Pre- and postflight testing and inflight monitoring revealed that the Apollo 16 crew did not experience any of the physiological problems that had troubled the Apollo 15 crew. This was attributed to several factors, including an improved work and rest schedule.
Before and after Apollo 16, researchers continued to study the crewmembers' cardiovascular response to exercise pre- and post flight, using a bicycle ergometer and other exercise equipment, and studied the response of the cardiovascular system to weightlessness using lower body negative pressure and passive stand tests.
The Flight Crew Health Stabilization Program, deemed essential after the exposure of an Apollo 13 crewmember to German measles, was continued on Apollo 16. The crewmembers were monitored inflight and their health was assessed pre- and postflight through ground-based testing. 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.
The Apollo Light Flash Investigation, studied reports by crewmembers since the beginning of the space program of seeing short-lived bright spots or light flashes while in a dark environment during space flight. It was suspected, and later deduced, that the light flash phenomenon was produced by cosmic radiation penetrating and stimulating the optic nerve.
In addition to the pre- and postflight medical testing, which occurred on all of the Apollo missions, the crew of Apollo 16 also conducted several inflight life sciences experiments. Since the travel to the moon placed the crew outside the protection of the Earth's atmosphere, an experiment was designed to measure the biological effects of high-energy galactic cosmic radiation (HZE particles) on living systems. The data gathered from this investigation was of concern since very high local concentrations of absorbed energy produced by an HZE particle can result in cellular damage.
Other investigations were designed to study microorganisms. Past viability studies indicated that the survival of some microbes was enhanced while others were adversely affected. These experiments therefore sought to determine the survivability of microorganism species and evaluate the possibility that the space environment may influence microbial genetic alterations.