A marathon without a finish line

Opportunity passes 42.195 kilometres of cumulative driving on 24 March 2015

Told in Opportunity’s imagined voice · the events are real · source

Eleven years and two months after its landing on Mars, the total driving distance of NASA's Mars Exploration Rover Opportunity surpassed the length of a marathon race: 26.219 miles (42.195 kilometers). — 01I was approaching Marathon Valley on Endeavour Crater’s rim. Over many separate drives, my odometer was nearing 42.195 kilometres—the length of an Olympic marathon. Reaching rocks for science had brought me much farther than the original mission plan.

02Winds sometimes cleaned dust from my solar panels, helping restore the power available for work. Engineers also dealt with memory problems. They reformatted flash memory and later used RAM-only operations, which required returning data before the rover powered down.

This series of images shows simulated views of a darkening Martian sky blotting out the Sun from NASA's Opportunity rover's point of view, with the right side simulating Opportunity's current view in the global dust stor — 03A 46.5-metre drive carried me past marathon distance. The total had taken roughly eleven years and two months to build. I was the first human enterprise to exceed that distance on the surface of another world.

04The team celebrated on Earth, but distance was not the mission’s main purpose. Moving between sites let instruments examine different rocks and ancient environments. At Endeavour, the rover had found evidence of wet conditions less acidic than those studied earlier.

The big idea

A rover’s long life matters because it lets scientists compare more places. Maintenance and new operating strategies can keep that investigation going.

Think about it

Why is a long rover route useful even when the goal is geology rather than a distance record?

Fact file

Milestone date: 24 March 2015; The day the cumulative odometer exceeded marathon distance.; Source ↗
Marathon distance: 42.195 km; Accumulated across many drives over roughly eleven years and two months. Not one uninterrupted race.; Source ↗
Milestone drive: 46.5 metres; JPL reports this drive as the one that carried the rover beyond marathon distance.; Source ↗

In this chapter: Wheels, solar power, onboard memory and navigation cameras

Sources: Main record · NASA Science · Cleaning events and memory workarounds

Machine illustration: AI-made. Photos: NASA Image and Video Library, credited on each picture.

Chapter 4 of 5