With an experiment on the Chinese space station "Tiangong", European researchers want to track down the origin of so-called gamma-ray bursts. "In recent years, two possible models have prevailed," says astrophysicist Jochen Greiner from the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching. "However, we can only make the ultimate decision between the two via the polarization of the gamma rays from these flashes."

The new "Polar 2" measuring device, in which the MPE is involved, is intended to record the direction of oscillation of the gamma-ray bursts. The European research team wants to determine whether the gamma radiation is polarized or not. So whether their waves all oscillate synchronously in one direction or chaotically mixed up.

China bears the costs

The instrument is being built at the University of Geneva and is being financed by the Swiss Space Agency (SSO). At the end of next year it is to be sent into space and mounted on the space station. "Polar-2" is one of about a dozen projects selected by the United Nations Office for Outer Space Affairs (UNOOSA) in 2019 for China's next space station. China bears the costs for operation and rocket launch.

Gamma-ray bursts (GRBs) are the largest explosions in the universe. They are formed when a massive star explodes at the end of its life, or when two neutron stars merge. Although the lightning bolts were discovered more than 50 years ago, it has not yet been clarified how exactly they occur. The researchers want to get closer to an answer to these questions with the "Polar-2" project.