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NASA Primes Retired Test Shuttle Enterprise For One Last Flight

Enterprise,NASA's first space shuttle prototype, which in 1985 was delivered tothe Smithsonian as a museum piece after proving that awinged spacecraft could land safely as a glider, is now being readiedby the space agency for what is planned to be its final ferry flight atopa modified Boeing 747 jetliner.

Enterprise's upcoming flight comes as a result of NASA's plan to retirethe three space-worthy shuttles remaining in its fleet later thisyear. All three are expected to be placedon public display, with one, Discovery, heading for the Smithsonian'sStephen F. Udvar-Hazy Center, the annex to the National Air andSpace Museum in Chantilly, Va., where Enterprise hasbeen exhibited since 2003.

"If we indeed receive a flown orbiter as expected, we can't begreedy and have two of them here so we'll need to look for a new homefor Enterprise," explained curator Valerie Neal in an interviewwith collectSPACE.com.

Though the Smithsonian and NASA have yet to choose a new museum for OV-101(the space agency's designation for Enterprise), or whether it willbe placed on permanent loan from the national collection or providedoutright to its new home, the two organizations recognized theneed now to make sure that Enterprise could be safely moved.

"The people who are starting to work on the logistics for flyingthe orbiters to their different new homes decided that they better takea goodlook at Enterprise and just validate that it is ferry-worthyafter all these years," said Neal. "The assumption all along isthat it is and a quick look assessment had indicated that yes, it isintact." Now that they're getting really serious about the possibilityof a ferry flight, they wanted to take a very close look ? amicroscope look ? at the critical features and junctures."

So an eleven-person team from NASA's shuttleoperations contractor United Space Alliance (USA) was sent from theKennedy Space Center in Florida to the Smithsonian's Udvar-Hazy Center to"shake down" Enterprise and make sure it is ready to go.

"They have been here for two weeks and have worked their waypretty methodically all around the vehicle," Neal described. "Sofar, they've found everything to be in good order."

Just enough different

"There does not appear to be any type of big problem or show-stopperor anything like that," reported Neal. "This is really kind ofa confidence building exercise just to make sure, because Enterpriseis just enough different from the vehicles that remain thatthey're concerned [if] everything will fit with the equipment we'reusing today or is there any kind of anomaly here that we need to be awareof that will affect what our standard procedure is."

Built between 1974 and 1976 by Rockwell (now Boeing) inCalifornia, Enterprise was used for NASA's Approach and Landing Test(ALT) program, making 13 flights between February and October 1977while attached to the modified 747 Shuttle Carrier Aircraft (SCA).During the last five of thoseflights, Enterprise separated from the jet at altitude and wasthen piloted by two NASA astronauts to a landing at Edwards Air ForceBase.

The prototype orbiter was later used for vibration and "fit"checks, the latter to make sure that the support facilities and launch padwas properly configured for the shuttle.

Originally, Enterprise was to be refitted for spaceflight butdesign changes during the construction of OV-102, named Columbia, madeit impractical. Still the two shared more in common than whatseparated them.

"This vehicle very much closely matches the real airframe onthe spacecraft," said Klint Combs, USA's manager for orbiter handlingand mechanisms, who has led the team of USA technicians workingon Enterprise. "They were going through the design process andthey wanted to make sure that what they were designing for aspacecraft to land as a glider, they were testing what they were going tofly."

"She does resemble inside a lot like Columbia," described MartinBoyd, who as NASA's lead structures engineer for the orbiter fleethas been overseeing the work by Combs and his team. "It isunique because [Enterprise] doesn't exactly look like ours. It isstructurally, but because it doesn't have all the plumbing and all thehyper-systems and all the stuff in there, we get to kind of get in thereand say, 'Wow, that's what it really looks like behind all of that otherstuff.'"

As similar as Enterprise may be to the otherspace shuttles from the inside, its tiles on the outside were differentenough to provide a concern for flight.

"We were somewhat concerned about the adherence of the foam,"explained Combs to collectSPACE.com, referring to the polyurethanefoam blocks that were used to replicate the appearance of the thermalheat shield tiles on the real orbiters, "so we did a bunch of pulltests to verify the bond of the foam to the aluminum skin of thevehicle. We were particularly concerned in the aft, where hydraulicsystems have leaked out over the decades. The foam back there issaturated, so we were concerned that may have affected the bond but thoseareas passed as well."

Continuereading at collectSPACE.com about the problems found with Enterpriseand view two exclusive photo galleries, including "How to display aretired space shuttle" and "Preparing Enterprise for flight."

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