United Space Alliance, the space shuttle prime contractor, will eliminate half its remaining workforce -- up to 2,800 jobs -- this summer, soon after NASA launches its final two shuttle missions in April and June, the company announced Friday.

Through earlier layoffs and attrition, USA's workforce in Florida, Texas and Alabama has dropped from around 10,500 in October 2009 to a current level of around 5,600. In late July or early August, the company will implement another major workforce reduction, affecting between 2,600 and 2,800 employees across the company.

Of that total, 1,850 to 1,950 job losses are expected in Florida, 750 to 800 in Texas and 30 to 40 in Alabama.

"The accomplishments of this team are unmatched in human spaceflight," Virginia Barnes, USA President and Chief Executive Officer, said in a company statement. "It will be difficult to say goodbye to such tremendously talented and dedicated teammates, and we are committed to making this transition as smooth as possible for them."

NASA plans to launch the shuttle Endeavour April 29 on a mission to deliver supplies, spare parts and a $2 billion physics experiment to the International Space Station. The shuttle Atlantis is scheduled for launch June 28 on the program's 135th and final flight, carrying another load of critical supplies to the station.

NASA's oldest shuttle, Discovery, completed its final mission in March.

President Bush announced the shuttle program's retirement in 2004, calling on NASA to complete the space station and end shuttle flights by the end of fiscal 2010. Because of a variety of technical issues, the final three flights slipped into 2011.

"We have been stepping down our workforce over the last, really, three years," shuttle Program Manager John Shannon told reporters last month. "Back in late 2006, the shuttle program had 14,000 contractors. We're currently down to just over 6,000 contractors. We had 1,800 civil servants at that time, we're just over 1,000 at this time.

"So it's been this gradual phase down. We're at a point now where it's primarily operations and sustaining engineering for the different elements that are left, and we require those out to the end of the program."

But after Atlantis lands in July, USA will implement the workforce reduction announced Friday.

"It'll be a significant layoff and the rest of the contractors will either go to other jobs within their companies or they'll be laid off and civil servants will be assigned to other tasks," Shannon said. "That's coming up in probably the late July timeframe. The shuttle program will transition at that time to what's called the Space Shuttle Program Transition and Retirement Team."

The transition team, made up of only a few hundred managers and engineers, will be responsible for "safing" Discovery, Endeavour and Atlantis, removing components that might be used in follow-on programs and preparing the orbiters for their eventual display in museums.

NASA Administrator Charles Bolden announced Tuesday that Discovery will be sent to the Smithsonian Air and Space Museum's Steven F. Udvar-Hazy Center near Washington. Atlantis will remain at the Kennedy Space Center and Endeavour will be displayed at the California Science Center in Los Angeles.

"Though USA will be a significantly smaller company after the space shuttle program is completed, we are optimistic about our future," Barnes said in the USA statement. "USA has a great deal to offer in the way of skills, experience and expertise, and we are looking forward to providing our unique capabilities to a wide variety of new and existing customers."