Spaceflight Now

Schedule mapped out to final space shuttle launch

Posted: April 10, 2011

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The powerful booster rockets for the final space shuttle launch continue to be stacked segment-by-segment inside the Vehicle Assembly Building in preparation to propel Atlantis skyward this summer.

File image of solid rocket booster segments being stacked. Credit: NASA
Technicians began piecing the solid motors together on March 29 when the base for the left-hand booster was hoisted atop the shuttle's mobile launching platform. The aft segment of the right-hand booster followed suit on March 31.

The bottom segments of each booster get anchored to the platform by explosive bolts that pop at liftoff to release the shuttle.

Once those sections were secured in place, the next parts were cleared to enter the VAB. The left-aft-center segment arrived on April 1 and mating of the right-aft-center was finished on April 6. The right-forward-center was transferred just hours later and the left-forward-center was installed on April 8.

Still to come are the left- and right-forward motor segments planned for Monday and Wednesday.

Meanwhile, efforts to strengthen the external fuel tank's ribbed midsection were completed in March. The modifications are identical to those incorporated on shuttle Discovery's tank flown in February to prevent stress cracks on the tank's structural beams.

Atlantis' fuel tank is scheduled for mating to the solid rocket boosters on April 25. A couple of weeks will be spent readying the combined hardware before the orbiter joins in.

The astronauts visited Kennedy Space Center on April 7 and 8 for their CEIT -- the crew equipment interface test. Commander Chris Ferguson, pilot Doug Hurley and mission specialists Sandy Magnus and Rex Walheim got up-close and personal with Atlantis and the payloads.

"Atlantis in top form! Amazing contrast between the pristine interior and the exterior scars of many previous spaceflights," Ferguson tweeted.

Commander Chris Ferguson sits aboard Atlantis during the CEIT. Credit: NASA
At the orbiter processing facility, Atlantis is almost ready to emerge. Final testing is being completed in preparation for the May 12 trip from the hangar to the nearby VAB to go vertical.

The fully assembled space shuttle vehicle -- the orbiter, fuel tank and boosters -- is slated for rollout to launch pad 39A on the evening of May 20, arriving at the seaside complex in the predawn hours of May 21.

Once mounted atop the pad, Atlantis' three auxiliary power units will undergo a hot-fire test to ensure the devices are in good shape for controlling the ship's hydraulics. The gantry then rotates to enclose the orbiter the next day.

The practice countdown and emergency training for the four astronauts begins at the end of May and lasts a few days. The crew will get suited up and strap aboard Atlantis on June 2 for the simulated launch morning, culminating with an evacuation drill from the shuttle after a pretend ignition and shutdown of the three main engines.

That event will be followed by a special fueling exercise for the external tank on June 7. A half-million gallons of supercold liquid hydrogen and liquid oxygen get loaded aboard the tank to check the strengthened ribbed midsection. In the subsequent days, inspections will be performed to verify the modifications have held and that there are no concerns about the tank's structure.

Then the mission payloads are delivered to the launch pad for installation into Atlantis. The Italian-made Raffaello logistics module and a cross-bay carrier holding an in-space refueling experiment for the International Space Station arrive at pad 39A on June 16 for insertion into the shuttle starting June 20.

The astronauts travel from Houston to the Florida spaceport on June 24 to begin final launch preparations and even tour the payload bay that day for a sharp-edge inspection before the doors are closed for flight.

Countdown clocks begin ticking June 25 for the three-day sequence leading to blastoff June 28 at 3:40 p.m. EDT.

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