International Space Station Status Report #99-36
2 p.m. CDT, Thursday, September 23, 1999|
Mission Control Center, Houston, Texas
The International Space Station continues to orbit the Earth with its systems operating in good fashion as NASA managers prepare to meet with their Russian counterparts next week in Moscow for updates on the testing of the ISS’s next component, the Zvezda Service Module.
The Joint Program Review at the Russian Space Agency, planned for September 30, is not expected to produce a firm launch date for the Service Module. A discussion of the schedule of the current work being performed on Zvezda at the Baikonur Cosmodrome in Kazakhstan to prepare it for launch will be part of the agenda.
Zvezda will be launched atop a Proton rocket to serve as the early living quarters for the first permanent residents of the ISS and will take over control and propulsion capability for the expanding station from the Zarya module, which was launched last November. About nine days after its launch, the ISS will link up with Zvezda using Zarya’s jet thrusters during a series of rendezvous maneuvers.
Earlier this week, U.S. and Russian flight controllers noted a slight decrease in the power output of the ISS at the time one of Zarya's six power-producing batteries was undergoing routine cycling. At the same time, the ISS’ rotational rate was being decreased slightly as part of the regular housekeeping of the station performed by ground controllers to maintain even heating on both Zarya and the Unity module.
To alleviate the reduction in power during these procedures, commands were uplinked to the ISS to change its orientation, enabling Zarya’s solar arrays to gain a more favorable angle to the sun for power generation. The slight reduction in power led to ground controllers removing power from some non-essential equipment until normal power generation was restored. The power generation reduction was later attributed to multiple operations being conducted simultaneously with only five of Zarya’s six batteries available for power production. Battery # 1 remains off-line because of inconsistencies noted in its operation. It will be replaced by Atlantis’ crew members during the next visit of a shuttle to the station early next year, along with voltage and sensor equipment associated with the battery.
The ISS is orbiting at an altitude with a high point of about 246 miles and a low point of about 233 miles. Since the launch of Zarya last November, the ISS has completed more than 4,800 orbits of the Earth.
Space Station viewing opportunities worldwide are available on the Internet at:
The next International Space Station status report will be on September 30. For further information, please contact the NASA Public Affairs Office at the Johnson Space Center, Houston, Texas, 281-483-5111.
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