Neutron activation analysis, gamma ray spectrometry and radiation environment monitoring instrument concept: GEORAD

Geological processes on Earth can be related to those that may have occurred in past epochs on Mars, if analytical methods used on Earth can be operated remotely on the surface of the Red Planet. Nuclear analytical techniques commonly used in terrestrial geology are neutron activation analysis (NAA) and gamma-ray spectroscopy (GRS), which determine the elemental composition, elemental concentration and stratigraphical distribution of water in rocks and soils. We describe a detector concept called GEORAD (GEOlogical and RADiation environment package) for the proposed ExoMars rover within the ESA's Aurora Programme for the exploration of the Solar System. GEORAD consists of a compact neutron source for the NAA of rocks and soils and a GRS. The GRS has a dual role since it can be used for natural radioactivity studies and NAA. A fully depleted silicon detector coupled to neutron sensitive converters measures the solar particle and neutron flux interacting with the Martian surface. We describe how the GEORAD detector suite could contribute to the geological and biological characterisation of Mars both for the detection of extinct or extant life and to evaluate potential hazards facing future manned missions. We show how GEORAD measurements complement the astrobiological objectives of the Aurora programme. © 2004 Elsevier B.V. All rights reserved.