All eyes on India's cryo engine as GSLV readies for lift-off on Thursday
CHENNAI: All eyes at the Sriharikota spaceport will be on the indigenous cryogenic engine which forms the third and upper stage of the GSLV-D6 rocket that will lift off at 4.52pm on Thursday with GSAT-6, a 2,117kg communication satellite.
This will be the ninth flight of the Geostationary Satellite Launch Vehicle and the third development flight using a cryogenic engine. The success-failure score of the development flights has been 1-1.
Indian Space Research Organisation (Isro) had used up six of the seven cryogenic engines it got decades ago, and now have to master the technology for future launches of heavy satellites. Isro is building a more powerful cryogenic engine to be used in its GSLV-MIII vehicle to carry four-tonne satellites. This is also the designated carrier for Isro's proposed manned missions.
After the mission readiness review committee and the launch authorization board cleared the launch, the 29-hour countdown for the launch started at 11.52am on Wednesday.
GSLV-D6 vehicle was configured with all its three stages including the CUS similar to the ones successfully flown during the previous GSLV-D5 mission in January 2014, an Isro statement said. GSLV-D5 had successfully placed GSAT-14 satellite carried on-board in the intended GTO very accurately.
The metallic payload fairing of GSLV-D6 has a diameter of 3.4 m. The overall length of GSLV-D6 is 49.1 m with a lift-off mass of 416 t.
The cryogenic upper stage (CUS) being flown in GSLV-D6 is designated as CUS-06. A cryogenic rocket stage is more efficient and provides more thrust for every kilogram of propellant it burns compared to solid and earth-storable liquid propellant rocket stages.
The cryogenic stage is technically a very complex system compared to solid or earth-storable liquid propellant stages due to its use of propellants at extremely low temperatures and the associated thermal and structural challenges. Oxygen liquefies at -183 degree Celsius and Hydrogen at -253 degree Celsius. The propellants, at these low temperatures, are to be pumped using turbo pumps running at around 40,000 rpm.
The main engine and two smaller steering engines of CUS together develop a nominal thrust of 73.55 kN in vacuum. During the flight, CUS fires for a nominal duration of 720 seconds. S-band telemetry and C-band transponders enable GSLV-D6 performance monitoring, tracking, range safety/ flight safety and preliminary orbit determination (POD).
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All eyes on India's cryo engine as GSLV readies for lift-off on Thursday - The Times of India
Countdown begins for launch of Indian military satellite
Posted on August 26, 2015 by
Stephen Clark
India’s Geosynchronous Satellite Launch Vehicle rolls out to the Second Launch Pad at its launch base on Sriharikota Island on India’s east coast. Credit: ISRO
A government-owned communications satellite heading for geostationary orbit 22,300 miles above Earth is set for launch Thursday to on a nine-year mission to to support the Indian military.
The 4,667-pound GSAT 6 spacecraft will lift off aboard India’s Geosynchronous Satellite Launch Vehicle at 1122 GMT (7:22 a.m. EDT) Thursday from the Satish Dhawan Space Center, a spaceport situated about 50 miles north of Chennai on India’s east coast.
Shrouded inside the GSLV’s metallic nose fairing, the satellite is India’s 25th geostationary communications satellite and has a mission to serve “strategic users,” according to the Indian Space Research Organization. Indian news reports said the prime customer for the new signal relay craft is the Indian military.
ISRO officials said the 29-hour countdown began Wednesday, and launch crews planned to fill the rocket’s four liquid-fueled boosters and second stage with storable hydrazine and nitrogen tetroxide propellants later in the day. Fueling of the GSLV’s third stage with cryogenic liquid hydrogen and liquid oxygen will come in the final hours of the countdown.
The first stage’s solid propellant load was packed inside the motor when it was assembled.
Launch is scheduled for 4:52 p.m. local time Thursday at the Indian launch base, and 161-foot-tall GSLV will fire away on the power of four hydrazine-burning strap-on Vikas booster engines and a solid-fueled core motor. At peak power, the first stage and the boosters will generate more than 1.7 million pounds of thrust.
The four liquid-fueled boosters will ignite at T-minus 4.8 seconds and ramp up to full thrust before the solid first stage fires when the countdown clock reaches zero.
The core motor will consume its propellant load by T+plus 1 minute, 46 seconds, followed by shutdown of the four Vikas booster engines at T+plus 2 minutes, 29 seconds. A single second stage Vikas powerplant will take over and burn until just shy of the mission’s five-minute point, during which time the GSLV’s payload fairing will release once the rocket is out of the dense lower atmosphere — a milestone projected at T+plus 3 minutes, 50 seconds.
A cryogenic upper stage engine will ignite at T+plus 4 minutes, 54 seconds, for a nearly 12-minute firing to propel the GSAT 6 satellite into an oval-shaped geostationary transfer orbit. Spacecraft separation is schedule for T+plus 17 minutes, 4 seconds, according to ISRO.
India’s GSAT 6 communications satellite is pictured before encapsulation inside the GSLV’s payload fairing. Credit: ISRO
The launch is targeting an orbit with a high point of 22,353 miles (35,975 kilometers), a low point of 105 miles (170 kilometers) and an inclination of 19.95 degrees.
Thursday’s launch marks the third time the Indian-built cryogenic engine, which burns a super-cold mixture of liquid hydrogen and liquid oxygen, has flown on the GSLV. Earlier GSLV flights, dating back to the rocket’s maiden mission in 2001, employed a Russian-made cryogenic third stage.
The all-Indian version of the GSLV, called the GSLV Mk.2, failed on its first launch in April 2010 due to a failure in the upper stage engine’s liquid hydrogen turbopump. The second test launch of the GSLV Mk.2 in January 2014 was successful.
The launch of GSAT 6 is the ninth flight of the GSLV in both its all-Indian and part-Russian configurations. ISRO considers four of the eight launches to date as successful.
Thursday’s launch, designated GSLV-D6 by ISRO, is India’s third space mission of the year after two flawless flights of the smaller Polar Satellite Launch Vehicle.
GSAT 6 will fire its on-board propulsion system to circularize its orbit 22,300 miles above the equator, where it will park itself at 83 degrees east longitude and unfurl a nearly 20-foot (6-meter) S-band antenna, the largest reflector of its kind ever flown on an Indian communications satellite.
The spacecraft carries S-band and C-band communications payloads with five spot beams and one nationwide beam.
Countdown begins for launch of Indian military satellite | Spaceflight Now
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