| Global warming is a reality and increasingly | | | | When they reached L1, they would be dealt off |
| its consequences are upon us. We may think | | | | the stack into a cloud. There's nothing to |
| that global warming does not affect us but | | | | assemble in space." Angel proposes to design |
| the fact is it has already started to have | | | | lightweight flyers made of transparent film |
| disastrous consequences. Flash floods, | | | | pierced with small holes and would be two |
| droughts, receding icebergs, cyclones are | | | | feet in diameter, 1/5000 of an inch thick and |
| some of the manifestations of global warming. | | | | weigh about a gram, the same as a large |
| Although we are aware and worried about it | | | | butterfly. He suggests using "MEMS" |
| and trying our best to control it but no | | | | technology mirrors as tiny sails that tilt to |
| significant impact could be seen. Scientists | | | | hold the flyers position in the orbiting |
| have come up with new strategies to tackle | | | | constellation. The weight of all flyers |
| the problem. Now a scientist has suggested an | | | | would be 20 millions tons. But conventional |
| ambitious idea to contain global warming. Put | | | | rocket launch system at $10,000 a pound would |
| sunshades in space. That's right. University | | | | be too prohibitive. His alternative would |
| of Arizona astronomer Roger Angel suggests | | | | cost only around $20 a pound. Â He |
| putting sunshades in space and has detailed | | | | suggests deploying a total 20 |
| his idea in a paper "Feasibility of cooling | | | | electromagnetic launchers launching a stack |
| the Earth with a cloud of small spacecraft | | | | of flyers every 5 minutes for 10 years. The |
| near L1" in the Proceedings of the National | | | | electromagnetic launchers would use |
| Academy of Sciences. He suggests launching a | | | | hydroelectric power but even if it uses |
| constellation of trillions of small | | | | coal-generated electricity, each ton of |
| free-flying spacecraft a million miles above | | | | carbon used would reduce the effect of 1000 |
| Earth into an orbit aligned with the sun, | | | | tons of atmospheric carbon. Â Once |
| called the L-1 orbit. This spacecraft would | | | | propelled beyond Earth's atmosphere the flyer |
| form a long, cylindrical cloud and would have | | | | stacks would be steered to L-1 orbit by |
| a diameter about half that of Earth, and | | | | solar-powered ion propulsion, pioneered by |
| about 10 times longer. It is suggested that | | | | European Space Agency's SMART-1 moon orbiter |
| about 10 percent of the sunlight passing | | | | and NASA's Deep Space 1 probe. "The concept |
| through the 60,000-mile length of the cloud, | | | | builds on existing technologies," Angel said. |
| pointing lengthwise between the Earth and the | | | | "It seems feasible that it could be developed |
| sun, would be diverted away from our planet. | | | | and deployed in about 25 years at a cost of a |
| This would result in uniformly reduced | | | | few trillion dollars. With care, the solar |
| sunlight by about 2 percent over the entire | | | | shade should last about 50 years. So the |
| planet and would balance the heating of | | | | average cost is about $100 billion a year, or |
| carbon dioxide in Earth's atmosphere. Â | | | | about two-tenths of one percent of the global |
| The use of space shade was first mooted by | | | | domestic product." He added, "The sunshade |
| James Early of the Lawrence Livermore | | | | is no substitute for developing renewable |
| National Laboratory in 1989. Â "The | | | | energy, the only permanent solution. A |
| earlier ideas were for bigger, heavier | | | | similar massive level of technological |
| structures that would have needed manufacture | | | | innovation and financial investment could |
| and launch from the moon, which is pretty | | | | ensure that. "But if the planet gets into an |
| futuristic," Angel said. "I wanted to make | | | | abrupt climate crisis that can only be fixed |
| the sunshade from small 'flyers,' small, | | | | by cooling, it would be good to be ready with |
| light and extremely thin spacecraft that | | | | some shading solutions that have been worked |
| could be completely assembled and launched | | | | out. |
| from Earth, in stacks of a million at a time. | | | | |