Ariane 5 GS: Thaicom 4

At the time of the failure of the first Ariane 5 ECA flight in 2002, all Ariane 5 launchers in production were ECA versions. Some of the ECA cores were modified to use the original Vulcain engine and tank volumes while the failure was investigated; these vehicles were designated Ariane 5 GS. The GS used the improved EAP boosters of the ECA variant and the improved EPS of the G+ variant, but the increased mass of the modified ECA core compared to the G and G+ core resulted in slightly reduced payload capacity. Ariane 5 GS could carry a single payload of 6,600 kg (14,600 lb) or a dual payload of 5,800 kg (12,800 lb) to GTO. The Ariane 5 GS flew 6 times from 2005 to 2009 with no failures.