IRS-1A

IRS-1A, Indian Remote Sensing satellite-1A, the first of the series of indigenous state-of-art remote sensing satellites, was successfully launched into a polar Sun-synchronous orbit on 17 March 1988 from the Soviet Cosmodrome at Baikonur. IRS-1A carries two sensors, LISS-1 and LISS-2, with resolutions of 72 m and 36 m respectively with a swath width of about 140 km during each pass over the country. Undertaken by the Indian Space Research Organisation (ISRO). It was a part-operational, part-experimental mission to develop Indian expertise in satellite imagery.

History
The availability of Landsat imagery created a lot of interest in the science community. The Hyderabad ground station started receiving Landsat data on a regular basis in 1978. The Landsat program with its design and potentials was certainly a great model and yardstick for the IRS programme. IRS-1A was the first remote sensing mission to provide imagery for various land-based applications, such as agriculture, forestry, geology, and hydrology. The mission's long-term objective was to develop indigenous remote sensing capability.

Satellite description
The satellite bus, measuring 1.56 m x 1.66 m x 1.10 metres, had the payload module attached on the top and a deployable solar panels stowed on either side. Attitude control was provided by four-momentum wheels, two magnetic torques, and a thruster system. Together, they gave an estimated accuracy of better than ± 0.10° in all three axes.

Instruments
IRS-1A carried two "Linear Imaging Self-Scanning Sensor", LISS-1 and LISS-2, with a spatial resolution of 72 m and 36 m respectively. The three-axis-stabilised Sun-synchronous satellite carried LISS sensors which performed "push-broom" scanning in visible and near-infrared bands to acquire images of the Earth. Local equatorial crossing time (ECT) was fixed at around 10:30 of the morning.

Launch
IRS-1A was launched on 17 March 1988, at 06:43:00 UTC. It had a perigee of 863 km, an apogee of 917 km, an inclination of 99.01°, and an orbital period of 102.7 minutes.

Mission
IRS-1A was operated in a Sun-synchronous orbit. IRS-1A successfully completed its mission on 1 July 1992 after operating for 4 years.