Perseverance Passes Opportunity's Mars Distance Record, Driving Mostly on Its Own Autonomy

On October 11, the odometer on NASA's Perseverance rover rolled past 45.22 kilometers, or 28.10 miles. That was enough to edge out the previous record for distance driven on another world, held by Opportunity, which covered 45.16 kilometers of Martian terrain between 2004 and 2018. The margin is only 60 meters. The record itself is the first of its kind to fall.

What stands out is who did the driving. Perseverance has covered more than 90 percent of that distance on its own, using its AutoNav system to read the terrain and pick a safe path between waypoints set by scientists on Earth. Opportunity and its twin Spirit used an early version of the same capability for around 5 percent of their distances. The lineage goes back further, to Sojourner, the dog-sized rover that landed in 1997 and traveled about 100 meters.

JPL scientists offer a comparison to show how far the technology has come. Sojourner took 20 measurement points of the ground ahead of it. Perseverance processes 200,000 with each glance. It can do this at or near top speed, effectively thinking while driving, and has managed as much as 412 meters (1,351 feet) in a single sol, a Martian day that runs about 40 minutes longer than an Earth day.

Perseverance left Earth in July 2020, and it did not travel alone. It carried the Ingenuity Mars Helicopter, the first controlled aircraft flown on another planet. The plan called for five test flights in 30 days. Ingenuity instead made 72 flights over three years, covering 17 kilometers and climbing nearly 24 meters in Mars' very thin atmosphere.

The rover is now on the western rim of Jezero Crater, in a region called Lac de Charmes, and it is headed toward a site named Idubi. Idubi may once have been a hydrothermal system, similar to the kinds of environments thought to have helped life arise on Earth. Another target, Rainbow Falls, is a chunk of Mars torn from the ground by the impact that formed Jezero.

The rocks here are very old. Ken Farley, a Caltech professor of geochemistry and former Perseverance project scientist, says they are probably older than 4 billion years. "There are few rocks on Earth older than 4 billion years," he says, "so we are in an area that is very deep in the history of the solar system." On Earth, erosion and plate tectonics have destroyed or recycled most rock that old, though some survives and may hold traces of early life.

Perseverance has already found what may be the best candidate yet for evidence of extraterrestrial biology: a leopard-spot speckled rock called Cheyava Falls, in an ancient basin that held water several billion years ago. The article contrasts this with the disputed biosignature reported for the exoplanet K2-18b and the equally contested phosphine on Venus. Farley's view is that the place giving the richest information is the one you can bring samples from.

That is where the story turns uncertain. NASA's Mars Sample Return program lost its funding earlier this year, so the timing of any retrieval is unclear. The samples Perseverance has collected are bagged and waiting on Mars. Bringing them home would help address whether life arose there, and would inform later efforts to send humans to Mars and back. For now the rover keeps driving toward Idubi, mostly steering itself, with no mission yet funded to carry its samples home.