Many crewmembers are trained to draw blood required for life science experiments or general health monitoring, and some can perform eye and dental exams. An ultrasound device and a portable echocardiogram (Holter monitor) are available for health monitoring and diagnosis. NASA’s flight surgeons on the ground are always available for consultation.

  Before flight, all astronauts receive a thorough medical checkup to ensure they are healthy and have no emerging medical issues that would compromise their health or the mission. Great care is taken to keep everyone onboard well. While health matters are confidential, no flights in the US space program have been terminated due to crew health issues.

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  —

  On shuttle missions to the International Space Station, one person with good organizational skills, often a woman, was the designated loadmaster. (On the ISS, everyone shares that role.) The job is to manage the transfer of supplies and equipment coming up and equipment, experiment samples, and trash going down. The space shuttle could carry tons of stuff each way, but today’s cargo capacity on Progress, SpaceX, and expendable small vehicles is limited. It took days to unload and reload the shuttle; now it can be done more quickly, but it still takes careful planning, strategy, and choreography to pack, load, unload and stow hundreds of items of various sizes and mass. The goal is to fit the maximum amount of mass without altering a vehicle’s center of gravity. Sequencing is part of the process: what must be unloaded first has to be loaded last, and things must be loaded in a way that the loadmaster has access to all the storage space. Food, clothing, equipment, tools, experiment hardware, and other materials are prepacked into standard-sized soft containers and bags for easy handling and stacking. Trash, broken devices, and dirty clothes are now loaded into expendable vehicles that burn up in the atmosphere. Experiment hardware and samples are returned to Earth via crewed spacecraft, such as Soyuz and SpaceX.

  Once materials have been unloaded from the delivery craft, the next part of the job is to unpack and stow everything in its proper place on the ISS so it can be located when needed. Items are barcoded and inventoried, and their locations tracked. Nothing is more frustrating than not finding something where it is supposed to be. No one wants to lose track of essential items. The logistics of keeping an orbital space station well supplied and removing what is no longer needed is an essential function that most people don’t consider, and the loadmaster’s job is a crucial although less well-known role.

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  —

  US astronauts began to fly on Russia’s Soyuz spacecraft during the Shuttle-Mir program, and Soyuz has been a reliable mode of transportation to and from the International Space Station ever since. Even before the space shuttle program ended, some US crewmembers arrived at the ISS and departed on Soyuz, just as some Russian ISS crewmembers came and went on the shuttle, as negotiated by the space agency partners. The same was and still is true for European, Canadian, and Japanese astronauts, who can travel on any available spacecraft.

  The Soyuz spacecraft is a three-person capsule, with seats in a tight row and almost no wiggle room for the pressure-suited crew. The commander is always a cosmonaut. The other two are either a copilot, flight engineer, or passenger. US astronauts have served as copilot assisting the commander and ready to take control if necessary, and as flight engineer with limited duties in the highly automated craft. The flight time from launch to docking at the ISS ranges from three or four hours to three days, depending on the orbital mechanics of rendezvous.

  Likewise, crew positions are similar on SpaceX Crew Dragon and Boeing Starliner commercial spacecraft. For the test flight of each, two crewmembers flew as commander and pilot. For operational service the SpaceX crew includes a commander, pilot, and one or more mission specialists. Megan McArthur served as pilot of a 2021 SpaceX mission, Nicole Mann commanded a 2022 mission, and Jasmine Moghbeli commanded a mission in 2023. Two women—Anne McClain and Nichole Ayers—were assigned as commander and pilot of the SpaceX Crew Dragon-10 mission in early 2025. Shannon Walker, Kayla Barron, Jessica Watkins, and Jeanette Epps were mission specialists on other SpaceX flights, monitoring timelines, telemetry, and consumables. Peggy Whitson, a retired NASA astronaut, flew as an Axiom Space Company astronaut and commander on a SpaceX Crew Dragon spacecraft and is set to command another Axiom-SpaceX flight in 2025. In 2024, the Boeing Starliner made a crewed test flight with Suni Williams as pilot but has not yet flown an operational mission.

  Jobs Wherever You Are

  Being an astronaut is a 24/7 commitment. Some days have a normal schedule, and then there are long periods of training and travel when the clock doesn’t matter. The work to be done must be done then. One job can be performed wherever you are: being a public figure and role model. The Astronaut Office wisely regulates public appearances to avoid interfering with primary work responsibilities and schedules but still expects all astronauts to do a share of public outreach, typically at least once a month but more often right after a flight, when crews make the rounds of international partners’ home countries and space agencies.

  Astronauts are considered to be the “face” of NASA and ambassadors for space exploration and STEM education. They represent NASA wherever they are, whether on the ground or in space, in the United States or abroad, and in public or private settings. Although they are widely admired, like other celebrities they can be subject to public criticism if they misstep. NASA has always been sensitive to their public image and has prepared them for media attention, which they learn to handle adroitly.

  The NASA Public Affairs Office receives and responds to thousands of requests for astronaut appearances. Astronauts are typically scheduled for at least one public appearance a month, which can be at the White House or before Congress, at a convention or on a television program, at a school or a science camp, at civic club meetings or ceremonies, on a radio program or a documentary film shoot. Most public appearances involve travel and time away from work and home. Astronauts may be called upon to explain the rationale for particular NASA programs, advocate for space exploration, describe their upcoming or just-completed mission, inspire students to study hard and dream big dreams, or make goodwill visits around the world.

  Since the explosion of social media, most astronauts have websites and write blogs and posts that reach people electronically with an informal, in-person intimacy. Through social media platforms, astronauts actively broadcast their activities and thoughts about their work. While in space, they do frequent media interviews and audio and video broadcasts, and through downlinked video and ham radio transmissions they engage in live conversations with students. Astronauts mark special occasions, tell stories, explain what they are doing, answer questions, demonstrate weightlessness, and connect with people—all of which spark a positive impression of the space program.

  Not everyone is initially comfortable with so much public exposure, but gradually they learn to handle and usually enjoy it. Of the 1978 class of astronauts, Rhea Seddon remarked that there was wide variation in comfort level with the press. “Some people didn’t want to talk to the press at all, and other people were like, ‘Here’s my life’ or ‘Hey, that’s part of the job.’ ” [49] Kathy Sullivan and Judy Resnik enjoyed doing radio and TV commentary with network news anchors for the early shuttle missions, talking about their roles without using technical jargon in a way that helped the public understand what was happening. Both were on duty for STS-1, with Sullivan doing commentary for the ABC network and Resnik joining host Tom Brokaw on NBC Today.[50]

  Media exposure and public appearances are key to astronauts being seen as role models, and the women astronauts have grown to be comfortable with that image. Said Mary Cleave of public relations duties, “I like the role model part of it.”[51] She was concerned about math anxiety and girls’ losing interest in math and science during their early teen years. Cleave and other women have been keen about their potential to prompt girls and young women to consider doing something they wouldn’t have thought of before and sharing the message, “If I can do it, so can you.” Many carry that enthusiasm for outreach into retirement, when they can devote far more time to public appearances and extend their reach as role models. Nicole Stott, for example, travels widely, almost full-time, as a retired astronaut, using art as an entree to think about exploring space and taking care of spaceship Earth.

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  The women interviewed for this book who have moved on from NASA are clear that being an astronaut is a highly satisfying career. The work is varied, intense, challenging, and fuels their drive to excel, often taking them outside their knowledge comfort zones. They consider it a hard-earned privilege and are grateful for the many opportunities that come with the job. Most tellingly, they would do it all over again if they could, and they now focus on encouraging younger people, especially girls and young women, to aim high, too.

  CHAPTER 6

  Balancing Acts: Risks and Rewards of Being an Astronaut

  America’s women astronauts often say how fortunate they feel to have been chosen for this career. To be among the seven hundred or so people to date who have left the planet to live and work in space—about one hundred of them women—is a rare privilege. Although the number of people venturing into space is increasing with other nations’ space programs and the growth of commercial spaceflight, the sixty-one US females are the ones who really proved that women belong in space. They went from standing out as women to fitting in as full-fledged astronauts, not a distinctive group different from the men. They train, work, and fly together as equals. They are astronauts, period. Yet astronauts who happen to be women occasionally encounter circumstances where they are different or are treated differently for physical or medical reasons, and at times some people think that they are treated differently, perhaps unfairly. Some individuals suspect that managers do not fully recognize their potential, and they must advocate for themselves. The tension between fitting in and standing out is a balancing act. So, too, is making trade-offs between the risks and rewards of being astronauts.

  All astronauts, men and women, accept the inherent risk of catastrophic death in training or spaceflight. Seventeen spaceflight crewmembers have lost their lives in US spacecraft—Apollo 1, Challenger, and Columbia—and at least five others died in T-38 or commercial aircraft accidents while on duty. This is not a trivial risk. In addition, there have been near-misses in flight when technical problems in the spacecraft or spacesuit could have become catastrophic—an electrical short, a leak in air pressure or fluid flow, a tiny crack or metal shaving somewhere. There are also risks related to parachute and survival training activities, simulated high altitude and space environment in hypobaric and vacuum chambers, and underwater neutral buoyancy training. Risks are managed and mitigated to make the work environment as safe as possible, but risk of accidental injury or death is never zero.

  Astronauts also face risks that are less obvious and immediate but may gradually affect their physical and behavioral health. Both spaceflight and the return to Earth are stressful as astronauts adapt to microgravity and readapt to normal gravity environments. So far, only a few physical stresses and changes seem to have potential for long-lasting, detrimental effects. Long spaceflight may provoke emotional and behavioral stress through isolation from family and friends, confinement, a taxing work schedule, poor sleep, little privacy, even the quality of food. Countermeasures, such as regular exercise, varied menus, and frequent email and video contact with family and friends help to reduce these risks. Frequent travel, long absences, erratic work hours, time in preflight quarantine—simply not being there—also pose risks to astronauts’ relationships and family life.

  Offsetting risk considerations are many rewards of being an astronaut: opportunities to see the beautiful Earth from above, magnificent sunrises and sunsets, the deepest black of space punctuated by an infinity of bright stars; the satisfaction of executing all the tasks of a challenging mission, often doing something never done before; the sense of contributing to something bigger than oneself; participating in the history of exploration, expanding knowledge, doing research that will have benefits on Earth; working with brilliant, capable, and dedicated colleagues in the spacefaring enterprise in the United States and elsewhere in the world; and being an inspiration to others of all ages. There is also the satisfaction of pushing oneself past previous boundaries and achieving one’s full potential. Women astronauts interviewed for this book cited all of these reasons for taking the risks.[1]

  It is unlikely that any astronaut, after working so hard and aspiring for so long, would sacrifice such rewards to avoid the inherent risks of spaceflight. To date, four men have resigned for various reasons while in astronaut training and another three left after qualifying but seeing no upcoming flight opportunities.[2] No woman has walked away from this career before flying in space. When astronauts leave NASA, it is typically because they have new opportunities to pursue, know that they will not fly again, want to prioritize their family, or are ready to retire.

  General Health Risks of Spaceflight: Bodily Responses to Microgravity and Radiation

  Some risks of being an astronaut are obvious and immediate, such as the possibility of death in an aircraft or spaceflight accident or injury from a training accident. Others—radiation exposure, for example—are latent, and effects may not appear until years later.

  All astronauts have exceptionally good health and fitness. When astronaut applicant finalists report to the Johnson Space Center for interviews and evaluation, they undergo detailed physical and psychological exams to assess any health-related risks that might affect the individual or future mission success. The applicants’ detailed medical histories also are reviewed. Applicants may be disqualified for hundreds of reasons, among the most common being visual, cardiovascular, kidney, and thyroid abnormalities, and psychological/behavioral disorders.[3] Applicants who pass this rigorous assessment may then be selected for astronaut training. The admission standards are the basis for annual evaluations of continued health and fitness for spaceflight. These are itemized in a standards document issued by the NASA chief medical and health officer.[4]

  Most members of the astronaut corps participate in a longitudinal (lifetime) study of astronaut health, with annual evaluations and monitoring for issues that might be associated with their time in space. This study originated in 1992 but includes data from astronauts since 1959 and is continually updated.[5] In addition to annual medical evaluation and recertification for flight, astronauts also have pre- and postflight physical exams, medical consultations during flight, and medical debriefings after flight. Many participate in biomedical experiments during flight, providing a wealth of health data available for study.

  Decades of experience with humans traveling, living, and working in space, from the briefest flights to increasingly longer duration missions, have yielded evidence of the profound effects of microgravity (weightlessness) on the human body, from transient system-level disruptions (or adaptations) to changes at the cellular level. The longer the time in space, the longer the recovery time may be.

  A number of effects on the body in microgravity have been recognized for years: fluid shifts from the lower to upper body, decreased bone density through loss of calcium and other minerals, loss of muscle strength and mass, changes in red and white blood cell production and in immune response, disturbance of the neurosensory system related to balance and body position, and cardiovascular deconditioning, among others. Most of these changes are reversible naturally or with in-flight countermeasures and rehabilitation upon return to normal gravity on Earth. These physiological findings are recognized as normal adaptive responses to the microgravity environment that typically do not pose an immediate or long-term health risk. With longer-duration missions on the space station, additional changes have been noted. For example, some astronauts have experienced changes in visual acuity related to swelling of the optic nerve and other factors. There is currently no evidence of long-term cardiopulmonary, neurological, or muscular-skeletal health consequences if exercise and dietary protocols are followed on missions lasting up to six months.

  NASA experts periodically compile research findings in space biology and space life sciences to summarize current knowledge about health risks of spaceflight and what happens to the body in space. Astronauts on Skylab, the first US space station in the early 1970s, monitored and tested their bodies during missions lasting one to three months, and the results gave the first comprehensive account of bodily changes in space.[6] Space Physiology and Medicine, first published in 1982 and updated intermittently, has become a standard reference for system-by-system explanations of the body’s responses to microgravity, as well as discussions of radiation, toxic hazards, psychologic and psychiatric considerations, and various other topics.[7] The most recent edition appeared in 2016 with intended use as a textbook for clinicians and researchers. A comparable compilation and textbook, Principles of Clinical Medicine for Space Flight, edited and in part written by two NASA physician-astronauts and most recently issued in 2019, likewise explains the nature of the spaceflight environment, the bodily systems that respond to spaceflight, and the medical systems and procedures in place to deal with adverse physiological or psychological issues that may arise. While addressing the many hazards and changes to human beings in space, the book nevertheless indicates that “the expectation of healthy well-adapted crew-members…for standard 6-month missions has been firmly cemented.”[8] Adaptation to spaceflight and readaptation on Earth are predictable, normal, and do not impair astronauts’ ability to work productively.