A look at Mars’ first fully wind-powered plane
In the nearly 120 years since the birth of the airplane, humans have been able to design airplanes that break the sound barrier and fly through Earth’s skies upside down. Flying high in another world, however, is an entirely different matter.
A team of aerospace engineers from the University of Arizona and NASA’s Ames Research Center were inspired to design a new concept for off-world aerial exploration: the Mars Sailplane. Their concept, recently detailed in the review Aerospace, describes an aircraft that relies not on an engine or motor, but on the power of the wind to soar above the clouds.
Creating a vehicle capable of long-term flight on Mars has always been a difficult task to get off the ground. There are many conditions on the Red Planet that make flying planes very different from those on Earth, such as vast dust storms, less surface gravity, and an atmosphere 100 times thinner than ours. But in 2021, the Martian helicopter, Ingenuity, proved that powered flight on another was possible. On its maiden flight, the small rotor helicopter climbed about 10 feet from the Martian surface and was able to hover for about half a minute.
[Related: There are no shortcuts when you build a drone destined for Mars]
Since then, Ingenuity has completed 29 successful flights above the surface. Yet one of the vehicle’s biggest challenges is its constant need for solar power to operate. “Fixed-wing aircraft are limited by propulsion,” says Adrien Bouskela, lead author of the glider study and a mechanical engineering researcher at the University of Arizona. “So what can we do to extend flight paths, [or] the fuel available on board? »
It turns out that the solution to the problem was already widespread in nature. To widen an aircraft’s flight path, the team created a model that uses a technique called “dynamic flight”, where a bird takes advantage of wind energy to perform complex aerial maneuvers. The skill was originally observed in avifauna like frigatebird and albatross. In fact, albatross wings are so specialized for soaring that they can ride air currents thousands of miles above the ocean without needing to land and rest. The intertwining of dynamic flight with aerospace technology means that gliders could fly for days or even months without fuel or an engine, venturing into places that previous NASA missions could never explore.
The Mars Sailplane team also plans to design the craft to be completely autonomous, given that it will need to be able to monitor atmospheric changes and adapt quickly to stay adrift. Bouskela and his collaborators have already devised a computer algorithm to do this on Earth, but it will need to be modified on Mars if the glider is to survive there.
“There will have to be a piece of code in there that monitors the wind, records the wind, maps the wind, and then finds an optimal trajectory within it,” says Bouskela.
Gliders are not only energy efficient, but also economical. These craft are usually inexpensive to produce, lightweight, and because they are inflatable, small enough to fit in a shoebox. Jekan Thanga, an associate professor of aerospace and mechanical engineering at the University of Arizona, says it’s possible they could one day be deployed as a secondary payload on future Mars flagship missions, or even be packaged in a fleet of CubeSats. Such a simple development process certainly makes mass production a compelling idea.
[Related: This novel solar sail could make it easier for NASA to stare into the sun]
But the project has design and production hurdles to overcome before a space agency gives it the green light. One of the team’s biggest challenges is determining how the vehicle will accomplish its entry and descent into the Martian atmosphere. Additionally, Thanga says the timeline for deploying such craft is still up in the air. This is where some sort of carrier vehicle would come in handy; “It will take a little longer to deploy, and that is why we are also considering secondary vehicles, such as hot air balloons or an airship,” Thanga explains.
Once the craft finally lands on the surface of the red planet, the glider’s flight time will sadly be over. But although it is grounded, it can still be used.
At this time, the team imagines that the glider will have a “second life” as a weather station. As it is equipped with cameras and temperature, pressure and gas sensors, the craft will continue to observe and record atmospheric data from its remote location. Eventually, with enough gliders perched, the information they return could be used to create better numerical models of Mars’ enigmatic weather systems.
“We have some data on the Martian atmosphere, but… not enough,” says Alexandre Kling, NASA researcher and co-author of the study. “So the purpose of the mission is to learn more about the environment.”
Once the technology develops even further, Thanga notes that an “entire ecosystem of flying vehicles” could explore places like Mars’ Grand Canyon more closely, as well as the planet’s volcanic regions and highlands. Until then, the glider project is still in an early prototype phase, but could be ready for a space mission in two or three years with proper funding. In the meantime, the team plans to put the craft through its paces here on Earth soon: later this summer, engineers will take the models to an airfield and fly them 15,000 feet in the air, high enough for the wind conditions resemble those of Mars.
There’s still a lot to learn before these prototype gliders are ready to soar through the Martian skies, but as Kling points out, high risk brings high reward.
“We can fly to Mars,” Kling says. “I’m not saying it’s easy, but it’s so, so promising.”