Mars Mission Hopes Up as 11-pound Exploration Plane Created

The current situation on Mars

There are currently eight spacecraft, including three operated by NASA, orbiting Mars. These spacecraft gather images of the planet’s surface at a resolution of about one foot per pixel. Alongside these spacecraft, three rovers traverse the ground, mapping smaller areas of the planet with precision.

What lies in the hundreds of miles between the rovers and orbiters? Atmospheric climate processes and geological features, such as volcanoes and canyons. That is what most interests planetary scientists.

“You have this really important, critical piece in this planetary boundary layer, like in the first few kilometres above the ground,” said Alexandre Kling, a research scientist in NASA’s Mars Climate Modeling Center.

“This is where all the exchanges between the surface and atmosphere happen. This is where the dust is picked up and sent into the atmosphere, where trace gases are mixed, where the modulation of large-scale winds by mountain-valley flows happen. And we just don’t have very much data about it”, he continued.

Kling is part of a team of engineers at the University of Arizona who aim to fill this data gap. The team are designing a motorless sailplane that can soar over the surface of Mars for days at a time, using only wind energy for propulsion.

The sailplane is equipped with flight, temperature and gas sensors as well as cameras. Hypothetically, the sailplanes would weigh only 11 pounds each. The team details its proposal in a paper published in the journal Aerospace.

Soaring over Mars

There are challenges to flights on Mars, however, which is due to the thin Martian atmosphere. The University of Arizona team are not the first team to try it. Notably, NASA’s 4-pound Ingenuity helicopter landed in Mars’ Jezero Crater last year. However the helicopter was only able to fly for about three minutes at a time, and it reached maximum heights of just 12 meters.

Adrien Bouskela, an aerospace engineering doctoral student at the University of Arizona, said in the paper: “These other technologies have all been very limited by energy”.

He continued: “What we’re proposing is just using the energy in situ. It’s kind of a leap forward in those methods of extending missions. Because the main question is: How can you fly for free? How can you use the wind that’s there, the thermal dynamics that are there, to avoid using solar panels and relying on batteries that need to be recharged?”

Lightweight, wind-powered sailplanes may be the answer. The planes, which have a wingspan of about 11 feet, will use several different flight methods, including simple static soaring when sufficient vertical winds are present. But they can also use a technique called dynamic soaring, which takes advantage of how horizontal wind speed often increases with altitude, a phenomenon that is particularly common on Mars.

The planes fly at a slight upward angle into the slow-moving, low-altitude wind. When they reach the faster, high-altitude wind, they turn and let the high-speed wind power them forward at a slight downward angle. When they start to run out of energy from the high-speed wind, the planes repeat the process, weaving their way forward. With this nimble manoeuvring, the sailplanes can continually harvest energy from the atmosphere, flying for hours or even days at a time.

“It’s almost something you have to see it to believe,” said paper co-author Jekan Thanga, a University of Arizona associate professor of aerospace and mechanical engineering.

The land-bound rovers have mostly captured images of Mars’ flat, sandy plains, which are the only areas where the rovers can safely land. However, the sailplanes would be able to explore new areas by taking advantage of how wind patterns shift around geologic formations such as canyons and volcanoes.

“With this platform, you could just fly around and access those really interesting, really cool places,” Kling said.

Balloons, blimps, and payloads

The team proposes sending the sailplanes to Mars as part of a larger mission, on a secondary payload. On the spacecraft, the sailplanes will be packaged in CubeSats, miniature satellites not much larger than a laptop. Once the CubeSats are launched and the planes released, the planes would either unfold or inflate and rigidize at their full size.

The team is also exploring the possibility of a balloon or blimp carrying the sailplanes into the atmosphere. This would slow the sailplanes’ descent and allow them to take off when wind conditions are optimal or when they approach a high-interest area. The sailplanes could potentially redock on the balloon or blimp after a flight and go on to complete multiple missions.

Martian Summers

After landing on the Martian surface, the planes could continue to relay information about the atmosphere back to the spacecraft, essentially becoming weather stations.

Meteorologists can predict weather on Earth because there are weather stations all over our planet that form a network of information, and all the data they gather is continually fed back to predictive models. So, each Mars sailplane that retired from flying could become another all-important node in this network.

“If we run out of flight energy, or if our inertial sensors suddenly fail for whatever reason, we expect to then keep doing science,” Bouskela said.

“From the planetary science perspective, the mission continues”, he added. The team has done extensive mathematical modelling for the sailplanes’ flight patterns based on Mars climate data. However, there’s still more research to do about flight trajectories, potential docking systems and more.

This summer, they will test experimental planes at about 15,000 feet above sea level, where Earth’s atmosphere is thinner and flight conditions are more akin to those on Mars. “We can use the Earth as a laboratory for studying flight on Mars,” Shkarayev said.

The team at the University of Arizona ultimately hopes NASA will fund the mission and allow it to join a larger-scale Mars mission already in development. The low-cost nature of the sailplane effort means it could come to fruition relatively quickly, perhaps in years rather than the decades needed for a full-scale mission.