Like the self-driving cars on Earth, Perseverance will navigate using an array of sensors feeding data to machine vision algorithms.PHOTOGRAPH: NASA/JPL-CALTECH

Later this month, NASA is expected to launch its latest Mars rover, Perseverance, on a first-of-its-kind mission to the Red Planet. Its job is to collect and store geological samples so they can eventually be returned to Earth. Perseverance will spend its days poking the Jezero Crater, an ancient Martian river delta, and the samples it collects may contain the first evidence of extraterrestrial life. But first it has to find them. For that, it needs some damn good computers—at least by Martian standards.

Perseverance is significantly more autonomous than any of NASA’s previous four rovers and is designed to be what Philip Twu, a robotics system engineer at NASA’s Jet Propulsion Laboratory, calls a “self-driving car on Mars.” Like the ones on Earth, Perseverance will navigate using an array of sensors feeding data to machine vision algorithms. But whereas terrestrial autonomous vehicles are packed with the best computers money can buy, the main computer on Perseverance is about as fast as a high-end PC … from 1997. The only way Perseverance’s poky brain is able to handle all this autonomous driving is because NASA gave it a second computer that acts like a robotic driver.

NASA’s Mars 2020 mission will have an autopilot that helps guide it to safer landings on the Red Planet.Credit: NASA/JPL-Caltech

The view of the Sea of Tranquility rising up to meet Neil Armstrong during the first astronaut landing on the Moon was not what Apollo 11 mission planners had intended. They had hoped to send the lunar module Eagle toward a relatively flat landing zone with few craters, rocks and boulders. Instead, peering through his small, triangular commander’s window, Armstrong saw a boulder field—very unfriendly for a lunar module. So the Apollo 11 commander took control of the descent from the onboard computer, piloting Eagle well beyond the boulder field,to a landing site that will forever be known as Tranquility Base.

“There had been Moon landings with robotic spacecraft before Apollo 11,” said Al Chen, entry, descent and landing lead for NASA’s Mars 2020 mission at the Jet Propulsion Laboratory in Pasadena, California. “But never before had a spacecraft on a descent toward its surface changed its trajectory to maneuver out of harm’s way.”

Chen and his Mars 2020 colleagues have experience landing spacecraft on the Red Planet without the help of a steely-eyed astronaut at the stick. But Mars 2020 is headed toward NASA’s biggest Martian challenge yet. Jezero Crater is a 28-mile-wide (45-kilometer-wide) indentation full of steep cliffsides, sand dunes, boulders fields and small impact craters. The team knew that to attempt a landing at Jezero—and with a rover carrying 50% more payload than the Curiosity rover, which landed at a more benign location near Mount Sharp—they would have to up their game.

“What we needed was a Neil Armstrong for Mars,” said Chen. “What we came up with was Terrain-Relative Navigation.”