INTERNATIONAL SPACE STATION STATUS REPORT #99-46
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: http://spaceflight.nasa.gov/realdata/sightings/

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, 281-483-5111.

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