9 a.m. CST, Wednesday, November 24, 1999

Mission Control Center, Houston, Texas

The International Space Station celebrated its first year in orbit Saturday with no problems affecting the
overall operation of the complex in orbit.

Routine battery cycling and preparations to raise the International Space Station’s altitude have been the
focus of the last week as flight controllers monitor systems aboard Zarya and Unity.

With batteries 1 and 2 still disconnected from the electrical bus, engineers cycled the remaining batteries
with no issues. The four batteries currently getting their charge from Zarya’s twin solar arrays are handling all
electrical needs of the station.

Battery 2 was taken off line early last week when it did not discharge properly. Plans are in work by Russian
controllers to possibly recover partial use of battery 1, but those efforts are in the early stages of
development. The ISS actually can operate with no problems on as few as three batteries.

Also in planning is the full discharge-charge of the four usable batteries in a procedure called ‘battery
restoration.’ This is done about every six months on each battery system to maintain the unit and its
associated electronics lifetime to provide the maximum electrical capability to station systems.

A software patch soon will be uplinked to allow for additional data readings to be available from Zarya’s
systems through Unity’s early communications system via the NASA Tracking and Data Relay Satellite
System. The majority of these additional ‘parameters’ center around the battery systems to allow more
insight on electrical currents, voltage and resets.

ISS flight dynamics experts have developed a reboost procedure that will be carried out next week to slightly
raise the station’s overall altitude in preparation for the arrival of the Zvezda service module early next year.
Details of the burn plan using Zarya’s control thrusters are still being finalized, but the result of the burn will
minimize, or even eliminate, the need for an additional orbit adjust burn prior to Zvezda’s launch.

Here on the ground, mission operations personnel are in the process of upgrading the Mission Control
Center software, which has no impact on station operations.

The International Space Station continues to operate in excellent shape as it orbits at an altitude of 236 by
226 statute miles. Since the launch of Zarya a year ago Nov. 20, the ISS has completed more than 5,764
orbits. Space Station viewing opportunities worldwide are available on the Internet at:


The next International Space Station status report will be issued Thursday, December 2. For further
information, please contact the NASA Public Affairs Office at the Johnson Space Center, Houston, Texas,