June 16, 2019

Indian rocket successfully delivers radar observation satellite to orbit


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An Indian Polar Satellite Launch Vehicle lifts off from India’s spaceport on Sriharikota Island early Wednesday, local time. Credit: ISRO

An Indian rocket fired into space Wednesday with a high-power radar imaging satellite designed to peer through clouds and darkness to resolve signs of pollution, natural disasters and foreign military movements.

The 145-foot-tall (44.4-meter) Polar Satellite Launch Vehicle lifted off with more than a million pounds of thrust at 0000 GMT Wednesday (8 p.m. EDT Tuesday) from the Satish Dhawan Space Center, a spaceport on India’s southeastern coast with the Bay of Bengal.

The launcher’s solid-fueled first stage steered the rocket on a southeasterly course from the coastal space base, propelling the PSLV into a clear morning sky a few minutes before sunrise.

Liftoff occurred at 5:30 a.m. local time in India, marking the country’s third space launch of the year. Wednesday’s launch, designated PSLV-C46, was the 48th flight of India’s workhorse PSLV since its debut in 1993.

After a two-minute firing, the PSLV’s first stage burned out and jettisoned to fall into the sea. A second stage Vikas engine, consuming liquid propellants, ignited to continue the push into orbit, followed by burns of the rocket’s third and fourth stages.

Telemetry downlinked from the rocket indicated it hit its marks, and live video streaming from the PSLV’s fourth stage showed the 1,355-pound (615-kilogram) RISAT 2B radar observation satellite separating from the launcher less than 16 minutes into the mission.

Officials from the Indian Space Research Organization confirmed the PSLV placed the RISAT 2B spacecraft into an on-target 346-mile-high (557-kilometer) orbit, with an inclination of 37 degrees to the equator. Moments after separating from the rocket in space, RISAT 2B began transmitting its status to ground controllers, and ISRO officials declared the launch a success.

“I am extremely happy to announce that PSLV-C46 has successfully injected RISAT 2B precisely in the designated orbit,” said K. Sivan, ISRO’s chairmen, in a post-launch speech at the launch control center.

Designed for a five-year mission, RISAT 2B carries an X-band radar imaging instrument capable of resolving structures and features on Earth’s surface, regardless of daylight or weather conditions. Earth-looking optical telescopes are inhibited by cloudy weather, and only produce usable imagery during daytime.

The satellite was developed by ISRO — the Indian space agency — and carries a dish-shaped radar antenna that was folded up to fit inside the rocket’s payload compartment. Now that the satellite is in space, its radial band antenna will be unfurled to its full diameter of 11.8 feet (3.6 meters).

“This has been a much-awaited satellite with complex new technologies, X-band synthetic aperture radar, and one of the most cutting edge technologies in the world — one that is world-class — the 3.6-meter radial band antenna,” said P. Kunhikrishnan, director of ISRO’s UR Rao Satellite Center in Bangalore.

The spacecraft will supply 2 kilowatts of power to the radar instrument, which is able to collect imagery in spotlight, strip and mosaic modes. The imaging resolution of RISAT 2B’s radar has not been disclosed by ISRO.

According to an information kit released by ISRO, RISAT 2B will provide imagery to support applications in agriculture, forestry and disaster management.

Orbiting radars can also detect features, such as camouflaged military assets, on the ground that can escape detection with optical Earth observation satellites. The enhanced observing capability of radar satellites makes them useful for military and intelligence agencies.

The orbit selected for the RISAT 2B satellite does not provide global radar observation coverage, but it offers regular passes over Indian territory and neighboring Pakistan, a longtime strategic rival to India in the region.

At least four Indian radar observation satellites are currently scheduled for launch this year, beginning with RISAT 2B. The first in a new generation of high-resolution optical surveillance satellites, known as Cartosat 3, will launch on a PSLV mission as soon as June, according to Indian news reports.

RISAT 2B is the first Indian radar satellite to launch since 2012.

The predecessor RISAT 2 satellite has been in space since 2009, and remains operational, according to the Hindu, an English-language Indian news paper. RISAT 2’s X-band radar was supplied by Israel.

The RISAT 1 Earth-imaging craft was launched in 2012 with an Indian-produced C-band radar, and is no longer collecting data, the Hindu reported.

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Follow Stephen Clark on Twitter: @StephenClark1.


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