NASA plans to name a new space shuttle program manager Friday to replace Ronald Dittemore, the widely-respected man in charge during the Columbia disaster who announced his retirement late last month, sources say. The identity of Dittemore's replacement is not yet known and a NASA headquarters spokesman reached at home late Wednesday said he had no knowledge of any such announcement. But sources said a successor has, in fact, been selected and that an announcement is planned for Friday in Washington.

Dittemore, a former flight controller, flight director and chief of shuttle engineering, was named shuttle program manager in 1999. He won widespread respect in the aftermath of the Feb. 1 Columbia disaster for holding daily news briefings to keep the public informed about the progress of NASA's ongoing investigation.

CBS News reported Dittemore's plans to retire April 19. The following week, he told reporters he had made plans to retire before Columbia's launch and that he initially put those plans on hold following Columbia's loss. But he said it was important for NASA to select a replacement as soon as possible, before return-to-flight activities mature, so the new program manager can have time to absorb the intricacies of the job.

"It would be very important to have new leadership in place, to have that foundation established," he said. "And as you move forward over the coming months, building on that foundation from a new leader perspective, you're going to be that much more prepared, both from a leadership point of view and a team responding to that leadership, to move right into return to flight and then, picking up the flight rate again.

"I believe personally this transition time frame would be extremely beneficial to allow this new leader time to prepare, the time to respond to recommendations, the time to implement recommendations, to have a strong foundation, to have a strong springboard to jump forward into the coming years."