Description
Almost anything can rotate — from gymnasts to satellites — but not everything can rotate stably. The stability of a rotation depends on its axis and moment of inertia. We are developing an apparatus for a simple demonstration of this concept in 0g. Every object has three principal moments of inertia. The first principal moment, with the greatest inertia, and the third principal moment, with the least inertia, are both considered stable. The second principal moment, however, is not stable, and will undergo chaotic rotations. Attempting to rotate an object around this so-called intermediate axis of rotation can cause the object to tumble chaotically, which for objects like satellites or gymnasts, can be catastrophic. Using this principle, we aimed to design a device that takes advantage of the inertial centrifugal force resulting from the unstable rotations in order to shift weights within the device. As a result, the device’s second and third principal moments of inertia switch during the unstable rotation. This experiment is made to the standards of equipment on board the International Space Station (ISS), including concerns over material off-gassing, flammability, and overall size, as we hope to test this experiment on board the ISS.
Intermediate Axis Theorem with Shifting Weights
Almost anything can rotate — from gymnasts to satellites — but not everything can rotate stably. The stability of a rotation depends on its axis and moment of inertia. We are developing an apparatus for a simple demonstration of this concept in 0g. Every object has three principal moments of inertia. The first principal moment, with the greatest inertia, and the third principal moment, with the least inertia, are both considered stable. The second principal moment, however, is not stable, and will undergo chaotic rotations. Attempting to rotate an object around this so-called intermediate axis of rotation can cause the object to tumble chaotically, which for objects like satellites or gymnasts, can be catastrophic. Using this principle, we aimed to design a device that takes advantage of the inertial centrifugal force resulting from the unstable rotations in order to shift weights within the device. As a result, the device’s second and third principal moments of inertia switch during the unstable rotation. This experiment is made to the standards of equipment on board the International Space Station (ISS), including concerns over material off-gassing, flammability, and overall size, as we hope to test this experiment on board the ISS.