Polar Satellite Launch Vehicle

The PSLV or Polar Satellite Launch Vehicle is an expendable launch system operated by the Indian Space Research Organisation (ISRO). It was developed to allow India to launch its Indian Remote Sensing (IRS) satellites into sun synchronous orbits, a service that was, until the advent of the PSLV,commercially viable only from Russia. PSLV can also launch small size satellites into geostationary transfer orbit (GTO).

A sun-synchronous orbit (also rarely called a heliosynchronous orbit) is a geocentric orbit which combines altitude and inclination in such a way that an object on that orbit passes over any given point of the Earth's surface at the same local solar time. The surface illumination angle will be nearly the same every time. This consistent lighting is a useful characteristic for satellites that image the earth's surface in visible or infrared wavelengths (e.g. weather, spy and remote sensing satellites). There is, of course, a yearly oscillation of the actual solar time of passage because of the eccentricity of the Earth's orbit.

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