Cygnus Approaches ISS
This morning, Orbital and NASA together decided to postpone the approach, rendezvous, grapple and berthing operations of the Cygnus cargo logistics spacecraft with the International Space Station until after the upcoming Soyuz crew operations are complete. The Soyuz crew is due to arrive at the ISS very late on Wednesday, September 25. The earliest possible date for the next Cygnus approach and rendezvous with the ISS would be Saturday, September 28. An exact schedule will be determined following the successful completion of Soyuz operations.
Over the past 24 hours, the Orbital team developed and tested a software fix for the data format mismatch that necessitated a postponement of the first rendezvous operation that was scheduled for the early morning of September 22. 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.
"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. Meanwhile, Cygnus has all the resources needed to remain in orbit for an extended period of time," said Mr. Frank Culbertson, Orbital's Executive Vice President and General Manager of its Advanced Programs Group.
22 September update:
Following the discovery of a data format discrepancy between an on-board International Space Station (ISS) navigation system and a similar system on Cygnus at around 1:30 a.m. this morning, today's rendezvous with the station was postponed. At this time, NASA and Orbital are developing a detailed plan for a second rendezvous attempt early Tuesday morning.
A software update has been developed and will be tested on a ground-based simulator during the day on Sunday. Upload to Cygnus and in-orbit testing of the software "patch" is planned for Sunday night and into Monday morning. Once this has been accomplished and verified, the current plan is for Cygnus to begin a second rendezvous approach late Monday night, with final approach to the ISS and grapple taking place early Tuesday morning. The Cygnus spacecraft remains healthy, with all major subsystems operating as expected.
Cygnus was launched into low Earth orbit aboard Orbital's Antares rocket from Pad-0A at the Mid-Atlantic Regional Spaceport at Wallops Island, Virginia on September 18, 2013. The goal of the mission is to demonstrate the complete Orbital commercial delivery system from the launch of the Cygnus advanced cargo logistics spacecraft aboard Antares and the rendezvous of Cygnus with the ISS, through unloading of cargo from Cygnus and loading of disposal cargo, to Cygnus departure from the ISS and reentry over the Pacific Ocean.
The Orb-D1 mission is the final development milestone under the NASA Commercial Orbital Transportation System (COTS) agreement. With the successful completion of the COTS mission, Orbital is slated to deliver up to 20,000 kg of supplies over eight missions to the ISS under the Commercial Resupply Services (CRS) contract with NASA through 2016.