Solid-rocket motor builder Alliant Techsystems (ATK) Aerospace of Magna, Utah, laid off 247 workers the week of May 17 as work winds down on NASA’s space shuttle program and on a Minuteman ICBM-related contract.

ATK spokesman George Torres said the move, due mainly to the impending retirement of the space shuttle, was one of a series of planned layoffs that have reduced the Aerospace division’s work force from 4,500 to 3,000 employees. He said that 450 employees were laid off earlier this year.

ATK Aerospace builds the giant solid-rocket motors for the space shuttle and also has worked on a number of other space, ICBM and missile defense programs.

The company is under contract to build the solid-rocket motors for NASA’s planned Ares rockets, which are based on the shuttle hardware. But those vehicles, along with the rest of NASA’s Moon-bound Constellation program, have been targeted for termination by the White House.