Astronaut Health Human travel to Mars and beyond is no longer science fiction. Through shuttle research we know how the body changes, what we and Performance need to do to fix some of the problems or—better yet—prevent them, the importance of monitoring health, and how to determine the Introduction human body’s performance through the various sequences of launch, Helen Lane spaceflight, and landing. Basically, we understand how astronauts Laurence Young keep their performance high so they can be explorers, scientists, How Humans Adapt to Spaceflight: and operators. Physiological Changes Vision, Orientation, and Balance William Paloski Astronauts change physically during spaceflight, from their brain, Sleep heart, blood vessels, eyes, and ears and on down to their cells. Laura Barger Many types of research studies validated these changes and Charles Czeisler demonstrated how best to prevent health problems and care for the Muscle and Exercise John Charles astronauts before, during, and after spaceflight. Steven Platts Daniel Feeback During a shuttle flight, astronauts experienced a multitude of Kenneth Baldwin gravitational forces. Earth is 1 gravitational force (1 g); however, Judith Hayes during launch, the forces varied from 1 to 3 g. During a shuttl e’s Cardiovascular John Charles return to Earth, the forces varied from nearly zero to 1. 6g, over Steven Platts approximately 33 minutes, during the maneuvers to return. In all, Nutritional Needs in Space the shuttle provided rather low gravitational forces compared with Helen Lane other rocket-type launches and landings. Clarence Alfrey Scott Smith The most pervasive physiological human factor in all spaceflight, Immunology and Infectious Diseases Brian Crucian however, is microgravity. An astronaut perceives weightlessness and Satish Mehta floats along with any object, large or small. The microgravity Mark Ott physiological changes affect the human body, the functions within the Duane Pierson Clarence Sams space vehicle, and all the fluids, foods, water, and contaminants. Habitability and Environmental Health We learned how to perform well in this environment through the Habitability Janis Connolly Space Shuttle Program. This information led to improvements in David Fitts astronaut s’ health care not only during shuttle flights but also for the Dane Russo International Space Station (ISS) and future missions beyond Vickie Kloeris Environmental Health low-Earth orbit. Shuttle research and medical care led directly to John James improved countermeasures used by ISS crew members. No shuttle Thomas Limero mission was terminated due to health concerns. Mark Ott Chau Pham Duane Pierson Astronaut Health Care Philip Stepaniak 370 Major Scientific Discoveries How Humans Adapt Laurence Young, ScD to Spaceflight: Principal investigator or coinvestigator on seven space Physiological Changes missions, starting with STS-9 (1983). Alternate payload specialist on Vision, Orientation, and Balance STS-58 (1993). Change in Microgravity Founding director of the National Space Biomedical Research Institute. Gravity is critical to our existence. Apollo Program professor of As Earthlings, we have come to rely on astronautics and professor of health sciences and technology at Earth’s gravity as a fundamental Massachusetts Institute of Technology. reference that tells us which way is down. Our very survival depends on “The Space Shuttle Program provided a golden era for life sciences research. our ability to discern down so that we The difference between science capabilities on spacecraft before and after the can walk, run, jump, and otherwise Space Shuttle is enormous: it was like doing science in a telephone booth in the move about without falling. To accomplish this, we evolved specialized Gemini-Apollo era while shuttle could accommodate a school-bus-size laboratory. motion-sensing receptors in our inner This significantly added to the kind of research that could be done in space. ears—receptors that act like biological We had enormous success in life sciences, especially with the Spacelabs, for guidance systems. Among other things, quality of instrumentation, their size, and opportunity for repeated measurements these receptors sense how well our on the astronauts on different days of flight and over many different flights heads are aligned with gravity. Our including Space Life Sciences flights 1 and 2 and ending with Neurolab. brains combine these data with visual information from our eyes, pressure “Our research led to a much more complete understanding of the neurovestibular information from the soles of our feet changes in spaceflight and allowed us to know what issues require (and the seats of our pants), and countermeasures or treatment, such as space motion sickness, as well as what position and loading information from research needed to continue in Earth laboratories, such as the role of short radius our joints and muscles to continuously centrifuges for intermittent artificial gravity to support a Mars exploration mission.” track the orientation of our bodies relative to gravity. Knowing this, our brains can work out the best strategies for adjusting our muscles to move our One thing we learned during the shuttle physical activities, such as running, limbs and bodies about without losing era, though, is that astronauts’ nervous jumping, climbing ladders, driving our balance. And, we don’t even have systems adapt very quickly. By the automobiles, and flying planes. to think about it. third day of flight, most crew members The Space Shuttle––particularly At the end of launch phase, astronauts overcame the loss of gravitational when carrying one of its Spacelab find themselves suddenly thrust into stimulation. Beyond that, most or Spacehab modules and during the microgravity environment. Gravity, exhibited few functionally significant the human-health-focused, the fundamental up/down reference side effects. The downside to this rapid extended-duration Orbiter medical these astronauts relied on throughout adaptation was that, by the time a missions (1 989 through 1995)–– their lives for orientation and shuttle mission ended and the provided unique capabilities to study movement, suddenly disappears. astronauts returned to Earth, they had neurological adaptation to space. As you might expect, there are a forgotten how to use gravity for By taking advantage of the shuttle’s number of immediate consequences. orientation and movement. So, for the ability to remove and then reintroduce Disorientation, perceptual illusions, first few days after return, they suffered the fundamental spatial orientation motion sickness, poor eye-head/eye- again from a multitude of side effects reference provided by gravity, many hand coordination, and whole-body similar to those experienced at the researchers sought to understand movements are issues each astronaut beginning of spaceflight. During the the brain mechanisms responsible for has to deal with to some degree. Earth-readaptation period, these tracking and responding to this postflight affects limited some types of Major Scientific Discoveries 371 stimulus. Other researchers used these disorientation, and motion sickness such as car sickness, sea sickness, air stimuli to investigate fundamental and symptoms. Over time, however, the sickness, or sickness caused by carnival functional aspects of neural adaptation, brain would learn not to anticipate this rides. To complicate our understanding while others focused on the operational inner-ear information during head tilts of the mechanisms of space motion impacts of these adaptive responses and the symptoms would abate. sickness further, landing-day motion with an eye toward reducing risks to sickness was not even predicted by the space travelers and enabling future How Often Do Astronauts Have incidence or severity of early in-flight missions of longer duration. Space Motion Sickness? motion sickness. The only predictable aspect was that repeat flyers usually had Many astronauts report motion sickness Space Motion Sickness fewer and less severe symptoms with symptoms just after arrival in space and each subsequent flight. What Is Space Motion Sickness? again just after return to Earth. For example, of the 400 crew members who Many people experience motion How Do Astronauts Deal With flew on the shuttle between 1981 and sickness while riding in vehicles ranging Space Motion Sickness? 1998, 309 reported at least some motion from automobiles to airplanes to boats sickness symptoms, such as stomach Crew members can limit head to carnival rides. Its symptoms include awareness, headache, drowsiness, movements during the first few days of headache, pallor, fatigue, nausea, and pallor, sweating, dizziness, and, of microgravity and during return to Earth vomiting. What causes motion sickness course, nausea and vomiting. For most to minimize the symptoms of space is unknown, but it is clearly related to astronauts, this was a short-term motion sickness. For some astronauts, the nervous system and almost always problem triggered by the loss of gravity drugs are used to reduce the symptoms. involves the specialized motion-sensing stimuli during ascent to orbit and, again, Promethazine-containing drugs receptors of the inner ear, known as the by the return of gravity stimuli during emerged as the best choice during the vestibular system. descent back to Earth. It usually lasted early 1990s, and were frequently used The most popular explanation for only through the few days coinciding throughout the remaining shuttle