Progress 31Progress 31 was a Soviet uncrewed Progress cargo spacecraft, which was launched in August 1987 to resupply the Mir space station.LaunchProgress 31 launched on 3 August 1987 from the Baikonur Cosmodrome in the Kazakh SSR. It used a Soyuz-U2 rocket.DockingProgress 31 docked with the aft port of the Kvant-1 module of Mir on 5 August 1987 at 22:27:35 UTC, and was undocked on 21 September 1987 at 23:57:41 UTC.DecayIt remained in orbit until 23 September 1987, when it was deorbited. The deorbit burn occurred at 00:22:00 UTC and the mission ended at 01:02 UTC.