As the Customs Declaration notes, any condition onboard that might lead to the spread of disease has yet to be determined. The returning astronauts are isolated first in a trailer (far right) and then in a suite of rooms at the Manned Spacecraft Center in Houston for 21 days following possible exposure. While still in quarantine aboard the U.S.S. Hornet, the astronauts retrieve their logs and gear from Columbia through a connecting tunnel. Mike Collins takes the opportunity to write a thank you on the wall above the sextant mount (top right) to the trusty space capsule that flew them to the Moon and safely home again. By the third lunar landing, it is conclusively determined that the Moon is sterile, and further crews do not have to endure quarantine.