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10 a.m. CDT, Thursday, July 29, 1999
Mission Control Center, Houston, Texas
International Space Station Status Report #99-28
Flight controllers in Houston and Moscow spent a relatively quiet week monitoring systems on the International Space Station (ISS) as the orbiting outpost’s systems continued to operate in excellent condition.

The focus of attention remained on the conditioning of the six batteries in the Zarya module and the “deep cycling” of the batteries to insure that they will provide the proper output of electricity. The “deep cycling” effort involves the discharge and recharge of each battery to maintain as long a life as possible for the operation of ISS systems.

Russian flight controllers at the Russian Mission Control Center in Korolev, outside Moscow, will conduct the battery discharge/recharge procedures periodically throughout the lifetime of the station.

NASA flight controllers, meanwhile, continued their analysis of a problem with the port omni antenna on the Unity module used for a backup communications system called the Early Communications System. The system, however, is working properly through the starboard antenna with no impact to operations or commanding to the station. A replacement antenna for the port side of Unity may be flown to the ISS aboard Atlantis in December during the next station resupply mission to the ISS on STS-101.

Russian space officials are considering adding a replacement battery to the manifest for Atlantis on that same flight which would be installed by the crew members in the Zarya module. One of Zarya’s batteries is providing a slightly different voltage output than the other five, although it is operating satisfactorily.

The International Space Station is oriented with Unity pointed toward the Earth and Zarya pointed toward space in a slow spin to conserve propellent and to maintain an even temperature for both modules.

The ISS is flying in a slightly elliptical orbit with a high point of 255 statute miles and a low point of 237 statute miles, circling the Earth every 92 minutes. The facility has completed almost 4000 orbits of the Earth since the launch of Zarya last November.

Space Shuttle launch updates, including the next visit of astronauts to the International Space Station, are available on the Internet at:

Space Station viewing opportunities for locations worldwide are available on the Internet at:

The next International Space Station status report will be issued on August 5.

EDITORS 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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