KENNER, La. - Greg Meche, a mud engineer with M-I Swaco, discusses, May 28, 2010, what transpired aboard the Deepwater Horizon rig when it exploded, April 20. The Coast Guard and Minerals Management Service are co-chairing the joint investigation launched to determine the cause of the initial incident and fire aboard the mobile offshore drilling unit (MODU) Deepwater Horizon. U.S. Coast Guard photo by Petty Officer 2nd Class Thomas M. Blue.