Update: The rendezvous has now been delayed to no earlier than September 28. Although initial testing of the software patch went well, time was very limited for Cygnus to execute its maneuvers before the scheduled arrival of the new crew complement. With the latest delay, the new crew members will be safely on board and settled before the cargo vessel’s next try.
Orbital Sciences’ final demonstration mission to qualify its Cygnus cargo vessel for supply missions to the International Space Station hit a slight snag on September 22. As NASA reports:
Orbital Sciences has confirmed that this morning, around 1:30 a.m. EDT, its Cygnus spacecraft established direct data contact with the International Space Station (ISS) and found that some of the data received had values that it did not expect, causing Cygnus to reject the data. 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 orbital mechanics of the approach trajectory.
The hold up is not too surprising for a first attempt and appears to be a fixable problem. The reschedule is going to make for a hectic few days for the crew, however, as the Cygnus berthing will now take place just one day before the arrival of crew complement Michael Hopkins, Oleg Kotov, and Sergey Ryazanskiy on September 25.
Orbital Sciences is now reporting that their software patch has been developed and tested on the ground. It is being uploaded to Cygnus September 22-23 and a second rendezvous will begin the evening of September 23, with final rendezvous and grapple hopefully taking place the following morning.
Image caption: Rendition of Cygnus approaching the International Space Station (Credits: NASA/Orbital Sciences).