US investigators probing the events that brought down space shuttle Columbia and killed seven astronauts are close to completing a rough draft of their final report.
Meanwhile, engineers in Texas continue testing how much wing damage is possible from a high speed collision with foam insulation.
The chairman of the 13 member board, retired US Navy Admiral Harold Gehman, said he hoped the report would be completed and delivered to Nasa and to Congress by late next month.
Tests continued at the Southwest Research Centre in San Antonio, where engineers were firing chunks of foam insulation at a mock-up of the space shuttle wing.
The experiments were testing the theory that Columbia’s left wing was fatally damaged when the space shuttle was launched in January.
Photos showed that pieces of insulation peeled off the shuttle’s external fuel tank and smashed into the wing as the craft soared towards orbit.
An evaluation during the mission, based on the photos, concluded that the wing could not have been damaged enough to cause problems for Columbia.
But on February 1 the shuttle disintegrated while returning to Earth at the end of its mission.
Seven astronauts were killed and debris was scattered over East Texas and parts of Louisiana.
The shuttle fleet has been grounded while the board investigated the accident.