NASA plans to build a new rocket engine test stand at the John C. Stennis Space Center on the Mississippi Gulf Coast, Sens. Thad Cochran and Trent Lott, both R-Miss., said Tuesday.

The new stand will test NASA’s J-2X engines, which will be used in the second stage of the Ares I launch vehicle.

Cochran and Lott said the announcement represents an estimated $175 million investment at Stennis to support the Constellation Project, the agency’s plan to send missions back to the moon and eventually to Mars.

“This announcement is mutually beneficial for NASA, Mississippi and the nation in promoting the United States’ goal of returning man to the moon,” Cochran said in a statement.

“NASA benefits by utilizing the talented work force at Stennis whose knowledge and skills, developed over the years since the Apollo era, have made Stennis the leader in rocket engine testing that it is today,” Cochran said.

The Stennis Space Center, which opened in the 1960s, is NASA’s primary center for rocket propulsion testing.

Lott said the decision to build a new rocket test stand there “helps cement the center’s future as the nation’s premier rocket testing facility.”

The senators said this is the largest project NASA initiated at the Stennis Space Center since the mid-1960s, during the Apollo era. Testing of the J-2X engine is set to begin in December 2010.