Cassini spacecraft carries measuring instrument co-designed by Czech scientist


Last Friday's successful touchdown of the Huygens probe on Saturn's moon Titan made world headlines. The European-built probe was to explore conditions on Titan which are believed to be similar to those on the Earth some 4.5 billion years ago. The Huygens mission is seen as a landmark for the European Space Agency but it is also a personal triumph for many of the scientists who have spent years and sometimes decades working on the US-European Cassini-Huygens mission. Among them is the Czech astronomer Jiri Svestka who co-designed one of the measuring instruments carried by Cassini.

Huygens probe, photo: CTK
After its landing, the European-built space probe collected data on Titan and relayed it back home via its mother ship, NASA's Cassini spacecraft. One of the measuring devices onboard Cassini is the Cosmic Dust Analyser, co-designed by the Czech scientist Jiri Svestka from the Prague Observatory. Marcel Grun is the head of the Prague Observatory and Planetarium.

"The Cosmic Dust Analyser is a result of an international effort coordinated by the German Max Planck Institute for Nuclear Physics. We built up on a long term cooperation we established back in the Communist days. The Czech contribution was apparently so significant and esteemed that for the first time the Czech flag has appeared on an official emblem of such a space expedition. I'm glad that it was not through some academic agreements but thanks to concrete cooperation of a small institution in the Czech Republic with such a significant partner as the Max Planck Institute."

The Cosmic Dust Analyser provides direct observations of dust grains in interplanetary space. As Marcel Grun points out we are talking about particles from one millionth of a gram to one millionth of a millionth of a gram that can be compared to the particles found in cigarette smoke.

"The Cosmic Dust Analyser is unique in that it builds on previous instrumentation developed for the Galileo and Ulysses probes. The state-of-the-art device is so sensitive that it can detect one single impact a month or ten thousand impacts per second. Not only does it register the dust particles themselves but it can analyse them, and primarily thanks to Dr Svestka it can measure the electric charge of the tiny particles and their interactions."

Titan, photo: CTK
While the Huygens probe had its "three hours of fame" last Friday when it transmitted data from the surface of Titan, the Cassini spacecraft will orbit Saturn for at least three more years while its measuring instruments will explore the interplanetary space around it.

"The main measurement is aimed at Saturn and its surroundings where there is a lot of dust. After all, Saturn's rings, especially the more distant ones are composed of tiny dust particles. We need to find out how big they are, how they interact, how they are influenced by the magnetosphere. While bigger cosmic bodies are ruled by gravity, it is electromagnetic powers that determine the behaviour of tiny dust particles. So it's vital to measure their electric charge to understand what the surroundings of Saturn look like and how they are influenced by the interplanetary environment."