Space Shuttle Atlantis Heads Back to Launch Pad as Storm Weakens

CAPE CANAVERAL,Fla. - NASA's massive transport vehiclehauling the Atlantis orbiter towards a storm shelter stopped in its tracksTuesday and once more headed back to its Florida launch pad in an unprecedentedmove.

"We aregoing back to the pad," NASA KSC spokesperson Bruce Buckingham said shortly before3:00 p.m. EDT (1900 GMT). "We expect to be back there in about fivehours."

Theannouncement came about five hours after top shuttle officials gave the word tomove Atlantis into reinforced shelter inside NASA's 52-story Vehicle AssemblyBuilding (VAB) - known as a rollback - to weather high winds from TropicalStorm Ernesto. Ernesto was expected to pass within 15 nautical miles (27 miles)of Atlantis' Pad 39B launch site sporting wind speeds in excess of 40 knots (46miles per hour).

"It does notmake sense to fool with Mother Nature," said Wayne Hale, NASA's shuttle programmanager, in a Tuesday teleconference before Atlantis changed course. "You wantto do what is safe and we decided it would be most prudent to go back to thebarn and wait it out there."

ButAtlantis, which has been delayed from a planned Aug. 27 launch to theInternational Space Station (ISS), was midway though its 4.2-mile trek to theVAB when its crawler transport stopped, then slowly began reversing directionon course for the launch pad.

"Note evenin Apollo did we do that," NASA spokesperson Bill Johnson said of Atlantis'rollback reversal.

A NASApress briefing to discuss Atlantis' return to the launch pad is slated to beginhere at KSC by 4:30 p.m. EDT (2030 GMT).

Earliertoday, Atlantis' STS-115 crew - commanded by veteran shuttle astronaut BrentJett - left KSC and returned to NASA's Johnson Space Center (JSC) in Houston,Texas for additional training. But a JSC spokesperson told SPACE.comthat the six STS-115 astronauts had not been taken out of quarantine, in whichthey have only limited access to family and friends to avoid sickness beforelaunch.

Atlantishas been plagued by weather-related delays for its planned STS-115 space shot,a mission to resume ISS construction by delivering new solar arrays and trusssegments to the ISS.

NASA'swindow to launch Atlantis extends through Sept. 7, when the space agency hassaid it would stand down to avoid launch and landing conflicts with ISS-boundRussian Soyuz spacecraft next month. If the agency fails to launch Atlantis bySept. 7, the next firm opportunity to do so opens in late October.

Atlantis'launch pad return was prompted by updated forecasts for Tropical Storm Ernesto,which weakened as it entered the Florida Straits Tuesday morning.

"The stormhas weakened and we will not exceed our wind requirements," Buckingham said.

NASA launchdirector Michael Leinbach said Monday that it would take at least eight days"give or take", once Atlantis returns to the launch pad, to again primeAtlantis for liftoff. That means the shuttle could make another launch attemptwithin its current window, if things go NASA's way.

Leinbach,NASA shuttle weather officer Kathy Winters and other mission managers have keptclose tabs on Tropical Storm Ernesto.

When NBCreporter Jay Barbree asked Leinbach what he would doif, in fact, shuttle officials were able to stop Atlantis' rollback mid-strideand return to the launch pad, he answered with a mix of humor and cynicism.

"If thatscenario played out, I'd buy you dinner, I'd buy Kathy dinner," Leinbach said."That's so extraordinarily rare, that's way out there."

• VIDEO: First Tasks of NASA's STS-115 Mission
• Gallery: Prepping Atlantis
• Complete Space Shuttle Mission Coverage
• NASA's STS-115: Shuttle Atlantis to Jump Start ISS Construction
• The Great Space Quiz: Space Shuttle Countdown