A subsidiary of Raytheon Co. will continue providing services to NASA’s astronaut training facilities in Houston under a $56.9 million contract extension.

Officials at Raytheon Technical Services Co. LLC, of Reston, Va., said the company supports operations at NASA’s Neutral Buoyancy Laboratory and Space Vehicle Mockup Facility. Both facilities offer low-gravity training to prepare astronauts for space shuttle and International Space Station programs.

The Raytheon unit provides about 70 employees for operations and engineering support at the facilities.

The extension is part of a contract awarded in 2003. It runs from April 1, 2008, to Sept. 30, 2010, and includes an additional one-year option that could increase the contract value to $78.3 million, Raytheon officials said.

The parent company, Raytheon Co., is based in Waltham, Mass. It ranks No. 6 on Washington Technology’s 2007 Top 100 list of the largest federal government prime contractors.