A prelaunch automated computer check of an Ariane 5’s Vulcain 2 main engine triggered a last second abort. A launch abort so close to the irreversible firing of the two solid rocket boosters (SRBs) is rare for Arianespace with the last launch to be halted in this fashion occurring more than 6 years ago in 2011.
During the launch period of an Ariane 5, the Vulcain 2 main engine throttles up. The rocket’s main engine is a cryogenic power plant that consumes supercooled Liquid hydrogen and oxygen. Seven seconds after the Vulcain 2 engine ignites, the rocket’s two side-mounted SRB’s ignite at which point lift off is inevitable. The seven seconds between main engine ignition and liftoff is used by onboard systems to check and recheck every inch of the the Ariane 5’s hardware. It is during this period that Tuesday’s launch was halted.
In an official statement posted on the company’s website, Arianespace explained that “During the final seconds of the launch countdown for Arianespace Flight VA239, the checkout process detected an anomaly on the launcher as the Vulcain cryogenic main stage engine was being ignited. As a result, the final countdown was interrupted.” Additionally, it has been confirmed that the Ariane 5’s payloads are secure with Didier Faivre, director of the Guiana Space Center for CNES stating that, “Everything is fine. The launcher, the satellites are OK. We will be analyzing the problem to be able to launch again as soon as possible. I would, of course, like to apologize to our customers for this delay.”
Arianespace had a similar last second abort occur in March 2011. Engineers on that mission replaced the suspect actuators housed within the Vulcain 2 engine. The launch was then successfully completed three weeks later.
Flight VA239’s payload is the Intelsat 37e and BSAT 4a telecommunication satellites. The Intelsat 37e was developed by Boeing and will facilitate broadband, wireless communications, television broadcasting and government services. The BSAT 4a satellite was built by Space Systems and will support HD, 4K and 8k Ultra HD broadcasts for Broadcasting Satellite System Corp over Japan.
Image source: Arianespace