Shuttle Discovery poised for her final flight Thursday

The countdown for the delayed flight of the space shuttle Discovery remains on track today for a Thursday launch from America's Space Coast.

NASA weather officer Kathy Winters forecasts an 80% favorable weather rating at launch time.

Plagued by several leaks and cracks on the shuttle's fuel tank and later an injured crew member, the original launch date of Discovery had been set for early-November.

However, the November 5 launch attempt revealed a gaseous hydrogen leak at a connection point on the back side of the fuel tank. Hours later as the launch team drained the tank of it's super cold fuels, several cracks were discovered beneath the foam insulation.

Additional cracks were discovered following a fueling test, and it was elected to return the space shuttle back to the high bay of the vehicle assembly building a few days before Christmas to perform further x-rays of the tank and make repairs.

On January 15, as crack repairs on the top section of the fuel tank were nearing completion, Discovery astronaut Tim Kopra suffered a hip fracture following a bike accident near Houston. He was replaced a few days later by Stephen Bowen.

Bowen comes fresh off the last flown space shuttle flight last May, and will become the only astronaut to have ever launched on back-to-back shuttle missions.

Over the past month, Kopra helped coach Bowen on the detailed tasks he was to have performed during the two planned spacewalks.

Discovery astronauts Alvin Drew and Nicole Stott will split Kopra's duties as flight engineer during the launch and landing phases, respectively, of the flight.

Launch of Discovery on her final voyage upon the ocean of space is set for Thursday at 4:50:24 p.m. EST, from launch complex 39-A at the Kennedy Space Center.

Once launched, Discovery's all veteran crew of commander Steven Lindsey, pilot Eric Boe and mission specialists Drew, Bowen, Michael Barratt, and Stott will spend two days performing rendezvous maneuvers to catch up with and dock with the International Space Station.

Once at station, Discovery will deliver the final American segment known as the Permanent Multipurpose Module, a bus sized cylindrical segment which will be used for storage. It will begin to free up more space inside the station's working and living segments.

The orbiter is scheduled to dock with the station on Saturday at 10:15 a.m.

Formally known as the Leonardo logistics module, the PMM has actually flown to the space station several times most recently two flights ago.

Inside the PMM will be 6500 pounds of cargo, spare parts, R2 - a robo-naut which will be used outside the outpost; and personal crew supplies to help resupply earth's orbiting outpost in space. Discovery's middeck will carry another 1500 pounds of supplies, too.

Robonaut will remain in the PMM through Discovery's flight, and will later be moved so that it's two halfs can be mated together and placed outside the station in the weeks to come.

Bowen and Drew will perform two spacewalks during this 35th shuttle flight to earth's outpost in space, during flight days 5 and 7 -- Monday and Wednesday of next week.

The duo will install a alternative power cable between the Tranquility and Unity modules on the first spacewalk; relocate a failed ammonia pump module to another part of the station; and perform work on a camera and the railway system on the truss segment.

The second orbital excursion will focus on the change out of a bracket on the European Columbus module; and a Japanese glass bottle which the space walkers will fill up with the vacuum of space for a museum display back on earth.

After 170 revolutions of the planet, Discovery will head home to Florida on March 7 for a midday landing upon the Space Coast at about 12:44 pm EST.

NASA could decide a few days into Discovery's flight to perform a historic photo opportunity.

NASA and Russia's mission control center's could elect to have a Russian Soyuz TMA craft undock and perform a fly around of the space station to take several last pictures of Discovery docked to her port-of-call.

A "go" for the fly around will add an additional day to the mission, according to NASA Test Director Steve Payne this morning.

Payne added that the configuration of Discovery and three international cargo crafts will allow for the fly around.

Landing will mark the conclusion of Discovery's nearly twenty-seven year storied career.

Discovery's mission will also mark the first of the final three space shuttle flights left, with Endeavour flying her final scheduled flight on April 19 and Atlantis on June 28.