In Memory of Johannes Geiss

Prof. Dr. Johannes Geiss, Honorary Director of the International Space Science Institute (ISSI) in Bern and External Scientific Member of the Max Planck Institute for Solar System Research (MPS), passed away on 30 January, 2020. He was 93 years old.

Johannes Geiss began his unprecedented scientific career at the University of Göttingen, where he received his doctorate in the early 1950s as a student of the later Nobel laureate Wolfgang Paul. After research stays at the University of Bern, the University of Chicago, and the University of Miami, he accepted a call to the University of Bern in 1960, where he established a laboratory for extraterrestrial research and operated it until his retirement in 1991. In 1982 Johannes Geiss was appointed External Scientific Member of the Max Planck Institute for Aeronomy, which was later renamed Max Planck Institute for Solar System Research (MPS).

Even after his retirement, Johannes Geiss remained a man of action in the field of space research. He played a major role in the founding of the International Space Science Institute in Bern, which he headed initially as founding director and until his death as honorary director.

In addition to isotope geochronology, his scientific interest was primarily focused on space plasmas. His groundbreaking experiments on board the Apollo missions on the Moon, for example, determined the properties and composition of the solar wind. With further experiments Johannes Geiss investigated among other things the composition of matter in the Earth's environment, the Sun and the interstellar gas. He was involved in numerous space missions such as Ulysses, SOHO, and Cassini/Huygens.

With Johannes Geiss, European space research loses a unique and visionary leader.