28. As Apollo 9 never flew to the moon, we will skip to Apollo 10, effectively a dress rehearsal for the actual landing. In fact, the astronauts came within ten miles of the lunar surface. Could they have actually stepped on the moon?
From Quiz I Love You to the Moon and Back
Answer:
Yes, but they would then not have been able to return to Earth
When the Apollo 10 mission was planned, NASA considered the possibility that the two astronauts aboard the lunar module making up the crew could be tempted to violate their orders and actually make the landing, securing themselves the title of first human beings on the moon. The way to keep them in line was as simple as it was cruel - the ascent stage was short-fueled and, had they landed, they would not have been able to reach orbit again. If they had tried to be first on the moon, they'd have paid for it with their lives. While commander Thomas Stafford never flew to the moon again, both other Apollo 10 crew members later set foot on the moon, as commanders of Apollo 16 (Young) and Apollo 17 (Cernan), respectively.