Go Atlantis

If you want to be an astronaut, patience could be a useful trait.

Space Shuttle Atlantis is scheduled to lift off on the STS-115 construction mission to the International Space Station at 15:15 GMT (11:45am EDT), but today’s launch is far from the first attempt to get this mission off the ground.

Atlantis’ latest flight was delayed from April 2003 by the grounding of the space shuttle fleet in the wake of Columbia’s loss, and has only returned to the schedule with the successful completion of the STS-121 ‘return to flight’ mission of Discovery this July. That milestone cleared the way for Atlantis to resume space station construction flights, hopefully at the beginning of the launch window that opened on August 27.

But that was not to be. Two days before that planned launch date, the lightening rod atop the fixed service structure – the Shuttle’s launch tower – was struck by the most powerful bolt of lightening ever recorded at the Kennedy Space Center. The mission management team elected to postpone the mission for twenty-four hours to allow extra testing and inspection in the wake of the lightening strike. As the testing progressed, another 24 hour delay was added, moving the earliest possible launch time to August 29.

On August 28, however, weather forecasts were showing that the track for hurricane Ernesto would potentially bring it close enough to the Cape to expose the Shuttle to unacceptable wind levels. This prompted a decision to remove Atlantis from the launch pad and roll it back to the Vehicle Assembly Building where it could safely shelter from the hurricane.

The rollback began on the morning of August 29, but the Shuttle made it only half-way back to the VAB. As it had been crawling slowly away from the launch pad, the weather forecast in relation to hurricane Ernesto had been steadily improving, and half-way through the journey the mission management team took the unprecedented decision to reverse the rollback, and send the Shuttle back to it’s launch pad.

Atlantis easily rode out the weakened tropical storm Ernesto, cocooned in the Rotating Service Structure at the launch pad. Inspection teams found no major damage after the storm passed, and a new target launch date of September 6 was set.

The countdown got under way September 3, but the day before the launch, a problem was discovered with one of Atlantis’ three power generating fuel cells, and a 24 hour postponement was called while the issue was investigated. That slipped another day while options were assessed, and with the Mission Management Team finally happy with its plans to deal with the fuel cell issue, launch was set for September 8.

During fuel tanking on the September 8 launch attempt, a problem was observed with a liquid hydrogen engine cut-off sensor in the Shuttle’s external fuel tank. The launch team allowed the countdown to proceed as they grappled with this now-familiar problem, hoping analysis of the problem would allow a sound rationale for continuing with the launch. Ultimately, the count proceeded down to the T-9 minute hold, at which point the Mission Management Team prudently decided that they needed to stick to the established mission rules for this scenario, and call for a twenty-four hour scrub-turn-around.

Which brings us, and the six exceptionally patient and understanding crewmembers of the STS-115 mission, to today’s launch attempt. Should the launch not proceed today, the next opportunity to fly will not come until late September, after the next ISS crew rotation using the Russian Soyuz spacecraft.

Weather forecasts currently show an 80% probability of acceptable conditions for launch, and no other technical issues are being worked.

Here’s hoping the crew finally gets rewarded for their patience with a safe ride to orbit today.

Go Atlantis!

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