Look to the sky at about 10:30 a.m. Saturday, June 30, and you may see NASA's bubbleheaded Super Guppy — essentially a supersized flying aluminum can.

If weather permits, the cargo plane carrying a piece of a space shuttle mock-up from Houston will signal its arrival in Seattle with two passes around Lake Washington before landing at Boeing Field for an 11 a.m. ceremony.

The turboprop Super Guppy may be old, slow and odd-looking, but it gets the job done, said David Elliott, NASA's Super Guppy project manager.

"It's ideal for this kind of work. With its 25-foot diameter, we can fit just about anything in it."

Besides its swollen shape, the Super Guppy's most distinctive feature is the way it's loaded.

The front ends swings away, allowing unobstructed access to a cargo compartment that can swallow objects 25 feet high, 25 feet wide and 111 feet long.

The plane bound for Seattle is the last flying member of a family of eight Guppy aircraft that dates to the early 1960s.

The aircraft were created to carry outsized cargo by expanding the fuselage of Boeing Stratocruisers or related aircraft — planes readily available as airlines switched from propeller-driven planes to jetliners.

When the first such plane was created, one observer said it looked like a Pregnant Guppy, and the name stuck.

Early on, its work included carrying Saturn IV rocket parts to Florida's Cape Canaveral, replacing a two-week barge trip that sometimes damaged the rockets.

Elliott said some experts have concluded that without the work of the Guppy, the U.S. might not have fulfilled President Kennedy's goal of putting an American on the moon by the end of the 1960s.

Four airplanes of a larger version, the Super Guppy, were made.

Elliott, who'll be a flight engineer on this mission, said the current Guppy rolled off a Boeing production line in 1957, although many of its parts have been modified or replaced.

Its specialty, he said, is carrying objects that are large but not heavy — a good fit for NASA, which moves aircraft and space-related components.

"There are new aircraft that could replace it, but we don't have the budget for that," Elliott said.

NASA got the current Super Guppy from the European Space Agency in 1997 under terms of an international-space-station barter agreement.

The plane previously had been used by Airbus to move aircraft pieces among manufacturing sites in France, Germany and the United Kingdom.

Although the Super Guppy operates out of Houston, it spends its downtime across the state in El Paso, where the dry desert air helps preserve the plane.

The 2,400-mile trip to Seattle will be a series of hops that should take 2 ½ days, with the plane cruising at about 250 mph. An additional day has been added into its schedule in case the plane is delayed by bad weather.

Jack Broom: 206-464-2222 or jbroom@seattletimes.com