IRS-1B


IRS-1B, Indian Remote Sensing satellite-1B, the second of the series of indigenous state-of-art remote sensing satellites, was successfully launched into a polar Sun-synchronous orbit on 29 August 1991 from the Soviet Cosmodrome at Baikonur. IRS-1B carries two sensors, LISS-1 and LISS-2, with resolutions of and respectively with a swath width of about during each pass over the country. It was a part-operational, part-experimental mission to develop Indian expertise in satellite imagery. It was a successor to the remote sensing mission IRS-1A, both undertaken by the Indian Space Research Organisation.

History

IRS-1B was the second remote sensing mission to provide imagery for various land-based applications, such as agriculture, forestry, geology, and hydrology.

Satellite description

Improved features compared to its predecessor : gyroscope referencing for better orientation sensing, time tagged commanding facility for more flexibility in camera operation and line count information for better data product generation.
The satellite was a box-shaped 1.56 m x 1.66 m x 1.10 metres bus with two Sun-tracking solar panels of 8.5 square metres each. Two nickel-cadmium batteries provided power during eclipses. The three-axis stabilised Sun-synchronous satellite had a 0.4° pitch/roll and 0.5° yaw pointing accuracy provided by a zero-momentum reaction wheel system utilising Earth/Sun/star sensors and gyroscopes.

Instruments

IRS-1B carried two solid state push broom scanner Linear Imaging Self-Scanning Sensor :
  • LISS-1
  • LlSS-2
The satellite carried two LISS push broom CCD sensors operating in four spectral bands compatible with Landsat Thematic Mapper and Spot HRV data. The bands were 0.45-0.52, 0.52-0.59, 0.62-0.68, and 0.77-0.86 microns. The LISS-1 sensor had four 2048-element CCD imagers with a focal length of generating a resolution of and a swath width. The LISS-2 sensor had eight 2048-element CCD imagers with a focal length of generating a ground resolution of and a swath width. The LISS-2 imager bracketed the LISS-1 imager providing a overlap. Data from the LISS-1 were downlinked on S-band at 5.2 Mbps and from the LISS-2 at 10.4 Mbps to the ground station at Shadnagar, India. The satellite was controlled from Bangalore, India.

Mission

IRS-1B was operated in a Sun-synchronous orbit. On 29 August 1991, it had a perigee of, an apogee of, an inclination of 99.2°, and an orbital period of 102.7 minutes.
IRS-1B successfully completed its mission on 1 July 2001, after operating for 10 years.