2 p.m. CST, Wednesday, March 31, 1999
Mission Control Center, Houston, Texas

International Space Station flight control teams in Moscow and Houston turned their attention from system monitoring to system testing in preparation for the next visit of a space shuttle to the orbiting outpost.

Most of this week and early next, U.S. and Russian operations personnel are testing the station's power system as part of preparations for the arrival of Discovery and the STS-96 crew in late May.

The testing involves gradually increasing the power used aboard Unity by turning on several heaters in hopes of gathering insight that may be useful in planning the best method for warming the module prior to Discovery's docking with the station. The power test is being conducted while the station's orbital environment is similar to what it will be in late May when Discovery arrives.

Though the testing is not yet completed, preliminary reports show that the increased power levels can be handled with no issues. Final analysis of the test will be completed next week.

Meanwhile, flight controllers continued an analysis of a minor problem with one of the two antennae aboard Unity. The antenna, one of two that are used by the US early communications system, has shown a slight degredation in its ability to receive signals from the ground when the station was in certain orientations. The slightly reduced communications capability has had minimal impact on operations.

Engineers are continuing to evaluate the information and possible causes for the problem. While the analysis continues, managers have elected not to fly a spare antenna on Discovery's mission, but will add an inspection task into the spacewalk that will take place during the docked phase of the flight.

The US communications system, installed on Shuttle mission STS-88 last year, is one of two complementary communications systems on the station, including a Russian communications system onboard Zarya.

The International Space Station is in an orbit with a high point of 251 statute miles and a low point of 241 statute miles, circling the Earth once approximately every 92 minutes. The station has completed more than 2,000 orbits of Earth since its launch.

ISS viewing opportunities from the ground can be found on the Internet at:

Space shuttle mission STS-96 aboard Discovery, targeted for launch May 20, will be the next mission to visit the station, delivering interior supplies and US and Russian cranes to be installed on the station's exterior. Updates on preparations for the launch of Discovery can be found in the Kennedy Space Center's shuttle status report located on the Internet at:

The next International Space Station status report is planned to be issued on Wednesday, April 7, 1999.

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