How to Fly a Helicopter on Mars

(via Popular Mechanics) The atmosphere on Mars at the planet’s surface is as thin as our planet’s air at 100,000 feet of altitude. Helicopters have never flown that high. Mars flight is not going to be easy. Yet NASA’s Jet Propulsion Laboratory wants to fly a chopper on the Red Planet, where the air on the ground is thinner than atop the highest mountains of Earth.