on june 1 , 1990 , during a spacewalks , alexander serebrov dons an improved riding armchair that had been delivered to mir with kvant 2 . unlike u . s . astronauts , when were untethered flights with a similar procedure , the soviet cosmonaut remains bound to the station with a safety tether , so there is no space system to catch him up in time of an emergency .
US shuttle Atlantis docks with the Mir space station.