Peter Signer died on Friday, Dec. 10, 2021. After a long illness, he peacefully fell asleep at the age of 92. He was a Fellow of the Meteoritical Society since 1967. His name is memorialized in the Baur-Signer ion source in noble gas mass spectrometry and the Signer-Nier model for cosmogenic noble gases.
Following his dissertation at the University of Bern on a mass spectrometric study of the 176Lu decay constant with Friedrich Houtermans and a seven-year stay with Alfred O. Nier at the University of Minnesota, Peter Signer was appointed professor for Geo- and Cosmochronology at ETH Zurich in 1965. He founded the Laboratory for Noble Gas Mass Spectrometry, which he led until his retirement in 1994 and which is now headed by Henner Busemann in the third generation.
In Minneapolis, Peter contributed much to a better understanding of noble gases in meteorites. In by now classical works, he developed the Signer-Nier model describing cosmogenic noble gas production in iron meteorites and with Hans Suess he coined the terms “solar” and “planetary” for different noble gas components in meteorites. In his first years at ETH, he proposed to capture ions from the solar wind with metal foils on space missions, an idea that was ultimately realized by his colleagues at the University of Bern as the famous solar wind experiment during the Apollo lunar missions. Under his leadership, the ETH noble gas laboratory received worldwide recognition, first of all with work on lunar samples and meteorites, studying solar, cosmogenic and primordial noble gases. Further major activities – in close collaborations with colleagues in Earth and environmental sciences - included surface exposure dating of terrestrial samples with "cosmogenic" noble gases, as well as studies of lake dynamics with noble gases, e.g. by tritium-3He dating.
Peter Signer was an enthusiastic lecturer who reminded generations of Earth Science students about the importance of the other planets for understanding Earth.
Peter is survived by his wife Gerti and their two children Ina and Reto. We mourn with them a good friend and teacher.