The attempted rendezvous of an unmanned cargo ship at the International Space Station will happen no earlier than Saturday following a technical glitch, NASA said Monday.

The rescheduling postpones the berthing of the Cygnus capsule by one week and will allow time for three new ISS crew members to launch aboard a Russian Soyuz from Kazakhstan on Wednesday, the US space agency said.

A software problem delayed the Cygnus spacecraft's planned approach to the research outpost Sunday, and the manufacturers of the capsule have since figured out how to fix what they called a data format mismatch.

"However, that process, together with the impending Soyuz crew operations, resulted in a tight schedule to the point that both Orbital and NASA felt it was the right decision to postpone the Cygnus approach and rendezvous until after Soyuz operations," NASA said in a statement.

Astronaut Michael Hopkins of NASA and Oleg Kotov and Sergey Ryazanskiy of the Russian space agency are to depart Kazakhstan at 4:58 pm (2058 GMT) Wednesday and arrive at the space station at 10:47 pm (0227 GMT Thursday).

The orbiting space lab is typically staffed by six international astronauts -- traveling in overlapping groups of three -- who live on board for missions that last six months.

The Cygnus capsule, built by Virginia-based Orbital Sciences, launched on Wednesday on a demonstration mission meant to show it can successfully deliver cargo to the space station.

Orbital Sciences has a $1.9 billion contract with NASA that requires the company to deliver freight to the ISS over the course of eight flights by the beginning of 2016.

The company is one of just two private US firms enlisted by NASA to carry payloads to the ISS.

California-based SpaceX already showed it could send its reusable Dragon capsule to the ISS bearing cargo in May 2012.