0191-9067/85 $3.00 + .00 Copyright ® 1985 SUN SAT Energy Council LASER PROPULSION TEST ONBOARD SPACE STATION TAKASHI ABE and KYOICHI KURIKI Institute of Space and Astronautical Science Komaba 4-6-1, Meguroku Tokyo,Japan Abstract — A laser propulsion system (LAPS) onboard the Space Station (SS) is studied. In this system, the laser power is supplied from the laser system onboard SS to a subsatellite being deployed from SS. The satellite can control its orbital transfer by converting the laser power to a thrust. The technology for the system is reviewed and the LAPS test onboard SS is proposed. INTRODUCTION The mission of the orbital transfer from low Earth orbit (on which Space Station (SS) is constructed) to the other orbit (e.g., the geosynchronous Earth orbit) is highly desired. These missions require a thruster having the following qualities: 1) high Isp, 2) high reliability, and 3) light weight. The laser propulsion system (LAPS) is a candidate for these missions. In fact, it can have a high Isp (500 sec-2000 sec) (1), in comparison with a conventional chemical rocket (Isp ~ 400 sec) (see Fig. 1) (1). Furthermore, the system becomes simple and lightweight, since the laser power as an energy source is transferred remotely. In this article, we review the technology for LAPS and propose a LAPS test onboard the SS. REVIEW OF TECHNOLOGY FOR LAPS Laser Power Transmission Figure 2 shows the relation between the radius of the transmitter (Df the receiver (Dr), and the beam transmission range (2). This relation is determined by the defraction limit. As can be seen from this figure, the electromagnetic wave having a shorter wavelength is desirable for the larger transmission range, for fixed values of Dt and Dr. Thruster for Laser Propulsion In Fig. 3, two types of the thruster structures are shown schematically (1). In the one-port type engine, a laser beam is introduced from the nozzle exit, while, in the two-port type engine, a laser beam is received at first and is introduced into the absorption chamber. In both of them, the laser energy is absorbed mainly by the
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