In scientific research, there is great satisfaction when theoretical work is eventually supported by experimentation. Such was the case this week for a team of Italian and US scientists when they received preliminary confirmation of a 10-year-old theory from a fluid science experiment that is currently orbiting the Earth on the Foton-M3 spacecraft.
Although the Foton was only launched a week ago, the scientists are already very excited about the data they have received from their experiment, known as GRADFLEX (GRAdient-Driven FLuctuation EXperiment). The first results are qualitatively consistent with detailed theoretical predictions made over the past decade.
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.
Although the early research involved ground-based 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.
The first images from the experiment were downloaded to the Payload Operations Centre in Kiruna, Sweden, and received on Earth after only a few orbits, explained Professor Marzio Giglio, leader of the team from the Department of Physics and CNR-INFM (Istituto Nazionale per la Fisica de
|Contact: Olivier Minster|
European Space Agency