The grid on the floor of the RLV Hangar is filling up with pieces of Columbia debris that have been collected by workers in the field. The Columbia Reconstruction Project Team is attempting to reconstruct the bottom of the orbiter as part of the investigation into the accident that caused the destruction of Columbia and loss of its crew as it returned to Earth on mission STS-107. To date, more than 35,000 pieces have been shipped to KSC; 1,218 are identified.