13 crew, feeling they needed additional training time so the crew was switched to Apollo 14, which saw Shepard and Mitchell walk on the Moon. For projects Mercury and Gemini, a prime and a backup crew had been designated, but for Apollo, a third group of astronauts, known as the support crew, was also designated. Slayton created the support crews early in the Apollo program on the advice of McDivitt, who would lead Apollo 9. McDivitt believed that, with preparation going on in facilities across the U.S., meetings that needed a member of the flight crew would be missed. Support crew members were to assist as directed by the mission commander. Usually low in seniority, they assembled the mission's rules, flight plan, and checklists, and kept them updated. For Apollo 10, they were: Joe Engle, James Irwin and Charles Duke. Flight directors were Gerry Griffin, Glynn Lunney, Milt Windler and Pete Frank. Flight directors during Apollo had a one-sentence job description: "The flight director may take any actions necessary for crew safety and mission success." CAPCOMs were Duke, Engle, Jack Lousma and Bruce McCandless II. Call signs and mission insignia The command module was given the call sign "Charlie Brown" and the lunar module the call sign "Snoopy". These were taken from the characters in the comic strip, Peanuts, Charlie Brown and Snoopy. These names were chosen by the astronauts with the approval of Charles Schulz, the strip's creator, who was uncertain it was a good idea, since Charlie Brown was always a failure. The choice of names was deemed undignified by some at NASA, as was the choice for Apollo 9's CM and LM ("Gumdrop" and "Spider"). Public relations chief Julian Scheer urged a change for the lunar landing mission. But for Apollo 10, according to Cernan, "The P.R.-types lost this one big-time, for everybody on the planet knew the klutzy kid and his adventuresome beagle, and the names were embraced in a public relations bonanza." Apollo 11's call signs were "Columbia" for the command module and "Eagle" for the lunar module. Snoopy, Charlie Brown's dog, was chosen for the call sign of the lunar module since it was to "snoop" around the landing site, with Charlie Brown given to the command module as Snoopy's companion. Snoopy had been associated for some time with the space program, with workers who performed in an outstanding manner awarded silver "Snoopy pins",