Zarya and Unity modules of ISS orbiting Earth. Photo: NASA

The International Space Station is operating in excellent shape with no problems affecting its operation in low Earth orbit. One year ago Wednesday, Endeavour returned from the first assembly mission, having delivered and joined the Unity module to the already-orbiting Zarya control module.

Much of the last week, flight controllers in Houston and Moscow have managed battery charging and watched over other systems on the station. Electrical power management continues to be the focus using four of six batteries inside Zarya. Batteries 1 and 2 remain disconnected from the electrical bus.

The Zarya software patch that was uplinked last week now allows insight into 68 additional electrical power system parameters through Unityís early communications system. The data also can be viewed on computer terminals in the Mission Control Center in Houston. Using the early comm system allows more frequent review of these systems using NASAís Tracking and Data Relay Satellite System.

Russian flight controllers continue to review the problem seen during a test last week of the automatic docking system called Kurs. The leading candidate for the discrepancies seen on the alternate system's relative velocity readings is electromagnetic interference (EMI) from other systems on the Station. The test will be rerun at a later date with power levels reduced to identify if EMI is, in fact, the cause of the problem. At present, hardware does not appear to be an issue. The Kurs system is used during the final rendezvous and docking of the ISS with the Zvezda service module scheduled for launch early next year.

Battery "capacity restoration" is continuing with battery 6 completing its deep discharge yesterday. Battery 3's restoration will begin next. Capacity restoration maximizes the useful life of the batteries.

The International Space Station continues to operate in excellent shape as it orbits the Earth at an altitude of 246 by 234 statute miles. Since the launch of Zarya in November 1998, the ISS has completed more than 6,134 orbits.