> If you had a battery plane with solar panels that could land to gather energy, then it could fly again, but the landing and takeoff might be extremely hazardous, with rocks and very high speeds.
I've also wondered if you could use beamed microwave power to power a Mars airplane. For example, you could have a solar base station on the surface, and every hour or so the airplane would circle it closely and recharge its batteries. This only makes sense if you can make the microwave rectenna on the airplane much lighter than the equivalent solar cells. An airplane that never needs to land has some definite advantages. On the other hand, an easy way of acquiring geological samples is not one of them.
I've also wondered if you could use beamed microwave power to power a Mars airplane. For example, you could have a solar base station on the surface, and every hour or so the airplane would circle it closely and recharge its batteries. This only makes sense if you can make the microwave rectenna on the airplane much lighter than the equivalent solar cells. An airplane that never needs to land has some definite advantages. On the other hand, an easy way of acquiring geological samples is not one of them.