The small team began working in 2023, testing the accuracy of the algorithm they’d developed using data from 264 previous rover stops. The algorithm compared rover panoramic photos to MRO imagery and correctly pinpointed the rover’s location for every single stop.
How Ingenuity helped
Key to Mars Global Localization is the rover’s Helicopter Base Station (HBS), which Perseverance used to communicate with the now-retired Ingenuity Mars Helicopter. Equipped with a commercial processor that powered many consumer smartphones in the mid-2010s, the HBS runs more than 100 times faster than the rover’s two main computers, which, built to survive the radiation-heavy Martian environment, are based on hardware introduced in 1997.
As a technology demonstration designed to test capabilities, the Ingenuity mission was able to risk employing more powerful commercial chips in the HBS and the helicopter even though they hadn’t been proven in space. It paid off: Expected to fly no more than five times, the rotorcraft completed 72 flights.
The power of the HBS processor inspired Verma to look for ways the Perseverance mission might harness it. “It’s almost like a gift. Ingenuity blazed the trail, proving we could use commercial processors on Mars,” Verma said.
Tapping into the HBS computer has had its challenges. To address reliability, the team developed a “sanity check”: The algorithm runs on the HBS multiple times before one of the rover’s main computers checks to ensure the results match. During testing, the team repeatedly found the rover’s position was off by 1 millimeter. They discovered damage to about 25 bits — a minuscule fraction of the processor’s 1 gigabyte of memory — and developed a solution to isolate those bits while the algorithm runs.
Alongside the broader Mars Global Localization process, the team’s sanity check and memory solutions are expected to find new uses as faster commercial processors are employed in future missions. In the meantime, the team has already turned their sights to the Moon, where difficult lighting conditions and long, cold lunar nights make knowing exactly where spacecraft are located all the more critical.
More about Perseverance
NASA’s Jet Propulsion Laboratory, which is managed for the agency by Caltech, built and manages operations of the Perseverance rover on behalf of NASA’s Science Mission Directorate in Washington, as part of NASA’s Mars Exploration Program portfolio.
To learn more about Perseverance: