Rosetta-Mission: “Chury’s” nucleus is non-magnetic Braunschweig geophysicists present recent results in Vienna

Knowledge about the magnetic properties of the planets and other solar system bodies allows for insight into their composition, dynamics, and history. After the Rosetta-Lander Philae’s amazing landing on the surface of comet 67P/Churyumov-Gerasimenko in November 2014, the results of the magnetic field measurements of the two instruments from Braunschweig are now available. The geophysicists from Braunschweig present their newest results in the journal “Science” as well as at the European Geosciences Union General Assembly (EGU) on April 14th, 2015 in Vienna.

“Churyumov-Gerasimenko is remarkably non-magnetic”, says Dr. Hans-Ulrich Auster, leader of the lander-magnetometer team from the Institut für Geophysik und extraterrestrische Physik (IGEP) at the TU Brauschweig. Due to its small size, it was not expected to find signs of a dynamo process inside the comet’s core, like the process that drives the Earth’s magnetic field. However, it was speculated that iron rich, magnetic dust particles could have been aligned along the magnetic field 4.5 billion years ago, which would present as a remnant magnetization.

But the Measurements of the ROMAP magnetometer from Braunschweig on board lander “Philae” show only magnetic fields on the surface that are very similar to those measured by the Rosetta orbiter magnetometer RPC-MAG. “That fact that the measurements in orbit and at the surface are remarkably similar is irrefutable evidence that the surface magnetic field is mirroring the properties of the magnetic field in the cometary coma”, explains IGEP scientist Dr. Ingo Richter, instrument manager of the orbiter magnetometer.

Comet 67P “sings” at the surface, too

The oscillations that are being detected since August 2014, called the “song” of the comet by the scientists, is also dominating the magnetic field directly above the surface. The contribution of the comet’s intrinsic magnetic field is well below 2nT, or about a fiftythousandth of Earth’s magnetic field. The combination of data from orbit and at the surface as well as the mutiple touchdowns make it possible to conclude that magnetic fields in the region where this comet was formed did not play a significant role in compacting decimeter-sized grains”, says Prof. Dr. Karl-Heinz Glaßmeier, leader of the Rosetta orbiter magnetometer team. As strong magnetic fields play an important role in understanding the formation of the solar system, the scientists are looking forward to the discussions with their international colleagues.