The withdrawal of GSAT-11 from its planned Ariane 5 ECA launch (with Azerspace 2/Intelsat 38) caused a major interruption in Arianespace’s launch schedule. The heaviest satellite produced by the Indian Space Research Organisation (ISRO) at 5,725kg, GSAT-11 arrived at the Kourou launch site in French Guiana to some fanfare on 30 March, ready for its launch. However, the satellite was soon put on an aircraft back to India on 23 April as it was deemed that extra checks were needed. The cause was concern over power system redundancy following the post-launch failure in late March of the smaller ISRO designed GSAT 6A satellite, apparently due to power system failure.

As a result of GSAT-11’s withdrawal, the May launch of that satellite and Azerspace 2/Intelsat 38 was cancelled and is now thought unlikely to take place before late summer – although ISRO hopes its testing will be over by 17 May. Theoretically, a flight in late June/early July might be possible if it can be returned in time, but it would be a rush, and an August flight is more likely.

Ariane 5’s early summer launch schedule looks surprisingly bare, with the next launch (of an Ariane 5 ES) on 25 July carrying four Galileo satellites. Following this, the six metric ton Hellas-Sat 4/Saudigeosat-1 could be launched in August, although it would ideally need a smaller satellite to pair with it. The delayed 3.5 metric ton Azerspace 2/Intelsat 38 would fit the bill, although it is more likely that the GSAT-11 will return to fly with it.

Complicating matters in respect of the Kourou range is the Vega launch of the ADM Aeolus wind monitoring mission, planned for 21 August.

Update on 23 May 2018: The Times of India reports that GSAT-11 has passed all of its testing and is ready for launch. ISRO is now negotiating with Arianespace for a launch date.