Exploration of Saturn’s rings aided by UK scientists

Scientists at the University of Sussex have produced synthetic ‘cosmic dust’ to help space researchers understand information gathered by a mission to Saturn.

CASSINI, an unmanned probe launched by NASA in October 1997, is due to go into orbit around Saturn this summer. One of the aims of the CASSINI mission is to study the planet’s famous rings. It is already recognised Saturn’s rings are made of cosmic dust, but very little is known about the composition of the dust.

Cosmic dust moves at speeds of up to 70,000 mph. When dust from Saturn’s rings hits CASSINI’s onboard detector, it will be obliterated in the collision. CASSINI will record data generated from dust impacts for transmission back to Earth.

The University of Sussex team’s plastic ‘cosmic dust’ particles are being used in related experiments on Earth. The new particles, just a thousandth of a millimetre in size, are being tested by a second group of scientists, led by Dr Mark Burchell, at the University of Kent. The aim is to ensure that CASSINI’s data are properly understood by comparison with laboratory-based experiments using various synthetic dusts of known compositions.

Lead scientist for the Sussex chemists, Professor Steve Armes, said: “After several centuries of speculation, we may finally find out what Saturn’s rings are made from.”

The key development is the ability to make the synthetic dust electrically conductive. The equipment used to accelerate synthetic dust in the laboratory only works when the dust is electrically conductive. Before the invention of the conductive Sussex particles, scientists were limited to tests using iron particles for the study of metallic cosmic dust. It was impossible to investigate the three other known types of cosmic dust found in outer space because the constituent materials – carbon, ice or silicate – are electrical insulators.

Professor Armes explained the breakthrough. He said: “We took electrically insulating plastic particles and coated them with a second plastic called polypyrrole to produce the synthetic dust. Unlike most plastics, polypyrrole is electrically conductive. This conductive coating allows our synthetic dust to be accelerated to the same speeds as cosmic dust. The new synthetic dust contains more than 90 per cent carbon, so their composition is ideal for understanding the behaviour of the organic cosmic dust found in outer space. We have also made good synthetic mimics for the silicate-based cosmic dust.”