Dynamic Properties of the International Space Station throughout the Assembly Process

Attitude control and spacecraft dynamics have always demanded serious attention from spaceflight personnel. Proper utilization of the basic tools of dynamics and controls can help alleviate the problems associated with the somewhat unpredictable nature of attitude control in the most basic spacecraft. Soon a new spacecraft will be placed in orbit that will truly test man, machine and the forces that bind them. The International Space Station is the culmination of works from 15 nations. It will orbit the Earth 200 miles high and will signal a new era in manned spaceflight and international cooperation. This platform of science will not miraculously appear overnight. Five years of on- location construction, requiring over 45 launches, will finally place the million-pound station in orbit. The dilemma is that each pound will transform the previous stage into an entirely new spacecraft, one with its own dynamics and means for control. This paper will describe this 5-year ordeal and monitor the stability of every configuration of the ISS while it's under the influence of Earth's gravity. Of 112 separate configurations, the ISS can be confirmed stable throughout only 24. The remaining configurations are unstable about one, some or all of its body axes. Rendezvous maneuvers complicate matters, as the U. S. Space Shuttle has serious effects on the completed Station's dynamics, making it unstable about roll, pitch and yaw. Location of the principal axes in relation to body coordinates varies greatly and causes the station to rotate about its intermediate axis. In addition, dynamic analysis for a single construction phase is explained, calculated and compared to actual mass properties provided to NASA by Lockheed Martin's Systems Engineering Modeling and Design Analysis Laboratory with an error of less than one percent.Air Force Inst of Tech Wright-Patterson AFB OH School of Engineering is the author of 'Dynamic Properties of the International Space Station throughout the Assembly Process', published 1998 under ISBN 9781423560432 and ISBN 1423560434.