The launch of the Insat-4C telecommunications satellite, currently scheduled to occur in July, will mark the end of India’s total reliance on foreign rockets to launch its largest payloads, according to a senior officials of the Indian Space Research Organi sation (ISRO).

ISRO has been launching the country’s remote sensing satellites since 1988 with rockets designed and built in India. But while those satellites typically weigh less that 1 metric ton, the Insat satellites weigh in at around 2 metric tons and up until now have needed to be launched from abroad. Beginning with Insat-1A in 1982, a total of 13 Insat satellites were launched by foreign rockets — four by the United States and the rest by Europe’s Arianespace launch consortium.

Insat-4C is the third of seven advanced telecommunications satellites that ISRO expects to put in orbit by 2010. The launch of the first two satellites in the series — Insat-4A and 4B — had been contracted out to Arianespace for launch from Europe’s spaceport in Kourou, French Guiana.

“Those were the last. We have not signed any more launch contracts with Arianespace,” ISRO spokesman S. Krishnamurthy told Space News. Insat-4A was launched in December 2005, and the launch of Insat-4B by Arianespace is slated for 2007.

“Beginning with Insat-4C all our communications satellites will be launched from India by our geostationary satellite launch vehicle (GSLV),” Krishnamurthy said in a telephone interview April 18. “We have achieved self reliance not only in satellite technology but also in launchers.”

The GSLV made its first successful operational flight when it launched the Edusat spacecraft September 20, 2004, which is used for linking together classrooms in different schools and colleges. On its second flight scheduled for the first week of July, it will carry Insat-4C.

According to ISRO’s annual report for 2005-2006, Insat-4D is slated for launch on board a GSLV during the third quarter of the government’s 2007-2008 budget year. (India’s budget year ends in March). Its 18 transponders will cover Asia, Africa and Eastern Europe, the report said.

Insat-4E will carry a digital multimedia broadcasting payload and cover the whole of India through five spot beams. Its launch aboard a GSLV is planned for the second quarter of the 2008-2009 budget year, according to the annual report.

The launch of Insat-4F will take place during the 2009-2010 budget year, a year after the launch of Insat-4G, a proposed Ku-band satellite carrying 18 transponders in addition to a satellite navigational payload.

“Because it is likely to be heavier than others, this is the only satellite for which we might seek help from Arianespace if our GSLV-Mk 3 is not ready by then,” Krishnamurthy said. According to the annual report, the GSLV-Mk 3 is expected to launch satellites weighing up to 4 metric tons and will be ready for a test flight during the 2008-2009 budget year.