The space shuttle Atlantis sits in its hanger in Cape Canaveral, Fla., on Feb. 1. Its sister ship, Discovery, is to be transported to the Washington region in April. (Bill O'Leary/Washington Post)

A figurative “for rent” sign hangs on the front gate of John F. Kennedy Space Center.

Among the facilities available: A space shuttle launchpad, slightly used; a giant crawler for moving rockets, still servicable; two enormous mobile launch platforms; two space shuttle maintenance hangars; a 15,000-foot concrete runway, one of the world’s longest; and the blocky, 52-story Vehicle Assembly Building, with four soaring rocket assembly bays — and no waiting.

America’s spaceport turns 50 this year, and a wrenching middle-age transition is under way.

“I have a lot of facilities that we, NASA, no longer need,” said Robert Cabana, Kennedy’s director and a four-time space shuttle flier. “I don’t have the money to maintain them, I don’t have the money to tear them down. They’re just going to sit and rot.”

That is, unless NASA can find some tenants.

“We’re putting out the word officially and unofficially that Kennedy Space Center is open for business,” said Scott Colloredo, chief architect for ground systems here.

At the apex of the space shuttle program, some 18,000 people worked here. Now, just 7,500 do. On a recent Wednesday morning, parking lots across the vast complex sat two-thirds empty. Since 2009, Cabana has handed pink slips to 9,000 engineers, technicians and office workers.

“Do you know what that feels like?” Cabana asked as he stood inside one of Kennedy’s hangars. He looked up at the space shuttle Discovery, where three workers were crawling inside the engine compartment. In April, Discovery will make a final flight to Dulles International Airport. Retirement awaits it at the National Air and Space Museum’s Udvar-Hazy Center.

Cabana outlined a vision for the spaceport’s future. Instead of serving a single customer — the enormous shuttle program — he foresees Kennedy launching rockets from NASA and from private companies now racing to build a new generation of crewed space vehicles.

But that vision depends on the rapid maturation of a commercial space industry. Critics say Congress has not delivered enough cash to support private development, and expected launch dates have already slipped.

In 2010, President Obama spoke here and vowed to seed a commercial space industry, to replace the canceled Constellation program to return Americans to the moon. With NASA money, American companies would build rockets and spaceships to travel to low Earth orbit. They would deliver astronauts and cargo to the international space station and, someday, to privately owned space stations.

For 2012, the Obama administration and NASA asked for $850 million to spread among American space companies. Congress provided less than half that, $406 million. “Congress hasn’t sufficiently funded it,” said Dale Ketcham, director of the Spaceport Research and Technology Institute at the University of Central Florida. “It’s an Obama idea so Republicans don’t like it.”

A top NASA advisor, Vice Admiral Joseph Dyer, said he felt “a sea change in energy” during a January meeting with NASA officials, a downturn in optimism regarding private space efforts. Dyer leads the Aerospace Safety Advisory Panel, which meets with NASA quarterly. “If the new [lower] funding level continues into the future, we believe the program is in jeopardy,” Dyer said.

In 2010, Obama also pledged $40 million to transform Kennedy into a diversified research park. Energy, biotechnology and other high-tech companies were supposed to race for the funds — and the services of skilled workers along the 50-mile Space Coast.

But Congress never delivered the $40 million; except for a few small projects, Kennedy has not diversified.

Situated on Merritt Island, the space center and adjacent Cape Canaveral Air Force Station have launched all 165 of NASA’s human spaceflights. During the Apollo program, the workforce swelled and surrounding Brevard County boomed from a sleepy area known for its Indian River oranges and grapefruit into a vibrant region with a surfeit of well-paid jobs. In the two decades to 1970, the population of the county swelled tenfold, to 250,000, as America aimed for the moon. Space became a seemingly permanent industry.

These days, ta visitor is far more likely to catch sight of wild pigs or sunning alligators than a roaring rocket. The grounds are redolent with space-age nostalgia. At launch complex 14, a weathered plaque marks John Glenn’s first launch into orbit 50 years ago. A NASA documentary shot that day shows Glenn striding in a silver suit to the van that will take him, pre-dawn, to the floodlit launchpad.

Those were dramatic — and optimistic — times.

Today, not all is gloom. The spaceport has recently managed to claw back a few hundred jobs. Lockheed Martin moved into a “clean room”, where the Apollo capsules were prepped 40 years ago, putting 150 people to work. The company is building the Orion capsule for NASA, with a test launch scheduled for 2014. NASA is developing Orion to travel into deep space; the test vehicle is set to arrive here in May.

Boeing plans to move into one of the three space shuttle hangars. The state of Florida rented the building last fall for 15 years and subleased it to the company, which hopes to eventually put 550 people to work building a capsule to fly to the international space station.

NASA has asked Congress for $400 million in the coming year to retrofit launchpads and other facilities. By 2017, NASA hopes, it will fly a giant new rocket, the Space Launch System, on an uncrewed test flight.

To accommodate the rocket, workers have already torn down the big gray tower on one of the two space shuttle launch pads. Cabana said NASA recouped $621,000 from selling miles of copper wire stripped out of the 25-story structure.

NASA also plans to retrofit a mobile launch tower it never used. Built for the canceled Constellation rockets, the 39-story cross-hatched steel tower cost nearly $500 million and sits parked on Kennedy property.

The future of the second shuttle launchpad remains uncertain. Colloredo said NASA officials were talking with “two or three” potential customers.

One is California-based Space Exploration Technologies, or SpaceX. The company already occupies an old Air Force hangar and a smaller launchpad on Cape Canaveral, where it is readying a rocket and a capsule for an uncrewed test flight to the international space station in April or May. The company’s founder, PayPal billionaire Elon Musk, has sketched out grand plans for bigger rockets that would call for the huge concrete curtain of the shuttle launchpad.

But there’s still no word on who might be interested in renting the huge Vehicle Assembly Building. For now, the decommissioned space shuttle Atlantis rests on the building’s floor, its engines removed, its windows blinkered.

Behind Atlantis, a sea of gunmetal gray desks, tables, cabinets, office chairs and other discarded furniture awaits removal. Among the castoffs is a lone white refrigerator, its door ajar. It bears a handwritten note that says, “Free to good home.”