The Kristall (Russian:Кристалл; English:Crystal) (77KST, TsM-T, 11F77T) module was the fourth module and the third major addition to the Mir space station. As with previous modules, its configuration was based on the 77K (TKS) module, and was originally named "Kvant 3". It was launched on May 31, 1990 on a Proton rocket. It docked to Mir autonomously on June 10, 1990.