POWER STAR: Harvesting the Sun's Energy in Space
Dr. David Hyland
3:30pm, Guggenheim 220Reception to Follow
The advance of civilization will require substantially more powerful sources of energy than are presently available. Aside from the Earth’s supply of radioisotopes and fossil fuels, the abundant supply of fusion-based energy produced by the sun remains to be efficiently harvested. The collection of solar energy in space could potentially be an order-of-magnitude more effective than ground-based technology because in space, solar insolation is continuous and not attenuated by the atmosphere. These potential advantages have motivated efforts to design space solar power systems since the early 1960s.
A solar power system consists of a space segment that collects solar energy, converts the energy into radiation (typically in a wavelength band to which the atmosphere is mostly transparent), then transmits the radiation to a ground facility that converts the radiation into electrical power. Since the ground-based power collection technology is (relatively) well developed, we concentrate here on the space segment, called the Solar Power Satellite(s) (SPS).
In this presentation, an SPS is assumed to be a space system in geostationary orbit that collects solar power via photovoltaics and transmits it to ground collection stations using microwave radiation. Previous system designs developed over the past several decades entail gigantic, articulated structures with many (in some cases, thousands of) moving parts and require on-orbit infrastructure and in-space construction using advanced robotics. The concept described here combines solar cell / microwave patch antenna printing technology with well-established inflatable satellite technology (based upon the Echo relay satellites). A Power StarTM is a large, deployable, thin-skinned balloon upon which solar cells and microwave transmitters are printed. For launch, the system is compactly folded into a spherical canister. Once attaining orbit, the canister is opened; the balloon inflated via sublimation of an interior coating; the skin rigidified, and the balloon finally evacuated. I review the state of manufacturability in printing technology, inflatable satellite technology, the retro-directive phased array technology for beam direction and shaping, and the power distribution design to address the “elbow problem”. Considerations of solar pressure effects, orbit maintenance, and thermal response are also presented.
In summary, while capable of substantial power generation, even with low efficiency solar cells, the
design has no moving parts, requires no in-space construction, and can be packaged in many existing
launch vehicle payload fairings, With these features, and according to current economic analyses, the
design can provide a first revenue system in one launch.