Introduction of Cartosat-1

In the area of Satellite based remote sensing in the past, the first generation satellite IRS-1A and 1B were designed, developed and launched successfully during 1988 and 1991 with multi-spectral cameras with spatial resolution of 72.5 m and 36 m. respectively. Subsequently, the second generation remote sensing satellites IRS-1C and 1D with improved spatial resolutions of 70 m in multi-spectral and 5.8 m. in Panchromatic bands and a wide field sensor with 188m resolution and 800 Km. swath, have been developed and successfully launched in 1995 and 1997 respectively. These satellites have become the principal components in the National Natural Resource Management System and the data was used in various applications, viz., agriculture and soil, land form and land use studies, water resource, forestry, drought and flood monitoring, cartography, town planning and coastal zone monitoring. Especially IRS-1C/D data has been used for cartographic and town planning application up to 1:10,000 scale. These satellites also provide stereo pairs of imageries to get height information to an accuracy of approximately 10 meters.

With the above scenario, India has a lead in the civilian remote sensing field in the world not only in terms of realisation and launching of complex satellites with high, medium and coarse resolution cameras, but also in the application areas as well. In order to maintain this lead and also provide continuity of data to global users, Cartosat-1 with two improved fore and aft PAN cameras with better than 2.5 m. spatial resolution is planned to be realised for launch by middle of 2003. This paper briefly presents the technical elements and the planned data products of the Cartosat-1 spacecraft.

CARTOSAT-1 Mapping Applications

With improved spatial resolution and stereo imaging capability it will enable the generation of Digital Elevation Models (DEM) and other value added products. The data from CARTOSAT-1 is expected to provide enhanced inputs for large scale mapping applications and stimulate newer applications in the urban and rural development, land and water resources management, disaster assessment, land cover change detection, relief planning and management, environmental impact assessment and various other Geographical Information Systems (GIS) applications.

CARTOSAT-1 Satellite Sensor Specifications

Resolution	2.5m
Launch Date	May 5, 2005
Launch Location	Sriharikota, India
Nominal Altitude	617.99 km
Orbits Per Day	15
Orbital Repeat Cycle	116 days
Nominal Wait Time to Acquire Adj.Path	11 days
Max. Wait Time for Revisit	5 days
Node for P/L Operations	Descending Node
Local Time for Equatorial Crossing	10:30 AM
Orbital Parameters
Semi-major axis	6996.128 km
Eccentricity	0.001
Inclination	97.87 degrees

CARTOSAT-1 Satellite Sensor

CARTOSAT-1 is a state-of-the-art remote sensing satellite built by ISRO (Indian Space Research Organization) which is mainly intended for cartographic applications in India. The 1560 kg satellite was launched by the PSLV on May 5, 2005 from the newly built second launch pad at Sriharikota, and is the eleventh satellite to be built in the Indian Remote Sensing (IRS) satellite series. Weighing 1560 kg at lift-off, CARTOSAT-1 is launched into a 618 km high polar Sun Synchronous Orbit (SSO) by PSLV-C6.

CARTOSAT-1 carries two panchromatic cameras that take black-and-white stereoscopic pictures in the visible region of the electromagnetic spectrum. The satellite images have a spatial resolution of 2.5 meter and cover a swath of 30 km. The cameras are mounted on the satellite in such a way that near simultaneous imaging of the same area from two different angles is possible. This facilitates the generation of accurate three-dimensional maps. The cameras maneuver across the direction of the satellite's movement to facilitate the imaging of an area more frequently. The images taken by CARTOSAT-1 cameras are compressed, encrypted, formatted and transmitted to the ground stations.

CARTOSAT-1 also carries a Solid State Recorder with a capacity of 120 Giga Bits to store the images taken by its cameras. The stored images can be transmitted when the satellite comes within the visibility zone of a ground station.

After its separation from the fourth stage of PSLV, CARTOSAT-1 is made to accurately point towards the earth through a series of complex maneuvers. This is followed by a thorough checkout of the satellite, switching on the cameras and fine tuning of the orbit.