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ExoMars Rover

Elements of the ESA-NASA ExoMars programme 2016-2018 (Credit: ESA) . Current design of the ExoMars rover (Credit: ESA) . Various wheel design options for the ExoMars mission as investigated by DLR

ESA, the European Space Agency, is planning to conduct a series of Mars missions jointly with NASA in 2016, 2018, and 2020. ExoMars as one of these missions would be led by ESA and has been under study since 2004. That mission would land an approximately 200 kg surface rover on Mars. Primary objective of the mission is the detection of organic compounds as well as any biomolecules that may have sustained under the currently adverse conditions at the immediate surface over geological timescales. ExoMars must be regarded as a logical step in the international Mars exploration programme which primarily seeks to address the question whether Mars in its past has harbored any microbial life. The ExoMars mission launch has recently been delayed to 2018 as a consequence of the budget available for Mars exploration in ESA’s programs. NASA’s contribution to the mission is to provide the launch services and the landing system. On the other hand, the first joint ESA-NASA mission to Mars in 2016 will be an orbiter that likely will include an ESA-developed small landed element to demonstrate Europe’s capability to land on Mars.

The "Exploration Systems" division of the Institute of Space Systems is a member of the industrial team developing the ExoMars rover, with the role of lead for development of the wheels. This task builds upon numerous prior technology development work in the area done for ESA and for terrestrial applications that had still been conducted at the Institute of Space Simulation of DLR in Cologne. The ExoMars wheel design concept, already validated through prototyping and tests, features a metallic flexible wheel that, similar to air tyres but without a pressure vessel, deflects under the operational load which leads to less wheel sinkage in the surface soil when compared to a rigid wheel of similar size. This results in a smaller overall motion resistance and at the same time in a smaller required wheel slip for the same net traction in comparison to a rigid wheel such as those used on the NASA Mars Exploration Rovers (MER’s) "Spirit" and "Opportunity". This is advantageous with respect to required energy per unit distance driven and relative to mobility performance on weak soils. The wheel development task, aside from actual design and test work, also includes extensive modeling of the wheel-soil interaction which is essential for being able to size the wheel in the first place.