Thursday, May 20, 2010
Book Review: Paradise Regained.
And what solutions they are. Avid science fiction fans will already be familiar with proposals to mine the Moon for Helium three, to use asteroids for mining and comets for water and to have orbital power stations, but these innovations will capture other readers’ imaginations.
However, all but the hardest of hard science fiction fans cannot fail to be moved by gravity tractors, and solar concentrators (which, after all, are designed to move asteroids and comets) and “Dyson Dots”. You may have heard of Dyson Spheres, the hypothetical all encompassing shells of matter Freeman Dyson proposed advanced technical civilizations would build around stars to capture all available solar energy. “Dyson Dots” are much less grand, but still quite amazing. Basically they are variants of the solar sail, but which can be much heavier as unlike the standard solar sail, which we want to move around, the Dyson Dot sails are meant to stay in place acting as a sunscreen, reducing the amount of sunlight reaching the earth in order to combat global warming. A fleet of solar sails just in front of the L1 point would effectively lower solar insolation without getting in the way of most astronomical activities Unless you are looking at the Sun, of course.
The scale of this is staggering; you would need 70,000 10 km square solar sails, weighing about 37 million metric tons to reduce the solar constant by 0.25 percent. This array of solar sails has to be held in place by an intricate array of software constantly checking the position of the elements and modulating the sails.
When I say Dyson Dots are less grand than Dyson Spheres, they are still stunningly, mind beggaringly HUGE in scale.
While the authors emphasise the grand sweep of their ideas, they do point out the limitations of space based systems and other drawbacks, for example the act of mining the Moon will raise dust that will interfere with other Moon-based industries.
BUUTTT … You knew there would be a but didn’t you. Events have overtaken some aspects of the book. The Constellation program, which would have supplied the ARES 5 heavy lifter, has been discontinued. In an effort to provide a broad sweep of history in a short space many aspects of biological evolution and the rise of civilization are turned into cartoon parodies of themselves. My “favourite” howler was in the section on evolution, on page 23, where the authors say “… a shellfish mutated to develop a crude interior skeleton. The first armoured fish … had evolved.” NO NO NO! This is so wrong its not funny. Another problem is the age of many of the suggested readings. No one could really argue with Attenborough’s “Life on Earth”, it’s a sensational book even now, but finding it will be problematical. Also, the science has moved on. There’s a lot of really good contemporary books out there (eg Richard Fortey’s “Life; an unauthorized Biography”; heck, even Bill Bryson’s “A Brief History of Almost Everything” would have been good).
As well, the authors are pitching Space as a solution to environmental problems, with global warming as a particular case study. Unfortunately, global warming needs to be dealt with very soon. We are already committed to significant warming, and need to have mitigation systems in place before 2050 or even further warming will cause significant problems. To get the Dyson dots in place needs massive resources, NASA’s proposed Ares 5 would have been able to launch 188 metric tons, so you would need around 200,000 Ares 5 launches to build a sunshield (see above). Even if the Ares had not been canceled, you would need to launch an Ares 5 every day for 100 years to build your Sunsheild. We can’t even get a ISS supply mission happening once a week. Or you do it in space using asteroid mining. But you still have to develop and launch your space mining and orbital factory facilities. You still have to head out, find appropriate asteroids, guide them back into Earth orbit, mine them and build and launch 70,000 solar sails into the L1 point. That’s not going to happen before 2050 even with the best will and crash space development programs. Our children and grandchildren will be facing severe global climate problems before the very first solar sail is launched. And the cost! People who are quibbling over the cost of cap and trade vs carbon tax initiatives would faint (or go into apoplexy) at the cost of a Dyson Dot solution.
In summary, a fantastic, gorgeous broad sweep book buzzing with ideas, marred by technical errors and conceptual problems.
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