Abstract
The advances in the field of robotics enabled successful exploration of the Moon and Mars. Over the years, rover missions have demonstrated deployment of various scientific payloads for robotic field geology on these extra-terrestrial bodies. The success of these missions clearly emphasizes the need to further advance rover technology in order to maximise scientific return. The success of future robotic surface exploration missions will depend on two key factors- autonomy and mobility on soft sandy and unstructured terrains. The main contribution of this paper is that it brings together vital information pertaining to various terrain characterisation techniques in to a single article. Special care is taken in structuring the paper so that all the relevant terrain characterisation methods that have been used in past planetary exploration missions and those under consideration for future space exploration missions are covered. This paper will not only lists advantages and disadvantages of various terrain characterisation techniques but also presents the methodology for evaluating and comparing terrain characterisation techniques and provides a trade-off study of existing and potential approaches that could improve the mobility of future planetary exploration rovers. This survey shows that further advances in currently deployed technology are required in order to develop intelligent, on-board sensing systems which will detect and identify near surface and sub-surface terrain properties to enhance the mobility of rovers.