Adapting elastically to Martian environment: Low Tg elastomer blends for Martian applications

Although the interest in Mars exploration is growing very rapidly, the availability of materials tailor-made for the Martian environment is limited. The conditions on Mars surface differ significantly from Earth. The density of its atmosphere is significantly lower, resulting in lower pressure and higher temperature range (from -130°C to 30°C). Dust storms consisting of erosive particles are frequent on its surface. The biggest destructive factor is the cosmic radiation, which easily reaches the Martian surface due to the lack of a magnetosphere.
A crucial material widely used in engineering is rubber due to its high elastic and damping performance. Rubber returns to its original shape after deformation. This makes it the perfect material for e.g., designing tires, seals, cable covers or dampers for the use in rovers, habitats and space suits. To withstand the harsh environmental conditions, rubber must be properly designed. Up to now, no rubber compound available on the market is able to fulfill the requirements. For this reason, nowadays, the tires of Martian rovers are manufactured from aluminum. Therefore, they do not exhibit the elastic properties resulting in a high transfer of vibrations and wear of the tires caused by dynamic deformation and contact with pointy rocks. Moreover, the rovers need to move at very low speed to minimize dynamic shocks that may damage their sensitive equipment. Thus, they are designed to track only around 100 m a day with a maximum of 0.18 km/h. Application of rubber tires with good damping performance would allow to increase the speed of Martian rovers which enables the exploration without
posing a too high threat to the sensitive equipment. Moreover, for future crewed missions and colonization the performance of rovers necessitates the use of rubber to reach higher speed and carry more load with sufficient vibration reduction.
To meet the low operating temperatures on Mars a blend of Butadiene Rubber (BR) and Silicone Rubber (VMQ) is used (Tg -100°C, -120°C, respectively) to decrease Tg as much as possible without losing the required properties. BR compounds exhibit high wear resistance, whereas VMQ compounds show very good thermal and aging resistance. Therefore, BR/VMQ blending will be performed to combine their advantageous properties. However, this is a challenging task due to their low chemical compatibility. To overcome this issue, a chemical coupling based on the thiol-ene click reaction between the elastomers is developed. With, this the designed compounds will be ready to face the Martian environmental conditions exhibiting a good elastic performance.