March 27, 2009
Discovery Astronauts Make Final Preps To Come Home
Astronauts on the space shuttle Discovery conducted a review of the ship's flight systems on Friday as part of their work to ensure their safe return home Saturday afternoon.
The seven-member crew will end a nearly two-week mission that left the International Space Station completely powered with a new set of solar wings."We'll keep our fingers crossed," said shuttle commander Lee Archambault, referring to Discovery's return, for which favorable landing weather is expected.
The astronauts conducted their pre-landing tests, checking the ship's thrusters and other flight systems.
They also exchanged a friendly "aloha" with students at the Honolulu school President Barack Obama graduated from three decades ago.
Archambault relayed Obama's regards, something the president had requested the crew to do during a phone call earlier this week.
Astronaut Richard Arnold II told the students it was gratifying to see the space station after all the construction work was completed.
"We pulled away and saw the solar arrays that we installed and then deployed," said the former schoolteacher.
"We're all really proud to bring that extra power to the station," added fellow astronaut John Phillips.
Discovery had to depart the ISS by Wednesday to accommodate an incoming Russian Soyuz spacecraft set to arrive on Saturday with a fresh crew.
During their eight days aboard the ISS, the shuttle astronauts installed the space station's final set of solar wings, which will provide the station with the extra power needed to conduct all the science experiments that are planned after the station's population doubles to six.
Discovery also delivered a new urine processor that got the space station's water-recycling system working, along with an iodine flush that eliminated bacteria that had tainted the lines.
The space station also took on a new crewmember, a Japanese astronaut who replaced Sandra Magnus, who is finally headed home after 4 1/2 months in orbit.
During its re-entry into the Earth's atmosphere, Discovery will test a new type of thermal tile that is intentionally flawed with a quarter-inch-high "speed bump" molded into it. NASA wants to assess the disturbance in the flow of hypersonic air over the bump, located under the ship's left wing, and measure the amount of heating downstream.
The experimental tile will be exposed to temperatures of nearly 3,000 degrees Fahrenheit during the shuttle's descent. Since the tiles in this area of the shuttle are 3 inches thick, NASA officials say they have no concern about damage to the wing.
A slash in the left wing of the shuttle Columbia led to its destruction in 2003, and the deaths of all seven astronauts on board.
A Navy plane using an infrared camera will fly below Discovery as it moves over the Gulf of Mexico towards Florida, and will monitor heating on the bottom of the shuttle.
This new tile was developed as a potential enhancement for the space shuttles, which are set to be retired by the end of 2010. It is also under consideration for Orion, the craft that will replace the shuttles and will transport astronauts to the space station and ultimately the moon and Mars.
Image Caption: Surrounded by his fellow STS-119 crew members, Pilot Tony Antonelli answers a question from a student at Punahou School in Honolulu. Photo credit: NASA TV
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