the cancellations of Apollos 18 and 19 were announced in September 1970, it made more sense to use astronauts who had already flown lunar missions as backups, rather than training others on what would likely be a dead-end assignment. Subsequently, Roosa and Mitchell were assigned to the backup crew, while Pogue and Carr were reassigned to the Skylab program where they flew on Skylab 4. 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 Apollo crew commander James 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 16, they were: Anthony W. England, Karl G. Henize, Henry W. Hartsfield Jr., Robert F. Overmyer and Donald H. Peterson. Flight directors were Pete Frank and Philip Shaffer, first shift, Gene Kranz and Donald R. Puddy, second shift, and Gerry Griffin, Neil B. Hutchinson and Charles R. Lewis, third shift. 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 Haise, Roosa, Mitchell, James B. Irwin, England, Peterson, Hartsfield, and C. Gordon Fullerton. Mission insignia and call signs The insignia of Apollo 16 is dominated by a rendering of an American eagle and a red, white and blue shield, representing the people of the United States, over a gray background representing the lunar surface. Overlaying the shield is a gold NASA vector, orbiting the Moon. On its gold-outlined blue border, there are 16 stars, representing the mission number, and the names of the crew members: Young, Mattingly, Duke. The insignia was designed from ideas originally submitted by the crew of the mission, by Barbara Matelski of the graphics shop at the Manned Spacecraft Center in Houston. Young and Duke chose "Orion" for the lunar module's call sign, while Mattingly chose "Casper" for the command and service module. According to Duke, he and Young chose "Orion" for the LM because they wanted