Nuclear Instruments and Methods in Physics Research A 539 (2005) 198–216 Neutron activation analysis, gamma ray spectrometry and radiation environment monitoring instrument concept: GEORAD R.M. Ambrosi a,Ã , D.L. Talboys a , M.R. Sims a , N.P. Bannister a , M. Makarewicz b , T. Stevenson a , I.B. Hutchinson c , J.I.W. Watterson d , R.C. Lanza e , L. Richter f , A. Mills g , G.W. Fraser a a Department of Physics and Astronomy, Space Research Centre, University of Leicester, University Rd, Leicester LE1 7RH, UK b Agency’s Laboratories Seibersdorf, International Atomic Energy Agency, Wagramer Str. 5, P.O. Box 100, A-1400 Vienna, Austria c Department of Electronic and Computer Engineering, Brunel University, Uxbridge, Middlesex UB8 3PH, UK d School of Physics, Schonland Research Centre for Nuclear Science, University of the Witwatersrand, P.O. WITS, Johannesburg 2050, South Africa e Nuclear Engineering Department, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room NW13-221, Cambridge, MA 02139, USA f German Aerospace Research Establishment (DLR), Institute for Space Simulation, Porz-Wahnheide, Linder Hohe, D-51147 Koln, Germany g Department of Geology, University of Leicester, University Rd, Leicester LE1 7RH, UK Received 11 October 2004; accepted 14 October 2004 Available online 28 November 2004 Abstract 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. ARTICLE IN PRESS www.elsevier.com/locate/nima 0168-9002/$-see front matter r 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.nima.2004.10.031 Ã Corresponding author. Tel.: +441162231812; fax: +441162522464. E-mail address: rma@star.le.ac.uk (R.M. Ambrosi).