One last time: Discovery prepares to bring itself out of orbit to landing in Florida America’s most experienced space shuttle, Discovery, is about to close its remarkable 27-year career.
The orbiter is set to fire its thrusters to bring it out of the sky and into a glide path that runs into Kennedy Space Center (KSC) in Florida.
Discovery is destined for a museum on its return – Nasa is retiring its three remaining reusable spaceplanes.
The “leader of the fleet” has been on a 12-day mission to the International Space Station.
Duties included delivering a new store room and a sophisticated humanoid robot. The ship’s crew also performed two spacewalks to carry out maintenance tasks on the exterior of the platform.
The landing at KSC is timed to occur just before midday Florida time (1657 GMT).
Once back on the ground, Discovery will be decommissioned. It is expected to be displayed at the Smithsonian Institution.
Endeavour and Atlantis, Nasa’s other two orbiters, are booked to visit the ISS in the coming months.
When the fleet is no more, the plan is for US astronauts to fly to the space station on Russian Soyuz rockets until perhaps the middle of the decade.
A number of American companies then hope to be in a position to sell launch services to Nasa on a range of new vehicles.
The intention is that the agency should put its efforts into leading the development of a large rocket – known as the Space Launch System – and a sophisticated capsule that can send astronauts beyond the space station to destinations such as asteroids.
Congress has set out the broad capabilities it expects to see in this rocket and has given a deadline of 2016 for its introduction.
However, Nasa has said it cannot deliver such a vehicle in the time and within the budget the politicians have specified.
A parting view: Discovery’s crew took this picture of the ISS as they left to return home This article is from the BBC News website. © British Broadcasting Corporation, The BBC is not responsible for the content of external internet sites.