On a recent morning, NASA let reporters take a peek into the retired space shuttle Discovery, which is headed to the Smithsonian. Right now it's in a customized hangar (or processing bay) at Kennedy Space Center.
Technicians are "safing" it, stripping it of explosive charges designed to blow hatches in an emergency. The shuttles won't need that when they're on display in museums.
Surprise: It's cramped inside. Seven astronauts had to pack into a modest crew compartment and, just above it, the flight deck. All the spaciousness is in the rear, in the payload bay, where the shuttle hauled jumbo telescopes and satellites and chunks of the International Space Station. So when people called it a "space truck" they were not joking. It's a pickup. A space pickup.
Discovery first flew in 1984 and has logged 148 million miles in space, which is equivalent to flying to the sun and most of the way back.
"It's sad. There's a lot more left in them. The airframes are certified for 100 flights. This one had 39 flights," said senior mechanical technician Bill Powers, 58, who works for United Space Alliance, the primary contractor for the shuttle.
"It's not wore-out. It's just broke-in. It could fly another 20 years. We get into the guts of this thing, it's pristine," said Tim Keyser, lead mechanic for the orbiters.
The fleet was small, just five spaceships, plus a prototype, named Enterprise, that was used in low-altitude tests but never made it to orbit.
Collectively they have flown 537 million miles (but since it's NASA there's an exact number: 537,114,016). Discovery, Endeavour (also parked in a hangar here) and Atlantis are the three surviving orbiters. The two oldest shuttles met disaster. Challenger blew up in 1986 as it soared into the Florida sky, and Columbia disintegrated over Texas as it returned to Earth in 2003.
The tragedies are recorded in various NASA documents with an identical, to-the-point phrase: "Loss of vehicle and crew."
The space shuttle goes into the history books with a mixed record. It was never truly loved. It was confined to low-Earth orbit and never flew higher than 384 miles above the surface.
But in its twilight it has flowered into something attractive. It could do things that the next generation of spacecraft won't be able to do.
NASA administrator and former shuttle commander Gen. Charlie Bolden speaks for many: "We are going to miss this incredible flying machine."
Versatile is the word that the engineers use.
The space shuttle could not only carry 50,000 pounds of cargo into orbit, it could house seven astronauts, dock with orbiting space stations, grab satellites and telescopes and pull them into the payload bay for repairs, and even haul enormous amounts of cargo back to Earth for a soft landing.
In retrospect, that was arguably too much spaceship for most of what was needed for missions in low-Earth orbit. NASA wants to get away from using a single vehicle to carry humans and cargo. It's safer and cheaper to send cargo separately, on unpiloted rockets.
Cost will always tarnish the shuttle's reputation. Once sold to Congress with promises of weekly flights for just $7 million a pop, the shuttle program never managed to make spaceflight routine or inexpensive. The shuttle program, in its totality, has cost more than a billion dollars per flight. All told, it adds up to $209 billion.
The historians will also note that the shuttle had a fundamental design flaw.
Rather than stacking components in a line, the shuttle's components at launch were arrayed side by side. The orbiter (the spaceship itself) was adjacent to a huge external fuel tank and two solid rocket boosters. That configuration meant the failure of one component could cause the failure of an adjacent one.
Which happened twice. In the Challenger accident, a jet of flame from a solid rocket booster ignited the external fuel tank, creating an explosion that rocked the orbiter and sent it plunging into the ocean. In the second, foam falling during liftoff from the external tank damaged a protective tile on the leading edge of one wing of Columbia. That damage proved fatal when the orbiter disintegrated upon re-entry.