Nasa's Mars rover Opportunity has begun its assault on Victoria Crater.
Opportunity looks back at the tracks it created with its "toe dip"
The vehicle drove just far enough to get all six wheels past the bowl's rim, and then backed up three metres (10ft).
Data returned to Earth will help engineers assess how much grip the robot will have when it makes its full descent into the impact crater.
The 60m-deep (200ft) depression has exposed faces of layered rock that could shed significant new light on the Red Planet's geological past.
Victoria Crater is about five times wider than Endurance Crater, which Opportunity spent six months exploring in 2004, and about 40 times wider than Eagle Crater, where the rover first landed.
Opportunity's first venture in Victoria Crater was described as a "toe dip".
Data suggested the rover experienced a fair degree of slippage on the retreat manoeuvre, and came to rest with its front wheels lodged over a sand ripple near the top of the crater lip.
"We will do a full assessment of what we learned from the drive today and use that information to plan Opportunity's descent into the crater," said John Callas, rover project manager at Nasa's Jet Propulsion Laboratory, Pasadena in California.
The rover team is concerned not to rush the descent, aware that the vehicle could get stuck or even topple over.
The US space agency's (Nasa) second rover, Spirit, is on the other side of the Red Planet in a near-equatorial position. It is studying a plateau called Home Plate in the Gusev Crater region.
Huge dust storms on Mars have hampered the work of both vehicles recently. Engineers put the robots on a minimal workload for over a month as their solar panels struggled to generate power under opaque skies.