WASHINGTON — J. Scott Neish has resigned as president of Aerojet and as interim president and interim chief executive of GenCorp Inc., Aerojet’s parent company, effective immediately, GenCorp announced Jan. 6.

Scott Seymour, a former executive with Northrop Grumman Corp., was named permanent president and chief executive of GenCorp, as well as president of Aerojet, also effective immediately, GenCorp of Sacramento, Calif., said in a news release. Seymour has been a consultant to Los Angeles-based Northrop Grumman since March 2008, the release said.

Neish had been president of Aerojet, a maker of space and missile propulsion systems, since November 2005 and took the interim posts at GenCorp in March 2008. Aerojet spokesman Glenn Mahone said Neish’s appointment to the GenCorp positions was never intended to be permanent and that when he resigned from those he also elected to leave Aerojet.

Seymour served in various executive positions with Northrop Grumman, most recently as corporate vice president and president of Northrop Grumman Integrated Systems, a post he held from 2002 to March 2008. During that time, Northrop Grumman Integrated Systems unsuccessfully bid to build NASA’s space shuttle successor, the Orion Crew Exploration Vehicle.

Warren Ferster is the Editor-in-Chief of SpaceNews and is responsible for all the news and editorial coverage in the weekly newspaper, the spacenews.com Web site and variety of specialty publications such as show dailies. He manages a staff of seven reporters...