According to reports, SpaceX's seventh International Space Station resupply mission will be launched from Cape Canaveral Air Force Station at 10:21 am on Sunday.

It will carry payload of 1,150-pound, which is a 5-foot diameter ring called a 'docking adapter', which is needed to connect with the orbiting research complex.

The capsules, being developed, comprise an advanced version of the SpaceX Dragon cargo ship that will blast off on a Falcon 9 rocket, and Boeing's CST-100; the rockets will be assembled at Kennedy Space Center and United Launch Alliance Atlas V will launch them.

The International Docking Adapter, or IDA, is among the first two that will set up a pair of berthing ports on the outpost's Harmony node. The ports will be receiving the new US crew vehicles, and probably international vehicles or US cargo craft outfitted with the same standardized docking system.

The adapters will be detached robotically following flying up in the Dragon's unpressurized 'trunk' and installed later by spacewalking astronauts. It is expected that NASA's Scott Kelly and Kjell Lindgren will perform the first spacewalk, probably in mid-August.

Addition of the adapters is another step in direction of a configuration, which according to NASA, is the station's largest; its construction was completed in 2011. Last month, ground teams used a robotic arm in order to relocate a storage module. Earlier, three spacewalks laid hundreds of feet of cables, which assisted in preparing for the docking adapters.