Headquarters: Houston

Employees: 8,700

Revenue: $1.8 billion (2007 figure)

During the 15 years since Lockheed Martin and Boeing formed United Space Alliance (USA) to take over the day-to-day operations of NASA’s space shuttle fleet, the Houston-based venture has on occasion talked about taking the orbiters off NASA’s hands and operating them as a commercial launch service.

But with the shuttle slated for retirement this fall after flying its four remaining missions, USA has less-lofty ambitions: finding new work. While USA has other NASA-related contracts, the vast majority of the company’s employees work on the space shuttle.

Until recently, USA had been counting on NASA’s Constellation shuttle replacement and lunar exploration program to absorb a sizeable piece of the company’s work force. USA was well positioned to continue providing launch operations support at NASA’s Kennedy Space Center in Florida for the shuttle replacement system — the Orion Crew Exploration Vehicle and its Ares 1 launcher. Moreover, the company had secured subcontractor roles for itself on the teams selected to build those vehicles.

Now that the Constellation program has been marked for cancellation, however, USA is scrambling to line up government contracts, looking as far afield as the U.S. Army Corps of Engineers for new opportunities. In early March, for example, a USA executive told Space News the company thinks its Florida-based work force — accustomed to the logistical challenges of maintaining complex and critical hardware — would be well suited for repairing and overhauling combat vehicles returned from Iraq and Afghanistan.

While USA looks for work to take the place of NASA’s recently canceled Exploration Ground Launch Services solicitation, which was intended to support Constellation, as well as support contracts at Johnson Space Center in Houston that soon will be scaled back, the company also is looking for a new chief executive to replace Richard Covey, who retired March 26. Covey’s replacement — to be selected by Boeing per USA’s original operating agreement — will have to guide the company through the end of the space shuttle program and whatever lies beyond.