On June 8, 1959, the US Navy fired a Regulus I missile from the USS Barbero (SSG-317) and directed it to land at the Naval Auxiliary Air Station at Mayport, Florida, near Jacksonville. While the sub was docked at Norfolk, Virginia, Postmaster General Arthur Summerfield helped place two blue and red metal containers, holding 3,000 letters, inside the sub’s missile prior to the flight.

The missile was fired from the submarine shortly before noon and arrived at Mayport twenty-two minutes later. The 3,000 letters inside the missile were identical letters from the Postmaster General that were addressed to President Eisenhower, Vice President Nixon, cabinet members and top federal officials, all members of congress, Supreme Court justices, U.S. governors, postmasters generals from around the world and the officers and crew of the Barbero. Summerfield’s letter was an enthusiastic announcement of the experiment, which had not been publicly announced beforehand.