Mission typeEarth observation
Remote sensing
COSPAR ID1991-061A
SATCAT no.21688
Mission duration3 years (planned)
12 years and 4 months
Spacecraft properties
Launch mass975 kg
Power600 watts
Start of mission
Launch date29 August 1991,
06:48:43 UTC
RocketVostok-2M s/n I15000-079
Launch siteBaikonur, Site 31/6
End of mission
Last contact20 December 2003
Orbital parameters
Reference systemGeocentric [1]
Perigee altitude859 km
Apogee altitude915 km
Period102.7 minutes
Epoch29 August 1991
← IRS-1A
IRS-1C →

IRS-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 three cameras, LISS-1, LISS-2A and LISS-2B with resolutions of 72.5 metres (238 ft) and 36.25 metres (118.9 ft) respectively with a swath width of about 140 kilometres (87 mi) 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 (ISRO).[2]


IRS-1B was the second remote sensing mission to provide imagery for various land-based applications, such as agriculture, forestry, geology, and hydrology.[3]


Improved features compared to its predecessor (IRS-1A): gyro referencing for better orientation sensing, time tagged commanding facility for more flexibility in camera operation and line count information for better data product generation.[2]

The spacecraft was a box-shaped 1.6 x 1.56 x 1.1-metre bus with two Sun-tracking solar arrays 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 gyros.[3]


IRS-1B carried three solid state push broom scanner Linear Imaging Self-Scanner (LISS) cameras:

  • LISS-1 (72.5 metres (238 ft) each band ground resolution)
  • LlSS-2A and 2B (36.25 metres (118.9 ft) each band ground resolution) [4]

The satellite carried three 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 162.2 centimetres (63.9 in) generating a resolution of 72.5 metres (238 ft) and a 148 kilometres (92 mi) swath width. The LISS 2A/B sensors had eight 2048-element CCD imagers with a focal length of 324.4 millimetres (12.77 in) generating a ground resolution of 36.25 metres (118.9 ft) and a 74 kilometres (46 mi) swath width. The two LISS 2 imagers bracketed the LISS 1 imager providing a 3 kilometres (1.9 mi) overlap. Data from the LISS 1 were downlinked on S-band at 5.2 Mbps and from the LISS 2 A/B at 10.4 Mbps to the ground station at Shadnagar, India. The satellite was controlled from Bangalore, India.[3]


IRS-1B was operated in a Sun-synchronous orbit. On 29 August 1991, it had a perigee of 859 kilometres (534 mi), an apogee of 915 kilometres (569 mi), an inclination of 99.2°, and an orbital period of 102.7 minutes.[1]

IRS-1B successfully completed its mission on 20 December 2003, after operating for 12 years and 4 months.[2]

See also


  1. ^ a b "IRS-1B: Trajectory 1991-061A". NASA. 17 April 2020. Retrieved 3 May 2020. This article incorporates text from this source, which is in the public domain.
  2. ^ a b c "IRS-1B". Indian Space Research Organisation. Indian Space Research Organisation. 2008. Archived from the original on 20 March 2011. Retrieved 3 May 2020.
  3. ^ a b c "IRS-1B: Display 1991-061A". NASA. 17 April 2020. Retrieved 3 May 2020. This article incorporates text from this source, which is in the public domain.
  4. ^ "IRS (Indian Remote Sensing Satellites) - Overview and early LEO Program of ISRO". Retrieved April 8, 2013.

External links

  • ISRO IRS-1B link