5 p.m. CDT, Thursday, July 15, 1999
Mission Control Center, Houston, Texas
International Space Station Status Report #99-26
International Space Station activities continue to focus on the maintenance of on-board batteries to ensure as long a life as possible and the troubleshooting of a balky antenna on the backup communications system. Flight controllers continue to watch over ISS systems as well, despite two instances of power outages at the Russian Mission Control Center late last week and again today.
Battery restoration, the discharge and recharge of individual batteries or deep cycling, resumed this week with batteries number 1 and 2. Though the initial plan this week was to restore only battery number 2, the onboard software also began the process on battery number 1 at the same time. When the flight control team identified that battery 1 also was discharging, an evaluation was conducted and a determination was made that the simultaneous discharge of the two systems was a safe and viable operation. Therefore, the decision was made to proceed to completion of the procedure on both batteries. The process drains the battery voltage prior to performing a complete recharge in order to condition the battery for proper usage. This is done about every six months on the batteries and is a similar process to what one would do on the ground with a cellular or cordless phone at home.
Flight controllers continue to evaluate the cause of a loss of communication with the station through the left side antenna that is part of the backup communications system known as the Early Communications System. The system is working properly through the right side antenna and has no impact to operations or commanding to the ISS. Managers continue to study the data and may perform further tests on the system to verify its health prior to determining whether it needs to be replaced. One option is to replace it with a spare during a space walk on the next visit of the space shuttle to the ISS in December.
Two separate power outages at the Russian Mission Control Center - one last Thursday and the second earlier today - had no affect on station operations. Last Thursday's outage lasted about 5 hours and was caused by an unusually strong hail storm, which also affected backup generator power availability. Today's power failure lasted only an hour with the backup generators providing contingency-level power. Today's outage appears to have been caused by maintenance activities related to the earlier storm. The town of Korolev, outside Moscow where the center is located, was also affected by the outage.
The International Space Station's orientation has Unity pointed toward Earth and Zarya pointed toward space in a slow spin about its axis to conserve fuel and maintain even temperatures on all surfaces.
The International Space Station is in a slightly elliptical orbit with a high point of 256 statute miles and a low point of 238 statute miles. It has completed more than 3,702 orbits of Earth since its launch and circles the Earth once approximately every 92 minutes.
Space Shuttle launch updates, including the next to visit the International Space Station, are available on the Internet at: http://www-pao.ksc.nasa.gov/kscpao/status/status.htm
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 22.
Note: For further information, please contact the NASA Public Affairs Office at the Johnson Space Center, Houston, Texas, 281-483-5111.
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