Space shuttle Discovery touched down safely at 3:14 P.M. (Eastern Daylight Time) at Kennedy Space Center in Florida, completing its 13-day mission to the International Space Station (ISS). The landing time was pushed back from 1:39 P.M. due to uncertain weather at the landing site earlier in the day.

Discovery delivered a 45-foot (14-meter) truss segment to the ISS, completing the station's 335-foot (102-meter) "backbone," as well as the final set of solar arrays needed to power the station once its crew swells from three to six in the coming months. The ISS now boasts 38,400 square feet (3,570 square meters) of U.S. solar panels, nearly a full acre, generating about 120 kilowatts of electricity. (Unlike solar-powered buildings here on Earth, the space station doesn't need to worry about cloud cover.)

The space shuttle Discovery will detach from the International Space Station (ISS) today at 3:53 P.M. (Eastern Daylight Time) and head back to Earth. It's scheduled to land at Kennedy Space Center in Florida on Saturday afternoon.

After undocking, the shuttle will perform a fly-around of the ISS so the Discovery crew can photograph the station with its full complement of solar arrays. The mission delivered the final pieces of the ISS's solar backbone in anticipation of the crew size expanding from three to six in the coming months. Once the shuttle distances itself from the ISS, the shuttle's crew will conduct a final inspection of Discovery's thermal shield with the orbiter's boom-mounted sensor. A similar inspection was performed before docking.

The space shuttle Discovery is moving closer to the International Space Station (ISS) as it prepares for a planned docking to the ISS at 5:12:46 P.M. (Eastern Daylight Time). According to NASA, the shuttle was 1,310 miles (2,100 kilometers) out as of 11:54 A.M. and was gaining on the ISS by about 600 miles (965 kilometers) with every 90-minute orbit. A series of maneuvers and thruster firings will ease Discovery into position for rendezvous.

Discovery launched without event Sunday after myriad delays stemming first from concerns about gaseous hydrogen valves aboard the orbiter and then from an unrelated hydrogen leak at the launch pad. A further wrinkle arose yesterday when a wayward piece of space junk headed toward the ISS had NASA considering an avoidance maneuver for the station. But the space agency later determined that the object would sail safely past. (It did indeed pass without incident early this morning.) The shuttle mission is delivering materials, including a replacement unit for a urine-to-water recycling system and additional solar arrays, to double the station's crew capacity from three to six.

The much-postponed launch of space shuttle Discovery on a mission to the International Space Station (ISS) finally looks set to go. The shuttle is scheduled to blast off from Kennedy Space Center in Florida tonight at 9:20 (Eastern Daylight Time), delivering the final pieces of the ISS's solar arrays and helping to boost the station's capacity from three to six crew members.

The shuttle's climb into space should be visible—weather permitting—in the night sky along the East Coast, according to Joe Rao of the Hayden Planetarium in New York City. The glow of Discovery's three main engines, he writes in his blog, will look like "a very bright, pulsating, fast-moving star, shining with a yellowish-orange glow." In the Southeast, the bright light of the solid-rocket boosters will be visible as they burn for the first two minutes of flight.

The next space shuttle launch has been pushed back again due to lingering safety concerns stemming from the last shuttle mission in November. NASA needs more time to analyze and possibly conduct further testing on the three flow-control valves that regulate the flow of hydrogen gas from the main engines to the external fuel tank, the space agency announced late Friday. Before the postponement, Discovery had been scheduled to depart on its servicing mission to the International Space Station as early as Friday, which was itself a pushback from an original launch date of February 12.

The safety issue came to light after the Endeavour mission in November, when engineers discovered that one of the valves had been damaged in flight. NASA removed and inspected the valves on Discovery but has been working to identify why Endeavour's valve broke and what safety risks a similar occurrence might pose to the Discovery mission.