The Mercury missions were valuable for dispelling, as well as verifying, numerous medical concerns. Significant aerospace medical information derived from the Mercury program included the determination that all measured physiological functions remained within anticipated ranges throughout all flights. However, postflight tests suggested some temporary impairment of cardiovascular function; results from the longest duration Mercury flight (Gordon Cooper's 1.5-day Mercury 9 flight) showed postflight orthostatic intolerance. Weight loss was also noted, primarily caused by mild dehydration. No significant degradation of pilot function was attributable to space flight and there was no evidence of abnormal sensory, psychiatric, or psychological responses to space flight. The radiation doses received by the astronauts were considered medically insignificant. Finally, it was determined that sleeping and consuming food and beverages during space flight were possible.
Project Mercury had taken the critical first step into space and had given reassuring answers to a number of fundamental questions: Could humans survive in space? Could a spacecraft be designed to launch them into orbit? Could they return safely to Earth?