On December 5, 2015 at 17:09 MSK (14:09 UTC) the Air and Space Forces conducted a successful launch of a Soyuz-2.1v space launcher from the launch pad No. 4 of the launch site No. 43 at Plesetsk. The launcher, equipped with the Volga boost stage, carried two satellites that were declared as military and that were designated Cosmos-2511 and Cosmos-2512.
The main payload, presumably Cosmos-2511, was a new ocean monitoring satellite, Kanopus-ST. It was described as being capable of detect underwater submarines as well as collecting data for civilian remote-sensing and meteorological research. However, the spacecraft failed to separate from the boost stage and is expected to re-enter the atmosphere in the next few days.
The second satellite, presumably Cosmos-2512, is a KYuA-1 radar calibration sphere. It was deployed successfully.
It was the second launch of the Souyz-2.1v modification of the Soyuz launcher. The first launch took place on December 28, 2013.