The US space agency's (Nasa) robotic rover Opportunity has begun its escape attempt from a sand trap on the surface of the Red Planet, officials have said.
Engineers simulated the conditions faced by the rover
The rover has driven more than 7cm (2.75 inches) on three drives since Friday in an effort to extricate itself from the dune.
Opportunity has been bogged down in the Martian soil since a drive on 26 April.
Images show that some of the soil that was causing problems by sticking to the wheels has now come off.
Engineers have been simulating the conditions faced by Opportunity with a test rover driving over manmade dunes at Nasa's Jet Propulsion Laboratory (JPL) in Pasadena, California.
Their tests have allowed them to formulate a set of commands that will allow the rover to drive out to freedom.
The rover has been positioned across the ridge of an elongated dune or ripple of soft sand that is about one-third of a metre (one foot) tall and 2.5m (8ft) wide.
On two drives over the weekend, the wheels turned about two-and-a-half rotations, enough to drive 2m if the rover had not been experiencing slippage in the soil.
On Monday, the team commanded the rover to drive an equivalent of 4m (13ft) if there had not been slippage. Opportunity gained an additional 2.7cm (one inch).