While no person has ever set foot on Mars, humankind has managed to conduct extensive explorations of the surface of Earth’s planetary neighbour using robotic rovers. One of them, NASA’s six-wheeled Perseverance rover, has now set a record for the longest distance driven by any vehicle on a world beyond Earth.
The US space agency has announced that the car-sized Perseverance has trekked 45.2 km since arriving on Mars roughly 5-1/2 years ago, passing the distance mark previously established by another NASA rover, Opportunity, from 2004 to 2018. Perseverance and Opportunity both also beat the driving distances of any rover that operated on the moon.
Perseverance, carrying a suite of scientific instruments, has searched for evidence of ancient microbial life on Mars — a planet that long ago was wetter and warmer than the cold and desolate place it is today — and collected rock and soil samples for a potential future return to Earth.
Jezero crater
Since landing on February 18, 2021, Perseverance has driven in and around Jezero Crater, an area in the Martian northern hemisphere believed to have been flooded with water and home to a lake basin billions of years ago.
NASA said the rover achieved its milestone on Sunday as it drove toward an area called Idubi, through the region off the crater’s western rim nicknamed Lac de Charmes, where it is surveying some of the most ancient terrain ever encountered in the solar system.
It is one of two NASA rovers currently traversing the Martian surface, with the Curiosity rover operating in Gale Crater near the Martian equator. Curiosity has driven 38.15 km since landing on Mars in 2012.
Steven Lee, project manager of the two rovers at NASA’s Jet Propulsion Laboratory in California, said Perseverance is showing no signs of slowing down.
“Perseverance’s engineering hardware and instruments are in excellent shape with all redundant systems still available. A recent assessment of all systems concluded that they are capable of operating well into the 2030s, likely beyond,” Lee said.
China’s Zhurong rover also gathered important scientific data on Mars, operating in the northern lowlands in 2021 and 2022.
Self-driving capability
Perseverance often has relied upon its self-driving capability, an autonomous navigation system called AutoNav. Lee said 90% of its drives are done autonomously, with no human intervention.
“Perseverance takes stereo images of the terrain ahead, generates a 3D software map, and selects the safest path towards a drive goal,” Lee said.
The rover also employs its Vision Compute Element, a co-processor computer that lets it process images and run its self-driving software quickly during drives, Lee said, while previous rovers needed to pause to “think” before each drive segment.
“Perseverance builds on the 29-year legacy of our past Mars rovers — Sojourner, Spirit, Opportunity and Curiosity — each incorporating prior lessons and improving our ability to drive on another world,” Lee said.
Perseverance’s mobility system mechanisms are being tested to show it can drive 100 km or more, Lee said, with the hardware to be tested to the equivalent of 150 km to 300 km in the effort.
Potential biosignature
Lee said the rover’s biggest achievement was almost certainly its discovery, disclosed last year, of a potential biosignature, or possible sign of ancient microbial life. This was found in reddish rock believed to have formed 3.2 billion to 3.8 billion years ago in a river channel feeding the lake that once filled Jezero Crater.
The Lac de Charmes terrain, Lee said, may yield clues to early planetary geological processes, such as the effects of large meteorite impacts. Jezero Crater was formed by such an impact early in Martian history.
“The terrain we’re currently exploring may contain rocks older than any found on Earth,” Lee said.
The rover’s original mission envisaged 20 km of driving. NASA recently approved an extension of the rover’s mission to explore the crater rim until roughly the end of 2028.
“There is evidence from orbital measurements that some areas of the rim were once hydrothermal systems with warm or hot groundwater. These areas may once have provided a warm, watery subsurface environment conducive to life. Indeed, some paleontologists hypothesize that life on Earth began in such environments,” Lee said.
The rover’s plutonium-based power system is performing as expected, Lee said, adding it has “many years of useful energy still available.”
