Discovery touches down safely

— -- After one of the most harrowing space shuttle missions in recent memory, shuttle Discovery made a picture-perfect return to Earth Wednesday under the control of only the second woman to land the spacecraft.

"Houston, Discovery, wheels stop," called Discovery's commander Pamela Melroy after bringing the shuttle to a halt on Cape Canaveral's concrete runway at 1:01 p.m. ET.

"Copy, wheels stop, congratulations on a tremendous mission and a great landing, Pam," said astronaut Terry Virts from Mission Control in Houston.

The spacecraft made a now-rare trip above the U.S. heartland to reach its landing strip on the Florida coast. Most shuttles approach Florida on a path that takes them over Central America and the Caribbean Sea rather than gliding over the continental United States, because of concerns that debris from a crumbling shuttle could cause casualties on the ground.

After firing its engines at 11:59 p.m. to slow its orbit, Discovery made a tightly controlled fall from space and into the atmosphere. The shuttle flashed across the Pacific Ocean and crossed land at the western coast of Canada. It then soared across the northern Rocky Mountains and passed over Rapid City, S.D., Kansas City, Mo., Memphis, Birmingham, Ala., and Columbus, Ga., before making its trademark dive at the runway.

The spacecraft's unusual heartland tour was the result of a request by Melroy. Landing was originally scheduled to take place before dawn, but Melroy asked for a mid-afternoon slot so her crew could shift their sleep patterns more easily. The change in touchdown time meant that the shuttle had to soar across the United States from coast to coast, a trajectory NASA has avoided since the breakup of shuttle Columbia showered debris on Texas in 2003.

The shift to a daylight landing also allowed for better visibility, making the challenging task of landing Discovery slightly easier for Melroy. Only one other woman has landed the shuttle. Astronaut Eileen Collins made the first shuttle landing by a woman in 1998 and landed the spacecraft again in 2005 before retiring from NASA.

Shuttle flights have been eventful for the last few years, plagued by surprise plot twists such as computer failures aboard the International Space Station and gouges in the shuttle's heat shield.

But few flights could match Discovery's for drama. During the 15-day flight, the space station suffered not one but two major failures, both of the solar-power system that provides the station's electricity. The Discovery astronauts were asked to perform emergency spacewalks to fix both problems.

To perform one repair, astronaut Scott Parazynski rode a jury-rigged extension of the station's robotic arm farther from the main space station than any astronaut had every gone before. There he stitched up a torn solar panel and hacked through a tangle of wires to allow the panel to be unfurled to its full length.

Despite the efforts, the station's future is in doubt. Managers don't know whether they'll be able to launch a European laboratory to the station in December as planned. The problems during Discovery's mission delayed other work at the station, putting construction there nearly a week behind schedule.

Nor do station officials know how they're going to fix the second solar-power problem: debris inside a wheel that rotates a second set of solar panels. Unless the debris can be cleaned, the wheel can't be rotated and the station's power supply will be too small to accommodate a Japanese laboratory that is supposed to arrive at the station in April.