CHANDRAYAAN 1 SPACE CRAFT DESCRIPTION

Description Spacecraft for lunar mission is : Cuboid in shape of approximately 1.5 m side. Weighing 1380 kg at launch and 675 kg at lunar orbit. Accommodates eleven science payloads. 3-axis stabilized spacecraft using two star sensors, gyros and four reaction wheels. The power generation would be through a canted single-sided solar array to provide required power during all phases of the mission. This deployable solar array consisting of a single panel generates 750W of peak power. Solar array along with yoke would be stowed on the south deck of the spacecraft in the launch phase. During eclipse, spacecraft will be powered by Lithium ion (Li-Ion) batteries. After deployment, the solar panel plane is canted by 30º to the spacecraft pitch axis. The spacecraft employs a X-band, 0.7m diameter parabolic antenna for payload data transmission. The antenna employs a dual gimbal mechanism to track the earth station when the spacecraft is in lunar orbit. The spacecraft uses a bipropellant integrated propulsion system to reach lunar orbit as well as orbit and attitude maintenance while orbiting the Moon. The propulsion system carries required propellant for a mission life of 2 years, with adequate margin. The Telemetry, Tracking & Command (TTC) communication is in S-band frequency. The scientific payload data transmission is in X-band frequency. The spacecraft has three Solid State Recorders (SSRs) Onboard to record data from various payloads. SSR-1 will store science payload data and has capability of storing 32Gb data. SSR-2 will store science payload data along with spacecraft attitude information (gyro and star sensor), satellite house keeping and other auxiliary data. The storing capacity of SSR-2 is 8Gb. M3 (Moon Mineralogy Mapper) payload has an independent SSR with 10Gb capacity.