India’s 101st space mission, the GSAT-10 communication satellite, will be launched Sept. 29 aboard an Ariane 5 rocket from the European spaceport at Kourou in French Guiana.

“The 3.4-ton heavy satellite, GSAT-10, has been integrated with the Ariane 5 rocket along with Astra-2F spacecraft of SES as co-passenger for the launch Sept. 29 at 2:48 a.m. Indian time,” an Indian Space Research Organization (ISRO) official says.

Astra-2F belongs to the Luxembourg-based leading satellite operator SES.

A minor snag detected Sept. 15 forced the European Space Agency to postpone the launch of the twin satellites by seven days from Sept. 22.

The cost of the GSAT-10, including its launch and insurance, is 7.5 billion rupees (more than $135 million). GSAT-10, weighing 3,400 kg (7,500 lb.) at liftoff, is the heaviest spacecraft ISRO has built. The satellite is expected to be operational by November.

“About 31 minutes after liftoff, GSAT-10 would be injected in a Geosynchronous Transfer Orbit with a perigee of 250 kilometers [155 mi.] and an apogee of about 36,000 kilometers,” the ISRO official says. “From there, the satellite would be moved to a geostationary orbit [circular, 36,000 km above equator] by using the satellite propulsion system in a three-step approach. After this, the solar panels and antennas would be deployed.”

In the weeks after launch, the payload will be turned on to perform a series of extensive in-orbit tests. GSAT-10 will be positioned at 83 deg. East, along with INSAT-4A and GSAT-12. The intended operational life of GSAT-10 is 15 years.

“After the satellite is injected into the elliptical geo-transfer orbit, ISRO’s master control facility at Hassan [180 km from Bangalore] will take control of it and perform the orbit raising maneuvers,” the official says.

GSAT-10’s transponders include 12 normal C-band, six lower extended C-band and 12 Ku-band.

GSAT-10 will be the second satellite, after GSAT-8, to carry the GPS-Aided Geo-Augmented Navigation (Gagan) payload, operating in the L1 and L5 bands, providing navigation services to airlines and ships. The Ku-band transponder also will help in accurately pointing ground antennas toward the satellite.