The historic moment happened at about 8.30am BST this morning (19 April), when NASA’s Ingenuity Mars Helicopter took off from the Jezero Crater on Mars. The 1.8kg rotorcraft ascended to 3m above the surface, where it was expected to remain for about 40 seconds.
Engineers and mission control specialists at NASA’s Jet Propulsion Laboratory in Southern California cheered and applauded as the first flight data was received at 11.50am. Flight control confirmed the aircraft had completed all stages of flight, including spin-up, take-off, hover, descent and landing. Altimeter data clearly showed the craft’s ascent, hover and descent, while a black and white image showed the craft’s shadow on the surface.
“We can now say that human beings have flown a rotorcraft on another planet,” said project manager MiMi Aung. “We have been talking for so long about our Wright Brothers moment on Mars, and here it is.”
She added: “We know that our time to make a difference at Jezero Crater on Mars is not over. This is just the first flight.”
Vehicles such as the Apollo 11 Lunar Module Ascent Stage have previously taken off from the surface of the Moon, but controlled flight of an aircraft is an entirely different proposition to rocketry.
The main challenge for the Ingenuity helicopter, as project manager Aung told Professional Engineering previously, is the maximum mass that can be lifted in such a thin atmosphere. The atmospheric pressure is only 1% that of Earth – a far bigger challenge than the boost afforded by the planet’s one-third gravity.
Stephen Wright, drone expert and senior research fellow in aerospace engineering at the University of the West of England, told Professional Engineering: "Making a drone fly anywhere is like climbing a slippery pole into the sky – on Mars the pole is very greasy.
To then build a machine that can do that trick, and then hurl it across the Solar System, tell it to unfold itself, and then go – it’s a spectacular achievement."
The craft’s two contra-rotating rotors have to spin at about 3,000rpm to create enough lift, 5-10 times more frequently than helicopters on Earth. For the 1.2m-diameter rotors, the maximum mass is 1.8kg.
“Within this mass allocation, the vehicle had to be designed and built to be capable of autonomous flight, able to survive in Mars environments such as the very cold temperatures at night [and] able to survive independently through solar power garnered from the Sun,” said Aung.
A lightweight combination of custom and off-the-shelf parts were used to overcome those challenges, including lithium-ion batteries, an inertial measurement unit and mobile phone-class computer elements and cameras.
A momentous flight
With a 15 minute and 27 second delay on radio signals between Mars and Earth, Ingenuity’s guidance, navigation and control systems piloted the flight.
The test began when the Perseverance rover, which serves as a communications base station for Ingenuity, received the day’s instructions from Earth. About an hour later, it was expected to transmit the commands to the helicopter, sitting 65m away.
Pre-flight checks include ‘wiggling’ its blades. When guidance, navigation and control systems deem the test results acceptable, they turn on the inertial measurement unit – an electronic device that measures a vehicle’s orientation and rotation – and inclinometer, which measures slopes.
The helicopter then adjusted the pitch of the blades, configuring them so they did not produce lift during the early portion of the 12-second ‘spin-up’. The rotor blades were instructed to go from zero to 2,537 rpm, the optimal speed for the first flight.
After a final systems check, the pitch of the rotor blades was commanded to change again, digging into the sparse molecules of carbon dioxide, nitrogen and argon available in the atmosphere. The first flight began a moment later.
The climb was expected to take about six seconds. While hovering, the helicopter’s navigation camera and laser altimeter were due to feed information into the navigation computer, ensuring it remained level and centred above its 10m-by-10m ‘airfield’ selected for its flatness and lack of obstructions.
After the hover, set to include a pivot to look towards the Perseverance rover, the craft descended and touched back down. It then sent data back to Earth via the rover, confirming the flight.
New opportunities
The achievement will be the embryonic basis for any future flight programmes on Mars and elsewhere in the Solar System. Aung previously told Professional Engineering that it could eventually lead to helicopters weighing 5-15kg capable of flying up to 5km in 3-5 minutes – a potential top speed of 100km/h. Carrying scientific payloads, they could “significantly extend the limits of scientific exploration”, she said. Potential missions include scouting or collecting samples from inaccessible regions.
Thomas Zurbuchen, associate administrator for science at NASA Headquarters, recently said: “While Ingenuity carries no science instruments, the little helicopter is already making its presence felt across the world, as future leaders follow its progress toward an unprecedented first flight.”
He added: “We do tech demos like this to push the envelope of our experience and provide something on which the next missions and the next generation can build. Just as Ingenuity was inspired by the Wright Brothers, future explorers will take off using both the data and inspiration from this mission.”
The Perseverance rover is expected to send back images of the flight from its Navcam and Mastcam-Z cameras. The helicopter was also due to take colour and black-and-white images during the flight.
Ingenuity is expected to make more flights above the surface of Mars following the successful test.
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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.