We have a pretty good idea of Mars’ surface thanks to spacecraft, rovers, and other such technology. But it’s what lies in the atmospheric climate processes and geological features, like volcanoes and canyons, that has piqued the interest of a research team based at the University of Arizona.
“You have this really important, critical piece in this planetary boundary layer, like in the first few kilometers 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.”
The UA team aims to fill this data gap by designing a motorless sailplane that can soar over the Martian surface for days at a time, using only wind for propulsion. Equipped with cameras and flight, temperature, and gas sensors, the sailplane weighs just 11 pounds.
Mars’ thin atmosphere makes flight challenging, and this is not the first rodeo of trying to address it. For example, NASA’s Ingenuity, a four-pound helicopter, landed in Mars’ Jezero Crater in 2021. However, its miniaturized flight technology, rotor-system span of about four feet, three-minute flying time, and 39-foot height limit leave a lot to be desired.
“These other technologies have all been very limited by energy,” said research team member Adrien Bouskela, an aerospace engineering doctoral student in UA Professor Sergey Shkarayev’s Micro Air Vehicles Laboratory. “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?”
The sailplane has a wingspan of about 11 feet and will use several different flight methods, including simple static soaring. It can also use a technique called dynamic soaring.
“With this platform, you could just fly around and access those really interesting, really cool places,” Kling said.
The team is pursuing how to deploy the sailplane from the spacecraft into the atmosphere. On the spacecraft, the sailplane will be packaged in CubeSats, miniature satellites about the size of a phonebook. Once the CubeSats are launched and the plane is released, the plane would either unfold or inflate to its full size. They’re also exploring a balloon or blimp carrying the sailplanes into the atmosphere.
After landing on Mars, the planes would continue to relay information back to the spacecraft, essentially becoming weather stations.
The team has done extensive mathematical modeling for the sailplane's flight patterns based on Mars climate data. And there's still more research to be conducted about flight trajectories, potential docking systems, and more.
The UA team ultimately hopes NASA will fund the mission and allow it to “catch a ride” on a large-scale Mars mission. The low-cost nature of the sailplane effort means it could come to fruition relatively quickly, Kling said, perhaps in years rather than decades.
Here, an interview (edited for clarity and length) with research team members Shkarayev, Bouskela, and Jekan Thanga, a UA Associate Professor of Aerospace and Mechanical Engineering.
Tech Briefs: What spurred the idea to undertake this research? What was the catalyst?
Shkarayev: Well, there are two ideas. I think the first one is from the atmospheric flight science. Conventional soaring, sometimes called static soaring, is based on steady atmospheric winds in vertical direction updrafts of thermals. The physics or mechanics of flight in thermals are very simple and have been used since forever. I thought that there is a lot of energy up there in unsteady atmospheric streams, and, therefore, in addition to the conventional way of soaring and gliding, we started studying horizontal winds — horizontal, steady, unsteady winds with gradients in a time and in space. So imagine all the turbulence up there, and we want to find trajectories of the glider. They sometimes call them optimal trajectories of flight paths that will utilize, at maximum, all the mechanical energy in the atmosphere.
And through the simulations we know how to do that. We do some dynamic analysis and the mathematical framework has been developed. We have it on hand, and all the simulations showed us toward those trajectories … so these trajectories later were designed into the autopilot. So you have our experimental platform, the Glider, the autopilot that has all the mathematics providing the optimal flight trajectory in the dynamic atmosphere, providing this dynamic soaring.
And the second idea is to use the fact that similar properties of atmosphere can be found on other planets.
Thanga: Since Curiosity, there has been a significant ballast mass that's been made available on the flagship missions. In fact, on Curiosity, it was about 190 kilograms, and that ended up being tungsten mass that was just dropped onto the Mars surface. And so, ever since, there’s been a community push to see how we could better utilize that mass as a secondary payload.
We investigated what techniques people have been doing in the past. And, in fact, in the 1950s there was an attempt by Goodyear to develop an inflatable plane for soldiers, particularly soldiers who get lost behind enemy lines … it never quite took off because of it being inflatable.
So ever since there’s been quite a steady research effort going on in application of inflatables, in particular space areas. But, in this case, one of the methods could be to unfold the wings, in the matter of a few seconds. The other option is to deploy the wings much like an accordion, in a very short period of time.
This all would ideally happen during what's commonly called the seven minutes of terror that the Mars crafts undergo as they're getting into a capture configuration. So this would happen in the last, maybe, two to three minutes.
Tech Briefs: What’s the next step in your research?
Bouskela: We went to an event at a designated airspace to fly the sail planes at 15,000 feet this summer. Unfortunately, we had some technical issues with our long-range communication systems, which made flight too risky when it came to loss of signal and loss of our test vehicle. So, essentially, we decided let’s go back to the lab, fix the long-range communication stuff, and go back and fly in October [15th, set to take place in Arizona].
The reason why we’re going [to 15,000 feet] is to get into the slightly lower density and kind of a stepping stone toward much higher altitude toward 60,000, 70,000 feet into the jet streams up there. And so it was kind of a first test of long-range capabilities to go into those higher altitudes.
Tech Briefs: How far off do you think you are from this method being implemented for use?
Shkarayev: Well, it’s a matter of technology readiness. You can speculate that we can achieve a readiness of the successful testing in real conditions, like at the end of the academic year, which is May 2023. But from there, somebody else should take it over. It's a matter for either the industry to continue developing the technology, or national labs — the university can get to the point when all the testing, all the development work is finished, but then at that point we’ll definitely need help for the money to continue the work.