Table of Contents

Microgravity Isolation Mount (MIM)

MIM: A Unique Canadian Space Technology

Experience has shown that spacecraft, such as the Russian Mir space station and the US Space Shuttle, do not provide the high-quality microgravity environment required for many science experiments. There are numerous causes for this deviation from the ideal "free-fall" environment such as the operation of on-board equipment (pumps, fans, thrusters, etc.), the movement of astronauts within the spacecraft, and variations in orbital characteristics such as atmospheric drag. While these disturbances are usually small and are most often not even felt by the astronauts, they can nonetheless have undesirable effects on space-based experiments. This is particularly significant for a large class of materials science experiments that involve fluid or vapour phases.

The Microgravity Isolation Mount (MIM) is a unique Canadian development that improves the microgravity environment for experimenters who use spacecraft such as Mir or the Space Shuttle. The MIM uses the principle of magnetic levitation to isolate experiments from the vibrations of the spacecraft. The MIM consists of three major components: a stator fixed to the spacecraft, a flotor which floats without contact relative to the fixed stator and a control unit which houses the brains of the system. Experiments are mounted on the MIM flotor and are controlled by the MIM control unit.

The MIM was built by MPB Technologies Inc. of Dorval, Quebec, under sponsorship from the Canadian Space Agency's Microgravity Sciences Program. The idea for MIM came from research conducted by Dr. Tim Salcudean of the University of British Columbia and from experiments conducted on NASA's KC-135 reduced-gravity aircraft by Canadian Astronaut Bjarni Tryggvason.

On April 23, 1996, a MIM unit was launched into space aboard the Russian Priroda module which subsequently docked with the Russian Mir space station. The MIM was activated for the first time by U.S. Astronaut Shannon Lucid during her six-month stay aboard Mir.

The first experiments to use the MIM facility aboard Mir were also sponsored by the Canadian Space Agency's Microgravity Sciences Program. These experiments used the QUELD II furnace (Queen's University Experiments in Liquid Diffusion) to develop new alloys and semi-conductor materials in space.

At the time of the mission, MIM had logged more than 200 hours of operational time on Mir and remained on the Russian space station for use in subsequent QUELD experiments and other experiments sponsored by the Canadian Space Agency and NASA over approximately three years.

A second MIM was sent into space with Bjarni Tryggvason on the US space shuttle mission STS-85. This mission was used to thoroughly characterize the MIM system using advanced control strategies. In addition, the effect of the vibration environment on representative materials science experiments was studied during the mission. The knowledge gained during this mission is being used to refine the requirements for isolation systems on the International Space Station (ISS).