Indian scientists have indigenously developed an aerostat which could be deployed for surveillance of Naxal-hit areas. Christened as 'Chakshu', this medium-sized aerostat is a result of a three-year collaboration between National Aerospace Laboratories (NAL), a Council of Scientific and Industrial Research (CSIR) lab, and Defence Research and Development Organisation.The 320-cubic metre helium-filled balloon can keep an eye on the happenings below it, remaining stationary at an altitude of 1.5 km. Three cameras can be mounted on the aerostat each having a range to scan developments in a 30 km radius. It can float in air for six hours to beam pictures.The scientists hope to carry out field trials after the DRDO flight testing range in Chitradurga in Karnataka is ready in 2011.