INTERNATIONAL SPACE STATION STATUS REPORT #99-28
10 a.m. CDT, Thursday, July 29, 1999
Mission Control Center, Houston, Texas

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:
http://www-pao.ksc.nasa.gov/kscpao/status/stsstat/current.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 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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