English: On 8 June 1959 a Regulus I missile, just like the one you see here, was loaded with 3,000 letters and launched from the submarine USS Barbero (SS-317). The missile traveled over 100 miles for approximately 22 minutes over the Atlantic Ocean. It made a successful landing at Mayport Naval Air Station in Mayport, Florida to deliver 3,000 letters that the U.S. Postmaster General Arthur E. Summerfield had written to key political figures such as President Eisenhower. Each envelope had a picture of the Regulus I and said "First Official Missile Mail.". See also en:SSM-N-8 Regulus