Nasa delays space shuttle landing

The shuttle took new solar panels to the International Space Station

Nasa has delayed attempts to land space shuttle Discovery due to concerns about heavy winds and cloud-cover.

The shuttle had been scheduled to land at Kennedy Space Center in Florida and controllers have one more opportunity on Saturday if the weather clears.

Its seven crew members had packed away their equipment as they made final preparations to come home.

Discovery launched on 15 March, docking with the International Space Station to deliver a final set of solar arrays.

As and when it finally returns to earth, the orbiter will have Sandra Magnus on board. She has been stationed at the ISS for four months.

Meanwhile a Russian space capsule with an American billionaire passenger on board has docked with the ISS.

The passenger, Charles Simonyi, is a software designer and is making his second trip as a space tourist.

He was accompanied by Russian and American astronauts.

On the tiles

The shuttle undocked from the ISS on Wednesday after eight days there.

The crew spent five hours on Thursday inspecting the shuttle's outer surface using a laser and camera mounted on a 15m (50ft) boom connected to Discovery's robotic arm.

The shuttle, as seen from the ISS, includes a novel heat-shield tile

The images were then sent back to Mission Control as part of a routine procedure that ensures the integrity of the shuttle's heat-shield tiles.

The tiles are designed to dissipate heat as the orbiter returns to Earth through an increasingly thicker atmosphere.

Under the shuttle's left wing is a single tile that includes a "bump", which interrupts the normally smooth airflow around the tiles.

The disrupted airflow will increase the temperature of the tiles around it by a small amount and is part of a test of candidate tiles for future missions.

Current designs for those missions mean spacecraft will endure significantly more heat on re-entry than the space shuttles, which might be retired next year.

Nasa is preparing space shuttle Atlantis to be rolled out towards the launch pad on 31 March.

Atlantis is scheduled for a 12 May lift-off on a mission to service the Hubble Telescope. The mission has been delayed since October 2008.