Risat1 undergoing final checks (Image courtesy: ISRO)

India’s space agency, ISRO, has commenced countdown for the launch of  country’s first indigenously-built spy/surveillance satellite.

The launch is scheduled for early Thursday (April 26) from Sriharikota, 80 kilmoeters from the southern city of Chennai.

“The 71-hour countdown commenced at 06:47 hours today (April 23, 2012). During the Countdown, propellant-filling operations of the liquid propellant second stage (PS2) and fourth stage (PS4) of the launch vehicle will be carried out. Besides, mandatory checks on the launch vehicle and spacecraft will be carried out,” said a press release by ISRO.

PSLV-C19 (Image courtesy: ISRO)

India’s launch vehicle PSLV-C19  would inject the 1,858 kg RISAT-1 satellite into an orbit of 480 km altitude at an inclination of 97.552 degree. The satellite will be put in its final orbital configuration at 536 km altitude using thrusters onboard the satellite.

Also, charging of batteries and pressurisation of propellant tanks onboard the satellite will be performed. Readiness of various ground systems such as tracking radar systems and communication networks will also be checked.

India has emerged a world leader in space technology, with the largest constellation of remote sensing satellites providing imagery in a variety of spatial resolutions from more than a metre ranging upto 500 meters. It has 11 remote sensing/earth observation satellites currently in the space.