U.S. Air Force's X-37B space plane in orbit more than 620 days

An artist's illustration of the U.S. Air Force's X-37B space plane in orbit. 

The solar-powered winged spacecraft has spent more than 620 days in orbit as part of the military's secret OTV-3 mission, which launched in December 2012.

Credit: NASA Marshall Space Flight Center

The U.S. Air Force's mysterious unmanned space plane has winged beyond 600 days in orbit on a classified military mission that seems to have no end.

The X-37B space plane is carrying out the Orbital Test Vehicle-3 (OTV-3) mission, a long-duration cruise that marks the third flight for the unpiloted Air Force spaceflight program.

The Air Force launched the miniature space shuttle into orbit on Dec. 11, 2012 using an expendable Atlas 5 rocket.

By the end of Friday (Aug. 29), the space plane had spent 627 days in orbit. That's one year, eight months, 19 days and counting, to be exact.

"The Air Force continues to push the envelope of the solar-powered X-37B capabilities," said Joan Johnson-Freese, a professor of National Security Affairs at the U.S. Naval War College in Newport, Rhode Island.

More Than 1,300 Space Shuttle Workers Get Layoff Notices

More than 1,300 space shuttle workers received layoff notices this week from United Space Alliance – a NASA contractor that is cutting 15 percent of its 8,100-person workforce ahead of the shuttle fleet's retirement next year.

Layoff notices were issued to 1,394 USA employees in all, company spokesperson Kari Fluegel told SPACE.com.

The layoffs take effect Oct. 1 and were announced earlier this month by USA officials.

"Our workforce has known for several years that the Space Shuttle Program has been scheduled to end, but layoffs are always difficult for everyone involved," said Virginia Barnes, USA president and chief executive, said in a July 6 statement. "We are committed to making this transition as smooth as possible."

Shuttle program ending
The Houston-based United Space Alliance is a partnership between Boeing Co. and Lockheed Martin that has operated the space shuttle fleet for NASA since 1995.

Fluegel said 902 layoff notices were issued to USA workers in Florida, which is home to NASA's Kennedy Space Center in Cape Canaveral that serves as both launch site and home port for the agency's three shuttles.

Another 478 layoffs were issued for Texas, which is home to NASA's shuttle mission operations, with 14 more in Alabama, where NASA's Marshall Space Flight Center is based.

About one-third of those recieving layoffs in each division nominated themselves for the cutbacks, Fluegel said.

NASA's space shuttle fleet is set to retire next year after 30 years of launching astronauts into low-Earth orbit. The shuttles began flying in 1981 and have flown on 132 missions so far.

Two final shuttle missions are currently scheduled (in November and February, respectively) to complete the International Space Station, which has been under construction since 1998 by a consortium of 16 countries.

Congress is discussing the possible addition on a third and final shuttle mission. If approved, that extra flight would likely launch next summer, NASA officials have said.

Fluegel said that if the extra shuttle flight is approved, it will not affect the impending Oct. 1 layoffs. But there could be repercussions for more layoffs ahead.

"This plan wouldn't be affected at all, but it would affect the timing, obviously, of when we would do layoffs, and how we'd do layoffs, next year," Fluegel said.