Encyclopedia Astronautica
1999.06.17 - ISS Status Report: ISS 99-22


International Space Station flight controllers prepared to maneuver the station slightly last weekend to avoid a possible close pass by orbital debris, but the maneuver was not carried out and ultimately was not required as the debris passed a harmless distance from the station early Sunday morning.

While monitoring the health of systems on board through Russian ground stations and the newly repaired early communications system, flight controllers were notified by the U.S. Air Force Space Command of a possible close approach of a spent Russian rocket body upper stage. While this is not a routine occurrence, it is an event that flight controllers deal with from time to time, as has been the case infrequently during the Space Shuttle program.

Early predictions showed the closest approach of the debris to the ISS would be within 1 kilometer, but the actual distance at the time of its closest approach on Sunday morning was 7 kilometers.

Flight controllers planned to maneuver the station Saturday night, but the uplinked procedure for maneuvering had one of the Zarya module's engines firing longer than is permitted by the module's onboard computer program. Therefore, Zarya's motion control system correctly canceled the burn automatically and the maneuver was not performed. Though the debris was ultimately not a problem, all of the procedures for debris avoidance maneuvers are being evaluated by both Russian and American flight controllers as a result.

The station's systems remain in excellent shape with maintenance work conducted by the last shuttle crew proving a total success. The complex's orientation is the same as before with Unity pointed toward Earth and Zarya pointed toward space conducting a slow spin about its axis to maintain even temperatures on all surfaces.

Meanwhile, at the Kennedy Space Center in Florida, the multi-element integrated test (MEIT) continues on components scheduled for launch to the ISS next year. This test connects components on the ground via cabling as they will be in space to verify they work together as well as they do individually. Additionally, the station's robotic arm - the Space Station Remote Manipulator System - supplied by the Canadian Space Agency has arrived at KSC for flight processing. The first piece of truss segment also arrived at KSC for pre-flight checkouts.

The next shuttle flight to visit the ISS is scheduled for December following the launch, docking and checkout of the Zvezda Service Module living quarters in November.

The International Space Station is in an orbit with a high point of 254 statute miles and a low point of 238 statute miles, circling the Earth once approximately every 92 minutes. The Station has completed more than 3,250 orbits of Earth since its launch. As it passes overhead at dawn or dusk, the station is easily visible from the ground.

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