Helicopters don’t fly, says another, they “beat themselves into the air”.
NASA is trying to do it on Mars. Of course, this helicopter will not have a human pilot inside its tiny fuselage. But all the challenges of terrestrial flight will still be there – and made much worse by the Martian atmosphere’s distinct features.
It is cold, down to -90ºC at night. The air – mostly carbon dioxide – is roughly 1% as dense as Earth’s atmosphere. But the agency’s Jet Propulsion Laboratory (JPL) in Pasadena, California, has already built a Mars helicopter, and plans to fly it above the Red Planet in less than two years. How has it achieved this feat – and, just as importantly, why?
“No one has ever built a Mars Helicopter before,” says project manager MiMi Aung. The main challenge, she says, is the maximum mass that could be lifted in such a thin atmosphere. While the lower gravity provides a welcome boost, the two contra-rotating rotors will have to spin at almost 3,000rpm – roughly 10 times more frequently than Earth helicopters. 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,” says Aung.
The JPL is confident in those capabilities thanks to stringent testing, including temperature profiles, radiation sensitivity and flights in a thin carbon dioxide atmosphere.
This remarkable achievement was done using a lightweight combination of custom-designed systems and parts, and parts currently available in industry, including lithium-ion batteries, an inertial measurement unit and mobile phone-class computer elements and cameras.
The Mars Helicopter will leave Earth next year, under the belly of the Mars 2020 rover on an Atlas V rocket. After a pause of a few months on the Martian surface, the solar-powered craft will make the first intrepid flights, lasting up to 90 seconds.
If successful, it could lead to future helicopters weighing 5-15kg capable of flying up to 5km in 3-5 minutes – a potential top speed of 100km/h – Aung tells Professional Engineering. Carrying 0.5-1.5kg scientific payloads, such a transport capability would “significantly extend the limits of scientific and exploration”, she says. Potential missions include scouting ahead and collecting high-definition terrain images, or collecting samples from inaccessible regions.
With things going the way they are, maybe those images and samples could help the first Martian settlers take a second chance for the human race. Sometimes, weird engineering can save the day.
Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.