Opportunity, the second of two Nasa rovers, has successfully landed on the Martian surface where it will search for signs of water on the planet.
The new rover touched down at 0505 GMT, halfway around the Red Planet from where the Spirit rover landed on 4 January.
Opportunity landed on a smooth, flat plain, in the highest altitude landing ever attempted by Nasa.
Spirit sent back striking colour photos of Mars but stopped working properly on Wednesday.
But US space agency scientists now say they are making good progress on fixing Spirit.
"We resurrected one rover and we saw the birth of another. This was one heck of a critical milestone," Ed Weiler, associate administrator for space science at Nasa, told a news conference.
Opportunity sent images back of its landing site showing an unfamiliar, largely featureless landscape except for a conspicuous outcrop of bedrock nearby.
"This is a beautiful, alien place. A world unlike any we've seen before," said Professor Steve Squyres, principal payload investigator.
The Martian bedrock has a slab-like form which scientists said could have been created either by volcanic activity or by the action of water.
The rover's airbags have made distinctive imprints in the Martian soil, suggesting it may be fine-grained and multi-layered. It is also much darker in colour to the soil at Spirit's Gusev Crater landing site.
"I said the soil at Gusev had some strange characteristics. That pales in comparison to this stuff," said Professor Squyres.
He added that Opportunity could have landed in a crater and that the bedrock could be the rim of that crater.
As confirmation of Opportunity's landing was beamed to Earth, mission controllers hugged each other and cheered.
The signal sent back to Earth suggested there were no faults with the rover.
A periodic fluctuation in the lander's signal first suggested that it rolled on the Martian surface for more than 20 minutes after landing.
But this was actually because Opportunity's antenna was pointed downwards and the signal was bouncing off the surface of Mars and creating interference.
Opportunity approached the Martian surface at a speed of 19,000 km/h (12,000 mph). It deployed a parachute to slow its descent and airbags to cushion its landing.
Rockets on the lander counteracted light gusts of wind during the descent.
Because of this, it touched down with a force of between two and three Gs - an exceptionally gentle landing. The rover was designed to withstand a landing of up to 40 Gs.
Opportunity landed with one of its three side "petals" pointing down. This meant it needed to rotate itself to an upright position, something Spirit did not have to do as that rover landed with its base pointing down.
Arnold Schwarzenegger (left) watched the drama with project manager Pete Theisinger
California Governor Arnold Schwarzenegger appeared following confirmation of the successful landing to greet ground controllers.
Dark grey landscape
The rover's landing site on Meridiani Planum, which is near the Martian equator, is thought to be dark grey, or black - rich in a mineral called grey haematite.
Project manager Pete Theisinger said Opportunity's twin Spirit had now been upgraded from "critical" to "serious". The fault could now take days or weeks to put right.
Nasa will want to trace the source of Spirit's problems because it could have implications for the way Opportunity is deployed.