June 16, 2019

Indian radar reconnaissance satellite set for launch


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An Indian Polar Satellite Launch Vehicle stands at the First Launch Pad at the Satish Dhawan Space Center in preparation for launch Wednesday. Credit: ISRO

An Indian satellite designed to collect all-weather, day-and-night radar imagery for military and intelligence authorities is scheduled for launch Wednesday on top of a Polar Satellite Launch Vehicle.

The RISAT 2B radar imaging satellite is mounted atop the Indian PSLV in preparation for liftoff at 0000 GMT Wednesday (8 p.m. EDT Tuesday) from the Satish Dhawan Space Center, India’s launch base on the country’s southeastern coast with the Bay of Bengal.

Launch preparations Tuesday were running smoothly, with final countdown activities and fueling underway, according to the Indian Space Research Organization. The PSLV’s second and fourth stages, which burn a mix of liquid propellants, were being filled Tuesday. The PSLV’s first and third stages burn pre-packed solid propellants.

The launch, which is timed for 5:30 a.m. local time in India, will mark the 48th flight of a PSLV since 1993, and the 14th mission to use the PSLV’s “Core Alone” configuration without any strap-on solid rocket boosters. It will also be the third PSLV launch of the year.

After firing off its launch pad on Sriharikota Island, located around 50 miles (80 kilometers) north of the Indian coastal city of Chennai, the PSLV will turn toward the southeast. The PSLV’s first stage, producing more than a million pounds of thrust at maximum power, will burn out and jettison nearly two minutes after liftoff.

A liquid-fueled Vikas engine on the rocket’s second stage will fire next, followed by separation of the PSLV’s two-piece, clamshell-like payload fairing at T+plus 2 minutes, 57 seconds. After second stage shutdown and separation, the PSLV’s third stage solid rocket motor will ignite at T+plus 4 minutes, 23 seconds, for a nearly two-minute burn.

Following a brief coast period, the PSLV’s fourth stage will ignite at T+plus 9 minutes, 34 seconds. Powered by two liquid-fueled thrusters, the fourth stage will fire more than five minutes to inject the RISAT 2B satellite into a 346-mile-high (557-kilometer) orbit, inclined 37 degrees to the equator.

Separation of the RISAT 2B payload is scheduled for T+plus 15 minutes, 29 seconds, to conclude the launch sequence.

Designed for a five-year mission, RISAT 2B carries an X-band radar imaging instrument capable of peering through clouds and darkness to resolve structures and features on Earth’s surface. Earth-looking optical telescopes are inhibited by cloudy weather, and only produce imagery during daytime.

The satellite was developed by ISRO — the Indian space agency — and weighs approximately 1,355 pounds (615 kilograms) at launch. RISAT 2B’s dish-shaped radar antenna, folded up to fit inside the rocket’s payload compartment, will be unfurled after the satellite arrives in space.

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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