Having a mirror sit there doesn't seem more advanced than having life support and equipment to do experiments with. Note also that part of the reason launch costs are so high is that the payloads currently worth launching are either people or very expensive one-of-a-kind high- tech satellites, so the tolerance for failure is very low. Loosening the requirements could give some cost savings.
On Apr 22, 5:56 am, Ken Caldeira <[email protected]> wrote: > See attached and following for relevant discussion. > > http://globalecology.stanford.edu/DGE/CIWDGE/labs/caldeiralab/Caldeir... > > ___________________________________________________ > Ken Caldeira > > Carnegie Institution Dept of Global Ecology > 260 Panama Street, Stanford, CA 94305 USA > > [email protected]; > [email protected]http://dge.stanford.edu/DGE/CIWDGE/labs/caldeiralab > +1 650 704 7212; fax: +1 650 462 5968 > > On Wed, Apr 22, 2009 at 10:34 AM, Andrew Lockley > <[email protected]>wrote: > > > When Angel's idea was discussed on discovery channel, the idea was to use > > small and relatively fragile mirrors, which is fraught with problems. > > Conversely, the thin, flexible films required for this technique are > > readily available, such as in the aptly-named 'space blankets' used for > > keeping disaster victims warm. The material used for crisp packets (potato > > chips) also have the necessary properties. Both are far stronger than would > > be needed for such an application. I'm unsure as to how thin and light such > > a material could be made. > > > Making a large 'star' out of long strips of such a material should be > > relatively easy. Small weights, similar to an electrical wire, could be > > fixed to the perimeter to keep the material taught as it spins. The > > techniques for spinning-up satellites are well established, and even a low > > torque should result in a good unfurl given time. Whether the resulting > > structure will 'drift' or 'wrinkle' remains to be determined. > > > I've always maintained a deep loathing for space-based geoengineering, as > > I've regarded it as an impractical fantasy. However, when you consider how > > lightweight and permanent such a structure could be, it doesn't seem quite > > so silly anymore. In the short term, wrapping deserts and glaciers would > > obviously be cheaper, but the maintenance, degradation and environmental > > impacts would all be significant. I think it would be worth considering how > > big a single star could be made. > > > I understand that it's possible to create small-scale experiments and > > piggyback them on existing missions. Would this be one worth testing? > > > A > > > 2009/4/22 Alvia Gaskill <[email protected]> > > >> What you have described includes Roger Angel's proposal to launch > >> remote controlled refractors from the surface of the Earth to the L1 > >> point. All of these ideas involve advanced technologies most likely > >> not available until the second half of the 21st century. Think about > >> how primitive the ISS and its associated delivery systems are and the > >> difficulty with launching and controlling satellites is today. I > >> hadn't seen the idea of increasing the amount of sunlight reaching the > >> Earth before as almost all of the current discussion is on reducing > >> sunlight. Boosting the solar radiation could be helpful in > >> terraforming other planets or moons and longer term may play an > >> important role in colonization of these worlds. What we learn from > >> geoengineering to stop global warming may pay dividends for thousands > >> of years. > > >> On Apr 21, 9:17 am, John Hampson <[email protected]> wrote: > >> > The idea of reflecting sunlight using mirrors at the Earth-Sun L1 > >> > Lagrange point is well established. It appears to be based on > >> > manufacturing mirrors on the Moon from refined regolith and launching > >> > them for assembly at L1: this is to reduce the launch costs of a > >> > massive mirror. > > >> > But has consideration been given to launching very low mass mirrors > >> > directly from Earth? Many large mirrors (say 100m diameter) made from > >> > thin reflective sheet (like space blanket) could be launched directly > >> > from Earth. The problems arise when you try to wallpaper a vacuum > >> > with them and then maintain their shape, orientation and position. > > >> > A rotating space-station, similar to the one in the film 2001 could be > >> > used for this purpose. The sheet would be unfurled across the sunward > >> > face of the space station and the rotational forces would stretch and > >> > maintain the mirrors shape, keeping it rigid. Once the mirror was > >> > stable the space station would detach and move on to the next piece of > >> > vacuum to be wallpapered, leaving hundreds of spinning mirrors in its > >> > wake. > > >> > Two types of mirror might be considered. A “passive mirror” would > >> > float away to be recovered and reused once out of position. To > >> > maintain its orientation it could be convex shaped against the solar > >> > wind and it might initially be launched against the solar wind using > >> > puffs of thruster gas from the space station to extend its life. > > >> > A better option would involve an “active mirror” having a number of > >> > solar-powered miniature ion-thrusters installed around its outer > >> > edge. These would maintain the mirrors rotation, orientation and > >> > position in space. This would avoid (or at least reduce) the > >> > hazardous activity of recovering out of position mirrors. > > >> > Active mirrors would be flexible because they could be remote- > >> > controlled and might be useful in Earth orbit to reduce warming, > >> > manipulate the weather and even replace street lighting in urban > >> > areas. At Lagrange points L4 and L5 they could reflect sunlight > >> > towards Earth in the event of cooling brought on by natural disaster > >> > (volcanic eruption or asteroid impact). > > >> > A spinning Earth orbit space station built for scientific purposes > >> > could include facilities to unfurl mirrors at relatively little extra > >> > cost. An entire fleet of low mass mirrors sent to this station might > >> > require less launch mass than is needed just to build a Moon base and > >> > could be a flexible and relatively low cost means to control global > >> > warming. > > >> > John Hampson > > > > Early_JBritInterplanetSoc1989.pdf > 2766KViewDownload --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. 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