Constraints on a potential aerial biosphere on Venus: I. Cosmic rays

The habitable zone high in the atmosphere of Venus, defined here by the combination of high temperature and acidity, lies between 51 and 62 km altitude and overlaps with the cloud layers. Here we study the hazard posed to this potential aerial biosphere by the ionising radiation of penetrating galactic cosmic rays (GCR) or extreme solar particle events (SPE) such as the 1859 Carrington Event and 775 AD event, modelled on the spectral shapes of the February 1956, August 1972 or October 1989 SPEs.93