Investigations have begun after a Proton-M rocket failed during lift-off from Baikonur, Kazakhstan, destroying the launch vehicle and its payload.
The 2 July launch was meant to loft three Glonass satellites into orbit, but failed immediately after take-off. The cause is as yet unknown.
It was the Proton's 387th launch, according to Flightglobal's Ascend SpaceTrak database, and its 53rd failure during its lifetime.
Approximately 10s after lift-off from the launch pad, smoke unexpectedly appeared from one of the engines and the rocket appeared to fishtail before veering in the opposite direction, leading to speculation of an engine failure and overcorrection by the on-board guidance system.
The rocket veered well beyond its intended course and began to rotate. Having spun nearly 180° to point back towards the ground, the nosecone containing the Glonass satellites was destroyed. It is unclear whether the rocket was detonated by ground crew, as is standard procedure during control-loss scenarios, or whether it exploded due to a fault.
No fatalities or injuries were reported, but Kazakh officials reportedly evacuated the area surrounding the launch site.
The launch was conducted on behalf of the Russian government, which is in the midst of launching a complete constellation of Glonass navigation satellites to compete with the USA's GPS and Europe's Galileo, amongst others.
International Launch Services, the US-based company that markets Proton commercially, deferred major comment to rocket-builder Khrunichev, the Russian company that builds Proton.
However, it adds: "Following the commission [of inquiry’s] findings, International Launch Services will conduct its own Failure Review Oversight Board. [This] will review the commission’s findings and corrective action plan, in accordance with US and Russian government export control regulations."
Khrunichev was not immediately available to comment.
Though Proton has suffered its share of failures - including two in 2012 and one in 2011 - its core stage is considered highly reliable.
Proton's last core stage failure occurred in 1982, according to SpaceTrak, when the steering system suffered a major malfunction 45s into the flight, and the rocket was destroyed by the on-board safety system.
Proton's core stage was powered by six RD-276 engines, fueled by liquid dinitrogen tetroxide and unsymmetrical dymethylhydrazine. The launch vehicle will eventually be replaced by the Angara, a new rocket scheduled for first flight in 2014.