According to Arianespace’s preliminary analysis, the interruption of the automated lift-off sequence was triggered by an anomaly affecting electrical equipment on one of the two solid-propellant boosters.
The countdown sequence for the launch of Ariane 5 on 5th September (flight VA239) was interrupted in the final seconds, leading to the postponement of the launch of the Intelsat 37e and BSAT-4a telecommunications satellites.
According to the results of Arianespace’s preliminary analysis, just after the ignition of Ariane 5’s main stage Vulcain engine, the on-board computer detected an anomaly affecting electrical equipment on one of the two solid-propellant boosters (EAP). This anomaly led to an interruption of the automated lift-off sequence.
This interruption is perfectly compliant with Arianespace procedures, which authorize a launch only if 100% of launcher equipment is fully operational. Analysis is ongoing to identify the anomaly’s cause and determine the measures to be taken in order to resume launch operations as soon as possible.
As the analysis is underway, Ariane 5 is being transferred to the Final Assembly Building (BAF) once the tanks have been purged. The two satellites remain under the fairing atop the launcher.
The target launch date is “around the end of September”. Arianespace says the postponement does not affect the other launches scheduled for the end of 2017.