火星直升机（去火星之前）

Veritasium's Derek Muller visits NASA JPL to see the Mars helicopter Ingenuity before it was mounted on the rover. He explains how it can fly in Mars's thin atmosphere with large, fast-spinning contra-rotating rotors and low mass, and covers power and cold.

Why HN likes it: HN repeatedly recommends it as an excellent explanation of why flying on Mars is hard and how the helicopter was built.

“a really excellent video that answers all your questions”