The board's chairman, retired Navy Adm. Harold Gehman Jr., had intended to release the report by the end of July to beat the August congressional recess. He wanted lawmakers to look over the 100-plus-page report while on vacation, to give them a jump-start when they returned to work in September and a slew of hearings on NASA.

But Gehman repeatedly stressed over the weeks: "We'd rather get it right than get it in a hurry."

Gehman notified key members of Congress about the need for more time, Brown said.

The board has accumulated a considerable amount of material for the report, Brown said, "and we have to decide where it goes, whether there's overlap with some of the chapters, some of the subject areas." Then it will be a matter of laying out the pages and compiling the graphics, she said.

She expects it to be released in Washington the last week in August.

At least half the report will deal with NASA management and cultural issues, according to Gehman. The rest will deal with the technical matters that led to Columbia's destruction over Texas on Feb. 1. All seven astronauts on board were killed.

The board has attributed the cause of the accident to the 1{-pound (675-gram) chunk of foam insulation that broke off Columbia's fuel tank during liftoff and slammed into the leading edge of the left wing. The resulting hole allowed deadly hot gases to penetrate the shuttle during atmospheric re-entry.

Earlier this week in San Antonio, accident investigators replicated the foam strike in a test that proved just how dangerous the lightweight insulation can be. A block of foam punched a 16-inch (41-centimeter) hole in a wing replica made of real shuttle parts.