India Launches Radar Imaging Craft on PSLV

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BANGALORE, India — India is poised to expand its space-based remote sensing capabilities following the successful launch of a radar imaging satellite April 26 aboard a domestic rocket.

Weighing 1,858 kilograms, Risat-1 was launched by an enhanced variant of India’s Polar Satellite Launch Vehicle (PSLV) during the early morning hours from the Satish Dhawan Space Centre at Sriharikota Island off India’s southeastern coast.

“The mission is a grand success,” K. Radhakrishnan, chief of the Indian Space Research Organisation (ISRO), declared during a televised postlaunch function.

ISRO spokesman S. Satish said the satellite was injected into a near-polar orbit with an altitude of 480 kilometers and an inclination of 97.55 degrees relative to the equator. Over the next day or two, Risat-1 will use on-board thrusters to climb to its operational 536-kilometer orbit, where it will circle the Earth 14 times per day, he said.

Satish said the mission was the 20th straight success in 21 PSLV launches to date and that Risat-1 is the heaviest satellite launched yet on the rocket. Similar variants of the vehicle were used to launch India’s Chandrayaan-1 lunar orbiter in 2008 and the GSat-12 communications satellite in 2011.

Risat-1 is equipped with a C-band synthetic aperture radar (SAR) capable of collecting Earth imagery at resolutions from 3 to 50 meters in various polarization modes. Unlike optical sensors, which rely on reflected light to capture imagery, radar sensors can collect useful data during both night and day, regardless of weather conditions.

Risat-1 is ISRO’s second radar imaging satellite but the first to carry an indigenously built SAR. The first satellite, Risat-2 —  launched hurriedly in April 2009 following the 2008 Mumbai terrorist attacks — used an X-band SAR supplied by Israel.

Risat-1 has a design life of five years and, according to Satish, will be used for applications including crop monitoring, disaster management and national security. He said the payload is expected to be activated by May1.