Agence France-Presse: BP dispatched Wednesday a giant “dome” on a high-stakes mission to contain the Gulf of Mexico oil spill, knowing failure would leave crude spewing into the sea for months and magnify the risk of an environmental catastrophe. A crane lowered the 100-ton dome onto the “Joe Griffin” before the barge embarked on the 12-hour journey from Port Fourchon on the Louisiana coast to the epicenter of the disaster some 50 miles (80 kilometers) offshore. A white silo with a dome-shaped top …