direct the next stages of technological development of the concepts and systems in directions which will produce space power systems which are not undermined at a later date by publically perceived problems that make solar power unacceptable. No other proposed source of major power has ever been subjected to this in-depth scrutiny in the formative stages. It is hoped that a written version of the Koomanoff presentation can be provided by the Space Power Division of the Department of Energy to researchers at an early date. The paper, “A Space Power Station Without Movable Parts,” by M. Pospisil (Astronomical Institute, Ondrejov, Czechoslovakia) was read by Dr. J. Grey, one of the three chairpersons. In this approach microwaves are transmitted toward earth by a distributed array of transmitters located on the concave surface of a half-cylinder satellite. The concave surface is always directed toward earth. The solar cells are located on the outer or convex surface and produce a power output which is zero about local midnight, but has a broad high power output during local day. The power output maximizes during periods of maximum power usage on earth. It was argued that the mechanical and electrical simplicity of this approach compensates for the lower efficiency use of the solar collectors. A preprint was available (79-177). “Satellite Solar Power Stations Designs with Concentrators and Radiation Control,” (A.V. Lukjanov, Moscow State University, Department of Physics) was read to the meeting by a co-worker. It was proposed that large but low mass/optical concentrators can be used to focus sunlight onto either photovoltaic or thermal converters. Two versions of satellites were proposed. One using 5-10 km collectors and the other using several tens of smaller collectors (1 km diameter) constructed on a common platform. In both schemes all SPS attitude control would be carried out by means of sunlight pressure (preprint 79-176 available). H. Stoewer presented “European Technology Applicable to Solar Power Satellite Systems,” which was co-authored by B. Tilgner and D. Kassing (ESA/ESTEC, Noordwijk, The Netherlands). The preprint of the paper (79-174) was provided at the meeting. It was pointed out that European technological experience applicable to the SPS includes: solar arrays and solar cells; electrical power distribution experience in space dealing with high de power distribution and conditioning and high power management; microwave power transmission and beam steering and phase control; large space structural experience gained in development of the shuttle pallet satellite concept; attitude orbit control; thermal control and ground receiver station experience on high gain antennas and local oscillators. It is possible that in the early stages of SPS development the Ariane launch vehicle may be useful in deploying test articles into space. Europe has an adequate space technology base from which it can embark successfully on selective SPS concept assessment and technology verification tasks. R.A. Henderson (British Aerospace Dynamics Group, Bristol, U.K.) presented the most novel conceptual paper of the session, “A Power Transmission Concept for a European SPS System. ” It was proposed that the power from a SPS be beamed via a laser to a receiver mounted on a 2.6 km diameter rigid balloon stationed at approximately 30 km altitude. The balloon concept was first proposed by E.C. Okress (IEEE Spectrum 12, 41-46, 1978). Power would be converted to microwaves in the balloon and transmitted as 1.25 GW beams to rectennas on earth. Waste heat in the laser-to-microwave conversion would be used to heat the ambient air in the balloon to support the hot air balloon. Overall systems efficiency of 7% was predicted for sunlight to busbar electricity. In this system much smaller rectennas are possible and tighter microwave beams can be used.
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