Raytheon has begun ground-based firings of a new variant of the Standard Missile 3 (SM-3) as part of an investigation into why the interceptor failed Sept. 1 in its first test flight, a company official said.

The motor firings, which began the week of Oct. 31, are aimed at replicating the glitch behind the SM-3 Block 1B missile’s failure to hit its target, Dean T. Gehr, director of strategy and growth for Raytheon Missile Systems in Tucson, Ariz., said in an emailed response to questions. The Block 1B, an upgrade to the SM-3 Block 1A now deployed aboard U.S. Navy ships, launched successfully from the USS Lake Erie cruiser but failed to complete the intercept.

Rick Lehner, a spokesman for the U.S. Missile Defense Agency (MDA), which is developing the SM-3 Block 1B as well as two even more capable variants of the SM-3, said the failure investigation should be completed in the spring of 2012.

The SM-3 Block 1B has a more advanced signal processor for target discrimination and a different divert and attitude control system — which steers and propels the interceptor’s kill vehicle — than its predecessor, which is now in service. The Block 1B will be deployed both on ships and on land in Europe as part of the MDA’s plan to defend that territory against attacks originating from the Middle East.