Space Shuttle Astronauts Set for Saturday Landing

NASA has cleared the space shuttle Discovery and its crew of seven astronauts for their planned Saturday landing after giving the spacecraft a clean bill of health today.

Mission managers declared Discovery fit for landing after a detailed analysis of data from a final heat shield check performed by the astronauts on Thursday.

?That is great news,? Discovery skipper Lee Archambault radioed Mission Control after hearing the news. ?We appreciate you passing that along.?

Archambault and his crew are due to land on a runway at NASA?s Kennedy Space Center in Florida at 1:39 p.m. EDT (1739 GMT) to end a 13-day flight that delivered the last pair of solar arrays to the International Space Station.

The new solar wings completed the station?s power grid and are expected to help the outpost support larger crews that can, in turn, perform more scientific research. During the flight, Discovery?s crew delivered a vital part for the space station?s new system to recycle astronaut urine, sweat and cabin condensation into drinking water in order to support larger crews.

The shuttle is also ferrying NASA astronaut Sandra Magnus back to Earth after a 4 1/2-month stay at the station. Her replacement, Japanese astronaut Koichi Wakata, launched to the station aboard Discovery on March 15 and will stay aboard the outpost for three months. Magnus will use a special recumbent seat that will allow her to sit in a reclined position during the descent to ease her return to gravity.

Prepared for landing

On Friday, Archambault and shuttle pilot Dominic ?Tony? Antonelli checked Discovery?s flight control systems and thrusters to prime the spacecraft for its return to Earth. They planned to practice landing Discovery on a computer-based simulator later today.

The shuttle crew also discussed their mission with students at the Punahou School in Honolulu, Hawaii, President Barack Obama's high school alma mater. The spaceflyers spoke with President Obama before departing the space station.

Discovery astronauts told the students they were proud to have helped the space station reach full power. They also advised any students interested in becoming astronauts to study hard in math and science, but also keep their sense of wonder. ?

?You have to like exploration and discovery,? mission specialist John Phillips said. ?If those are your passion, then this could be a good job for you.?

Shuttle entry flight director Richard Jones said the weather outlook at Discovery?s Cape Canaveral, Fla., landing strip is very favorable. NASA prefers to land its shuttles at the Florida spaceport to avoid the extra time and cost of ferrying orbiters from a backup runway in California.

Landing experiment on tap

Jones said scientists are also interested in a specific heat-resistant tile, one of the thousands lining the Discovery?s underbelly, which has been intentionally flawed as part of an experiment.

Made of a new type of material called BRI-18, the tile has a slight protuberance to serve as a ?speed bump? during Discovery?s re-entry that will interrupt the otherwise smooth hypersonic flow of superheated air around it. The bump does not pose a safety risk to the shuttle or its crew, mission managers said.

The bump is located near the rear of Discovery?s left wing and is about 4 inches (10 cm) long and just over a quarter-inch (0.76 cm) wide. A series of temperature sensors will record the extra heating aft of the bump to study the hypersonic air flow and tile for to aid the heat shield design of NASA?s space shuttle successor, the Orion Crew Exploration Vehicle.

A Navy chase plane will observe Discovery?s re-entry from below the spacecraft using a long-range infrared camera as the shuttle flies over the Caribbean at about Mach 15, Jones said.

?There?s a lot of people that are interested in seeing that data,? Jones said.

SPACE.com is providing continuous coverage of Discovery?s STS-119 mission with reporter Clara Moskowitz and senior editor Tariq Malik in New York. Click here for mission updates and SPACE.com's live NASA TV video feed.

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