736 
THE INDIAN REMOTE SENSING SATELLITE (IRS-1A) AND ITS 
APPLICATION POTENTIALS 
MG Chandrasekhar, V Jayaraman, K Radhakrishnan, 
CBS Dutt, B Manikiam, PP Nageswara Rao 
Indian Space Research Organisation 
Headquarters, Bangalore 
India 
ABSTRACT 
The Indian Remote Sensing Satellite (IRS) - 1A is the first of a series of 
indigenous remote sensing satellites that will serve the needs of resources survey 
and management. The operationalisation of IRS-1A and the effective use of IRS-1A 
data for various natural resources study is an important milestone in the Indian 
Remote Sensing Programme and it forms the back-bone for India's National Natural 
Resources Management System (NNRMS). The IRS-1A Satellite was launched on March 17, 
1988 and was declared operational on April 7, 1988. Since then the data from the 
Satellite is being collected on a routine basis and are supplied to users in India 
and abroad on an operational basis. Imaging Sensors on-board IRS-1A use state-of- 
art pushbroom scanners with CCDs as detectors and their characteristics in terms of 
spatial, spectral resolutions and swath were arrived at based on application needs 
of various remote sensing data users. The LISS-I (Linear Imaging Self Scanning) 
sensor has spatial resolution of 72 meters and swath 148 kms. The LISS-II sensors, 
two in number, provide spatial resolution of 36ms and ground swath 74 kms each and 
are designated as LISS-IIA and LISS-IIB and provide combined swath of 145 kms. 
Radiometric resolution of these sensors is 128 levels. The unique feature of this 
satellite is the dual resolution offered by the LISS-I (72 ms) and LISS-II (36 ms) 
sensors of IRS-1A which helps in looking at features in two different scales with 
uniform local conditions of the same area. This capability of overview of larger 
areas and at the same time providing an in-depth look at finer areas has been 
effectively made use of by the user agencies. 
Ever since its launch, the data from IRS-1A has been used extensively in various 
natural resources applications such as landuse/land cover, crop acreage estimations 
for rice and wheat, forest type identification, wastelands, soil salinity and land 
degradation, urban landuse, ground water targetting, hydrological studies relating 
to minor irrigation, command area studies, etc. IRS-1A data also has been used fob 
environmental studies relating to wild-life habitat analysis, estuarine eco-systems, 
turbidity levels of reservoirs and integrated drought management. In the field of 
coastal oceanography the potential of IRS data for coastal wetland mapping, mangrove 
identification and land form studies in Mahi estuary showed that IRS data are 
complementary to Landsat and SPOT. In addition IRS data is being operationally used 
in mapping the country's major flood, and related property losses and also in 
estimating the country’s total agricultural area for agro-climatic zones planning. 
Key Words : The Indian Remote Sensing Satellite (IRS-1A), LISS sensors, 
Application potentials, Natural resources management. 
1.0 INTRODUCTION 
Recognising the potentials and importance of systematic and periodic environmental 
data collection using space instrumentation, Indian Space Research 
Organisation/Department of Space, Government of India has conducted in the last two 
decades a variety of extensive studies using aerial flights and experimental 
satellite missions like Bhaskara I & II, with the active participation of user 
agencies. The IRS programme was initiated in early eighties in order to ultimately 
achieve a Natural Resources Information System for India. IRS-1A mission is the 
first step in evolving such an operational resources Management System for India. 
The IRS-1A satellite was designed and developed indigeneously and was launched on 
March 17, 1988 into a polar Sun-synchronous orbit of 904 km altitude by the Soviet 
Launcher VOSTAK from Bikanur. The orbital manoeuvres were completed and IRS-1A 
attained its designated Sun-synchronous orbit on April 7, 1988. Since then the data 
is collected on a routine basis as per the IRS referencing scheme and data products 
are supplied to the users on an operational basis. This paper briefly presents the 
specifications of the spacecraft and gives an account of its application potentials 
in the management of the natural resources of India (DOS, 1983). 
1.1 The Mission 
The polar sunsynchronous orbit of 904 kms altitude was chosen for IRS-1A with the 
equatorial crossing time of 10.25 AM in the descending node. Thus IRS-1A passes