1 p.m. CST, Thursday, December 16, 1999
Mission Control Center, Houston, Texas

The International Space Station is operating in excellent shape with no problems affecting its operation in
low Earth orbit. One year ago yesterday, 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 Unity’s 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 NASA’s 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. Space Station viewing opportunities worldwide are available on the Internet at:

http://spaceflight.nasa.gov/realdata/sightings/

NOTE: The next International Space Station status report will be issued Thursday, Jan. 6, 2000, unless
mission events warrant. The Mission Management Team will not meet again until Jan. 5. For further
information, please contact the NASA Public Affairs Office at the Johnson Space Center, Houston, Texas,
281-483-5111.