > to make it profitable. What if... Breaking out my trusty knife and fork of Devil's advocacy, I see the following issues with mining Europan water-ice. > Humans need water to live. Travelers beyond our system will need water. > Transporting water from Earth all the way "out there" will be expensive, not > only in money, but in the energy needed to carry it. Water is critical to > survival. Anyone disagree with that? Nope. Except that travelers would hypothetically be able to recycle water very efficiently, with water purification devices and / or simple boiling with solar energy. Due to the lack of atmosphere, exposed surfaces heat very rapidly in space (if within a few AUs of the sun, that is). More distant solar heating could perhaps be provided with giant-scale lenses and mirrors. Currently, NASA has technology to recycle water from human waste. Presuming a space-faring colony (there long enough to have people dying on a regular basis) would be in space too long to worry about niceities of burial, you could likely get quite a bit of water from a corpse as well. I'd imagine a 150 pound man would have about 110 pounds of water in him. > Our knowledge of Europa suggests that it consists of an ice mantle perhaps > several kilometers thick, with an ocean of liquid water, yes H2O, underneath. > Water is heavy and wiggly. But what about carving out chunks of ice like the > Eskimo do to make igloos, Whoops! Problem one: Eskimoes (more properly 'Inuit') don't make houses out of ice. First, they use a sort of dense snow, and second, they don't make igloos anymore. They all live in houses these days. Fact is, it's getting damned hard to retain traditional skills in Native communities, even up in Bush Alaska. All problems of pedantism aside, however... boosting it into an orbit, collecting it in great > masses, Why not just shoot it there with mass drivers? A mass driver works by magnetically propelling an item along a rail, for several kilometers. Works well in a vacuum. Of course, water is not magnetic, but 'packaged' ice could be fitted out with magnetic particles. and towing it with sail ships to rendesvous points "out there" as > needed? If you have solar sails, why bother with water ice? The best reason for masses of water wouldn't be for survival. A small sufficiency would do. Fuel? If you have a solar sail, it is propelled either with solar wind directly, or by photons energizing a sail to power an ion drive. Again, it's extremely efficient, and the ions can come from practically anything. Fuel for chemical drives? You only need a chemical rocket engine if you're fooling around with high-speed manuevers, atmospheric diving and escaping, and so forth. If you're up in deep space, it's sufficient to simply make up in numbers of automated solar sails, what you lack in individual efficiency. It would be collected for storage by starships or even left frozen to > be defrosted as needed. Imagine a starship towing a huge block of water ice > and carving off what it needs as it needs, thus obviating the need for huge > water storage tanks on board. Last issue: Europa isn't the only place in the solar system besides Earth with water. As I understand it, water ice is relatively common in asteroids and chondrites (amalgams of carbon, hydrogen, oxygen, nitrogen, and other basic organic chemicals). Chondrites are fairly common in the neighborhood of Jupiter / Saturn. So, your ice blocks are already up there, if they are needed. Last, best reason I can think of for a mass of water ice? Terraforming. In that case, it might work to, as Gail suggests, lift millions of tons of ice from Europa (presumeably because it would be the most economical place to find it, not the only place), drag it from Jupiter by solar sail, and then drop it on Mars, and send the solar sail back for another load. Last, best reason I can think of to bother with Europa, in the absence of a need for large masses of water ice? Life. An alternate life-system would be very compelling, and possibly profitable, reason to explore and exploit Europa. You'd need one, considering the distance, hardship, isolation, and hard radiation all around. > OK, folks, kick this one around, and > Watch the skies! > Gail Leatherwood I'm kicking, while I'm watching. Don't laugh. It's not easy! -- John Harlow Byrne == You are subscribed to the Europa Icepick mailing list: [EMAIL PROTECTED] Project information and list (un)subscribe info: http://klx.com/europa/
