When NASA’s Perseverance rover safely touched down on the red planet in early 2021, it wasn’t alone. It was carrying a passenger, safely stowed under the belly of the rover. That passenger was a small helicopter named Ingenuity.

This little rotorcraft was built and designed to be a technology demonstration for NASA, meaning it was simply a proof of concept to prove that powered flight could work on Mars. A few weeks after Perseverance had chosen a safe drop off location, Ingenuity was released from the rover down to the surface of Mars to prepare for flight. On April 20th 2021, Ingenuity became the first spacecraft to perform powered flight on another planet when it took off from the ground, hovered, and landed again. Since then, the craft has performed increasingly daring and adventurous flights on Mars, exceeding all expectations from the mission team. The success of Ingenuity opens the door to endless possibilities of how we can explore Mars and the rest of our Solar System with more advanced and complex machines built for flight.

The Perseverance rover and the Ingenuity helicopter stop to take a selfie together on Mars (NASA/JPL)

A demonstration in Ingenuity

The idea of sending a helicopter to Mars goes back to when the Perseverance rover was first being designed and constructed in 2014. NASA’s Jet Propulsion Laboratory published a conceptual design study into how a small, powered craft could fly on the red planet, after travelling with the rover. This concept became a reality in 2018 when NASA received enough budget for the helicopter to go ahead and to accompany the Perseverance rover that at the time was simply named ‘Mars 2020’. As Ingenuity was designed to be a technology demonstration, it did not carry a suite of scientific instruments or complex cameras like the rover. Its primary goal was to simply prove that a craft could take off in the thin Martian atmosphere, and perhaps take a few photos while doing so. It was intended to act as a scout for the slower rover, as it could fly to locations of interest in advance before sending the rover there.

The many components of the Ingenuity helicopter while in the design phase (NASA)

The troubles of flight on Mars

Since the 1990s, Mars exploration has been led by rovers. These mobile laboratories have proved to be a highly successful way to traverse and study the red planet, but they also come with problems. The first is that rovers move extremely slowly. The twin Spirit and Opportunity rovers could in theory move at a max speed of 180m per hour – but they would almost never be travelling at that speed. It would take months and often years for the rovers to reach their destination. Despite advances in materials and technology, Curiosity is a much larger rover than its predecessors and as a result is even slower, with a max speed of 140m per hour. The slow speed protects the integrity of the rover along with its suite of sensitive scientific instruments.

Another problem with driving on Mars is that the harsh terrain can be treacherous for wheels. After almost 9 years on Mars, Curiosity’s wheels are heavily punctured due to the sharp and jagged rocks. This may eventually become the demise of the rover. Rocks aren’t the only problem – with some rovers getting stuck in soft terrain. This was the case for the Spirit rover who became stuck in a sand dune in 2009. The rover was never able to free itself, and it ultimately ended the mission.

The difficulties of traversing Mars has spurred scientists to think about how a spacecraft could fly on the red planet, but naturally this comes with many challenges of its own. Mars has an extremely thin atmosphere, just 1% the thickness of Earths. The thin air means it would be extremely difficult for a craft to fly through the thin air unless it was moving very fast or was extremely light. This was a design constraint of Ingenuity, and engineers had to envision a craft that would be capable of flying in the thin air. The helicopter had to be small and lightweight, but produce enough thrust to be able to lift itself off the ground and carry a high-res camera, solar panels, and antenna so it can communicate with Perseverance. Ingenuity weighs just 1.8kilos in total, with a body size of just under 20cm. The twin blades are made from lightweight carbon fibre, with a wingspan of just over 1.2m.

To achieve flight in the thin air, Ingenuity’s’ blades have to move over 5 times faster of what would be needed to fly on Earth, equivalent to 2,400rpm. Early tests on Earth in vacuum chambers showed that Ingenuity was indeed able to fly in such thin air, as long as the blades were able to spin at these high speeds.

The Ingenuity helicopter while still attached to the underbelly of Perseverance. The rover dropped the helicopter to the surface before moving away (NASA/JPL)

First flights

As of June 2020, Ingenuity has performed 7 flights, exceeding expectations of the mission and completing all of its original goals to demonstrate flight on Mars.

The first flight on April 20th was a simple hover manoeuvre to test if the helicopter could fly at all, followed by 2 more complex flights in the following days which demonstrated the helicopters’ ability to move. Ingenuity even managed to image Perseverance while it was watching it fly on the second flight. The 4th flight on the April 30th was the first where Perseverance recorded sound of the helicopter flying. After the 5th and longest flight in early May, NASA announced that the little helicopter will now act as a scout for Perseverance, conducting flights every few weeks until the end of August when its mission will likely end.

Ingenuity flies in the skies over Jezero Crater during its 5th flight, imaged by the Perseverance rover (NASA/JPL)

The future of exploration with powered flight

The success of Ingenuity not only opens the door for future flight-based exploration of Mars, but it opens the possibilities of exploration on other planets and moons in our Solar System. Once such program is NASA’s flagship mission ‘Dragonfly’. Dragonfly is a drone currently under development that will be sent to Saturn’s moon Titan, the only known moon in the solar system with a dense atmosphere. In fact, the atmosphere on Titan is 4 times heavier than Earth’s. The thickness of the atmosphere means flights will be much easier on Titan than Mars, but Ingenuity will always remain the pioneer of powered flight on another world. Such aerial missions in the future could allow us to explore the cloud tops of Venus with ease, or map and survey larger areas of Mars in rapid time.

An artists impression of NASA’s Dragonfly flying on Titan, due to launch in 2026 (NASA/JPL-APL)