Perseverance rover passes 28-mile driving record on Mars

Record came after a scientific detour

The rover had come close to the milestone roughly two months before the announcement. On Sol 1947 it was about 200 meters short, a gap that NASA said could have been closed in one drive using the Autonomous Navigation system.

The team was not chasing the record at that point. Perseverance was working in an area rich in ancient rock formations, so it made a series of short hops between sites, ground away thin layers of rock and took detailed measurements up close. Once that work was finished, the rover resumed its journey and soon moved past the previous distance mark.

Engineers adapted the rover for rough ground

Crossing tightly packed boulder fields and steep hillsides gave NASA engineers hands-on experience of hazardous terrain. They ran thousands of computer simulations before adjusting several operating limits.

The rover can now tolerate tilts of up to 24 degrees, and the minimum clearance beneath its protective belly pan has been lowered to 20 centimeters, about 7.9 inches. Updated braking software is meant to help it steer clear of rocks, the current limits for its steering motors have been nearly doubled, and new "dynamic slip tables" in its flight software help anticipate wheel slippage on different surfaces. A slope-driving technique aims to keep the wheels on exposed bedrock.

Navigation without Earth-based directions

One of the more significant advances is onboard Global Localization, which lets Perseverance work out its position on Mars without waiting for instructions from Earth. The system runs on a powerful commercial processor originally installed in the Ingenuity Helicopter Base Station.

Open questions

• How far will Perseverance travel once it resumes its survey?