Spaceflight Insider

India sends GSAT-9 into orbit atop GSLV

GSLV-F09 / GSAT-9 launch

GSLV-F09 / GSAT-9 launch on May 5, 2017. Photo Credit: ISRO

In India’s second launch of 2017, a Geosynchronous Satellite Launch Vehicle (GSLV) Mk. II sent the GSAT-9 communications satellite into orbit. Liftoff took place at 7:27 a.m. EDT (11:27 GMT) on May 5 from the Second Launch Pad at the Satish Dhawan Space Centre in India.

Just like the launch vehicle’s name suggests, GSAT-9 was sent into an elliptical geostationary transfer orbit that would allow the satellite to independently circularize into a geosynchronous orbit (GEO) around Earth some 22,000 miles (36,000 kilometers). The craft’s final location is to be at 48 degrees East, just south of the Horn of Africa.

GSLV-F09 / GSAT-9 launch

GSLV-F09 / GSAT-9 launch. Photo Credit: ISRO

GSAT-9 was built by the Indian Space Research Organisation (ISRO). It weighs 4,920 pounds (2,230 kilograms) and is built on the I-2K satellite bus. With 12 Ku-band transponders, it will deliver TV for India as well as other members of the South Asian Association for Regional Cooperation, also called SAARC.

Moreover, the spacecraft will have the fourth GPS Aided GEO Augmented Navigation payload. GAGAN will send signals to Earth-based aircraft navigational systems to increase their accuracy to three meters.

For propulsion, GSAT-9 utilizes a hybrid approach. To circularize its orbit at GEO, it will use a chemical-based system. Once in its orbital slot, an electric Xenon ion propulsion system will maintain its orbit over the lifetime of the satellite, which is expected to be about 12 yeas. This spacecraft will validate the design for future missions, including satellites that are planned to be all electric.

The first stage of the three-stage, 161.1-foot (49.1-meter) tall GSLV rocket has a single solid-fueled S139 engine. It has four liquid-fueled strap-on boosters, each with a single Vikas 2 engine. Before lifting off, the boosters ignited four seconds before the core to ensure they were functioning properly. Once the core ignited, there was no turning back for the rocket.

When the countdown reached zero, mission GSLV-F09 started to climb uphill and to the southeast toward orbit with a total thrust of 1.74 million pounds-force (7,740 kilonewtons). The solid-fueled core burned for 100 seconds. The four boosters burned for an additional 56 seconds before cutting off.

At this time the second stage with a Vikas 4 engine ignited, consuming a hyperbolic mix of dinitrogen tetroxide and unsymmetrical dimethylhydrazine. It producing about 180,000 pounds (800 kilonewtons) of thrust for about 150 seconds before cutting off.

During the second stage’s powered flight, once the vehicle reached an altitude of around 68 miles (110 kilometers), the payload fairing jettisoned to reveal the satellite to the vacuum of space.

Once the second and third stages separated, the third stage, powered by a liquid oxygen and liquid hydrogen consuming CE-7.5 engine, ignited and continued to burn for about 12 minutes to place the spacecraft into a highly elliptical GTO. The satellite separated from the booster minutes later and started the process of deploying its solar arrays and began preparation for its series of engine firings to circularize to its final orbit.

The country plans two more launches over the next month or so. Up next is the launch of Polar Satellite Launch Vehicle, which will send CartoSat-2E and 36 secondary satellites into a polar orbit. It’s scheduled to launch in late May.

After that, the ISRO will launch the GSLV Mk. III on its maiden flight. It is expected to send GSAT-19E into orbit sometime in June.

In all, India is expected to see a total of 5 PSLV rockets, 2 GSLV Mk. II rockets, and one GSLV Mk. III launch in 2017. So far, it has lofted this mission as well as PSLV in February.

GSLV-F09 / GSAT-9 at the 2nd launch pad

GSLV-F09 / GSAT-9 at the 2nd launch pad. Photo Credit: ISRO


GSLV-F09 / GSAT-9 launch

Photo(s) Credit: ISRO


GSLV-F09 / GSAT-9 launch

Photo(s) Credit: ISRO


Video courtesy of ISRO



Derek Richardson has a degree in mass media, with an emphasis in contemporary journalism, from Washburn University in Topeka, Kansas. While at Washburn, he was the managing editor of the student run newspaper, the Washburn Review. He also has a website about human spaceflight called Orbital Velocity. You can find him on twitter @TheSpaceWriter.

Reader Comments


That is a pretty strange rocket. The main booster burns out before the strap-ons must dramatically lower performance. Lugging all that extra weight seems a odd design. Having a solid booster with liquid strap-ons is certainly not typical. Hyper-gothic fuels are generally used on deorbiting thrusters and ballistic missiles where storability is important. These days it is seldom used on main stages because of the low ISP.

The entire rocket looks like a bunch of available parts thrown together.

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