The US space agency (Nasa) has launched the first of two rovers to explore the surface of Mars.
A Delta II rocket carrying the Spirit vehicle lifted clear of the Cape Canaveral Air Force Station in Florida at 1758 GMT on Tuesday.
The Delta II with Spirit inside its fairing head skywards
(Image by Boeing/Bailie)
It was the third attempt at a blast-off - Sunday's and Monday's efforts were postponed because of stormy weather in the launch area.
Spirit is identical to the Opportunity rover which will go into space later this month, probably on the 25th.
A camera mounted on Spirit's rocket showed images as it sped on its flight path above the Florida coast and through the upper strata of the atmosphere at more than 15,000 kilometres per hour.
The Spirit space craft separated successfully from the Delta's third stage about 36 minutes after launch, while over the Indian Ocean.
Flight controllers at Nasa's Jet Propulsion Laboratory (JPL) in California received a signal from the space craft at 1848 GMT, reporting that all systems were operating as expected.
"We have plenty of challenges ahead, but this launch went so well, we're delighted," said JPL's Pete Theisinger, project manager for the Mars Exploration Rover (Mer) missions.
The American missions follow quickly behind that of Europe's Mars Express and Beagle 2 expedition to the Red Planet.
The European space craft, now more than one million kilometres from the Earth, left the Russian cosmodrome in Baikonur, Kazakhstan a week ago.
Over the next few months Mars and the Earth will be closer than at any time in recorded history, cutting the journey to less than seven months.
The US rovers are going to Mars to study its geology, seeking chemical signatures that would confirm that abundant water once existed on the planet's surface.
"The instrumentation on board these rovers, combined with their great mobility, will offer a totally new view of Mars, including a microscopic view inside rocks for the first time," Ed Weiler, Nasa headquarters associate administrator for space science, said earlier this week.
"However, missions to Mars have proven to be far more hazardous than missions to other planets.
"Historically, two out of three missions, from all countries who have tried to land on Mars, ended in failure.
"We have done everything we can to ensure our rovers have the best chance of success," Dr Weiler said.
Spirit is due to arrive on the Red Planet in the New Year, a few days after the Beagle 2 probe. It will be joined by the second Nasa rover at the end of January.
Only three Nasa space craft have ever touched down successfully on Mars before: the Viking landers of 1976 and Mars Pathfinder.
If all goes well, the rovers will head for two places that appear to have once been flooded by water.
Like Beagle 2, Nasa's rovers will bounce to airbag-cushioned landings at sites offering a balance of favourable conditions for safe landings and interesting science.
Spirit is aimed at the Gusev Crater and Opportunity at a site called Meridiani Planum.
"Gusev and Meridiani give us two different types of evidence about liquid water in Mars' history," said Dr Joy Crisp, Mer project scientist at the Jet Propulsion Laboratory in Pasadena.
"Gusev appears to have been a crater lake. The channel of an ancient riverbed indicates water flowed right into it.
"Meridiani has a large deposit of grey hematite, a mineral that usually forms in a wet environment."