Alpha particle x-ray spectrometer developed in Mainz transmits first data from comet Churyumov-Gerasimenko

APXS will be used for analytical measurements to determine the chemical composition of the comet surface


Even though the landing did not go quite to plan, there was still room for celebration. This is the first time in the history of space travel that it has proved possible to actually put research equipment on the surface of a comet. Despite the fact that the lander, Philae, bounced when it first touched down on Churyumov-Gerasimenko and ended up where it wasn't supposed to, the ESA mission ground crew still had reason to cheer. All ten instruments on board were able to transmit data, including the alpha particle x-ray spectrometer (APXS) developed in Mainz.

The most recently available information indicates that the alpha x-ray spectrometer is functioning as expected after Philae's landing. "We have measured power consumption and other parameters from which we can conclude that all operating processes are working as planned," said Dr. Göstar Klingelhöfer of Johannes Gutenberg University Mainz (JGU). This means that the APXS has extended its probe 30 to 40 centimeters and has taken measurements. "We invested a lot to make sure that the instrument could be deployed and were on edge as to whether the movement mechanism would work. We were very pleased when the first data arrived," said Klingelhöfer. As one of the lead scientists, he spent the hours and days after the landing at the European Satellite Control Center (ESOC) of the ESA in Darmstadt and at the Lander Control Center of the German Aerospace Center (DLR) in Cologne.

The alpha particle x-ray spectrometer, which was developed at the Institute of Inorganic Chemistry and Analytical Chemistry at Mainz University and the Max Planck Institute for Chemistry in Mainz, was designed to carry out investigations directly on the surface of the comet. The device bombards the surface with alpha particles and x-rays and by measuring the backscatter from the particles, researchers can deduce the chemical composition of the material and obtain information about the presence of the important elements carbon and oxygen.

It is not yet clear exactly what the APXS has actually measured. "We don't really know the current position of the APXS, but are assuming that comet dust may have entered the device," explained Klingelhöfer. However, exchange of information with other mission teams over the next few weeks and months should help clarify the current status and location of the lander and thus the situation on the comet. The first task of Klingelhöfer and his team – Johannes Brückner, Tom Economu, Ralf Gellert, Jordi Girones Lopez, Rudolf Rieder, Dirk Schmanke, Christian Schröder, Claude d'Uston, and others – is to analyze the data supplied by the alpha particle x-ray spectrometer. If the solar battery on Philae recharges when Churyumov-Gerasimenko approaches the sun, additional measurements may be possible.