INTERNATIONAL SPACE STATION STATUS REPORT #99-24
4 p.m. CDT, Thursday, July 1, 1999
Mission Control Center, Houston, Texas

International Space Station components continue to operate in good health with the exception being one of six batteries used to store solar energy in order to provide electrical power to the complex when it is in darkness.

ISS flight controllers in the United States and Russia began the first scheduled full charge and discharge of the six batteries on the Zarya module as part of a twice-yearly procedure to maintain as long a life on the electrical storage units as possible. Battery number six was completed as scheduled, but the same procedure on battery number one did not discharge fully as expected.

Though not an issue in terms of electrical power consumption by Station components, it is a 'lifetime' issue related to the onboard batteries, which under normal circumstances would be replaced routinely every five years or so. A procedure currently is being evaluated to assist in 'training' battery one prior to the full discharge of the remaining units.

The Station's current systems can actually operate on as few as three batteries if electrical usage is managed diligently. This would be similar to turning off lights, fans, or equipment in rooms of a house that weren't being used. This maintenance of "training" the batteries is similar to what one would do with a cellular phone or cordless tool battery here on the ground.

This procedure is performed on each battery every six months and is the first time to be done on Zarya's batteries. The next opportunity to perform this procedure will be after the Zvezda service module's arrival scheduled for November.

Here on the ground, the structural test article for one of the 40-foot-long truss segments arrived at the Johnson Space Center, Houston, to undergo acoustical vibration testing. This simulation will verify the launch environment for the actual hardware that will be delivered to space. The testing will continue through the summer and fall.

Meanwhile, the review continues of policies and procedures related to maneuvers of the Station in situations where a close approach with space debris is possible. This is in response to the recent predicted close pass of a spent Russian rocket upper stage. The debris ultimately passed 7 kilometers from the Station.

Though this procedure review continues, managers have elected to plan for possible future Station maneuvers by preparing uplink commands in advance to reduce the time required to build commands, called flight assignments.

This will allow a quicker response time to future close approaches to the Station that may require attitude maneuvers.

The International Space Station's orientation in space is the same as previously with Unity pointed toward Earth and Zarya pointed toward space. The Station is spinning very slowly about its axis to conserve fuel and maintain even temperatures on all surfaces.

The next shuttle flight to visit the ISS is scheduled for December following the launch, docking and checkout of the Zvezda living quarters in November. Updates on the status of shuttle launch preparations are available on the Internet at:
http://www-pao.ksc.nasa.gov/kscpao/status/status.htm

The International Space Station is in an orbit with a high point of 257 statute miles and a low point of 237 statute miles, circling the Earth once approximately every 92 minutes. The Station has completed more than 3,486 orbits of Earth since its launch. As it passes overhead at dawn or dusk, the Station is easily visible from the ground.

Space Station viewing opportunities for locations worldwide are available on the Internet at: http://spaceflight.nasa.gov/realdata/sightings/

The next International Space Station status will be issued July 8.

Note: For further information, please contact the NASA Public Affairs Office at the Johnson Space Center, Houston, Texas, 281-483-5111.