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.