Planned for September 5, 2017, launch of Arianespace Ariane 5 rocket with two communication satellites under the payload fairing was aborted seconds before liftoff.
This should be ordinary mission of Ariane 5 performed from Guiana Space Center - well prepared, perfectly conducted and just like 84 previous missions finished with success. Nothing seemed that Arianespace ground control center decide to abort launch slightly before liftoff.
Mission of Intelsat-37e & BSAT-4a preparations started with delivering both satellites to French Guiana. Intelsat-37e was delivered on August 3rd, 2017 and BSAT-4a arrived four days later. Satellites were delivered to Guiana Space Center and later tested, fueled and prepared for encapsulation. Weighing 6438 kg and built by Boeing Intelsat-37e was placed over the lighter (3520 kg) BSAT-4a on the Sylda adapter.
Rocket with satellites under the fairing was rolled out from assembly facility placed 2.7 km from ELA-3 launch site on Monday, September 4, 2017. Launch was scheduled for Tuesday, September 5, 2017 at 21:51 UTC.
Today rocket was tested and fueling process begun at 16:13 UTC. At T-7' synchronized counting procedure was initialized. One minute later propellant and LOX levels reached max values, procedure of pressurizing tanks begun. Two minutes before flight valves were opened and flight plan was loaded to main computer of the rocket.
As in the critical last ten seconds everything went just fine - main stage Vulcain 2 engine was ignited and few seconds later two solid fueled boosters should also fired at T=0. Unfortunately after around three seconds Vulcain-2 was cut off. Apparently main computer found an error after firing Vulcain-2 and due the algorithm it decided to abort mission and cut off main engine without starting both boosters. According to Arianespace executive vice president of missions Luce Fabreguette satellites are fine and secured. It was not confirmed if another flight attempt will not occur tomorrow or even this week.