> I work with modelers all the time. They continue to tell me what > they think I want to hear. I'm not familiar with Moore's Law, only > Murphy's.
LOL! Lies, damned lies, and ... computer simulations. Moore's Law guarantees that you'll be able to opinion-shop to virtually infinite levels of detail in the future. > Welcome back Michael, ;-> I was never gone, just uncharacteristically quiet. OK, actually, I do have something to say today, come to think of it, and it has to do with propulsion, energy supply and logistics in general in the neighborhood of Jupiter. Jupiter has this strong magnetic field, right? So you should be able to generate electricity by flying electrodynamic tethers through it. Jupiter also has quite an atmosphere, and heat for various purposes might be had by aerobraking through it. Aerobraking doesn't preclude scooping up some atmosphere while you're at it, and this might apply as well to aerobraking through Io's atmosphere (or even Callisto's, thin as it may be.) Jupiter has four smallish planets around it, Europa being one, so there must be ways to regenerate spacecraft momentum through slingshot trajectories *within* the Jovian system. Some of those trajectories might be oriented entirely around harvesting energy and materials. Materials? Jupiter has a system of rings within the orbit of Io that suggest lots of free water ice floating around, which could be scavenged, dissassociated for fuel, or used for other purposes. As well, Jupiter has a handful of moons within the orbit of Io, and smaller bodies within the rings, that would seem to pose relatively minor fuel burdens for takeoff and landing, and which might have their own highly available resources. I guess what I'm suggesting here is that exploration of the Jovian system and even under the surfaces of its icy moons might best be approached with an in situ resource utilization strategy where "situ" is the Jovian system as a whole, and "resources" include Jupiter's magnetic field, its upper atmosphere, its various ring materials, and the momentum (and maybe even the upper atmospheres) of its larger moons. Instead of trying to send huge self-contained probes, a better long-term investment strategy might be to incrementally build infrastructure that smaller probes could use when they arrive. If each step can be rationalized in terms of both science value and technology spin-off for non-Jovian missions, you might have the makings of a program that could crawl along on its belly under the perennial live-fire exercises of budgetary politics, maybe even gathering momentum as it goes. I think one of the keys to this whole scheme is to recognize that H2O is underappreciated for its value as a structural material. On Earth, this neglect makes sense - there aren't many places on Earth where the temperature is below freezing year around, and who'd want to live in those places? In Jupiter orbit, however, ice is going to be very hard stuff. Admittedly, ice at low temperatures is still ice - very brittle. It seems an unlikely material for structural or shielding applications. Just a little bit extra, however, and the brittleness problem goes away. Right now, I have a slab of ice-composite in my freezer about 1 cm thick, one that I can throw on a concrete floor without it shattering, and that doesn't bend even as easily a piece of plywood the same shape. What do you need to make your own? Use the expensive, exotic composite material additive that I used: layered toilet paper. Very lightweight stuff. As light as it is, most of its mass isn't even the core molecular fibers that account for most of its strength. A little goes a long way, and that's important if you plan to take it a long way, like out to Jupiter. Water ice has a low melting point. If you have some fine fiber, and some ice ore, it doesn't require a huge amount of energy to cast and machine strong parts using filtered water combined with fiber to make a slurry. As weak as sunshine is out at Jupiter's orbit, a parabolic reflector (perhaps started as an inflatable, then cut away to let in sunlight) might preheat ice ore materials enough to greatly reduce the amount of energy needed from other sources to reach ice melting point. Reflector arrays might also be used to good effect to mine surface ice, softening it by heating, so that it can be more easily removed. At some turnaround point, larger reflectors might be built from ice composite, with only a very thin layer applied to make them adequately reflective. In microgravity, you wouldn't need much structural strength anyway. An ice-composite reflector-backing might be only as thick as onionskin paper, but still effective as a stable structure for a reflector. For electrodynamic energy harvest systems, ice-fiber composites might also have a role in shielding the wires in the electrodynamic tether from micro-debris strikes. Obviously, you've got a problem in using ice in any energy-harvest systems requiring aerobraking. At best you could hope to aerobrake in situations that wouldn't raise the temperature of an ice-sheathed tether above freezing, or in situations where you hope for a return on investment even with ice-composite sheath being disposable, for some given production run based on atmospheric heating. I have only begun to get really crazy with this idea. Maybe I should stop here. (Hint: running low on structural cellulose out there? Have composites gotten too weak from radiation damage, and need to be recycled? Think carbonaceous chondrites, grow-lights and algae.) If I have a point, it's this: significant exploration of Jupiter's moons seems bottlenecked by issues of energy supply once a probe is out there. The Jovian system has lots of energy sources, however, and may have easily-extracted materials for in situ construction of energy harvesters. And if I have a question, it's this: who is thinking about approaches like these? Doesn't some of what I'm talking about lend itself to studying and eventual exploiting comets, asteroids and polar regions on Mars, maybe even the Moon if they find surface ice there? -michael turner [EMAIL PROTECTED] > > > I can buy parallel evolution producing similar > >> shapes of creatures. But the plants being green > >> strikes me as a particularly Earth-born conceit. > >> Even if the ice wasn't kilometers thick, I doubt > >> enough sunlight reaches Europa to make photo- > >> synthesis via chlorophyll a useful process... > > > >Hey, it's only a movie ;-) A more plausible > >picture wouldn't be much more exciting, at > >least pictorially, than ocean-floor photos > >on Earth. > > > >It might be 30 years before a probe shines > >light on anything down there. If Moore's Law > >holds for most of those years, we might see > >computer systems powerful enough to start > >simulating possible origins and evolution > >of life on Europa. That effort might produce > >some very interesting images indeed. > > > >-michael turner > >[EMAIL PROTECTED] > > > >> --- LARRY KLAES <[EMAIL PROTECTED]> wrote: > >> > IMAGE DESCRIPTION: > >> > > >> > In the future, life will > >> > be discovered on Jupiter's moon Europa. > >> > > >> > After a trip through interplanetary space, > >> > a delivery probe (upper left) will > >> > penetrate Europa's icy surface and release > >> > a camera probe (center) into the subsurface > >> > ocean. > >> > > >> > Heat, generated within the moon from Jupiter's > >> > gravitational forces, allows life to flourish. > >> > > >> > Jellyfish-like creatures float within a > >> > a current of small bubbles. Two plant-like > >> > stalks can be seen in the middle-left. A > >> > shelled creature sits on the sea floor > >> > on the bottom left. > >> > > >> > The delivery and camera probes are based on > >> > actual NASA designs. > >> > > >> > > >> > > >> > >http://www.irtc.org/ftp/pub/stills/2003-12-31/europa.jpg<http://www.irtc.or g > >/ftp/pub/stills/2003-12-31/europa.jpg> > >> > > >> > > >> > > >> > >> > >> > >> > >> > >> __________________________________ > >> Do you Yahoo!? > >> Friends. Fun. Try the all-new Yahoo! Messenger. > >> http://messenger.yahoo.com/ > >> == > >> You are subscribed to the Europa Icepick mailing list: [EMAIL PROTECTED] > >> Project information and list (un)subscribe info: http://klx.com/europa/ > >> > >> > > > >== > >You are subscribed to the Europa Icepick mailing list: [EMAIL PROTECTED] > >Project information and list (un)subscribe info: http://klx.com/europa/ > > > == > You are subscribed to the Europa Icepick mailing list: [EMAIL PROTECTED] > Project information and list (un)subscribe info: http://klx.com/europa/ > > == You are subscribed to the Europa Icepick mailing list: [EMAIL PROTECTED] Project information and list (un)subscribe info: http://klx.com/europa/
