Comet lander Philae of the ESA Rosetta mission has analytical equipment developed in Mainz on board

Alpha particle x-ray spectrometer will be used to determine the chemical composition of the surface of Churyumov–Gerasimenko


The ESA Rosetta mission, in which scientists from Johannes Gutenberg University Mainz (JGU) are also involved, today has reason to celebrate: the Philae lander has undocked from the Rosetta space probe after having been transported some seven billion kilometers through space and touched down on the comet Churyumov–Gerasimenko. On board Philae there are ten instruments designed to conduct scientific analyses of the comet, including an alpha particle x-ray spectrometer developed in Mainz. It is hoped that the investigation of the comet will provide valuable clues to the origin of our solar system.

The Mainz-based research team led by Dr. Göstar Klingelhöfer is looking forward to the data that the alpha particle x-ray spectrometer they developed will generate. It was activated in April 2014 and has already successfully passed numerous tests in subsequent months. "The results of all of our tests were very positive. We were pleasantly surprised," said Klingelhöfer. "The mechanism designed to position the alpha particle x-ray spectrometer on the surface is functioning perfectly." This is the first time in the history of space travel that a lander has touched down on a comet, providing scientists with the first opportunity ever to directly analyze the surface of a comet.

The tiny alpha particle x-ray spectrometer (APXS), which weighs only about 500 grams, is tasked with determining the chemical composition of the surface of comet Churyumov–Gerasimenko. The device functions by bombarding the surface with alpha particles and x-rays. The backscatter from the particles can then be measured. Using this data, researchers will be able to deduce the chemical composition of the surface material and obtain information about the presence of important elements such as carbon and oxygen. One unpredictable factor when it comes to putting the APXS in contact with the comet surface is the operation of its electric motors. "They have been specially constructed, but the motors can overheat," added Klingelhöfer. Together with his colleague Dr. Johannes Brückner and an international team, Klingelhöfer undertook various experiments in order to find ways to prevent the motors overheating. "However, the ambient conditions on the comet may actually be different to what we expect," said Klingelhöfer.