rahuldeshpande

Well said.

A direct link to images : http://www.isro.gov.in/rlv-td/reusable-launch-vehicle-techno...

From an article - Because a return signal from an ordinary target illuminated by a radar transmitter diminishes as the inverse of the fourth power of the distance, for the surveillance radar to work effectively, these satellites had to be placed in low Earth orbit. Had they used large solar panels for power, the orbit would have rapidly decayed due to drag through the upper atmosphere. Further, the satellite would have been useless in the shadow of Earth.