NASA's Pathfinder Aircraft Tracks Weather for Ferry Flight
Space shuttle Discovery returned to NASA's Kennedy Space Center on Sept. 21 perched on top of a modified Boeing 747 jumbo jet. But it wasn't an ordinary cross-country piggyback journey. C-9 pathfinder aircraft

Image: NASA's C-9 aircraft accompanied the 747-shuttle, flying about 100 miles ahead to act as a pathfinder, scouting weather conditions that might have required the ferry flight to deviate from its intended route or destination. Photo credit: NASA/Mary Ann Chevalier
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Discovery atop the Shuttle Carrier Aircraft

Image: The Boeing 747 Shuttle Carrier Aircraft, or SCA, with space shuttle Discovery on top, is ready for towing from the Shuttle Landing Facility's Runway 33 at Kennedy Space Center after touching down at 12:05 p.m. EDT on Sept. 21, 2009. Photo credit: NASA/Kim Shiflett
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In fact, the two-day ferry flight from California proved to be one of the greatest tests ever for the NASA C-9 "pathfinder" aircraft that scouts safe routes ahead of the shuttle.

"This shuttle return is the biggest challenge I have ever faced," said C-9 aircraft pilot Charles Justiz. "Had the weather been any more finicky, we likely would have landed somewhere else."

The pathfinder does just what its name implies, finds a path free of rain that could damage heat tiles and colder temperatures that might freeze propellants.

The team made three pit stops along the way: Rick Husband International Airport in Amarillo, Texas, for fuel, another re-fuel at Ft. Worth Naval Air Station in Texas, and an overnight stay at Barksdale Air Force Base in Shreveport, La.

Although the caravan faced several walls of storms on its 2,500 mile journey to Florida, weather was not much of an issue until the C-9 flew into the sunshine state's airspace.

"All the holes in the storms we thought were there ... weren't," Justiz said. "Today was quite an experience ... our entire team was busy today."

After taking off from Louisiana the morning of Sept. 21, the C-9 aircraft started running into a string of storms. Workers at Kennedy were unsure where Discovery would land, until minutes beforehand. MacDill Air Force Base in Tampa and Orlando International Airport were options if Kennedy's weather proved to be too dynamic.

"Once we left Barksdale, we didn't know what kind of weather we were going to get," said Don McCormack, ferry flight manager. "(NASA has) the best weather forecasters you can possibly have."

After five attempts, the C-9 aircraft finally found a hole and approached Kennedy's Shuttle Landing Facility from the north. Workers on the ground saw something much different, and directed the 747 with Discovery atop to land from the south on Runway 33. Touchdown occurred at 12:05 p.m., about 10 minutes after the pathfinder.

Discovery now is being prepared for its next mission: STS-131 targeted to launch to the International Space Station in March 2010.

Frank Ochoa-Gonzales
NASA's John F. Kennedy Space Center