When NASA's 2020 Mars rover lands on the red planet, it will release an unusual piece of cargo: a miniature helicopter specially built for the Martian skies.
The space agency announced its plan to send an autonomous aircraft to Mars last year, and has now unveiled the design for the tiny vehicle.
Building a helicopter that can survive the harsh environment of Mars is no mean feat; it has to be able to fly in the planet's thin atmosphere and survive temperatures of -75C at night (or lower away from the equator).
The final design features a body the size of a softball (roughly 3.5 inches in diameter), and weighs just under 4lb.
It has two sets of rotor blades, which are four feet long tip-to-tip, and will spin at 2,400rpm.
That's twice as fast as helicopter rotors on Earth.