United Space Alliance (USA) was expected to lay off 280 employees Jan. 7, cutting 4 percent of the Houston-based company’s current work force of about 6,700 employees nationwide, USA spokeswoman Tracy Yates said in a Jan. 4 e-mail.

Yates said the company planned to lay off 149 workers in Florida, 126 in Texas and five in other states.

“Of those being laid off, more than half — 153 — self-nominated for the layoff,” she said, adding that all employees are eligible for severance compensation and, in some cases, a critical-skills bonus.

Yates said the layoffs are necessary to align the company’s space shuttle work force with budget realities as the program heads toward retirement later this year. Although NASA plans to fly an extra shuttle mission in 2011 as mandated in the NASA Authorization Act of 2010, “recent changes and potential future changes to the Shuttle manifest are not impacting the January layoff.”

However, she said the company continues to assess work force needs as the space shuttle program winds down, and that the timing of the three remaining shuttle missions will have an impact on future layoffs.

“At this time we anticipate another workforce reduction in the spring, with additional layoffs following the end of the final shuttle mission,” she wrote.