urn:nasa:pds:context:instrument_host:spacecraft.sakig 1.0 1.7.0.0 Product_Context 2016-10-01 1.0 extracted metadata from PDS3 catalog and modified to comply with PDS4 Information Model urn:nasa:pds:context:investigation:mission.sakigake::1.0 instrument_host_to_investigation urn:nasa:pds:context:instrument:imf.sakig::1.0 instrument_host_to_instrument urn:nasa:pds:context:instrument:sow.sakig::1.0 instrument_host_to_instrument Reinhard, R and B. Battrick (eds), 'Space Missions to Halley's Comet', European Space Agency ESA SP-1066, ESA Pub Div, Moordwijk, Netherlands, 1986. reference.ESA-SP1066 'Encounters with Comet Halley, The first results', Nature, Volume 321, No. 6067, 15 May 1986. reference.NATURE321 SAKIGAKE Spacecraft SAKIG Instrument Host Overview ======================== Planet-A and MS-T5 are identical except for their scientific payloads. The main spacecraft body is a cylinder, 140 cm in diameter and 70 cm high. The spinning spacecraft is about 250 cm high, from the top of the high- gain antenna dish to the bottom of the medium-gain antenna. Its outer wall is covered by solar cells which produce 100 W of power under optimum conditions. An equipment platform mounted to a central thrust tube carries most of the subsystems, including the mechanically despun, high-gain antenna, two hydrazine fuel tanks, the thrusters, and the experiment sensors. A star scanner and a nutation damper are attached to the thrust tube. Planet-A and MS-TS weigh 139.5 kg and 138.1 kg, respectively, including lO kg of hydrazine propellant in each case. Both spacecraft are spin-stabilized, with the facility to change the spin rate. The spin axes of both spacecraft will be kept perpendicular to the ecliptic plane. The spacecraft/Earth geometry and the data-rate requirements preclude the use of a single antenna for the duration of the mission. The antenna subsystem therefore consists of a high-gain antenna, a medium-gain antenna as a backup, and a low-gain antenna for near-Earth operation. The despun high-gain antenna has an offset- parabolic reflector with a diameter of 80 cm and a gain of 21.5 dB in uplink and 22.5 dB in downlink transmission. The communications subsystem operates in 5-band using a 5 W transmitter. MS-T5 has four data formats(Table below). The data rates of both spacecraft are 2048 bit/s (without coding) in 'high bit rate' and 64 bit/s (with convolutional coding) in 'low bit rate' mode. The bit rate used will depend on the communication distance. The ground station for the mission has been built at Usuda, about 170 km northwest of Tokyo. The station's 64 m diameter dish antenna has a gain of approximately 63 dB. A 64 bit/s communication link (convolutionally encoded PCM) is expected to be possible from 1.1 AU, which will be the comet-Earth distance during the Planet-A encounter. -------------------------------------------------------------------------- Table. The MS-T5 scientific payload Experiment Mass Power Data rate Principal Investigator (kg) (W) Format 1/2/3/4 -------------------------------------------------------------------------- H 512/768/768/0 H. Oya, Faculty of Science, PWP 5.2* 1.7 L 32/48/48/0 Tohoku Univ., Sendai SOW 2.0 1.1 H 512/768/0/768 K. Oyama, Res. Div. Planetary L 32/48/0/48 Science, ISAS, Tokyo H 400/0/768/768 T. Saito, Faculty of Science, IMF 5.4** 2. L 25/0/48/48 Tohoku Univ., Sendai -------------------------------------------------------------------------- Format 1 PWP SOW IMF H = High bit rate 2 PWP SOW L = law bit rate 3 PWP IMF 4 SOW IMF * Includes dipole antenna, search coil and electronics ** Includes boom