NASA tests radar antenna for next-gen Martian helicopters

Each helicopter would carry ground-penetrating radar capable of detecting ice hidden within the upper layers of Mars’ regolith or loose rock and dust.

While orbiting spacecraft can identify large ice deposits deeper underground, NASA said they are less effective at mapping the shallower deposits that could prove particularly valuable to future astronauts seeking water, oxygen and rocket propellant.

The challenge for engineers was to develop an antenna capable of operating across a broad range of frequencies while remaining light, flexible and compact enough to fit beneath a Mars helicopter.

The solution is a modified Vivaldi antenna manufactured using flexible, metallised fabric. The design allows the antenna to bend during landing, including if it encounters rocks, before returning to its operational position during flight.

Christine Gebara, SkyFall ground-penetrating radar mechanical lead at JPL, said: “Although we managed to shrink the antenna quite a bit, it is about 1½ times longer than the helicopter’s legs.”

NASA engineers reinforced the antenna using polyester, Vectran fabric, flexible fibreglass tape springs and a lightweight magnesium mounting structure. The complete assembly weighs about 150 grams.

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“That means during landing, the Vivaldi has to bend out of the way – and if it lands on a rock, it bends even further. But when the helicopter takes off again, the antenna must spring back into place for data collection. Because SkyFall is expected to make dozens of flights exploring Mars, we needed an antenna that could repeatedly handle those pressures without losing its shape in flight,” Gebara said.

During testing at NASA’s Jet Propulsion Laboratory, the antenna was exposed to extreme temperature changes, repeated flexing and electromagnetic testing to simulate the demanding conditions expected during Mars operations.

The prototype ultimately withstood the equivalent of 200 Mars landings, more than double the number required for a successful primary mission, without any reduction in radar performance.

The SkyFall radar will operate across frequencies ranging from 500 to 2,500 megahertz, enabling it to penetrate several metres below the surface while also providing detailed information about Mars’ uppermost layers.

Adrian Tang, SkyFall’s ground-penetrating radar lead instrument scientist at JPL, said: “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.”

The technology could give future Mars missions a new capability to identify and map accessible water ice from the air.

SkyFall is intended to build on the success of NASA’s Ingenuity helicopter, which completed 72 flights over nearly three years and demonstrated the value of powered flight in Mars’ thin atmosphere.

NASA is now developing an engineering model of the antenna for further vibration, deployment and environmental testing as the SkyFall concept continues towards a potential launch in late 2028.