After more than 21 hours on the lunar surface, they returned to Collins on board ''Columbia'', bringing 20.87 kilograms of lunar samples with them. The two Moon-walkers had left behind scientific instruments, an American flag and other mementos, including a plaque bearing the inscription: ''Here Men From Planet Earth First Set Foot Upon the Moon. July 1969 A.D. We Came in Peace For All Mankind.''
The crew was quarantined upon recovery at the splashdown point and kept in isolation for 21 days to prevent contamination of Earth with lunar organisms or materials. Medical and biological tests performed during this time determined that no harmful organisms were present in any of the material returned from the moon and the quarantine was terminated. The crew suffered no ill effects from the mission.
The biomedical objectives of the Apollo 11 mission were achieved mainly by pre- and postflight testing and inflight monitoring of the crew. No inflight life sciences experiments were conducted during this mission. Before and after flight, researchers studied several physiological systems, including evaluation of the crewmembers' cardiovascular response to exercise, lower body negative pressure and passive stand tests. Using a bicycle ergometer and other exercise equipment, researchers studied the response of the cardiovascular system after exposure to weightlessness.
The clinical aspects of crew health and safety were investigated by performing medical examinations and conducting inflight medical monitoring as evaluation methods. Investigators also studied musculoskeletal changes, clinical disorders in space due to imbalance between bone formation and resorption, inflight weight loss and inflight caloric intake. Another important aspect of crew health and safety is the protection against radiation, so one experiment focused on analyzing natural and man-made radiation encountered in space, with the goal of finding ways of limiting the astronauts' exposure to radiation. Vestibular system experiments not only aided researchers in gaining a better understanding of the mechanisms that provide balance and coordination, but also contributed to alleviating the symptoms of space adaptation syndrome.
The endocrinology experiments sought to understand biochemical changes in crewmembers by studying the balance of fluids and electrolytes, regulation of calcium metabolism and the adaptation of metabolic processes to the space environment. Investigators also sought to determine the life support requirements during extravehicular activity (EVA) by studying metabolism and heat dissipation.
Scientists also utilized specific laboratory data to assess the health status of the astronauts prior to their commitment to space flight. This allowed them to detect and identify any alterations in the normal functions of the immunological and hematological systems which could be attributed to space flight exposure and to evaluate the significance of these changes relative to a person?s continuing participation in space flight missions. Biochemistry data, when integrated with the data obtained from a complete history and physical examination of each crewmember, permitted an objective assessment of crew physical status.
The detection of potentially pathogenic microorganisms was attempted, so that associated medical problems could be identified early and preventive measures could be established. These objectives included the identification of medically important microorganisms recovered from ill crew members to aid in diagnosis and treatment.