“Is this all astronomers could do for Global Climate Change?”

 

"Studies of ancient climates suggest Earth is now on a fast track to global warming, World Scientists say Humans are Causing Global Warming, Impact of Global Warming on Weather Patterns Underestimated, NASA Study Shows Antarctic Ice Sheet Shrinking, Arctic Lakes Disappear; Researchers Blame Global Climate Change", these were the some of the headlines I have noticed off and on line since 2005. All these craters around one topic "Global Warming", more recently former USA Presidential candidate Al Gore's "An Inconvenient Truth" movie which is about Global warming was a big hit. Frankly I enjoyed watching it; it's very well done movie to make the public alert about "Global climate change." 

But in the first article of "FOCUS", I'm not going to talk about Global Warming; obviously my article has some link in astronomy. Last few weeks I was following the Climate Changing issue very much (we had a program at British Council also), but I was pretty amazed when CNN announced in there program, "that the worldwide astronomers suggest the "Sunshade" as a solution to the current Global Warming." 

So what is this space “Sunshade”? I first learned about this theory about 2 or 3 years ago through an article. This theory was first purposed by James Early of the Lawrence Livermore National Laboratory in 1989. The earlier ideas were for bigger, heavier structures that would have needed manufacture and launch from the moon, which is pretty futuristic. But recently Roger Angel, a University of Arizona Regents' Professor suggests launching a constellation of trillions of small free-flying spacecraft a million miles above Earth into an orbit aligned with the sun, called the L-1 orbit. The spacecraft would form a long, cylindrical cloud with a diameter about half that of Earth, and about 10 times longer. About 10 percent of the sunlight passing through the 60,000-mile length of the cloud, pointing lengthwise between the Earth and the sun would be diverted away from our planet. The effect would be to uniformly reduce sunlight by about 2 percent over the entire planet, enough to balance the heating of a doubling of atmospheric carbon dioxide in Earth's atmosphere. 

The lightweight flyers designed by Angel would be made of a transparent film pierced with small holes. Each flyer would be two feet in diameter, 1/5000 of an inch thick and weigh about a gram, the same as a large butterfly. It would use "MEMS" technology mirrors as tiny sails that tilt to hold the flyers position in the orbiting constellation. The flyer's transparency and steering mechanism prevent it from being blown away by radiation pressure. Radiation pressure is the pressure from the sun's light itself. 

The total mass of all the fliers making up the space sunshade structure would be 20 million tons. At $10,000 a pound, conventional chemical rocket launch is prohibitively expensive. Angel proposes using a cheaper way developed by Sandia National Laboratories for electromagnetic space launchers, which could bring cost down to as little as $20 a pound. 

The sunshade could be deployed by a total 20 electromagnetic launchers launching a stack of flyers “every 5 minutes for 10 years”. The electromagnetic launchers would ideally run on hydroelectric power, but even in the worst-case environmental scenario with coal-generated electricity, each ton of carbon used to make electricity would mitigate the effect of 1000 tons of atmospheric carbon.

But it still perpetuates our unfortunate habit of trying to solve problems created by technology with more technology. If unforeseen consequences of technologies like automobiles and electricity created the problem of global warming, what makes us think another large-scale technology like trillions of orbiting spacecraft won't lead to even worse unforeseen consequences?

And here’s the summary,
• Each flyer would be two feet in diameter, 1/5000 of an inch thick and weigh about a gram, the same as a large butterfly. Not really a big number? Consider how many would be needed. 
• To build such a cloud, 20,000 billions 'butterflies' would need to be sent into space. 
• This would represent about 20 million tons. 
• And even with the electromagnetic space launchers developed at Sandia National Laboratories which promise to send objects in space for about $20 per pound, the total cost would be about $1,000 billion. 
• Of course, you will need to launch these trillion spacecraft. With each such launch sending out 800,000 flyers, the project would require 20 million launches over a decade.
• And Angel summarizes the costs: "It could be developed and deployed in about 25 years at a cost of a few trillion dollars. With care, the solar shade should last about 50 years. So the average cost is about $100 billion a year, or about two-tenths of one percent of the global domestic product." 
• Even if these numbers look — rightly — astronomic — please remember that the monthly U.S. trade deficit is in the $60 to $70 billion range — per month!
While I keep an open mind about the theory, I would like if you could make your comments about the theory, so we could start an online discussion.

-Thilina Heenatigala.