Freeman Dyson is credited with being the first to formalize the concept of the Dyson sphere in his 1959 paper “Search for Artificial Stellar Sources of Infra-Red Radiation”, published in the journal Science.
Dyson Sphere: centauri-dreams.org
However, Dyson was inspired by the mention of the concept in the 1937 science fiction novel Star Maker, by Olaf Stapledon, and possibly by the works of J. D. Bernal and Raymond Z. Gallun who seem to have explored similar concepts in their work. Such a “sphere” would be a system of orbiting solar power satellites meant to completely encompass a star and capture most or all of its energy output. Dyson speculated that such structures would be the logical consequence of the long-term survival and escalating energy needs of a technological civilization.
The New Scientist carries a report on a speculation about using the solar wind to generate power for use on earth, based on the paper by Harrop and Schulze-Makuch in the International Journal of Astrobiology, “The Solar Wind Power Satellite as an alternative to a traditional Dyson Sphere and its implications for remote detection”.
The concept for the so-called Dyson-Harrop satellite begins with a long metal wire loop pointed at the sun. This wire is charged to generate a cylindrical magnetic field that snags the electrons that make up half the solar wind. These electrons get funnelled into a metal spherical receiver to produce a current, which generates the wire’s magnetic field – making the system self-sustaining.
Dyson-Harrop Satellite
Any current not needed for the magnetic field powers an infrared laser trained on satellite dishes back on Earth, designed to collect the energy. Air is transparent to infrared so Earth’s atmosphere won’t suck up energy from the beam before it reaches the ground.
Back on the satellite, the current has been drained of its electrical energy by the laser – the electrons fall onto a ring-shaped sail, where incoming sunlight can re-energise them enough to keep the satellite in orbit around the sun.
A relatively small Dyson-Harrop satellite using a 1-centimetre-wide copper wire 300 metres long, a receiver 2 metres wide and a sail 10 metres in diameter, sitting at roughly the same distance from the sun as the Earth, could generate 1.7 megawatts of power – enough for about 1000 family homes in the US.
A satellite with the same-sized receiver at the same distance from the sun but with a 1-kilometre-long wire and a sail 8400 kilometres wide could generate roughly 1 billion billion gigawatts (1027 watts) of power, “which is actually 100 billion times the power humanity currently requires”, says researcher Brooks Harrop, a physicist at Washington State University in Pullman who designed the satellite.
Solar panels cost more per pound than the copper making up the Dyson-Harrop satellites, so according to Harrop, “the cost of a solar wind power satellite project should be lower than a comparative solar panel project”.
A smaller version of this satellite could help power some space missions perhaps in helping generate power for something like the Ulysses spacecraft, which went around the poles of the sun.
Fascinating stuff!
It occurs to me that getting a sharp enough focus for the laser beam may be restricted – everything else becoming feasible – to “base stations” having no atmosphere and therefore located in space not too far from the satellite.
A point to note about all such schemes where man’s power generation needs on earth are satisfied by using off-earth sources of energy (including solar energy which does not normally get to earth) is that all such power will eventually be dissipated as heat into the first 100m of the earth’s atmosphere. If such power is significant with respect to the solar radiation reaching the earth then cooling will need to be arranged for.
The k2p blog 
