NASA’s Mars Helicopter has passed another flight test

NASA’s Mars Helicopter — which is exactly what you think it would be — has recently finished another round of important tests and is expected to be integrated with the rover for the Mars 2020 launch this summer. Getting a heavier-than-air craft to fly on Mars is tough because Martian air is much thinner than Earth’s.Earlier this year, JPL conducted tests of the helicopter in “a simulated Martian environment” that put the helicopter through temperatures as low