SOLERO : Solar Powered Exploration Rover

This abstract presents a perform study on SOLERO, a new and innovative rover concept for regional mobility on planetary surfaces. A rover is the most suited element to bring scientific instrument to a specific site in order to examine geology, mineralogy or exobiology on extraterrestrial planets. In contrast with the Mars Pathfinder mission, the actual need increases in terms of range and duration. These aspects lead to redesign many aspect of the past rovers, in particular the development of most suitable all terrain performances, autonomous navigation and a new power management concept. In this paper we’ll focus on the locomotion and the energy utilization without contribution of batteries. To validate the SOLERO possibilities in these domains and its use for future planetary exploration missions, modelization, testing and Mars like mission simulation have been done. Due to extreme temperatures the use of batteries is a critical point and becomes too expensive in term of size and mass for long-time missions. In this case, a locomotion concept reducing power consumption with exclusive use of on board power generation has to be investigated. The SOLERO mechanical structure is an optimization of the “Shrimp” rover developed at EPFL. It has one wheel mounted on a fork in the front, one wheel in the rear and two bogies on each side. The parallel architecture of the bogies and the spring suspended fork provides a high ground clearance while keeping all its 6 motorized wheels in ground contact. This ensures excellent climbing capabilities over obstacles higher that the wheel diameter. Moreover, this original combination of wheeled locomotion and passive adaptation to help to reduce power consumption compared to active design such as legged rovers, without sensible reduction of climbing abilities. To remove the problems linked with energy storage, not only power reduction is important, but also the power management. SOLERO uses exclusively solar cells to generate the electrical power, because it’s currently the most adapted solution for local energy generation on a rover. However the use of solar power only, have several constraints linked with the incoming solar radiation (insolation). To determine SOLERO’s power budget and performances, a Mars insolation and environment model has been chosen as reference. The integrated solar power generation restricts the operation time and power to specific daytime. The electrical power provided by a solar panel of 0.3m2 is over 14W during the four hours around noon, this is sufficient for locomotion. The 1kg scientific payload needs less that 8W power and can be used during a maximal time of height hours during daylight. However, the limited power storage capacities and the reduction of power consumption for locomotion allowed this rover to be small, light and operational during more that 100 sols (Martian days). The total mass is only 10kg and its locomotion performance, in comparison with actual rovers, leads SOLERO to become the perfect candidate for long range mission on near-sun planets