NASA's self-driving Mars rover just set a distance record no off-world vehicle has reached

Perseverance has just done something no vehicle has ever managed away from Earth. NASA says the Mars rover has now travelled farther on another world than anything before it, while heading into a part of Jezero Crater scientists see as especially ancient.

On 11 October, Perseverance's odometer reached 28.10 miles, or 45.22 kilometres. That pushed it past the previous mark of 28.06 miles, or 45.16 kilometres, set by NASA's Opportunity rover, which explored Mars from 2004 to 2018.

The new total was logged on the 2,006th Martian day, or sol, of Perseverance's mission. NASA said the rover covered in about five and a half years a distance that took Opportunity almost 15.

It hit the milestone while travelling toward an area called Idubi, through a region off the western rim of Jezero Crater known as Lac de Charmes. Scientists working with the mission say this may be some of the oldest terrain ever explored in the solar system. The rocks there are so old that comparable material on Earth has been wiped away by erosion and plate tectonics. At Idubi, the team hopes to find signs of ancient hydrothermal systems.

Why this rover covers ground so quickly

In the clip below, NASA points to a big reason Perseverance has been able to rack up the miles: it does much of its driving on its own.

The rover uses an autonomous navigation system called AutoNav. As it moves, it takes images of the terrain, creates a 3D map of hazards and works out a route between waypoints chosen by planners on Earth. The team describes that ability as thinking while driving.

That matters because Perseverance can do this at or near its top speed. NASA says it can travel as much as 1,351 feet, or 412 metres, in a single sol. More than 90 percent of its total distance has been driven with AutoNav evaluating the terrain. For comparison, the first Martian AutoNav system used on Opportunity and its twin Spirit handled about 5 percent of their driving. NASA also says its first Mars rover, Sojourner, assessed the path ahead using 20 measurement points, while Perseverance processes 600,000 with every look.

Project manager Steven Lee said the rover is operating at a point where drives like this have become routine. He also said the mission was originally expected to drive no more than 12.4 miles, and that Perseverance has gone well beyond that with its mobility systems still fully operational. NASA has already approved the mission's first extension, which began in October and is expected to keep Perseverance exploring the crater rim through roughly the end of 2028.

A record built over decades of Mars rovers

Perseverance's new mark is the latest step in nearly three decades of NASA rover work on Mars.

Sojourner, a rover about the size of a microwave oven, covered around 330 feet, or 100 metres, during its 83-sol mission in 1997. Spirit and Opportunity, described as golf-cart-size twins, arrived in 2004 with 90-sol prime missions. Spirit travelled 4.8 miles, or 7.7 kilometres, before it was lost to the Martian winter in 2010. Opportunity stayed active for 5,111 sols, completed the first extraterrestrial marathon in 2015 and then held the overall distance record until now. Curiosity, which landed in Gale Crater in 2012 and is still operating, has logged more than 23.65 miles, or 38.07 kilometres.

Mark Maimone, deputy team chief for robotic operations on Perseverance, said the rover broke the record by making its own decisions about the path ahead. He said the vehicle now drives better than it did when it first landed, and that the team is still improving it. According to Maimone, newer software helps Perseverance steer less and roll more, while also checking its position against orbital maps during a drive.

He also pointed to one of the next problems engineers want to solve. Glare in the navigation cameras means the rover has to park by mid-afternoon if it is driving toward the sun. If that can be overcome, he said, future rovers could get a longer working day.

The miles matter because of where they lead

The headline record is not only about Mars either. Perseverance has also gone beyond the distances covered on the moon by Apollo 17 astronauts Gene Cernan and Harrison Schmitt, who drove 22.2 miles, or 35.7 kilometres, in 1972, and by the Soviet Union's Lunokhod 2 rover, which drove 24.2 miles, or 39 kilometres, in 1973.

NASA says the bigger point is what longer drives make possible. Covering more ground brings more geological variety within reach, which means more outcrops can be examined and more of Mars' history can be read in its rocks. That range has taken Perseverance from an ancient lakebed to a fossilised river system, where it found a potential biosignature at a rock called Cheyava Falls, and then up to the crater rim, where a different ancient environment, a hydrothermal one, may be waiting.

So far, the rover has collected 29 rock and regolith samples from the crater floor, a delta fan formed by a long-gone river and the crater rim. In that rim region, it has been studying impact-generated rocks that are about 4 billion years old, from a period of planetary history that has been almost entirely erased on Earth.

The route ahead is still mapped out. After Lac de Charmes, Perseverance is expected to continue along the crater rim and head south during the extended mission toward Rainbow Falls, a 328-foot-wide, or 100-metre-wide, block of ancient crust lifted by the impact that created Jezero.