Tuesday, 25 September 2007

Fluid theory confirmed

The Foton M-3. Credit ESA

The Foton M-3 capsule carries a 400 kg European experiment payload with experiments in a range of scientific disciplines - including fluid physics, biology, crystal growth, radiation exposure and exobiology.

The capsule spends 12 days orbiting the Earth, exposing the experiments to microgravity and, in the case of a handful of experiments also exposing them to the harsh environment of open space, before re-entering the atmosphere and landing in the border zone between Russia and Kazakhstan.

All liquids experience minute fluctuations in temperature or concentration as a result of the different velocities of individual molecules. These fluctuations are usually so small that they are extremely difficult to observe.

In the 1990s, scientists discovered that these tiny fluctuations in fluids and gases can increase in size, and even be made visible to the naked eye, if a strong gradient is introduced. One way to achieve this is to increase the temperature at the bottom of a thin liquid layer, though not quite enough to cause convection. Alternatively, by heating the fluid from above, convection is suppressed, making it possible to achieve more accurate measurements.

It was suggested that the fluctuations would become much more noticeable in a weightless environment. Now, thanks to the Foton mission, the opportunity to test this prediction has come about, and the results completely support the earlier forecast.

To the delight of the science team, the images visually support the theoretical predictions by showing a very large increase in the size of the fluctuations. Data analysis has also shown that the amplitude of the fluctuations in temperature and concentration greatly increased.

It may be that the results will influence other types of microgravity research, such as the growth of crystals. This research may even lead to some new technological spin-offs.

Read more: Fluid Theory confirmed by Foton