Ever wondered how astronauts feel when they are weightless?

A team of Scientists from the University of Leicester experienced zero-gravity last year. Daniel Brandt, Jim Aldcroft, Keith Sprake and Richard Branch - fresh from sitting their physics finals - joined 28 other teams from around Europe on the Airbus A300 over the Mediterranean Sea.

Their journey to Bordeaux had started almost a year before, when Aldcroft and Brandt came up with an idea to test how mixtures of particles of different sizes might settle in zero gravity conditions.

"We're trying to observe segregation of granular matter in reduced gravity conditions," says Branch.
In the presence of gravity, this separation phenomenon is more commonly known as the "Brazil nut effect", where the biggest nuts in a box of breakfast cereal, for example, rise to the top as the mixture settles.

This implies that the sizes of the particles in a mixture determine their final arrangement but no one has studied the role of gravity in the phenomenon. Out in space, how would a box of cereal settle? The idea has applications for planetologists trying to model how the debris resettles on small moons churned up after meteorite impacts.

"According to our theory, size shouldn't make a difference - what should make a difference is the density of the particles," says Branch.

In zero gravity, Aldcroft and Brandt's idea was that particles of different densities would separate into bands along the length of the box. How could the Leicester team test this idea? Mixtures of materials (ball bearings, sand and simulated Mars dust, for example) were packed into clear plastic boxes and vibrated at various frequencies to force them to settle.

For a full recollection of the experience, please visit Guardian Online





Picture Credit: photo ESA/Anneke Le Floc'h


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