Discovery heads into her mating operations with SCA ahead of final flight

by Philip Sloss

The NASA and United Space Alliance (USA) team at Kennedy Space Center (KSC) have begun the final preparations to transport Discovery to her retirement home outside of Washington, D.C. Rolling out of High Bay 4 of the Vehicle Assembly Building (VAB), the fleet leader made a sober roll to the Mate Demate Device (MDD) ahead of her farewell.

Discovery’s Final Preparations:

NASA 905 – the original Boeing 747 Shuttle Carrier Aircraft (SCA) that NASA purchased in 1974 – arrived at the Shuttle Landing Facility (SLF) on Tuesday evening, as work ramps up for a final time on Discovery at KSC

The SCA touched down on Runway 15 at the SLF after making the cross-country flight from Edwards AFB in California, where the aircraft is based

The 747 taxied to the south end of the landing field where the Mate Demate Device (MDD) is located and parked for final preparations to get it ready for Discovery to be mated to the aircraft over the weekend.

Ahead of Discovery’s arrival for mating operations, workers from USA and CSC Applied Technologies unloaded support equipment from the 747 and worked to lift and attach the ball mounts to the aft attach points on the plane on Wednesday. 

Ahead of the final roll, Discovery weighed in at approximately 167,000 pounds, including the 5,900-pound weight of the aerodynamic tailcone needed for the ferry flight; in comparison, when the orbiter was rolled over from OPF Bay 3 to the VAB (without the tailcone) for STS-133 in October, 2010, she weighed about 195,000 pounds in a flight configuration. 

“We’ve been using 145,000 pounds as a generic number for all the display sites,” Stephanie Stilson, NASA Flow Director for Orbiter Transition and Retirement said in March, “but each one before we ferry or deliver it will have an actual weight and CG (center-of-gravity) measurement so that the display sites will know exactly what they’re dealing with.”

In addition to the draining of internal fluid commodities and the removal of internal Reaction Control System (RCS) and Orbital Maneuvering System (OMS) tanks and plumbing, the Replica Shuttle Main Engines (RSME) lack almost all of the elements of the engine powerheads.

With Discovery arriving at the MDD on schedule at 7am on Saturday morning, she was aligned with the lifting sling that will lift Discovery off her landing gear and the orbiter will be leveled. Next, Discovery’s landing gear will be retracted and the landing gear doors will be closed. The sling was then to lift Discovery up high in the MDD so that the SCA can be positioned underneath.

However, that was delayed to Sunday due to high winds.

The schedule on Saturday involved work that was to be completed to the point of “soft mate,” which in this case means when the sling has lowered Discovery down onto 747 attach points, and an initial torque is put on the bolts.

With this moved to  Sunday, April 15th, workers finished Saturday’s delayed work, through to bolting Discovery to the SCA. The sling was then lowered around the orbiter so that the 747 started to bear Discovery’s weight, and then the sling was disconnected.

On Monday morning, April 16th, the mated Shuttle orbiter/747 duo pushed back out of the MDD, ready for takeoff at first light the next day.

The ferry flight on Tuesday, April 17th, is planned with additional time for low-level fly-overs of the Cape Canaveral and KSC area at the beginning of the flight and historic locations in the Washington, D.C. area at the end.

“The total time will be about three hours and forty minutes, counting the fly-arounds/fly-overs,” Henry Taylor, SCA crew flight engineer said. “The direct flight time is about two hours and twenty minutes, but the total time from liftoff to wheels stop will be about three (hours and) 40 (minutes).”

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Taylor also noted that when ferrying an orbiter, the SCA is limited to a top speed of 250 knots and a ceiling of approximately 15,000 feet, depending on the temperature. Discovery’s lighter weight, though, makes it easier to accomodate the fly-overs in a non-stop flight:

“It allows us to carry more gas,” Taylor added. “For a flight like this, it just gives us that flexibility to have fuel for fly-overs; if it was a heavy orbiter, we wouldn’t have the capability to do as much.”

Once Discovery arrives at Udvar-Hazy and takes Enterprise’s place in the James S. McDonnell Space Hangar, Stilson said there was still some remaining work to do to configure the orbiter for permanent display.

“You see Discovery, she’s got the tailcone on now, we’re going to remove that tailcone,” she said. “Two reasons for that: Smithsonian doesn’t want the tailcone, they want to show the engines; secondly, we need that tailcone to ferry Endeavour, so we have to bring that tailcone back here. Once we remove the tailcone, we will flare out the engines – right now they’re in a tucked position, but Smithsonian would like them more flared out.”

She also highlighted other post-ferry work: “There are some ferry struts that hold those engines in place that we need for future ferry flights, so we’ll replace those with struts that we can leave in place, permanent struts there. We’ll need to go in and reconfigure some vent doors, they want to close the vent doors, (and) some small things inside that they want us to reconfigure for them.

“There’s nozzles on the end of the OMS engines, they’re replicas, they’re made out of spares, but… we couldn’t ferry with them installed, so we’ll bolt those on once we get there, little things like that – final touches.”

To read about the orbiters –  from birth, processing, every single mission, through to retirement, click here for the links:

(Images: Via Larry Sullivan, MaxQ Entertainment/, L2 content and NASA)

(L2 and NSF are continuing to follow the orbiters through their transitional period. To join L2, click here:

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