Why the flight of the Ingenuity helicopter on Mars is so important

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Yesterday at 9:00 PM, Australian Eastern Standard Time, the Ingenuity helicopter – which landed on Mars with the Perseverance rover in February – took off from the surface of Mars. More importantly, it floated for about 30 seconds, ten feet above the surface and came right back down.

It may not sound like a huge achievement, but it is. Ingenuity’s Flight is the first powered flight of an airplane on another planet. It marks a milestone in the story of human space exploration.

While the Apollo 11 spacecraft famously landed on the Moon, upon relaunch it simply had to leave the Moon’s gravity and return to Earth. However, to keep flying in the environment of a world without atmosphere is a different story.

It took six years to make Ingenuity’s now historic helicopter. We can understand why, once we understand the complexity of what was required.

Why local flights on Mars are so important

There are several technological challenges of conducting a helicopter flight on another world. First and foremost, helicopters need an atmosphere to fly.

A helicopter’s blades or “rotors” must spin fast enough to generate a force called “lift”. But lift can only be generated in the presence of some kind of atmosphere. Although Mars has an atmosphere, it is much, much thinner than Earth’s – about 100 times thinner, in fact.

Flying Ingenuity in Mars’ atmosphere is therefore the equivalent of flying a helicopter on Earth at an altitude of 30,000 feet. For reference, commercial planes fly between 30,000-40,000 feet above the Earth’s surface, and the tallest we’ve ever been in a helicopter on Earth is 42,000 feet.

To test the craft on Earth, a pressurized chamber was needed from which a lot of air would have been extracted to simulate the Martian atmosphere.

Then there is the gravity of Mars, which is about one third of the gravity on Earth. This actually gives us a small advantage. If Mars had the same atmosphere as Earth, the lower gravity means we could lift Ingenuity with less force than we would need here.

But while Mars’ gravity works in our favor, it is offset by the lack of atmosphere.

Ingenuity’s success marks the first time such a flight has even been attempted outside of Earth. And the reason for this could be simply that, as outlined above, this task is very, very difficult.

Read more: ‘7 Minutes of Terror’: A Look at the Technology That Will Need Persistence to Survive the Mars Landing

Advanced manufacturing

There are two main ways Ingenuity was able to overcome the obstacles in the atmosphere of Mars. First, to generate lift, the two rotors (made of carbon fiber) had to spin much faster than any helicopter on Earth.

On Earth, most helicopters and drones have rotors spinning at about 400-500 revolutions per minute. The Ingenuity’s rotor turned at approximately 2,400 revolutions per minute.

It also has a clear airplane to wingspan ratio. Although Ingenuity’s body is about the size of a tissue box, the blades are 1.2m tip to tip.

Even sending the start-of-flight signal required a range of advanced technology. While radio signals only take a few minutes to travel between Earth and Mars, there was still a delay of hours for those signals to reach the helicopter.

This makes sense when you consider the journey those signals must take – from a computer on Earth, to a satellite dish, to the Mars Reconnaissance Orbiter, to the Perseverance rover, and then, finally, to the helicopter.

This image shows the Perseverance Mars rover with the Ingenuity helicopter about 4 meters behind it.
Credit: NASA / JPL-Caltech / MSSS