ROOPAK GOSWAMI & G.S. MUDUR
Terror contour
May 3 : The Indian Space Research Organisation (Isro) has used RISAT, a radar imaging satellite which can penetrate clouds to take pictures, to track down the helicopter of Arunachal Pradesh chief minister Dorjee Khandu.
With tremendous pressure on the concerned agencies to locate the missing chopper, Isro finally had to resort to the use of RISAT.
“Uptil now, pictures taken by the satellites are optical remote sensing satellites which do not have the capability to penetrate clouds. All the pictures had shown cloud presence which made it difficult to get good images,” a senior Isro official in Bangalore told The Telegraph.
The cloud-free pictures taken by RISAT are being shared with the security agencies which can then use its ground forces to get to the actual location.
RISAT has the unique capability for day-night imaging, and imaging in all-weather conditions including fog and haze, and also provides information on soil moisture.
The satellite uses synthetic aperture radar technology, equipped with several antennas to receive greater signals to be processed into high-resolution pictures. This is used for primarily monitoring the human movements in and around the country’s borders while mapping and managing natural disasters such as floods and landslides in civil areas.
Reference maps derived from the images taken by RISAT show roads, water bodies, settlements, international boundary which can be of tremendous help to the agencies concerned.
The resolution of RISAT is one metre, which is of much higher resolution than that of optical remote sensing satellites. The official said the satellite was deployed by Isro in 2009 and pictures have been taken of several places of the region.
In the Northeast, there is North Eastern Space Applications Centre (NESAC) under Isro which provides an operational remote sensing based natural resource information base to assist activities on development/management of natural resources and infrastructure planning in the region.
For satellite imagery experts in Hyderabad, the search for the missing helicopter has turned into a search for telltale scars in the state’s forest canopy and mountain terrain.
The National Remote Sensing Centre in Hyderabad is using a set of images captured by four Earth-observation satellites, including two radar satellites, yesterday and today to help in the effort to search for the helicopter missing since Saturday morning.
“What they’ll be looking for is some sort of anomaly in the terrain — some telltale scar in the forest that might have been caused by a possible helicopter impact,” a senior remote sensing scientist at the NRSC told The Telegraph.