John Brecher / msnbc.com

A crowd in the Georgetown neighborhood of Seattle watches NASA's Super Guppy aircraft approach Boeing Field, carrying a key piece of a space shuttle mockup that will go on display at Seattle's Museum of Flight.

SEATTLE — It may not be a real space shuttle, but it's ours.

Today NASA delivered a key piece of the mockup that astronauts used for space shuttle practice to the Museum of Flight in Seattle, my hometown. And it arrived aboard one of the most ungainly-looking airplanes ever built. The wingless mockup is known as the Full Fuselage Trainer, or FFT. The plane has a nickname that's more colorful: the Super Guppy.

The Super Guppy looks more like a Super Whale. The wide-body turboprop airplane has a cargo hold that's been built up into a bulbous shape, specifically to carry big stuff for outer space. Only five of the Guppies were ever produced, and they were used to cart spacecraft components around for the Gemini, Apollo, Skylab and shuttle programs. This Super Guppy is the only one of its kind still flying, and this week's odyssey with the most important piece of the Full Fuselage Trainer is one of the highest-profile flights the plane has ever taken.

For decades, the plywood-built FFT sat in a building at NASA's Johnson Space Center in Houston. The crew compartment — the part of the structure that was flown to Seattle today — was outfitted with all the buttons, switches, cockpit displays and middeck lockers that the real shuttles had. None of those gadgets worked, but they helped the astronauts get familiar with the layout before they started handling the real controls. Astronauts could also practice how they'd get out of the shuttle in the event of a landing-strip emergency.

With the end of the space shuttle era, NASA's Johnson Space Center no longer needed the FFT, so the space agency decided to donate it for display. The Seattle museum made a play for one of the flown shuttles, and even built a shuttle-sized, 15,500-square-foot Space Gallery to display it in. But Seattle lost out to Florida, California, New York and the "other Washington" in the competition for Atlantis, Endeavour, Enterprise and Discovery. The Full Fuselage Trainer served as the consolation prize.

Most of the FFT's plywood parts could be shipped up by traditional means for later assembly, but the shuttle crew compartment had to be transported all in one piece. That's why NASA's Super Guppy was called into service.

The airplane has a 25-foot-high, 25-foot-wide, 111-foot-long cargo compartment — big enough to hold the mockup's most awkward piece, even when it's bound up in shrink wrap and a protective steel frame. Over the past couple of days, the Super Guppy has been making a journey from its home at Ellington Air Force Base in Texas, over to California, and then up to Seattle at a top speed of around 200 knots. It wasn't exactly a record-setting pace — but what the Super Guppy lacks in speed, it more than makes up for in the "What the Heck Is That?" department.

The Guppy flew over my hometown and its surroundings with a Seattle-born astronaut, Greg Johnson, at the controls. Then it floated down to a landing right in front of the museum, which is adjacent to Boeing Field. One of the commentators at the museum called it a "beautifully ugly airplane."

Washington Gov. Christine Gregoire pointed to the craft with pride as the sky spit down rain. "When we get together in Washington state, we can land the big whale right behind me," she said.

Museum of Flight

NASA's Super Guppy and a chase plane fly above the mostly cloudy skies of Seattle.

Museum of Flight

After its touchdown at Seattle's Boeing Field, the turboprop-powered Super Guppy taxis over to the Museum of Flight next door.

Museum of Flight

The entire front of the Super Guppy swings open to reveal the cargo inside.

Museum of Flight

The 65,000-pound Tunner 60K aircraft cargo loader and transporter rolls toward the Super Guppy.

Museum of Flight

The cargo compartment for the Full Fuselage Trainer, wrapped in protective plastic, has been taken out of the Super Guppy for a short ride on the Tunner transporter to its new home in the Museum of Flight's Charles Simonyi Space Gallery.

Several thousand onlookers watched as the Super Guppy's entire front opened up to the side like a four-story-high door. 

"It's really cool that it's actually able to fly," Allison Kirkman, a 10-year-old student at Spirit Ridge Elementary School in Bellevue, Wash., told me as she watched from the tarmac. "It's an amazing plane, and how they built it is cool, too."

The shrink-wrapped shuttle crew compartment was moved out of the wide-yawning Super Guppy onto a 65,000-pound mobile transporter, then rolled over to the museum's Charles Simonyi Space Gallery. Over the next couple of months, the shuttle mockup will be assembled in a place of honor, alongside a Russian Soyuz capsule and a prototype lander that was used in Blue Origin's spacecraft development program. Museumgoers like Kirkman will be able to walk through the shuttle mockup's cargo bay — and they might even be able to crawl through the crew compartment, just like the astronauts did.

Kids, prepare to be amazed ... again.

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

Bill Ingalls / NASA

The prototype space shuttle Enterprise is seen mated on top of NASA's modified Boeing 747 Shuttle Carrier Aircraft at Dulles International Airport in Virginia on Friday. Enterprise was the first orbiter built for the space shuttle program, but never went into orbit. It was used primarily for ground and flight tests within the atmosphere. Enterprise had been on display at the Smithsonian National Air and Space Museum's Udvar-Hazy Center in Virginia, but is now being prepared for its new home at the Intrepid Sea Air and Space Museum in New York.

A day after the space shuttle Discovery took its place at the Smithsonian, the prototype shuttle Enterprise is perched on a modified 747 jet for its journey to New York. Now the timing of the trip depends on East Coast weather.

Overnight, Enterprise was towed out to Dulles International Airport and hoisted up into the air with two giant cranes. The jet, known as the Shuttle Carrier Aircraft or SCA, was brought underneath the 75-ton artifact. Then Enterprise was lowered down and "soft-mated" onto the plane at three attach points. The bolts will be tightened down for hard-mating on Saturday, in preparation for the big flight to New York.

This is the same process that Discovery went through in Florida leading up to Tuesday's flight to Dulles for its installation at the Smithsonian National Air and Space Museum's Steven F. Udvar-Hazy Center, next to the airport. On Thursday, Enterprise was moved out of the space it held since the center's opening in 2003, and Discovery was moved in.

NASA had been planning for Enterprise and the SCA to take off from Dulles as early as Monday morning, but this afternoon the space agency said the flight would be delayed due to a forecast of inclement weather in Washington as well as New York. "Managers will continue to review weather forecasts and announce a new flight date as soon as practical," NASA said in its advisory.

When forecasters give the go-ahead, the shuttle-jet combo will head up the East Coast and do a series of New York flyovers. You can expect to see the double-decker behemoth sailing over the Statue of Liberty as well as the Intrepid Sea, Air and Space Museum, the retooled ship where Enterprise will be put on display. After the flyovers, the Enterprise will be set down at New York's John F. Kennedy International Airport.

The shuttle-jet flight is old hat for Enterprise: The craft was the first vehicle built for the space shuttle program, and got its name in part thanks to a write-in campaign by "Star Trek" fans. Unlike the fictional starship, NASA's Enterprise never flew in space. Instead, it was used for ground tests as well as aerodynamic test flights atop the 747 carrier plane. Once the shuttle launches ramped up, Enterprise was deemed no longer needed for testing. It was handed over to the Smithsonian in 1985. The Udvar-Hazy Center's James S. McDonnell Space Hangar was specifically designed to show off the Enterprise.

After the 2003 Columbia tragedy, some sections of the Enterprise's wing panels were removed for impact tests, and those tests made a huge contribution to the accident investigation. That demonstrated that the shuttles can continue to benefit the space program long after their retirement.

It will take a few weeks for Enterprise to settle into its retirement home: The cranes will have to be set up for the shuttle's "demating" at JFK. Then Enterprise will have to be lifted onto a barge and brought up the Hudson River by a tugboat. The schedule calls for Enterprise to be hoisted aboard the Intrepid's flight deck sometime in June. It'll be put on display in a temporary climate-controlled pavilion this summer, and eventually housed in a permanent exhibit facility.

After Enterprise, there's one more shuttle-jet flight on tap: the transfer of Endeavour from NASA's Kennedy Space Center to the California Science Center in Los Angeles. That cross-country trip, due to take place in the latter part of this year, is likely to spark a nationwide frenzy of "Spot the Shuttle" sightings.

The last shuttle that flew in space, Atlantis, is going just down the road to Kennedy Space Center's visitor center, so there'll be no need to bring out the plane for that trip.

For more pictures of the Enterprise-747 mating, check out NASA Headquarters' Flickr gallery. And to get updates on the timing of Enterprise's flight and the flyovers, keep tabs on NASA's website as well as msnbc.com's space news section.

More about the shuttle shuffle:

• Astronauts revisit the shuttle's pros and cons
• How NASA selected the shuttles' future homes
• Seattle gets first pieces of shuttle trainer

Updated 5:20 p.m. ET.

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding Cosmic Log's Google+ page to your circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.