By Jonathan Amos
Science reporter, BBC News
The Atlantis orbiter has touched down on Earth after a 13-day mission to cement Europe's position on the International Space Station (ISS).
The spacecraft and its crew installed the 12.8-tonne Columbus science lab, an achievement that makes Europe a full member of the $100bn platform project.
Atlantis landed at Florida's Kennedy Space Center at 1407 GMT.
Now that the shuttle is down, the US military will be allowed to shoot an ailing spy satellite out of the sky.
The missile firing, which is likely to take place over the Pacific Ocean, could not be carried out until after Atlantis had returned for fear the ship might encounter debris on its high-speed descent.
Nasa officials earlier reported that four small steering jets on Atlantis had failed, but they stressed these thrusters were not needed to help de-orbit the shuttle or control its glide through the atmosphere.
Riding home on Atlantis was US astronaut Dan Tani, who has been a long-stay resident on the ISS since October.
His place on the platform has been taken by Frenchman Leopold Eyharts who went up with the shuttle and who will spend the coming weeks commissioning the Columbus lab.
The 1.3bn-euro ($1.8bn; £0.9bn) module is Europe's major contribution to the science endeavours on the station, and the first part of the ISS it will control, through an operations centre in Oberpfaffenhofen in southern Germany.
The lab's installation means the European Space Agency (Esa) acquires "rights" under the space station project plan, principally to fly one European astronaut every two years to the platform for a six-month stay.
Columbus is booked for an extensive programme of research that will take in experiments from the life sciences, materials science, fluid physics and other disciplines.
Knowledge gained in the weightless conditions experienced on the platform are expected to aid the development of more advanced electronics, new alloys, novel drugs, and better crops, to name just a few examples.
In addition to fitting Columbus, the Atlantis crew replaced an empty nitrogen tank on the station and retrieved a failed control-moment gyroscope that is one of four such mechanisms used to keep the ISS pointing in the right direction.
The mission has been deeply satisfying for Nasa. It now feels it has the shuttle system working at optimum efficiency.
"I can't say enough about how well the vehicle performed; how well Atlantis, and the team here in Florida who prepared her, did," said Bill Gerstenmaier, Nasa's spaceflight chief.
"It was just a great, great, great mission; I can't say enough about how well things went and how good things are."
The fuel sensor glitch experienced during recent launch campaigns seems to have been solved, and the shedding of shuttle tank insulation foam - the fatal flaw that downed Columbia and her crew in 2003 - has been minimised.
Agency managers have expressed confidence that they can complete the construction of the ISS by the time the orbiter fleet is retired at the end of 2010 to make way for a new human launch system.
ATV - SPACE CARGO TRUCK
Logistics ship will resupply the ISS with 4,860kg of cargo
Deliveries to include science equipment, food and clothing
Large tanks will transport vital air, water and fuel supplies
ATV project's estimated cost is about 1.3bn euros (£0.9bn)
At least four craft will follow the maiden ATV - Jules Verne
Named after the author who wrote about fantastic journeys
Already, the Endeavour orbiter is on the launch pad at Kennedy ready for an 11 March flight.
Ten more shuttle flights will be required after its return, a manifest it looks set to shoulder along with the Discovery shuttle.
Atlantis, on current planning, has completed its ISS duties and is set for one last outing in August or September this year to service the Hubble Space Telescope However, Nasa says no final decision has been taken on Atlantis' immediate future.
For Europe, attention turns to its new space station logistics ship, known as the Automated Transfer Vehicle (ATV).
Dubbed "Jules Verne" for its maiden voyage, the ATV is entering final launch preparations at the European Kourou spaceport in French Guiana where it is expected to leave Earth on 8 March.
The ATV will haul just under five tonnes of cargo (food, water, fuel and experimental equipment) to the ISS.
Preliminary launch dates for shuttles in the rest of 2008:
- 11 March, Endeavour: to deliver the first part of the Japanese science complex known as Kibo and the Canadian Dextre robot to the ISS
- 25 May, Discovery: to loft the second and main component of the Japanese Kibo lab together with its exterior robot arm
- 28 August, Atlantis: a flight to service the Hubble Space Telescope
- 16 October, Endeavour: a cargo flight to the ISS using the Multi-Purpose Logistics Module in Endeavour's payload bay
- 4 December, Discovery: taking up the fourth starboard "backbone" segment for the ISS; and the fourth set of solar arrays and batteries
Because Atlantis will not be able to reach the space station if it gets into trouble, or is damaged, on its Hubble flight, the Endeavour orbiter will be made ready on the pad for a rescue mission in case it is needed.
Launch dates for the remaining seven flights in 2009/10 are under review. The crew of the space station is expected to rise from three to six in mid-2009.