International Space Station Program officials from NASA and Roscosmos met Saturday morning and agreed to proceed toward a second docking attempt for the ISS Progress 38 cargo ship on Sunday, July 4, at approximately 12:10 p.m. EDT. They will meet again Sunday morning to reconfirm the status of the space station and spacecraft systems. NASA TV coverage of the second docking attempt for the Progress 38 cargo ship to the station will begin Sunday at 11:30 a.m.

The Progress 38 conducted two successful firings of its engines Friday night to put the craft in a parking orbit around 300 kilometers from the space station. Another engine firing is being conducted Saturday morning to start the process of returning the spacecraft back to the station for Sunday's docking attempt.

Russian specialists told program officials the cause of Friday's aborted docking was what they termed a "cancel dynamic operations" command that instructed Progress' computers to fly the vehicle past the station on its final approach for docking, as it is intended to do if the internal guidance system receives conflicting commands or commands that do not comply with its pre-programmed commands.

The Russian flight controllers said the command to cancel was caused by the activation of the TV transmitter for the TORU manual rendezvous system in the Zvezda Service Module, which interefered with the Kurs automated rendezvous system. TORU is used to override Kurs, which Progress normally uses for docking, in the event Kurs experiences a problem. The TORU TV system is designed to provide a view of Zvezda's docking target to station Commander Alexander Skvorstov, if he had to operate a joystick in the service module to dock Progress manually.

The Russian flight control team has confirmed the Kurs system operated normally and did not fail, as was initially believed. Kurs uses radio beacon signals beamed back and forth between the approaching spacecraft and the space station to measure distance between the two vehicles and the rate of closure by Progress to Zvezda.

Russian officials said the TORU system will not be activated Sunday for the second docking attempt as a precautionary measure and expressed full confidence Sunday's docking can be conducted without any further issue.

Overnight, Russian specialists conducted a successful test with both the prime and backup strings of the Kurs automated rendezvous system on both the Progress and Zvezda. Another test of both strings will be conducted Saturday night. A final test of the Kurs system, as is always conducted during the terminal phase of the rendezvous, will be performed about 50 minutes prior to docking when Progress is 15 kilometers from the station.

In the unlikely event the prime Kurs string of telemetry fails late in the rendezvous sequence on final approach, Kurs' backup string will take over through docking. If the second string should fail, an automatic abort would be triggered, and Progress would immediately halt its approach and back away from the station to a safe distance. Multiple docking attempts could be made if needed.

The Expedition 24 crew members onboard the space station were notified by the team in Mission Control in Houston that another docking attempt will be made Sunday. They have an off-duty day Saturday and will adjust their workday schedule to monitor the docking activities Sunday.