On April 22, 2017 at 04:16 UTC the Chinese “Tianzhou-1” unmanned supply spacecraft docked to the Chinese “Tiangong-2” space station. The unmanned supply spacecraft will pump propellants into the “Tiangong-2” space station, which launched last year and hosted two astronauts for a month-long stay in October and November. The refueling experiment will validate key technologies China needs to build and maintain a much larger orbital complex starting as soon as next year.