The Moon has no meaningful atmosphere, and its surface is frozen in geologic time. The only notable changes happen when something strikes the Moon from space. Little has changed since the Apollo astronauts last left the Moon in 1972, and in any case, NASA and international space agencies have kept a close watch ever since.

The four astronauts — NASA commander Reid Wiseman, pilot Victor Glover, mission specialist Christina Koch and Canadian Space Agency mission specialist Jeremy Hansen — spent Monday’s seven-hour lunar flyby taking photos and making observations from the Orion spacecraft, which they named Integrity.

Still marveling over their moon mission, the Artemis II astronauts received a thunderous welcome home Saturday from hundreds who took part in NASA's lunar comeback that set a record for deep space travel.