First controlled flight on Mars

The first controlled flight on Mars was achieved by NASA's Ingenuity Mars Helicopter at 7:46 a.m. UTC (12:33 Local Mean Solar Time, or Mars time) on 19 Apr 2021. The autonomous helicopter, which has a mass of just 1.8 kg (4 lb), flew for 39.1 seconds, climbing to an altitude of 3 m, hovering for around 30 seconds, then descending back to the ground.

The development of the Ingenuity helicopter was carried out by a small independent team at NASA's Jet Propulsion Laboratory, working separately from the main Mars 2020 (now Perseverance) rover project. As it was initially not clear if the idea of a Mars Helicopter was even technically feasible, the project had only a relatively small team and a limited budget (around $80 million – tiny when compared to other Mars exploration hardware). It was not until May 2018 that the experimental helicopter was deemed to be a mature enough design to be added to the planned payload of the Mars 2020 rover.

The difficulty in flying an aircraft on Mars comes from the planet's extremely thin atmosphere. Martian "air" (which is 95% carbon dioxide with negligible amounts of oxygen) has a pressure of just 610 pascals (0.006% of Earth's typical atmospheric pressure), making rotors and lifting wings much less effective. Ingenuity gets its lift from a pair of contra-rotating carbon-fibre rotors, each of which has a diameter of 1.2 m (4 ft) and spins at around 2,400 rpm (about five times the speed of the rotors on an Earth-based helicopter). On Mars this provides only enough thrust to lift a box-shaped fuselage about the size of a bag of flour. The whole vehicle has a mass of just 4 lbs (1.8 kg), which results in a weight of 1.5 lb (680 g) in Martian gravity.

Ingenuity is controlled by an onboard computer, which executes each flight plan autonomously. The delay in sending and receiving information between Earth and Mars mean that manual control would not be possible. Keeping the helicopter stable requires constant small control inputs, as the thin air makes it very easy to stall the rotors or lose control (similar to extreme high altitude flight on Earth, where conditions are similar).

Ingenuity is a technological demonstration, an experimental craft whose mission goals are simply to prove that controlled flight on Mars is possible, and to gather data on the aircraft's performance. It does not carry any scientific instruments aside from its own telemetry sensors and two onboard cameras. Lessons learned from its program of flight tests could, however, be used in the development of future Mars-bound aircraft – larger and more capable vehicles designed to scout terrain or reach inaccessible sites.