Magnetic Separation of Volatile Solid Particles Based on Field-Induced Translational Motion Under Short-Duration Microgravity Conditions

We designed an improved apparatus to separate and identify volatile solid particles at temperatures around 200 K using short-duration microgravity. Separation is based on the difference in diamagnetism of the mixed particles released in a region of monotonically decreasing magnetic field. The velocity of the translating particles in the microgravity region is considerably enhanced, which yields improved accuracy in measurement of the terminal velocity of the particles outside the magnetic field region. We achieved separation of a mixture of heterogeneous particles, including solid CO2, with high resolution. A particle's composition can be estimated from the value of magnetic susceptibility obtained from the terminal velocity because the particle's acceleration induced by the magnetic volume force is independent of particle mass. It is expected that material abundances of heterogeneous, volatile, solid particles, such as hexagonal ice, dry ice, ethane, methane, and CO, can be determined in this simple manner in cold regions on Earth and in the outer regions of the solar system.