WASHINGTON, Sept. 23 (Xinhua) -- U.S. space company Orbital Sciences Corp. said Monday the rendezvous of its Cygnus cargo ship with the International Space Station (ISS) has been postponed again to give way to Wednesday's scheduled arrival of new crew members at the orbital laboratory.
The unmanned Cygnus spacecraft was originally expected to be captured by a robotic arm operated by astronauts inside the space station on Sunday morning, but following the discovery of "a data format discrepancy" between the two vessels, the rendezvous attempt was rescheduled for Tuesday.
The company said it has developed and tested a software fix for the data format mismatch, but having Cygnus to dock on Tuesday, together with the impending Soyuz crew operations, will result in "a tight schedule."
"Both Orbital and NASA felt it was the right decision to postpone the Cygnus approach and rendezvous until after Soyuz operations," Orbital wrote in a status update on its website.
"The earliest possible date for the next Cygnus approach and rendezvous with the ISS would be Saturday, Sept. 28. An exact schedule will be determined following the successful completion of Soyuz operations," it said.
On Wednesday, Michael Hopkins of the U.S. space agency NASA and Oleg Kotov and Sergey Ryazanskiy of the Russian Federal Space Agency will depart from the Baikonur Cosmodrome aboard a Soyuz spacecraft. They are expected to arrive at the ISS about six hours later.
"This new schedule will allow the Orbital operations team to carefully plan and be well-rested before restarting the critical final approach to the space station," Frank Culbertson, Orbital's executive vice president, said in a statement. "Meanwhile, Cygnus has all the resources needed to remain in orbit for an extended period of time."
Cygnus was launched to the space station on Wednesday on a demonstration mission of proving its capability to reliably deliver cargo, only carrying 1,300 pounds (589 kg) of food, clothing and other items.
Orbital is the second U.S. company to send a commercial cargo craft to the space station. SpaceX was the first to send its own cargo ship with two successful commercial resupply missions and two demonstration missions under its belt.