The Mars rover Opportunity (search) is making progress getting itself unstuck from a sand dune that's immobilized it for the past two weeks, engineers said Monday.

Opportunity moved 4.6 centimeters — a bit less than 2 inches — over the weekend after scientists sent new driving directions last week, said Mark Maimone, a mobility software engineer at NASA's (search) Jet Propulsion Laboratory.

"This is good progress," Maimone said.

Opportunity's six wheels starting slipping on April 26 during a 295-foot planned trip. The rover eventually stopped moving and its wheels got stuck hub deep in soft soil while trying to drive over a foot-high sand dune.

Opportunity and its twin, Spirit (search), have been exploring opposite sides of Mars since landing in January 2004 and have uncovered geologic evidence of past water activity on the planet.