Space Solar Power from satellites could generate power from Sun
By William Atkins
Wednesday, 11 April 2007 23:31
Recently, officials with the U.S. Department of Defense (DoD) announced that scientists and other personnel at the National Security Space Office (NSSO) of the U.S. Pentagon might study SSP in the future with the idea of using satellites to collect solar energy for use on the Earth.
For this idea to work, space-based satellites in orbit around the Earth would need to be in geosynchronous orbits (that is, an orbit that has the same orbital period as the Earth so that an observer on the ground would see the satellite fixed at one location above him) or sun-synchronous orbits (that is, the satellite would always face the Sun so that the satellite passes over a given point on the Earth’s surface at the same time with respect to the Sun).
Besides satellites in geosynchronous or sun-synchronous orbits about the Earth, SSP could also be used from bases on the Moon, or even possibly from other space-related locations and celestial bodies.
Such a SSP system would use photovoltaics (PV) to convert energy from the Sun. PV technology consists of solar cells to convert solar energy into electricity. Then, energy collected from the Sun would be transmitted to the Earth with the use of microwave technology. Microwaves are electromagnetic waves with wavelengths in the range between 30 centimeters and one millimeter. The use of microwaves is commonly found in kitchen microwave ovens.
The use of the Sun to generate electricity has been used for years to operate satellites, especially those that travel far from the Sun. Unlike, such uses, SSP systems could eventually be used on a global basis in order to reduce, or maybe even eliminate, the dependence on fossil fuels. Although space solar power holds promising improvements to the environment due to virtually no negative by-products (once it is established), its global use is still far in the future of humankind.
And, the concept of SSP is not new. It was first described in 1968, but only talked about because it was deemed impractical with technology possessed in the 1960s. However, in 1973, Peter Glaser invented what was called the solar power satellite as a way to transmit power from an antenna on a satellite in space to an antenna on the Earth using microwaves. Consequently, in the 1970s and early 1980s, NASA researched the use of solar power satellite (SPS) systems that used large solar arrays to transmit power to the Earth through microwaves.
A very informative SSP article by John C. Mankins, of NASA’s Advanced Projects Office is called “A Fresh Look at Space Solar Power: New Architectures, Concepts, and Technologies”.
