The pride on the faces of Nasa mission controllers said it all. After a textbook landing on an unforgiving planet, their robotic explorer is alive and well, sending back postcards from Mars.
By Helen Briggs
BBC News Online
But as the corks popped in California, scientists in London were putting a brave face on the continued silence of Beagle 2.
The first pictures from Mars come in
Instead of boldly seeking life on the Red Planet, the tiny lander may be lying in pieces, like so many missions that have gone before it.
It is easy to speculate how Nasa succeeded where the British-led effort appears to have failed.
But in engineering terms, the landers are very different beasts. Beagle is little bigger than a bicycle wheel, can move only its robotic arm, and tips the scales at 60 kilograms.
Nasa's six-wheeled robot is the size of a golf buggy and weighs eight times more than Beagle, together with its landing apparatus.
There is also the question of money. Beagle was built at a cost of around £45m, from a hotch-potch of UK Government, European Space Agency (Esa) and private funding.
Spirit and its twin, Opportunity, due to land in late January, were built by the world's space heavyweight at a cost of £512m.
Professor Colin Pillinger, who conceived and masterminded the Beagle probe, is adamant that the amount of money spent on the lander was not an issue.
The bleak, rocky surface of Mars
The main constraint was mass - the mothership, Mars Express, could spare only 60 kg for its interplanetary passenger.
That meant a compromise between scientific kit and landing gear. Retro-rockets were not an option. Nor was a transmitter that could have sent radio signals to Earth to give feedback on the landing.
Spirit had both of these, lending high drama to its plunge through the Martian atmosphere.
Mission controllers at the Jet Propulsion Laboratory in Pasadena cheered as each crucial stage in the craft's descent kicked in - the deployment of parachutes, airbags and retro-rockets; then the bounce to rest, and the first dramatic pictures of the landing site.
Meanwhile, more than a week after landing, Beagle scientists are still uncertain about what has happened to their charge.
Nasa's conquering of Mars is a real triumph for both the US and the scientific community. Coming after the Columbia space shuttle disaster and the loss of two Mars missions in 1999 it is a great boost for the agency.
Nasa has now created all four of the probes that have survived the hard landing on Mars.
It has succeeded where other nations, including the Soviet Union, have failed.
The Viking missions of the 70s and Mars Pathfinder two decades later were landmarks in history.
Spirit's travels over the Martian surface in search of water, the catalyst for life, will open a new chapter in space exploration.
Europe, meanwhile, has Mars Express. The orbiter was always the mainstay of the mission with its suite of scientific experiments for seeking water and key chemicals under the Martian soil.
There is always a chance that the mothership will find its baby spacecraft where other attempts have failed.
But while the fate of Beagle may never be known, Esa has other plans to go back to Mars at the end of this decade.
The aim is to send a big cousin of Beagle to explore the biology of Mars followed by a mission to snatch a sample of Martian rock for return to Earth.
The British companies that helped build Beagle can make a key contribution to this programme.
It rests on the UK Government to decide whether to sign up to the plans and commit the money that could make some kind of "Beagle 3" a reality.