Discovery's crew is welcomed by the space station's current residents
Nasa's space shuttle Discovery has docked with the International Space Station (ISS).
The visiting astronauts are delivering the orbiting platform's fourth and final set of solar arrays.
Installation work will start on Wednesday when the "backbone" segment holding the folded-up solar wings is lifted out of Discovery's payload bay.
The truss will be slotted into place at the starboard, or right, side of the station on Thursday.
Electricity from the new solar arrays will support the expansion of the ISS crew to six people and provide the power necessary to fully exploit its science labs.
Discovery hooks up to the ISS
Currently, the normal live-aboard complement is three individuals; and the station partners want to double this in May.
Another key mission task is ISS crew rotation.
Discovery is dropping off Koichi Wakata, the Japanese space agency's (Jaxa) first live-aboard station crew member. US astronaut Sandra Magnus will be returning to Earth on Discovery in his place.
The docking occurred at 2120 GMT Tuesday, with hatches opening just under 50 minutes later.
Discovery's mission is the 125th to be made by a shuttle; the 28th to the ISS; and the 36th flight for Discovery itself.