Thursday, July 07, 2011

It all comes down to weather for Atlantis today


CAPE CANAVERAL – It all comes down to the weather for Friday's launch of Atlantis on the final mission in the space shuttle program.

And there are a lot of ifs, ands and buts as far as whether expected rain and cloud cover both at Kennedy Space Center launch pad 39A and the Shuttle Landing Facility will prevent the scheduled 11:26 a.m. liftoff.

There is a 70 percent chance of weather preventing launch.

“I wish we had better weather for you,” Shuttle Weather Officer Kathy Winters told a Thursday morning briefing about the tropical moisture over the state.

Conditions are expected to improve on Saturday with a 40 percent chance of acceptable weather and a 60 percent chance on Sunday, Winters said.

Since no severe weather – high winds and hail - was expected on Thursday, NASA decided to attempt getting a head start on operations by moving up roll back of the Rotating Service Structure - that protects Atlantis on the launch pad - by two hours.

The operation was scheduled for 2 p.m. but NASA decided to begin the operation at noon – only to be stymied by lightning that forced things back. It had hoped to avoid any weather later in the day that would have impeded the rollback.

Shortly before 2 p.m., NASA was reviewing data for all affected systems after one of a number of lightning strikes hit within 1/3 of a mile of the launch pad at 12:31 p.m. Assessment at the pad area itself was to be done in concert with the rollback that began at 2:38 p.m. and was completed 30 minutes later, marking yet another milestone in the final countdown.

There was no word late Thursday on any affects from the strike.

If Friday's weather does prevent liftoff, NASA could decide to wait until Sunday to make another attempt.

NASA Test Director Jeff Spaulding, citing crew rest and concerns over members of the launch team being able to reach their homes through the expected viewing crowd of nearly 1 million and being able to return sufficiently rested, said if a launch scrub is called anytime after L-minus four hours NASA most likely will opt for a 48-hour turnaround or the next attempt coming on Sunday.

If NASA decides to make a launch attempt on Saturday the preferred liftoff time would be 11:04 a.m. A Sunday attempt would be at 10:38.

NASA has reserved the Eastern Range for attempts today, Saturday and Sunday before the scheduled launch of a Delta IV rocket from Cape Canaveral Air Force Station on Thursday takes precedence.

Spaulding said there have been preliminary discussions about the possibility of NASA being able to secure Monday as a possible launch date should weather get in the way.

The main weather issues are clouds and rain in the vicinity of the launch pad and at the landing facility should a-never-before- attempted Return to Launch Site abort is necessary.

Weather at Trans Atlantic Abort sites – which also can be a launch constraint – is forecast to be good for today and Saturday. For Sunday forecasters are calling for a chance of thunderstorms at sites in Zaragoza, Spain and Istres, France but good weather for Moron, Spain.

Conditions at the U.S. sites at White Sands, New Mexico and Edwards Air Force Base in California are forecast to be good.

Weather also was not expected to impede the three-hour operation to load liquid oxygen and liquid hydrogen into the shuttle’s external tank that was scheduled to begin at 2 a.m. today.

"Our goal going into the meeting tonight is always to try to tank,” Spaulding told the briefing. “Our goal is to do what we can to get to that launch attempt.

"It's a really tough day if you make a decision to not go and it turns out to be good weather. And we've seen those kinds of things in the past."

Atlantis’ four-person crew of veteran fliers – Commander Chris Ferguson, Pilot Doug Hurley, and mission specialists Sandra Magnus and Rex Walheim - is scheduled to be awakened at 4:30 a.m., have a weather briefing at 6:56 a.m. and don their flight suits beginning about 7:05 a.m.

They are to depart crew quarters at KSC’s Operation and Checkout Building at 7:36 a.m. for the nine-mile trip to the launch pad where they are to begin boarding the orbiter at 8:05.

The flight will be the third for Ferguson, Magnus and Walheim and the second for Hurley.

If weather is still threatening as launch approaches, NASA could go as deep into the count as an additional, unplanned hold at T-minus 5 minutes to wait it out for the duration of the launch window, which at that point would be five minutes. The launch window is 10 minutes long but NASA targets the middle of the window for best performance for the orbiter.

Once launched, Atlantis and its crew are scheduled to spend 12 days in orbit with the main task being re-supplying the International Space Station, the final time a shuttle crew will perform those duties.

Landing at Kennedy Space Center is scheduled for 6:57 a.m. on July 20 unless NASA decides to add a day to the mission. If that’s the case landing would be scheduled for 6 a.m. on July 21.

On the mechanical side of things, three chillers on the launch pad that use chilled water to cool ground systems malfunctioned overnight Wednesday, Spaulding said. Two of the chillers were back in operation this morning. Only one is needed for launch.

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