India Makes It Two in a Row with Successful GSLV Launch

GSLV Mk.II rocket lifts off with GSAT-6 satellite. (Credit: ISRO)
GSLV Mk.II rocket lifts off with GSAT-6 satellite. (Credit: ISRO)

Another success for the Indian space program. On Thursday, ISRO successfully launched the GSAT-6 communications satellite into orbit aboard a GSLV Mk. II rocket.

This marks the second success in a row for the GSLV rocket, a feat the Indian space agency has not accomplished with the intermittently used  launch vehicle since back-to-back-successes in 2003-2004. It also raises the GSLV’s launch record over the past 14 years to .500, with four successes, four failures and one partial failure.

Launch VehicleLaunch DatePayloadResultNotes
GSLV Mk I(a)18 April 2001GSAT-1FailureDevelopmental Flight. Payload placed in useless orbit.
GSLV Mk I(a)8 May 2003GSAT-2SuccessSuccessful developmental flight
GSLV Mk I(b)20 September 2004GSAT-3SuccessSuccessful operational flight
GSLV Mk I(b)10 July 2006INSAT-4CFailureRocket destroyed by range safety officer after it veered off course.
GSLV Mk I(b)2 September 2007INSAT-4CRPartial failureSatellite placed in wrong orbit. Spacecraft reached planned orbit using own propulsion.
GSLV Mk II15 April 2010GSAT-4FailureFirst flight test of indigenous Cryogenic Upper Stage. Turbo pump failure sent upper stage and payload into Bay of Bengal.
GSLV Mk I(c)25 December 2010GSAT-5PFailureFirst flight of GSLV Mk.I (c). Range safety officer destroyed vehicle after first stage booster malfunction.
GSLV Mk II5 January 2014GSAT-14SuccessFirst successful flight with indigenous Cryogenic Upper Stage.
GSLV Mk II27 August 2015GSAT-6SuccessSecond successful flight with indigenous Cryogenic Upper Stage.

The flight marked the second successful flight of the nation’s indigenous Cryogenic Upper Stage (CUS), which is used on the upper stage. The first test of CUS failed due to a problem in its turbo pump. ISRO had used a limited supply of Russian-supplied cryogenic upper stage engines on previous GSLV flights.

After the successful launch, jubilant ISRO officials said they planned to increase the pace of GSLV launches to two annually in future years. This move would mark the end of a 14-year long period of development launches.

The space agency also is developing the GSLV Mk. III launch vehicle capable of carrying larger satellites. ISRO conducted a successful suborbital flight of the rocket in December 2014 using a live first stage and a dummy upper stage. A second flight with a functional cryogenic upper stage is planned for the end of 2016.

ISRO’s press release about Thursday’s launch follows.

GSLV Successfully Launches India’s Latest Communication Satellite GSAT-6

BANGALORE, India (ISRO PR) — In its ninth flight (GSLV-D6) conducted today, (August 27, 2015), India’s Geosynchronous Satellite Launch Vehicle, equipped with the indigenous Cryogenic Upper Stage (CUS), successfully launched GSAT-6, the country’s latest communication satellite, into a Geosynchronous Transfer Orbit (GTO). The achieved orbit is very close to the intended one.

The launch took place from the Second Launch Pad at the Satish Dhawan Space Centre SHAR (SDSC SHAR), Sriharikota, the spaceport of India. This was the fifth developmental flight of GSLV and the third to carry the indigenous CUS. GSLV-D6 was intended to further test and qualify the CUS developed by ISRO.

In its oval shaped GTO, the GSAT-6 satellite is now orbiting the Earth with a perigee (nearest point to Earth) of 168 km and an apogee (farthest point to Earth) of 35,939 km with an orbital inclination of 20.01 deg with respect to the equator.

After a smooth 29 hour countdown, the 416 tonne, 49 m tall GSLV-D6 carrying the 2117 kg GSAT-6, lifted off at 16:52 Hrs IST. About seventeen minutes after lift-off, GSAT-6 was successfully placed in GTO.

At 4.8 seconds before the countdown reached zero, the four liquid propellant strap-on stages of GSLV-D6, each carrying 42 tonne of liquid propellants, were ignited. At count zero and after confirming the normal performance of all the four strap-on motors, the mammoth 139 tonne solid propellant first stage core motor was ignited and GSLV lifted off. The major phases of the flight included the core motor burn-out, strap on burn-out, ignition of the second stage, separation of the core motor together with strap-ons, payload fairing separation, second stage separation, CUS ignition and its timely shut down after satisfactory performance. Following this, GSAT-6 separated from CUS about 17 minutes after launch.

Soon after its injection into GTO, the two solar arrays of GSAT-6 were automatically deployed and the Master Control Facility (MCF) at Hassan in Karnataka took control of GSAT-6.

In the coming days, GSAT-6’s orbit will be raised from its present GTO to the final circular Geostationary Orbit (GSO) by firing the satellite’s Liquid Apogee Motor (LAM) in stages. The satellite will be commissioned into service after the completion of orbit raising operations, deployment of its 6 m wide sieve shaped unfurlable antenna, the satellite’s positioning in its designated orbital slot of 83 degree East longitude in the GSO and in-orbit testing of its communication payloads.

Today’s flight of GSLV underscores the success of ISRO in mastering the highly complex cryogenic rocket propulsion technology.