Dynamic Rotation of Space Station Mir

Michael Foale
NASA Johnson Space Center, Houston

The Russian space station Mir is a solid body with unequal principal moments of inertia. Free body rotations initially begun about the middle principle axis, in general develop into rotations about the other pair of axes, in the course of free motion. This motion is problematic for a station that has lost attitude control, and that must maintain its solar arrays directed toward the sun to maintain electrical power. This paper uses methods of Euler to calculate the resultant motion of the Mir in inertial space, with given total angular momentum and specified initial angular velocities about the solid body axes. The results are used to illustrate the difficulty of setting up an initial free rotation suitable to provide constant illumination of the Mir solar arrays.

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