(2) Solar panels Solar panels are used to convert solar energy into electric energy for use by satellites;

(3) Sound waves need medium to propagate, while radio waves can propagate in vacuum; Its camera can send the captured image back to the lander through radio waves;

(4) When the Chang 'e-3 lander descends at a constant speed, its mass and speed remain unchanged, so its kinetic energy remains unchanged.

So, the answer is: Wei; Electricity; Radio waves; there will be no changes.