Nine human life sciences experiments were successfully completed on the G-7 flight, more than on any previous mission. Five of the experiments had been conducted on earlier flights, but all were important for collecting data on physiologic changes taking place over the first long duration flight. The Cardiovascular Conditioning Experiment had been conducted on the G-5 flight for four days; now it was extended to be performed over the entire course of the mission. This experiment investigated the effectiveness of the pneumatic cuff technique in preventing orthostatic intolerance, a condition of low blood pressure after space flight caused by the adaptive body fluid loss in microgravity. The inflatable leg cuffs worn by the pilot pressurized automatically every two minutes out of six in order to stimulate blood movement within the body.
The Inflight Exerciser experiment not only allowed the astronauts an opportunity to exercise in the constrained space of the Gemini capsule, but also measured the degree of cardiovascular adaptation or ''deconditioning'' of the human body during prolonged space flight by recording the performance and rate of recovery from exercise periods. Another related experiment used an inflight phonocardiogram to record astronauts' heart sounds in order to provide some insight into the functional cardiac status of astronauts during space flights.
The experiment titled Bioassays of Body Fluids was designed to obtain objective data concerning the effect of space flight on several of the systems of the human body. This investigation, as part of an overall evaluation, addressed areas where effects could be observed by alterations in the body chemistry. Plasma and urine samples were analyzed before flight to obtain baseline data, and after flight more samples were used to compare any observed differences. During flight, only the urine was sampled using the urine-sampling and volume-measuring system. Results of the analyses were used as an indication of the physiological status of the crewmembers during and following space flight.
The Bone Demineralization study investigated the occurrence and degree of any bone demineralization (loss of essential minerals like calcium from the bones) resulting from space flight to determine if corrective measures would be necessary during long duration space flight. A related experiment, the Calcium and Nitrogen Balance Experiment was to obtain data on the effects of 14 days of space flight on two of the largest metabolically active tissue masses in the human body, namely bone and muscle and, therefore, the functional integrity of the skeletal and muscular systems.
One of the innovations of this flight was the scheduling of two work and sleep shifts to coincide with the routines the astronauts were used to. The Inflight Sleep Analysis investigation, unique to Gemini 7, recorded the brain states of the pilot who wore scalp electrodes over several days of the mission, providing a little over 54 hours of interpretable data. The electrodes provided electroencephalogram (EEG) recordings (recordings of the brain waves corresponding to different alertness levels of the brain) to accomplish three objectives: 1) To assess objectively the pilot's depth of sleep during orbital flight in order to optimize work-rest cycles and to correlate sleep depth with pilot performance; 2) To assess the effects of the weightless state on the brain wave patterns of the normal EEG; 3) To assess objectively states of diminished alertness and to relate these to the general inflight pilot performance. The results of this test were used to train subsequent astronauts to adjust to sleeping in such a novel environment.
The Human Otolith experiment studied the ability of the astronauts to estimate horizontality with reference to the spacecraft in the absence of vision and primary gravitational cues, as well as the possible effect of prolonged weightlessness on otolith function (an organ of the inner ear responsible for maintaining balance and orientation). The Visual Acuity investigation studied the affects of space flight on vision.
In addition to the medical experiments, continuous, real-time physiological information on all Gemini crewmembers was monitored via telemetered data and voice transmissions. Data was provided by a two-lead electrocardiogram, an impedance pneumograph measuring respiration, an oral thermistor measuring body temperature, and a blood pressure measuring system. All of this hardware, including signal conditioners, was mounted on a biosensor harness that fit under the astronauts' flight suits. Additionally, some inflight film footage was utilized for postflight assessment of crew health.
The G-7 astronauts also performed navigational tests, taking fixes on stars with a hand-held sextant. Their ability to determine their position without the aid of computers was a space first, opening up the possibility of other means of spatial navigation. All the scientific experiments on G-7 were important for the progression of the space program to longer duration flights that would enable a voyage and landing on the moon.