NASA engineers made final preparations to start the shuttle Discovery's countdown later today, buoyed by forecasts calling for a 70 percent chance of acceptable weather during the ship's five-minute launch window Wednesday.

Cloudy weather over launch pad 39B today should give way to good conditions on Wednesday. Credit: NASA TV/Spaceflight Now

NASA test director Jeff Spaulding, who will oversee Discovery's countdown in the hours leading up to launch, told reporters today the launch team is not tracking any significant technical issues at pad 39B and that all systems are go for launch.

"A lot's happened over the last two-and-a-half years," he said. "Our focus during that timeframe has shifted from one of recovery and investigation to one of redesign, improvement and mission processing and now, to launch. Our launch team (is) well prepared and I know they're up to the task of returning our shuttle fleet to flight, of returning to the international space station and for returning our crew safely back home."

The countdown is scheduled to begin at 6 p.m. and if all goes well, Discovery will lift off on the 114th shuttle mission - the first since the Columbia disaster Feb. 1, 2003 - at 3:50:52 p.m. Wednesday. The ship's crew - commander Eileen Collins, pilot James Kelly, flight engineer Stephen Robinson, Andrew Thomas, Wendy Lawrence, Charles Camarda and Japanese astronaut Soichi Noguchi - arrived at the Kennedy Space Center Saturday night.

Forecaster Kathy Winters called for a 70 percent chance of acceptable weather Wednesday, although she said there was a chance inland thunderstorms could push into the launch area. The forecast is 60 percent "go" on Thursday and Friday should launch be delayed.

Winters said expected temperatures and humidity levels should help minimize the formation of ice on the shuttle's huge fuel tank, a major impact debris concern in recent weeks.

Spaulding said Discovery has enough on-board liquid hydrogen and oxygen, used by the ship's electrical generators, to make three launch attempts in four days. After that, the team would have to stand down for 72 hours to top off the tanks.

Asked about the mood at Kennedy as return to flight approaches, Spaulding said excitement is clearly building.

"Certainly for the last several months, it's been one where everybody has been pretty much having their head down, working very hard," he said. "We had a number of challenges over those months. And it's only recently, I think, that it's all come to fruition where we can see the light at the end of the tunnel.

"The excitement, I think has been building and growing," he added. "There's a great anticipation for launch ... and also maybe a quiet reserve as well just remembering where we've been. But we all do feel confident we've done it right."

Said Scott Higginbotham, payload manager for Discovery's mission: "It sure does feel good to be back in the saddle again."

"It's been too long, but here we are," he said. "I am very happy to report to you that all 28,000 pounds of international space station hardware that's in the payload bay of Discovery is ready to go."

The goal of Discovery's mission is to deliver critical supplies and equipment to the space station, along with a new stabilizing gyroscope that will be installed during the second of three spacewalks by Robinson and Noguchi. The spacewalkers also will test rudimentary heat shield repair techniques during their first excursion.

Assuming an on-time launch, Discovery is scheduled to land July 25 at 11:06 a.m.

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VIDEO: ASTRONAUTS ARRIVE AT KENNEDY SPACE CENTER PLAY
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VIDEO: DAY-BY-DAY PREVIEW OF DISCOVERY'S MISSION QT
VIDEO: DETAILED SUMMARY OF MISSION'S THREE SPACEWALKS QT
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