Kolkata (PTI): The all-weather Radar Imaging Satellite (RISAT), launched on April 20, has begun sending images, a top official of Indian Space Research Organisation said here on Friday.

"The RISAT has begun taking images since two days ago," ISRO chairman G Madhavan Nair said on the sidelines of an interactive session with members of the Calcutta Chamber of Commerce.

He said that the RISAT would take about a month to stabilise. India earlier bought images from the Canadian all-weather satellite before the RISAT was sent to the orbit.

The satellite, equipped with spying capabilities and capable of taking high-resolution images through clouds and using night vision, will help security agencies keep a watch on movement on the borders.

However, Mr. Nair was not very keen to term RISAT as a spy satellite, saying this would be mainly used for disaster management purpose. However, he explained, the pictures could be used for any purpose including defence.

RISAT is different from previous remote-sensing satellites as it uses the Synthetic Aperture Radar (SAR), equipped with many antennas to receive signals that are processed into high-resolution pictures.

The SAR, developed by the Israel Aerospace Industries, gives RISAT the defence capabilities.

The 300-kg satellite, orbiting at 550 km above earth, will also come handy in mapping and managing natural disasters such as floods and landslides besides increasing defence surveillance capabilities.

Meanwhile, speaking about Chandrayan-I, the first unmanned scientific mission to moon by India, Mr. Nair said the cameras of the satellite were capable of taking 10-metre close up shots of the moon's surface against 100 metres in other satellites.