The first commercial earth observation satellite to be developed
by the Indian Space Research Organisation IRS-1A was launched
in March 1988. To maintain continuity of data, an identical
satellite, IRS-1B followed in August 1991.
Data from these satellites has only been available for areas
within 2800km of the ground station at Shadnagar, Hyderabad,
India. More recently data has been received for much of North
America at the Norman ground station, Oklahoma, USA. Future
reception of IRS data is planned at many other sites, giving
near global coverage.
The satellites orbit with a repeat cycle of 22 days and
cross the equator at 10:30am local time. Data is recorded
in the blue, green, red and near infrared wavelengths, which
closely resemble the first four Landsat TM wavebands. The
imaging systems, named Linear Self Scanning Sensors (LISS),
have two configurations. The LISS-I scans images of 148km
x 174km with 72.5m resolution, while independent LISS-II
cameras scan four frames of 74km x 87km with 36.25m resolution,
which mosaic to cover a comparable area to the LISS-I frame.
An LISS-I image costs £1900 and a 4 frame LISS-II
composite costs £2850.
On
December 28th 1995 the next generation of Indian satellites
commenced with the launch of IRS-1C. The IRS-1C satellite
carries a PAN camera with 5.8m resolution, a 70km swath. Each
of these frames costs €2250. This is a steerable sensor
giving programmable stereo capabilities.
It also has an LISS-III
camera with green, red and near infrared bands with 23m resolution
and a middle infrared band with 70m resolution. The LISS-III
swath is approximately 145km and costs €2400 for a full
frame or €1600 for a quarter scene.
Together with an increasing number of Foreign Direct Receiving
Stations, the IRS-1C satellite has an onboard tape recorder,
enabling global coverage. IRS-1C will be particularly useful
for generation of high accuracy DEMs, and providing imagery
for land use, geological, environmental and urban applications.
IRS-1C also carries a WiFS camera with red and near infrared
wavebands at 188m resolution and 810km swath. The repeat
cycle of 5 days will enable monitoring of large scale changes
such as regional vegetation growth and stress.
On
December 28th 1995 the next generation of Indian satellites
commenced with the launch of IRS-1C. The IRS-1C satellite
carries a PAN camera with 5.8m resolution, a 70km swath. Each
of these frames costs €2250. This is a steerable sensor
giving programmable stereo capabilities. 
Together with an increasing number of Foreign Direct Receiving
Stations, the IRS-1C satellite has an onboard tape recorder,
enabling global coverage. IRS-1C will be particularly useful
for generation of high accuracy DEMs, and providing imagery
for land use, geological, environmental and urban applications.