India’s GSLV booster set to launch INSAT-3DR weather satellite
The Indian Space Research Organisation (ISRO) is gearing up to launch its Geosynchronous Satellite Launch Vehicle (GSLV). It will carry into orbit an advanced weather satellite named INSAT-3DR. Liftoff will take place at 4:10 p.m. local time (6:40 a.m. EDT, 10:40 GMT) Sept. 8, from the second launch pad at the Satish Dhawan Space Centre in Sriharikota, India.
The mission, designated GSLV-F05, will send the INSAT-3DR satellite into a geostationary transfer orbit (GTO) after a 17-minute flight. The spacecraft will use its own propulsion system to reach a geosynchronous orbit (GEO) at an altitude of about 22,370 miles (36,000 kilometers) to be stationed at 74 degrees East longitude.
The launch of GSLV-F05 was initially planned for Aug. 28. However it was postponed due to a technical issue found in a satellite component after a series of tests. The spacecraft was shipped to the launch site from the ISRO Satellite Centre in Bengaluru back on Aug. 5.
“After obtaining clearance from Mission Readiness Review (MRR) Committee and Launch Authorization Board (LAB), GSLV-F05/INSAT-3DR will be launched on Sept. 8 at 4.10 p.m. from the second launch pad at the Satish Dhawan Space Centre, Sriharikota,” a senior ISRO official told Deccan Herald.
Weighing about 2.2 metric tons, INSAT-3DR has dimensions of 7.9 by 5.25 by 4.9 feet (2.4 by 1.6 by 1.5 meters). It is an advanced meteorological satellite based on ISRO’s I-2K bus. The satellite consists of light-weight structural elements like Carbon Fibre Reinforced Plastic (CFRP) and features one solar array, capable of generating up to 1,700 watts of power. The spacecraft is designed to be operational for up to 10 years.
INSAT-3DR will provide meteorological services to India using a 6-channel imager and a 19-channel atmospheric sounder. It will also deliver rescue services thanks to its Data Relay Transponder (DRT) instrument and the Search and Rescue Transponder.
The multi-spectral imager onboard the spacecraft is capable of acquiring images of Earth in six wavelength bands significant for meteorological observations. It will produce images of the planet every 26 minutes, providing various parameters like outgoing long-wave radiation, quantitative precipitation estimation, sea surface temperature, snow cover, and cloud motion winds.
The atmospheric sounder will gather information about the vertical profiles of temperature, humidity and integrated ozone. The instrument has 18 narrow spectral channels in shortwave infrared, middle infrared and long wave infrared regions and one channel in the visible region.
The DRT will be employed for receiving meteorological, hydrological and oceanographic data from remote uninhabited locations over the coverage area. The data is relayed back for downlinking in extended C-Band.
The Search and Rescue Transponder will pick up and relay alert signals originating from the distress beacons of maritime, aviation and land based users to the mission control center in Bangalore.
INSAT-3DR is the second satellite in the series. The first spacecraft, INSAT-3D, was launched into space July 25, 2013, atop an Ariane 5 booster from Kourou, French Guiana. Once in orbit, INSAT-3DR will join the operational search and rescue service provided by INSAT 3D to various users, including the Indian Coast Guard, Airport Authority of India, Shipping, and Defense Services.
The GSLV that will be used in Thursday’s mission is an expendable launch system developed to enable India to launch its satellites without dependence on foreign launch service providers. It uses major components that have already been proven by the Polar Satellite Launch Vehicle (PSLV) launchers in the form of the S125/S139 solid rocket booster and the liquid-fueled Vikas engine. The overall length of the launcher is 161 feet (49 meters) with a liftoff mass of 415 metric tons.
The GSLV Mk II variant will be used for GSLV-F05. This version of the rocket uses an Indian cryogenic engine – the CE-7.5 – and it is capable of launching 2.5 metric tons into GTO. Previous GSLV vehicles (GSLV Mk I) have used Russian cryogenic engines.
For the upcoming flight, the GSLV launch vehicle is configured with all of its three stages including the Cryogenic Upper Stage (CUS). The CUS is more efficient and provides more thrust when compared to solid and earth-storable liquid propellant rocket stages.
“It will be the second flight using the indigenously developed cryogenic engine after it was successfully used for the first time to launch GSLV-D5 in 2014,” said K Sivan, the Director of the Vikram Sarabhai Space Centre.
The main and two smaller steering engines together provide the CUS a nominal thrust of about 16,535 pounds (73.55 kilonewtons) in a vacuum. During the flight, the CUS fires for a nominal duration of approximately 720 seconds.
The cryogenic stage is a complex system due to its use of propellants at extremely low temperatures and the associated thermal and structural challenges involved with sending it skyward. Oxygen liquefies at minus 297 degrees Fahrenheit (minus 183 degrees Celsius) and hydrogen at minus 423 degrees Fahrenheit (minus 253 degrees Celsius). The propellants, at these low temperatures, are pumped using turbopumps running at around 40,000 rpm.
GSLV-F05 will be the tenth flight of the GSLV booster. The maiden launch of the GSLV (GSLV-D1) was conducted April 18, 2001. That flight carried GSAT-1, however the satellite failed to reach the correct orbit. Attempts to save the spacecraft by using its onboard propulsion system to maneuver it into the proper orbit were also unsuccessful as it ran out of fuel several thousand miles below geosynchronous orbit.
Thursday’s liftoff will be the fifth orbital mission for India in 2016. The country’s next launch is currently scheduled for Sept. 26, when a PSLV rocket will take to the skies, lofting six Indian spacecraft and two Earth-observing satellites for the U.S. company BlackSky Global.
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