Planetary rover chassis require a careful balance of durability and low mass to survive launch, traverse extreme terrain, and operate through thermal cycles and abrasive dust. Michael F. Ashby, University of Cambridge, has established materials-selection frameworks that show the trade-off between specific strength and stiffness is central: materials with high strength-to-weight ratios reduce launch cost and improve mobility, but must also tolerate impact, fatigue, and environmental degradation.
Material trade-offs
Aluminum alloys and aluminum honeycomb sandwich structures are widely used because they offer good specific stiffness, manufacturability, and predictable behavior under cycling loads; NASA Jet Propulsion Laboratory has documented their use in past rover architectures to save mass while providing torsional rigidity. Titanium alloys such as Ti-6Al-4V provide higher strength and corrosion resistance and better high-temperature stability but at higher density and cost; they are suited for critical joints and load-bearing nodes where stiffness and fatigue life are paramount. Carbon-fiber-reinforced polymers deliver the best strength-to-weight and can be tailored for directional stiffness, yet they require careful thermal and radiation qualification and are sensitive to impact-induced damage; JPL and academic studies caution that composite delamination under micrometeoroid or rock impact is a practical risk.
Environmental and operational considerations
Planetary environments impose specific causes of degradation: abrasive regolith on Mars and the Moon accelerates wear on exposed surfaces, large diurnal temperature swings produce thermal fatigue, and vacuum or thin atmospheres change heat transfer and outgassing behavior. These consequences mean material choice cannot rely on static metrics alone; engineers must evaluate joint design, protective coatings, and redundancy. For missions where local human repair or in-situ resource utilization is plausible, simpler, more weldable metals may be favored to enable field maintenance or regolith-based construction, adding a cultural and logistical nuance to material selection.
Ultimately, the best balance is often a hybrid architecture using aluminum or aluminum sandwich panels for the primary chassis, titanium for concentrated load paths and fasteners, and composites where tailored stiffness and mass savings are critical. This multi-material approach reflects both the engineering evidence summarized by Michael F. Ashby, University of Cambridge, and the practical implementations and lessons documented by NASA Jet Propulsion Laboratory.