A.C. Charania
(SpaceWorks Engineering, Inc. (SEI), USA)

Niche markets (military installations, developing nation remote power, etc.) may be potential markets where Space Solar Power (SSP) satellites may be economically viable, given certain government support and Earth-to-Orbit launch cost assumptions. An operational demonstrator could be one approach for those markets. This paper examines such a concept, referred to by the authors as the SSP First Revenue Satellite (FRS). The FRS would be a mid-power (1-20 MW of delivered power) space-to-ground demonstrator of SSP. The purpose would be two-fold, prove the end-to-end technical capability and then demonstrate operations over multiple years. The FRS system would be turned over to commercial operators for public/private service. This is deemed to be a more feasible and useful mid-scale demonstration of SSP. This would be a hybrid public-private system consisting of low number of satellite systems. A notional SSP architecture is taken as a case study for this examination. Economic analysis is performed to look at the output prices such a venture would charge based upon various financing options. The objective of this analysis is to determine whether the FRS can be a commercially viable pathway for an SSP demonstrator.

Susumu Sasaki
(JAXA, Japan)

There are four major research activities associated with Space Solar Power Systems (SSPS) in JAXA. The first one is demonstration of wireless power transmission on ground both for microwave and laser. We will demonstrate the beam pointing technologies with kW-level in the range of 100 m scale. For laser, we also make research to establish the sun light-laser (1.06 micron m) direct conversion technologies for SSPS. The second one is preparation for demonstration experiments of wireless power transmission in orbit. The small scientific satellite now under development in Japan or JEM on the International Space Station is the possible platform to conduct kW-level space-to-ground power transmission experiment. The third one is to establish the technologies to construct 100 m square scale structures both for power generation/transmission panel 0.1m thick and thin film mirror less than several hundreds of g/m2. Scale models will be used to demonstrate the construction technologies on ground. The fourth one is to develop a realistic roadmap towards the commercial SSPS in mid-2030, considering technical feasibilities. The roadmap will include the feasible development scenario for future space transportation systems.

Masashi Iwashita
(Kobe University, Japan)

The microwave-beam control system is one of the most important and critical issues for realization of the Solar Power Satellite (SPS). The retrodirective antenna is a very promising technology using a pilot signal radiated from the receiving site to the transmitting antenna. We succeeded in the demonstration of the microwave-beam control with the retrodirective antenna system in the International Symposium on Solar Energy from Space at Toronto in September 2009. The system consists of 9 transmitting panels, each of which can radiate 2.45 GHz microwave power of 20 W, a rover with 4 rectenna panels, and a pilot signal transmitter. This rover is driven by DC electricity converted from received microwave-beam power at the rectenna panels. LED connected to the rectenna panel is also used to show receiving microwave-beam. The distance between the transmitting site and the receiving site is about 13 m in this demonstration. The retrodirective antenna system worked very well and the demonstration was a great successful.

Frank Little
(Texas A&M University, USA)

A free-flying satellite low earth orbit to earth demonstration of retrodirective controlled phased array wireless power transmission for space based solar power is planned. The objective is to demonstrate beam control and measure the beam pattern on the ground. The experiment will be part of a larger experiment to demonstrate deployment of a large antenna structure. The definition and design of a semi-autonomous transmission module to be attached to the antenna structure is described. The module is designed to be a lightweight sandwich structure with photovoltaic cells for energy generation on the top and the transmitting array on the bottom of the module structure. Communications and guidance, navigation and control are assumed to be functions of the larger structure deployment experiment. Energy generation and storage, power management and distribution and thermal control systems are developed to support retrodirective phased array antenna transmission experiments. .

Tomoaki Sakurai
(Keio University, Japan)

It is possible that when Dr. Peter Glaser proposed Space Solar Power Satellite (SSPS) in 1968, his motivation was purely scientific. But, after that many organizations such as JAXA, NASA, and ESA started to investigate the possibility of using the satellite power system to generate an alternative energy. The motivations and needs to produce energy from outside Earth sphere are boosted by concerns for environmental issues. On the other side, the concern of these agencies for the realization of this system is mainly centered on economic feasibility and the availability of technology. The SSPS is composed by for segments which are Satellite, Transportation to space (Rocket), Energy transmission, and Ground-base station. The technology in each segment has reached a very advanced level, but the entire system hasn't been created after many years of research done by these important agencies. To answer these questions, we would like to investigate feasibility problems related from both technological and economical viewpoints. Also, it is very interesting to understand the motivations and needs that push scientists to consider this system as a real project and also evaluate its competitive advantage in contrast with other existing or possible energy systems.