The Utah company that builds booster rockets for the space shuttle is laying off an additional 420 workers.
ATK Space Systems cited the phase-out of the space shuttle and Minuteman III ballistic missile program, the same reason it gave for laying off 550 of its 4,450 Utah workers in October.
ATK spokesman George Torres says Thursday's layoffs hit factory workers, engineers and administrative workers at a plant in Clearfield that refurbishes spent booster rockets, a manufacturing and test facility in Promontory, and a factory in Magna that made Minuteman missiles.
ATK says it gave the workers a week's pay for every year of service, up to a maximum of 26 weeks of pay. Torres says federal stimulus funds will also subsidize the cost of workers' health insurance for 15 months.