NASA’s SkyFall Helicopters to Hunt for Martian Water with Flexible Radar Antennas
After NASA’s Ingenuity helicopter proved that powered flight is possible on Mars, the agency is moving forward with a more ambitious rotorcraft mission. The proposed SkyFall mission would send three autonomous helicopters to scan the Martian surface for water ice, a key resource for future astronauts. Central to this effort is a novel flexible antenna that allows the helicopters to carry ground-penetrating radar while still landing safely.
The SkyFall Mission
The SkyFall mission would consist of one larger helicopter and two smaller ones, each equipped with four instruments, similar to NASA’s Ingenuity Mars Helicopter. The helicopters are designed to fly low and slow over the Martian landscape, projecting ground-penetrating radar in an ultra-wide frequency range of 500 to 2,500 MHz. This radar can penetrate several meters beneath the surface, with longer wavelengths reaching deeper while shorter wavelengths provide finer detail about the uppermost layers.
According to Adrian Tang, SkyFall’s ground-penetrating radar lead instrument scientist at NASA's Jet Propulsion Laboratory (JPL), the mission addresses a critical gap in current observation capabilities. "The only way to detect shallow subsurface ice remotely is to fly close to the ground," Tang said in a NASA press release. "By flying low and slow, a SkyFall helicopter could capture radar images that resolve the fine layering where dry soil gives way to ice, detecting its presence and mapping its extent."
Satellites can already map large ice deposits a few dozen meters beneath the surface, but they are blind to shallow deposits within 5 meters (about 16 feet). These near-surface ice reservoirs would be easier for astronauts to access, making them a priority for future crewed missions.
The Flexible Antenna Design
A key engineering challenge was integrating the radar antenna with the helicopter’s landing system. Because the antenna extends beyond the landing legs, it must be able to fold or bend during touchdown without breaking. The team selected a design based on the Vivaldi antenna—a flat, curvilinear structure resembling curved blades placed back to back—and downscaled it for the helicopters.
Christine Gebara, SkyFall’s ground-penetrating radar mechanical lead at JPL, explained the design requirement: during landing, the antenna has to bend out of the way, and if the helicopter lands on a rock, it bends even further. However, it must spring back into place after takeoff to collect data.
To achieve this flexibility, the antenna is sheathed in polyester and layers of Vectran—the same material used in the airbags of NASA's Spirit and Opportunity rovers—and incorporates flexible fiberglass tape springs and a lightweight magnesium mounting structure.
Testing at JPL
The antenna recently underwent a rigorous testing campaign at JPL’s Environmental Test Laboratory. Tests included bending and flexing to simulate landings, temperature cycling to mimic day-night fluctuations on Mars, and electromagnetic chamber tests to verify radar performance. During testing, the antenna was inverted to subject it to more stress than Martian gravity would impose.
The results were positive. The antenna survived twice as many landings as required for its primary mission—200 total—with no loss of signal performance. Tang called the outcome a significant milestone: "This test checked every box it was supposed to and answered our biggest technical questions... this was a major milestone, and the hardware performed exactly as expected."
Next Steps and Launch Prospects
The next phase involves building an engineering model for further testing, including vibration tests, deployment in a simulated Martian environment, signal testing, and outdoor trials at JPL’s Mars Yard.
SkyFall is expected to launch in late 2028 aboard NASA’s Space Reactor-1 Freedom, which would be humanity’s first nuclear-powered interplanetary mission. The spacecraft design is based on elements of the now-discarded Lunar Gateway space station, introducing some uncertainty about the mission timeline. Still, JPL engineers are proceeding with solving the technical challenges, and the successful antenna tests represent a step forward for the mission.