Background radiation effects and hazards in planetary instrumentation

Recent and proposed future planetary missions are becoming increasingly concerned with detailed geochemical assessment, often in a bid to ascertain the presence of water and life supporting geochemical systems. The instruments involved may use some kind of radioactive source, e.g. X-ray fluorescence spectrometry, Mِssbauer spectrometry, neutron scattering. Having radioactive sources on a lander/rover poses various potential problems, in regard to both safety to personnel involved in the building of the instrument and to radiation effects on spacecraft structure and on other instruments. Indeed background radiation effects from one instrument may dominate measurements in another resulting in loss of scientific performance. Drawing on experience with the Beagle 2 probe which contained two instruments with radioactive sources, we present a discussion on the management of radiation hazards and background effects posed by radioactive sources for such planetary missions.