(1) Solar cells can convert solar energy into electric energy, and machines can provide energy;

From the deformation of the heat formula Q=cm△t, it can be concluded that △t=Qcm, that is, when the absorbed heat and mass are constant, the smaller the specific heat capacity, the larger the temperature change range;

It is known that the surface temperature of the moon changes greatly, so it must be caused by the small specific heat capacity of sand;

(2) The material density of a lightweight and agile lunar rover must be small; Not afraid of cold and heat means that the material of the lunar rover can withstand high and low temperatures;

(3) Bigfoot can increase the contact area, which is beneficial to reduce the pressure; "Deep convexity and concavity" can increase the roughness of contact surface, which is beneficial to increase friction;

(4) According to Newton's first law, when an object is not acted by external force, it will remain stationary or move in a straight line at a uniform speed;

Because the detector is moving, it will move in a straight line at a constant speed along the original direction;

So, the answer is: (1) The sun, electricity, is smaller;

(2)① Low density, ② High temperature and low temperature resistance;

(3) Increasing the contact area is beneficial to reducing the pressure; Rough contact surface is beneficial to increase friction;

(4)B。