Commercial cargo ship aborts initial approach to station

CBS News

A commercial cargo ship making its maiden flight to the International Space Station aborted its initial approach to the lab complex early Sunday because of suspect navigation data.

Officials with Orbital Sciences Corp., builder of the Cygnus cargo craft, said engineers quickly identified the problem and were developing a software patch, but another approach was on hold until Tuesday.

In this artist's concept, an Orbital Sciences Corp. Cygnus cargo ship approaches the International Space Station. Launched on the program's maiden flight Wednesday, an initial approach to the station was aborted early Sunday because of a navigation glitch. A second attempt is expected Tuesday. (Credit: Orbital Sciences Corp.)

"This morning, at around 1:30 a.m. EDT, Cygnus established direct data contact with the ISS and found that some of the data received had values that it did not expect, causing Cygnus to reject the data," NASA and Orbital said in web site updates. "This mandated an interruption of the approach sequence.

"Orbital has subsequently found the causes of this discrepancy and is developing a software fix. The minimum turnaround time to resume the approach to the ISS following an interruption such as this is approximately 48 hours due to the orbital mechanics of the approach trajectory."

The Cygnus cargo ship, launched Wednesday from the Mid-Atlantic Regional Spaceport at NASA's Wallops Island, Va., was developed under a $288 million contract with NASA's Commercial Orbital Transportation Services, or COTS, program.

Orbital is one of two commercial cargo carriers hired by NASA to take over U.S. space station logistics in the wake of the space shuttle's retirement.

If the test flight is successful, Orbital will be clear to begin routine cargo delivery missions later this year under a separate $1.9 billion contract calling for at least eight missions to deliver some 40,000 pounds of supplies and equipment.

Space Exploration Technologies, or SpaceX, holds a $1.6 billion contract to conduct at least 12 space station resupply missions with its Dragon cargo ship. SpaceX has conducted two operational flights to the station.

The goals of the Cygnus demonstration mission are to test the spacecraft's navigation, command and control systems with a precisely orchestrated, stepwise approach to the station, including a simulated abort.

All of the planned tests going into Sunday's final approach were successful, but the GPS navigation issue early Sunday triggered a real abort and a 48-hour recycle.

While Orbital works through the navigation problem, Russian rocket engineers are preparing a Soyuz spacecraft for launch Wednesday to ferry three fresh crew members to the space station.

If any additional problems prevent Cygnus from completing its rendezvous Tuesday, a third attempt will be put on hold until after the Soyuz launch and docking later Wednesday evening. Company officials said before launch that Cygnus had enough propellant to loiter in orbit for an extended period if necessary.