NASA astronaut Suni Williams, veteran Russian cosmonaut Yuri Malenchenko and Aki Hoshide of Japan docked Tuesday slightly ahead of schedule at 08:51 a.m. Moscow time (0451 GMT). They will work at the orbiting laboratory until November.
They join current station residents -- Russians Gennady Padalka and Sergei Revin, and U. S. astronaut Joe Acaba.
The station, which orbits up to 410 kilometers (255 miles) above the Earth, is due to handle an unprecedented level of traffic.
Japan's HTV3 cargo ship will reach the station next week, the first of nine craft due to make contact with the orbiting satellite over a 17-day period.