A brief history of the first US JATO flight tests of August 1941
- Paper ID
IAF-85-453
- author
- company
US Air Force
- country
U.S.A.
- year
1985
- abstract
This paper describes a simple antenna despun spacecraft with high efficiency GaAs solar cells for communications application. The spacecraft is planned for use of the coming generation of the Japanese domestic communications satellite (CS-3). Most of recent communications satellites are of either 3-axis stabilized type with large solar wings or spin stabilized type with expandable solar cylinders. The size of solar arrays is important to satisfy the power requirement, which has been increasing as the increase of communications capacity per spacecraft. The spacecraft described in this paper is designed by a different approach: i.e. to achieve high level of primary solar power by using high efficiency solar cells with limited area of solar arrays. The spacecraft has other design features also; i.e. the use of light weight CFRP main body structure and light weight electronics design including the use of MIC’s. The spacecraft is compatible with the Japanese H-I launch vehicle. GaAs solar cells to be used for the spacecraft are expected to have an average efficiency of 17.5% at the beginning of life and 14.5% after 7 years in the geostationary orbit. The solar array consists of approximately 37,000 pieces of GaAs solar cells of 2 cm X 2 cm in size. The cells'are placed on light weight KFRP A1 honeycomb substrate panels by the shingle mount method. This provides an efficient use of the array area with respect to solar power generation. The output power available from the solar array is expected to be about 840 W at EOL equinox (7 years). The main body (central cylinder) of the spacecraft consists of a single body CFRP cone fabricated by the filament winding method. The spacecraft has two equipment platforms supported by the cylinder, on one of which are held communication modules, and spacecraft bus electronics and the propulsion subsystem are placed on the other platform. The spacecraft has a dry mass of approximately 470 kg, of which approximately 110 kg is allocated to communications transponders. CS-3 is now in the design phase and expected to be launched in 1988.