When I first heard about the Martian helicopter I dismissed the idea as folly. How would you even get the thing in the air? Well the Martian atmosphere is very thin, but the gravity on Mars is just over a third of what it is here on Earth (Mars and Earth comparison). Here gravity is 9.81 m/s2 and on Mars it is 3.6 m/s2.
So the helicopter is reality and will be launching with NASA’s Mars 2020 rover in July 2020. Can you imagine? Flying a helicopter millions of miles away with a multiple minute time delay to account for the time the control signals get to Mars and back, ranging from 4 to 24 minutes is going to be a big challenge.