After 26 years, 230 million kilometers, and a combined year in orbit, space shuttle Discovery is headed home one last time. The oldest, most utilized shuttle in NASA's fleet is inbound from its final visit to the International Space Station and is scheduled to touch down at Kennedy Space Center in Florida just before noon Eastern Standard Time on March 9. But Kennedy, the traditional home of the shuttle program, may not be the final destination for Discovery this time around.

Once Discovery lands, NASA will begin decommissioning the shuttle, turning the well-used spacecraft into an artifact of space history. The orbiter will become the first of three remaining shuttles to enter retirement; Endeavour and Atlantis each have one more mission on the calendar before the shuttle program draws to a close later this year.

"Within a couple weeks after landing, NASA will begin the work of 'safing' and preparing Discovery for display to the public in a museum," says agency spokesperson Michael Curie. Safing involves removing any materials that may be dangerous, such as fuel systems that have been exposed to hazardous chemical propellants.

But just where the orbiter will head after that remains unsettled—for the moment at least. Twenty-one organizations have expressed interest in hosting one of the three shuttles, Curie says, and NASA will make an announcement about the recipients on April 12. That date is a momentous one in space history, marking both the 30th anniversary of the first shuttle flight in 1981 and the 50th anniversary of the first human spaceflight in 1961 by Soviet cosmonaut Yuri Gagarin.

NASA will not specify which organizations submitted proposals, but several institutions have made public their bid for a retired shuttle, including Space Center Houston; the Intrepid Sea, Air & Space Museum in New York City; and the National Museum of the U.S. Air Force at Wright–Patterson Air Force Base in Dayton, Ohio.

Observers initially presumed that Discovery, as the grizzled veteran of the surviving shuttle fleet, would go to the Smithsonian National Air and Space Museum (NASM) in Washington, D.C. But NASA has requested an estimated $28.8 million to prepare and deliver each orbiter piggybacked on a specially adapted 747 to its final home. That sum roughly matches the museum's annual budget, and it is not clear where the necessary funds would come from. "NASA intended to offer Discovery to the National Air and Space Museum," Curie says. "That is still the intent, but again the final decision and announcement will be made April 12."

Museum staff are mum on the prospect of securing a shuttle. "The museum is involved in discussions with NASA about transfer of the orbiter and other artifacts from the shuttle program," NASM spokesperson Brian Mullen says. "The final disposition of shuttle artifacts will be the decision of NASA." Mullen says the museum would have no further comment until after the April announcement.

The Intrepid Museum, on the other hand, has made its shuttle intent as plain as possible, hosting an online petition and displaying on its Web site letters of recommendation from New York City Mayor Michael Bloomberg and U.S. Sen. Kirsten Gillibrand. "NASA wants to expose the shuttle and its story to the greatest number of people as possible," Intrepid president, Susan Marenoff, explained in an e-mail. "New York City has the greatest potential of any city in America to expose the shuttle and its story to the greatest number of people." As for that $28.8 million, Marenoff wrote, "New York and Intrepid can produce the funding for this. As a center of giving and philanthropy, New York City has the capability to fund the project, and the Intrepid Museum has a long history of tapping into that potential." As an example, she noted that the museum had recently raised $115 million for a refurbishment project.

Another institution whose shuttle desire is no secret is the National Museum of the U.S. Air Force—and that museum may have a leg up from a funding standpoint. President Barack Obama's 2012 budget request for the Department of Defense (DoD), released in February, included $14 million to help the museum secure the Atlantis orbiter for display. (The Air Force prefers Atlantis because it has flown five DoD missions.) The Air Force is interested because it "has been a full partner with NASA from its origins to today, contributing technical expertise and personnel throughout NASA's human spaceflight program," according to an e-mail from a museum spokesperson in response to questions. "The USAF has invested more than $8 billion over the years into the shuttle program, and has provided extensive and essential launch and recovery support." But given that Congress has yet to pass a 2011 budget, 2012 funding is not likely to be secured before NASA makes its decision.*

In the meantime, the end of Discovery's current mission, officially designated STS-133, will put the finishing touches on a long and distinguished service record. Since its first launch on August 30, 1984, Discovery has flown 39 times, more than any other shuttle, including some of the most notable missions in NASA history. In 1988 and 2005 Discovery successfully completed return-to-flight missions after the Challenger and Columbia disasters, respectively, and in 1990 Discovery deployed the Hubble Space Telescope, an orbiting observatory that remains one of the world's premier scientific instruments.

*Update (3/8/11): Comments from the Intrepid Sea, Air & Space Museum and the National Museum of the U.S. Air Force were added after publication.