Farewell to a persistent Mars helicopter

Farewell to a persistent Mars helicopter

He showed the world that it was possible: powered flight on another planet. In total, the small helicopter flew 17 kilometers through Mars’ thin atmosphere and reached a height of 24 meters, much further and higher than engineers dared to dream. Ingenuity, the first (and so far only) helicopter on another planet, made its final flight on January 18. This ends a historic NASA mission after three years.

One or more of Ingenuity’s rotors suffered damage during the final landing, NASA said last week. The helicopter had sent a photo of the Martian soil showing its shadow to Earth. It showed that a quarter of the surface of the rotors had broken off. NASA engineers are still in contact with the helicopter, but it is permanently paralyzed.

The small test helicopter (49 centimeters high) was a real go-getter. The plan was for Ingenuity to make five flights: there were 72 flights. He survived violent dust storms, a cracking cold Martian winter and a broken navigation sensor. “You may rest, but your legacy will continue to rise.” NASA said goodbye to X.

$85 million

“He has done very well,” says planetary researcher Sebastiaan de Vet of TU Delft (not involved in Ingenuity). “We have a new way to investigate planets. Before Ingenuity, we always focused on rolling carts.”

The helicopter (development costs around 85 million dollars) left for the red planet in the belly of Mars rover Perseverance in the summer of 2020. About seven months later, they landed together in the forty-five kilometer wide crater Jezero, just north of the Martian equator. Billions of years ago, water flowed there and perhaps there was microbial life there then. The passenger car-sized Mars rover will explore the crater at a speed of up to 0.14 kilometers per hour, looking for signs of fossilized microbial life.

It took the helicopter about a week after landing to descend from Perseverance’s undercarriage into the Martian sand. Perseverance then had to drive away immediately, so that the solar panels on top of the helicopter could receive the sun’s rays.

A day later, there was great relief among NASA engineers when it turned out that the helicopter had survived its first night alone. Temperatures in the crater can reach ninety degrees below zero at night, causing parts to crack and damage. It was now clear that the built-in heating, insulation and battery worked well.

NASA was really happy on April 19, 2021. The helicopter was the first vehicle to make a powered flight on another planet. A video taken by Perseverance showed the box-shaped helicopter flying up, hovering for a moment and then landing softly on its feet in the Martian sand. Ingenuity had reached a height of three meters. NASA compared this achievement to that of the Wright brothers, who in 1903 were the first humans to leave Earth with motor power.

Scout

Flying on Mars is extremely difficult. There is less air on the planet for the helicopter to push against (the density of the Martian atmosphere is only one-hundredth that of Earth). Ingenuity’s rotors therefore had to make about 2,400 revolutions per minute. The Mars explorer’s wingspan was 1.2 meters from tip to tip. After a command from Earth, the helicopter flew autonomously. Control from Earth was not possible, because radio signals to and from Mars take about twenty minutes.

Ultimately, Ingenuity did more than just technology testing. De Vet: “After its first five test flights, we had a successful helicopter on Mars. The cool thing is that NASA engineers then decided to use it as a kind of scout for Perseverance.” Ingenuity flew ahead of the Mars rover to look from above for interesting places for Perseverance to study.

The helicopter also looked for obstacles such as large rocks or soft sand. The latter proved fatal for Mars rover Spirit when its wheels got stuck in a pile of soft sand in 2009.

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The organization is now using the knowledge that NASA engineers have gained, such as that simple lithium-ion batteries are fine for such helicopter missions, for new helicopters. The Americans are already busy building Dragonfly, a helicopter that will fly above Saturn’s moon Titan. Engineers are also already thinking about a helicopter that will visit cliffs on Mars where other spacecraft cannot easily reach.

Mars rover Perseverance is still driving around on Mars, but from now on it has to do so without the help of Ingenuity. The helicopter now rests on top of an old riverbed in the crater.




SCIENCE