They also investigated the possible links between terrestrial seismic activity and high-energy charged cosmic particle fluxes with the Maria magnetic spectrometer. Kvant Coolant Loop Reactivation and Third Mir 20 (second Euromir 95) EVA Between January 12 and 16, the cosmonauts resumed work on the cooling system leak that began in November. They sealed a manifold on the coolant line and then refilled the loop with ethylene glycol that was sent up with Progress M-30. The SPK (or YMK) maneuvering unit was stored inside the Kvant 2 airlock. It was a large unit which hadn't been used since it was tested in 1990 and it was in the way of airlock egress so Reiter and Gidzenko moved it outside on a February 8 EVA and attached it outside. They also retrieved the two cassettes they deployed in October. They also attempted to perform a task on the Kristall antenna, but TsUP canceled the antenna work when the cosmonauts were unable to loosen the bolts on the antenna. 10th Anniversary of the Mir Base Block The Mir base block launched to orbit on February 20, 1986. On February 20, 1996, ITAR-TASS reported a 'holiday atmosphere' aboard the complex. Having already remained in orbit for four years longer than originally intended, the station held the promise of at least three more orbiting anniversaries. February 23–29, 1996 Progress M-30 Undocked and Soyuz TM-23 Launched On February 21, Soyuz TM-23 launched from Baikonur Cosmodrome with the cosmonauts for Mir Principle Expedition 21. To clear a docking port for the Soyuz TM-23, the Progress M-30 was undocked on February 22 and re-entered over the Pacific Ocean. The Soyuz docked on February 23 at the +X docking port on the rear of the Kvant module. An hour and a half after docking, the hatches opened and Yuri Onufrienko and Yury Usachov were greeted by the Mir 20/Euromir 95 crew. This began a week of joint operations where Mir 20 handed the station over to Mir 21, including familiarization with the current conditions of the projects and the station itself. Two days before the return flight, a water leak appeared in the Mir base block, but the cosmonauts were able to repair it. Mir 20/Euromir 95 Mission Ends Gidzenko, Avdeyev and Reiter donned their Sokol launch and reentry suits and entered the Soyuz TM-22 on February 29, 1996. They landed safely about 105 km from Arkalyk. Their mission