Evolution of human capabilities and space medicine

Abstract

NASA is the world’s largest civilian space and aviation engineering research agency and a showcase of U.S. technological advances. It is the true birthplace of modern space medicine, which continues to be primarily influenced by engineering requirements. This chapter brings together the historical evolution of space medicine and human factors driven by technological development and political imperatives of human space exploration. Sustaining life, minimizing health risks and chances of injury have been and continues to be the primary goals for space medicine practice. In the sixteenth century, Ramazzini (Bernardino Ramazzini. De Morbis Artificum Diatriba. Apud Guilielmum van de Water Academii Typographaphum [Publisher]. Geneva, Switzerland. 1703), the father of occupational medicine, observed that sailors on long voyages of exploration did not fare as well as those on land when afflicted by chronic disorders. His observations still apply to modern space medicine practice, which is rooted in the principles of preventive medicine. Thus, space medicine practitioners’ primary focus is on life support, food and water production systems, selection of cabin atmosphere and gas composition, hygiene, space habitat toxicology, radiation protection, and preventing infections. The principles of astronaut medical selection are to ensure “healthy” and disease-free candidates, while medical retention standards (annual clinical evaluations) and care ensures career longevity. Depending on the type and length of the space mission, certain medical conditions are considered compatible with the ability to perform assigned mission duties and a medical waiver is issued. Space medicine draws heavily on 50 years of aviation medicine knowledge and continues to be the central focus of today’s practice of “personalized medicine.” Traditionally, the knowledge underpinning space medicine practice lagged behind operational needs and remained largely empirical, relying on data from terrestrial analogs and simulations. Historically, extremely complex short duration missions to the Moon, followed by long duration low Earth orbit missions, did not permit adequate time for a systematic acquisition of biomedical knowledge base. Clinical and psychological research remained resource constrained for access to space, funding, and sufficient sample size of astronauts (the astronaut community constituted the astronaut sample size. Astronaut exposure to the space environment precluded a meaningful selection of a control group as well) due to political pressures of the “space race” and mounting costs from unexpected technological challenges. The national debate on the future of the space program, following the Apollo 17 mission, coupled with federal deficits due to the Vietnam War, resulted in significant reduction to NASA budgets, and termination of follow-on missions to the Moon. Excess Apollo program hardware was used to deploy the first U.S. space station (Skylab) and to conduct the first U.S.-Soviet collaboration in space: docking an Apollo and a Soyuz spacecraft. The U.S. investment in Skylab produced an unprecedented amount of data on the human responses to orbital long-duration space flight. The three Skylab missions constituted the most comprehensive and fundamental seminal knowledge used by all space-faring nations in designing medical support and habitability systems for human space flight. Despite the many operational and logistic challenges, and occasional in-flight crew illness, no U.S. missions resulted in an unscheduled termination, or loss of life, due to medical conditions. This in itself is a testimonial to the soundness and efficiency of the clinical infrastructure and space medicine skills and expertise evolved since the early 1960s. Budgetary and political imperatives led to periodic NASA management and programmatic reorganizations often affecting medical staff and programs. The number of NASA space medicine physicians (flight surgeons), remains small, and between 1960 and 1990 reached its peak of 35 individuals (not including astronaut physicians). Today, this small federal workforce is supplemented by military detailees and supported by contractors in the many demanding duties outlined throughout this textbook. The experimental nature of spacecraft designed by the U.S. and other space-faring nations are briefly detailed in the context of space medicine. The interaction of the environment and spacecraft design, leading to potential health risk(s) are summarily reviewed. Extravehicular systems and robotics, intended to minimize unsafe exposures, while enhancing human performance, are briefly discussed. Space tourism and evolving commercial infrastructure and the potential for space medicine practice expansion are also presented. Finally the socioeconomic, cultural, and health care impacts of space exploration are briefly addressed.