Apollo 9 in early 1969. However, LM problems again prevented it from being ready for the D mission by December, so NASA officials created another mission for Apollo 8 using the Saturn V to launch only the CSM on the first crewed flight to orbit the Moon, and the E mission was cancelled as unnecessary. Slayton asked McDivitt and Borman which mission they preferred to fly; McDivitt wanted to fly the LM, while Borman volunteered for the pioneering lunar flight. Therefore, Slayton swapped the crews, and McDivitt's crew flew Apollo 9. The crew swap also affected who would be the first crew
Apollo 15 operations on the Lunar surface inside it to sample, but found most of the rocks to be too large. Mission Control called up and said they would like the crew to dig a trench to study the soil mechanics and take a core sample. Irwin dug the trench, which Scott photographed. Then the core sample was taken from inside the crater. Returning to the Rover, they drove 650 ft (200 m) to a large boulder. Even walking short distances on the slope was time consuming so it was easier to just have the crew use the Rover to get there. The boulder was 10 ft