In 1937, Marietta Blau and her former student Hertha Wambacher discovered nuclear disintegration stars (Zertrümmerungsterne) due to spallation in nuclear emulsions that had been exposed to cosmic radiation at a height of 2300m on the Hafelekarspitze above Innsbruck. This discovery caused a sensation in the world of nuclear and cosmic ray physics, which brought the nuclear emulsion method to the attention of a wider audience. But the onset of political unrest in Austria and Germany, leading to World War II, brought a sudden halt to progress in that field of research for Marietta Blau.