Pit craters on Mars have attracted attention as a target for exploration. Mars helicopter, capable of vertical taking off, landing, and hovering, is suitable for this purpose. Recently, a coaxial rotor type helicopter has been proposed as a Mars exploration. We focused on this coaxial rotor for pit crater exploration. We investigated the aerodynamic performance of the coaxial rotor and its single rotor components in different configurations: with a flat plate and a triangular airfoil, at Reynolds numbers 6000, 11000, 16000, and in configurations of two and four blades per rotating surface. We used the thrust coefficient, torque coefficient, and Figure of Merit (FM) as an index of aerodynamic performance. The triangular airfoil was more efficient than the flat plate, but the rotor efficiency decreased due to a decrease in the Reynolds number. When the same number of blades were used, the coaxial rotor had a better thrust coefficient and worse FM than the single rotor.