Explained: ISRO’s RISAT-2B satellite works like a camera flash

The RISAT-2B satellite, launched by the Indian Space Research Organisation (ISRO) Wednesday morning, adds to India’s capability to observe the earth in all weathers and all conditions. The RISAT, or radar imaging satellite, is equipped with a sensor known as ‘synthetic aperture radar’, that takes what are known as ‘radar images’.

Very much like the flashlights of the camera, which release visible light to illuminate an object and then use the reflected light to create an image, the synthetic aperture radar send out hundreds of radio signals every second towards the subject (in this case, the earth) and capture the reflected signals to create a radio image, which can then be used by computers to build a real image.

Because the very large wavelength radio waves are not obstructed by clouds, dust or similar other obstacles in the atmosphere, they produce reliable images during day and night and all seasons.

ISRO said the images taken by RISAT-2B would be used for applications in agriculture, forestry and disaster management support. But services of such satellites are also in great demand from national security agencies as well.

Two satellites in RISAT series have earlier been launched by ISRO. RISAT-2 was the first one to be launched, in 2009, while RISAT-1, which had got delayed, was launched only in 2012. RISAT-1 is no longer operational.
After a very long time, ISRO’s PSLV rocket was used to launch just one satellite into space. In recent times, ISRO has been launching multiple satellites at one go.

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