NASA is sending a small, autonomous rotorcraft to Mars via the agency's Mars 2020 rover mission, currently scheduled to launch in July 2020. NASA says the goal of the mission is to "demonstrate the viability and potential of heavier-than-air vehicles on the Red Planet." BBC reports: Its design team spent more than four years shrinking a working helicopter to "the size of a softball" and cutting its weight to 1.8kg (4lbs). It is specifically designed to fly in the atmosphere of Mars, which is 100 times thinner than Earth's. NASA describes the helicopter as a "heavier-than-air" aircraft because the other type -- sometimes called an aerostat -- refers to aircraft like balloons and blimps. The helicopter's two blades will spin at close to 3,000 revolutions a minute, which NASA says is about 10 times faster than a standard helicopter on Earth.