and Snoopy posters were seen at NASA facilities, with the cartoon dog having traded in his World War I aviator's headgear for a space helmet. Stafford stated that, given the pins, "the choice of Snoopy [as call sign] was a way of acknowledging the contributions of the hundreds of thousands of people who got us there". The use of the dog was also appropriate since in the comic strip, Snoopy had journeyed to the Moon the year before, thus defeating, according to Schulz, "the Americans, the Russians, and that stupid cat next door". The shield-shaped mission insignia shows a large, three-dimensional Roman numeral X sitting on the Moon's surface, in Stafford's words, "to show that we had left our mark". Although it did not land on the Moon, the prominence of the number represents the significant contributions the mission made to the Apollo program. A CSM circles the Moon as an LM ascent stage flies up from its low pass over the lunar surface with its engine firing. The Earth is visible in the background. On the mission patch, a wide, light blue border carries the word APOLLO at the top and the crew names around the bottom. The patch is trimmed in gold. The insignia was designed by Allen Stevens of Rockwell International. Training and preparation Apollo 10, the "F" mission or dress rehearsal for the lunar landing, had as its primary objectives to demonstrate crew, space vehicle and mission support facilities performance during a crewed mission to lunar orbit, and to evaluate the performance of the lunar module there. In addition, it was to attempt photography of Apollo Landing Site 2 (ALS-2) in the Sea of Tranquillity, the contemplated landing site for Apollo 11. According to Stafford, "Our flight was to take the first lunar module to the moon. We would take the lunar module, go down to within about ten miles above the moon, nine miles above the mountains, radar map, photo map, pick out the first landing site, do the first rendezvous around the moon, pick out some future landing sites, and come home. Apollo 10 was to adhere as closely as possible to the plans for Apollo 11, including its trajectory to and from lunar orbit, the time line of events during the mission, and even the angle of the Sun at ALS-2. However, no landing was to be attempted. ALS-1, given that number because