Space medicine is the practice of medicine on astronauts in outer space whereas astronautical hygiene is the application of science and technology to the prevention or control of exposure to the hazards that may cause astronaut ill health. Both these sciences work together to ensure that astronauts work in a safe environment. The main objective is to discover how well and for how long people can survive the extreme conditions in space, and how fast they can adapt to the Earth's environment after returning from their voyage. Medical consequences such as possible blindness and bone loss have been associated with human spaceflight.
Hubertus Strughold (1898–1987), a former Nazi physician and physiologist, was brought to the United States after World War II as part of Operation Paperclip. He first coined the term "space medicine" in 1948 and was the first and only Professor of Space Medicine at the School of Aviation Medicine (SAM) at Randolph Air Force Base, Texas. In 1949 Strughold was made director of the Department of Space Medicine at the SAM (which is now the US Air Force School of Aerospace Medicine (USAFSAM) at Wright-Patterson Air Force Base, Ohio. He played an important role in developing the pressure suit worn by early American astronauts. He was a co-founder of the Space Medicine Branch of the Aerospace Medical Association in 1950. The aeromedical library at Brooks AFB was named after him in 1977, but later renamed because documents from the Nuremberg War Crimes Tribunal linked Strughold to medical experiments in which inmates of the Dachau concentration camp were tortured and killed.
Space medicine was a critical factor in the United States human space program, starting with Project Mercury.
Effects of space-travel
In October 2018, NASA-funded researchers found that lengthy journeys into outer space, including travel to the planet Mars, may substantially damage the gastrointestinal tissues of astronauts. The studies support earlier work that found such journeys could significantly damage the brains of astronauts, and age them prematurely.
In November 2019, researchers reported that astronauts experienced serious blood flow and clot problems while onboard the International Space Station, based on a six month study of 11 healthy astronauts. The results may influence long-term spaceflight, including a mission to the planet Mars, according to the researchers.
Heart rhythm disturbances have been seen among astronauts. Most of these have been related to cardiovascular disease, but it is not clear whether this was due to pre-existing conditions or effects of space flight. It is hoped that advanced screening for coronary disease has greatly mitigated this risk. Other heart rhythm problems, such as atrial fibrillation, can develop over time, necessitating periodic screening of crewmembers’ heart rhythms. Beyond these terrestrial heart risks, some concern exists that prolonged exposure to microgravity may lead to heart rhythm disturbances. Although this has not been observed to date, further surveillance is warranted.
Decompression illness in spaceflight
In space, astronauts use a space suit, essentially a self-contained individual spacecraft, to do spacewalks, or extra-vehicular activities (EVAs). Spacesuits are generally inflated with 100% oxygen at a total pressure that is less than a third of normal atmospheric pressure. Eliminating inert atmospheric components such as nitrogen allows the astronaut to breathe comfortably, but also have the mobility to use their hands, arms, and legs to complete required work, which would be more difficult in a higher pressure suit.
After the astronaut dons the spacesuit, air is replaced by 100% oxygen in a process called a "nitrogen purge". In order to reduce the risk of decompression sickness, the astronaut must spend several hours "pre-breathing" at an intermediate nitrogen partial pressure, in order to let their body tissues outgas nitrogen slowly enough that bubbles are not formed. When the astronaut returns to the "shirt sleeve" environment of the spacecraft after an EVA, pressure is restored to whatever the operating pressure of that spacecraft may be, generally normal atmospheric pressure. Decompression illness in spaceflight consists of decompression sickness (DCS) and other injuries due to uncompensated changes in pressure, or barotrauma.
Decompression sickness is the injury to the tissues of the body resulting from the presence of nitrogen bubbles in the tissues and blood. This occurs due to a rapid reduction in ambient pressure causing the dissolved nitrogen to come out of solution as gas bubbles within the body. In space the risk of DCS is significantly reduced by using a technique to wash out the nitrogen in the body's tissues. This is achieved by breathing 100% oxygen for a specified period of time before donning the spacesuit, and is continued after a nitrogen purge. DCS may result from inadequate or interrupted pre-oxygenation time, or other factors including the astronaut's level of hydration, physical conditioning, prior injuries and age. Other risks of DCS include inadequate nitrogen purge in the EMU, a strenuous or excessively prolonged EVA, or a loss of suit pressure. Non-EVA crewmembers may also be at risk for DCS if there is a loss of spacecraft cabin pressure.
Symptoms of DCS in space may include chest pain, shortness of breath, cough or pain with a deep breath, unusual fatigue, lightheadedness, dizziness, headache, unexplained musculoskeletal pain, tingling or numbness, extremities weakness, or visual abnormalities.
Barotrauma is the injury to the tissues of air filled spaces in the body as a result of differences in pressure between the body spaces and the ambient atmospheric pressure. Air filled spaces include the middle ears, paranasal sinuses, lungs and gastrointestinal tract. One would be predisposed by a pre-existing upper respiratory infection, nasal allergies, recurrent changing pressures, dehydration, or a poor equalizing technique.
Positive pressure in the air filled spaces results from reduced barometric pressure during the depressurization phase of an EVA. It can cause abdominal distension, ear or sinus pain, decreased hearing, and dental or jaw pain. Abdominal distension can be treated with extending the abdomen, gentle massage and encourage passing flatus. Ear and sinus pressure can be relieved with passive release of positive pressure. Pretreatment for susceptible individuals can include oral and nasal decongestants, or oral and nasal steroids.
Negative pressure in air fill spaces results from increased barometric pressure during repressurization after an EVA or following a planned restoration of a reduced cabin pressure. Common symptoms include ear or sinus pain, decreased hearing, and tooth or jaw pain.
Decreased immune system functioning
Astronauts in space have weakened immune systems, which means that in addition to increased vulnerability to new exposures, viruses already present in the body—which would normally be suppressed—become active. In space, T-cells do not reproduce properly, and the cells that do exist are less able to fight off infection. NASA research is measuring the change in the immune systems of its astronauts as well as performing experiments with T-cells in space.
On April 29, 2013, scientists in Rensselaer Polytechnic Institute, funded by NASA, reported that, during spaceflight on the International Space Station, microbes seem to adapt to the space environment in ways "not observed on Earth" and in ways that "can lead to increases in growth and virulence".
Increased infection risk
A 2006 Space Shuttle experiment found that Salmonella typhimurium, a bacterium that can cause food poisoning, became more virulent when cultivated in space. On April 29, 2013, scientists in Rensselaer Polytechnic Institute, funded by NASA, reported that, during spaceflight on the International Space Station, microbes seem to adapt to the space environment in ways "not observed on Earth" and in ways that "can lead to increases in growth and virulence". More recently, in 2017, bacteria were found to be more resistant to antibiotics and to thrive in the near-weightlessness of space. Microorganisms have been observed to survive the vacuum of outer space. Researchers in 2018 reported, after detecting the presence on the International Space Station (ISS) of five Enterobacter bugandensis bacterial strains, none pathogenic to humans, that microorganisms on ISS should be carefully monitored to continue assuring a medically healthy environment for astronauts.
Effects of fatigue
Human spaceflight often requires astronaut crews to endure long periods without rest. Studies have shown that lack of sleep can cause fatigue that leads to errors while performing critical tasks. Also, individuals who are fatigued often cannot determine the degree of their impairment. Astronauts and ground crews frequently suffer from the effects of sleep deprivation and circadian rhythm disruption. Fatigue due to sleep loss, sleep shifting and work overload could cause performance errors that put space flight participants at risk of compromising mission objectives as well as the health and safety of those on board.
Loss of balance
Leaving and returning to Earth's gravity causes “space sickness,” dizziness, and loss of balance in astronauts. By studying how changes can affect balance in the human body—involving the senses, the brain, the inner ear, and blood pressure—NASA hopes to develop treatments that can be used on Earth and in space to correct balance disorders. Until then, NASA's astronauts must rely on a medication called Midodrine (an “anti-dizzy” pill that temporarily increases blood pressure), and/or promethazine to help carry out the tasks they need to do to return home safely.
Loss of bone density
Spaceflight osteopenia is the bone loss associated with human spaceflight. After a 3–4 month trip into space, it takes about 2–3 years to regain lost bone density. New techniques are being developed to help astronauts recover faster. Research in the following areas holds the potential to aid the process of growing new bone:
Loss of muscle mass
In space, muscles in the legs, back, spine, and heart weaken and waste away because they no longer are needed to overcome gravity, just as people lose muscle when they age due to reduced physical activity. Astronauts rely on research in the following areas to build muscle and maintain body mass:
- Exercise may build muscle if at least two hours a day is spent doing resistance training routines.
- Hormone supplements (hGH) may be a way to tap into the body's natural growth signals.
- Medication may trigger the body into producing muscle growth proteins.
Loss of eyesight
After long space flight missions, astronauts may experience severe eyesight problems. Such eyesight problems may be a major concern for future deep space flight missions, including a human mission to Mars.
Loss of mental abilities and risk of Alzheimer's disease
On 2 November 2017, scientists reported that significant changes in the position and structure of the brain have been found in astronauts who have taken trips in space, based on MRI studies. Astronauts who took longer space trips were associated with greater brain changes.
"Under the effects of the earth's gravity, blood and other body fluids are pulled towards the lower body. When gravity is taken away or reduced during space exploration, the blood tends to collect in the upper body instead, resulting in facial edema and other unwelcome side effects. Upon return to earth, the blood begins to pool in the lower extremities again, resulting in orthostatic hypotension."
In space, astronauts lose fluid volume—including up to 22% of their blood volume. Because it has less blood to pump, the heart will atrophy. A weakened heart results in low blood pressure and can produce a problem with “orthostatic tolerance,” or the body's ability to send enough oxygen to the brain without fainting or becoming dizzy.
Soviet cosmonaut Valentin Lebedev, who spent 211 days in orbit during 1982 (an absolute record for stay in Earth's orbit), lost his eyesight to progressive cataract. Lebedev stated: “I suffered from a lot of radiation in space. It was all concealed back then, during the Soviet years, but now I can say that I caused damage to my health because of that flight.” On 31 May 2013, NASA scientists reported that a possible human mission to Mars may involve a great radiation risk based on the amount of energetic particle radiation detected by the RAD on the Mars Science Laboratory while traveling from the Earth to Mars in 2011–2012.
Fifty percent of space shuttle astronauts take sleeping pills and still get two hours or less of sleep. NASA is researching two areas which may provide the keys to a better night's sleep, as improved sleep decreases fatigue and increases daytime productivity. A variety of methods for combating this phenomenon are constantly under discussion. A partial list of remedies would include:
- Go to sleep at the same time each night. With practice, you will (almost) always be tired and ready for sleep.
- Melatonin, once thought to be an anti-aging wonder drug (this was due to the well-documented observation that as people age they gradually produce less and less of the hormone naturally). The amount of melatonin the body produces decreases linearly over a lifetime. Although the melatonin anti-aging fad was thoroughly debunked following a large number of randomized trials, it was soon in the spotlight once more due to the observation that a healthy person's normal melatonin levels varies widely throughout each day: usually, levels rise in the evening and fall in the morning. Ever since the discovery that melatonin levels are highest at bedtime, melatonin has been purported by some to be an effective sleep-aid – it is especially popular for jet-lag. Melatonin's efficacy in treating insomnia is hotly debated and therefore in the US it is sold as a dietary supplement. "These statements have not been evaluated by the FDA" is printed on the packaging even though melatonin has been studied very extensively.
- Ramelteon, a melatonin receptor agonist, is a relatively new drug designed by using the melatonin molecule and the shapes of melatonin receptors as starting points. Ramelteon binds to the same M1 and M2 receptors in the suprachiasmatic nucleus (the "biological clock" in the brain) as melatonin (M1 and M2 get their names from melatonin). It also may derive some of its properties from its three-times greater elimination half-life. Ramelteon is not without detractors who claim that it is no more effective than melatonin, and melatonin is less expensive by orders of magnitude. It is unclear whether Ramelteon causes its receptors to behave differently than they do when bound to melatonin, and Ramelteon may have a significantly greater affinity for these receptors. Better information on Ramelteon's effectiveness should be available soon, and despite questions of its efficacy, the general lack of side effects makes Ramelteon one of the very few sleep medications that could potentially be safely used by astronauts.
- Barbiturates and Benzodiazepines are both very strong sedatives. While they certainly would work (at least short term) in helping astronauts sleep, they have side effects that could affect the astronaut's ability to perform his/her job, especially in the "morning." This side effect renders barbiturates and benzodiazepines likely unfit as treatments for space insomnia. Narcotics and most tranquilizers also fall into this category.
- Zolpidem and Zopiclone are sedative-hypnotics, better known by their trade names "Ambien" and "Lunesta". These are extremely popular sleep-aids, due in large part to their effectiveness and significantly reduced side-effect profiles vis-a-vis benzodiazepines and barbiturates. Although other drugs may be more effective in inducing sleep Zolpidem and Zopiclone essentially lack the sorts of side effects that disqualify other insomnia drugs for astronauts, for whom being able to wake up easily and quickly can be of paramount importance; astronauts who are not thinking clearly, are groggy, and are disoriented when a sudden emergency wakes them could end up trading their grogginess for the indifference of death in seconds. Zolpidem, Zopiclone, and the like – in most people – are significantly less likely to cause drug-related daytime sleepiness, nor excessive drowsiness if woken abruptly.
- Practice good sleep hygiene. In other words, the bed is for sleeping only; get out of bed within a few moments of waking up. Do not sit in bed watching TV or using a laptop. When one is acclimated to spending many hours awake in bed, it can disrupt the body's natural set of daily cycles, called the circadian rhythm. While this is less of an issue for astronauts who have very limited entertainment options in their sleeping areas, another aspect of sleep hygiene is adhering to a specific pre-sleep routine (shower, brush teeth, fold up clothing, spend 20 minutes with a trashy novel, for example); observing this sort of routine regularly can significantly improve one's sleep quality. Of course, sleep hygiene studies have all been conducted at 1G, but it seems possible (if not likely) that observing sleep hygiene would retain at least some efficacy in micro-gravity.
- Modafinil is a drug that is prescribed for narcolepsy and other disorders that involve excessive daytime exhaustion. It has been approved in various military situations and for astronauts thanks to its ability to stave off fatigue. It is unclear whether astronauts sometimes use the drug because they are sleep-deprived – it might only be used on spacewalks and in other high-risk situations.
- Dexedrine is an amphetamine which used to be the gold-standard for fighter pilots flying long and multiple sorties in a row, and therefore may have at some point been available if astronauts were in need of a strong stimulant. Today, Modafinil has largely – if not entirely – replaced Dexedrine; reaction time and reasoning among pilots who are sleep-deprived and on Dexedrine suffer, and get worse the longer the pilot stays awake. In one study, helicopter pilots that were given two-hundred milligrams of Modafinil every three hours were able to significantly improve their flight-simulator performance. The study reported, however, that modafinil was not as efficacious as dexamphetamine in increasing performance without producing side effects.
Biomedical research in space is expensive and logistically and technically complicated, and thus limited. Conducting medical research in space alone will not provide humans with the depth of knowledge needed to ensure the safety of inter-planetary travellers. Complementary to research in space is the use of spaceflight analogues. Analogues are particularly useful for the study of immunity, sleep, psychological factors, human performance, habitability, and telemedicine. Examples of spaceflight analogues include confinement chambers (Mars-500), sub-aqua habitats (NEEMO), and Antarctic (Concordia Station) and Arctic (Haughton–Mars Project) stations.
Space medicine careers
Related degrees, areas of specialization, and certifications
- Aeromedical certification
- Aerospace medicine
- Aerospace studies
- Occupational and preventive medicine
- Global Health
- Public Health
- Disaster medicine
- Prehospital medicine
- Wilderness and extreme medicine
Medicine in flight
Ultrasound and space
Ultrasound is the main diagnostic imaging tool on ISS and for the foreseeable future missions. X-rays and CT scans involve radiation which is unacceptable in the space environment. Though MRI uses magnetics to create images, it is too large at present to consider as a viable option. Ultrasound, which uses sound waves to create images and comes in laptop size packages, provides imaging of a wide variety of tissues and organs. It is currently being used to look at the eyeball and the optic nerve to help determine the cause(s) of changes that NASA has noted mostly in long duration astronauts. NASA is also pushing the limits of ultrasound use regarding musculoskeletal problems as these are some of the most common and most likely problems to occur. Significant challenges to using ultrasounds on space missions is training the astronaut to use the equipment (ultrasound technicians spend years in training and developing the skills necessary to be "good" at their job) as well as interpreting the images that are captured. Much of ultrasound interpretation is done real-time but it is impractical to train astronauts to actually read/interpret ultrasounds. Thus, the data is currently being sent back to mission control and forwarded to medical personnel to read and interpret. Future exploration class missions will need to be autonomous due to transmission times taking too long for urgent/emergent medical conditions. The ability to be autonomous, or to use other equipment such as MRIs, is currently being researched.
Space Shuttle era
With the additional lifting capability presented by the Space Shuttle program, NASA designers were able to create a more comprehensive medical readiness kit. The SOMS consists of two separate packages: the Medications and Bandage Kit (MBK) and the Emergency Medical Kit (EMK). While the MBK contained capsulate medications (tablets, capsules, and suppositories), bandage materials, and topical medication, the EMK had medications to be administered by injection, items for performing minor surgeries, diagnostic/therapeutic items, and a microbiological test kit.
John Glenn, the first American astronaut to orbit the Earth, returned with much fanfare to space once again on STS-95 at 77 years of age to confront the physiological challenges preventing long-term space travel for astronauts—loss of bone density, loss of muscle mass, balance disorders, sleep disturbances, cardiovascular changes, and immune system depression—all of which are problems confronting aging people as well as astronauts.
Feasibility of Long Duration Space Flights
In the interest of creating the possibility of longer duration space flight, NASA has invested in the research and application of preventative space medicine, not only for medically preventable pathologies, but trauma as well. Although trauma constitutes more of a life-threatening situation, medically preventable pathologies pose more of a threat to astronauts. "The involved crewmember is endangered because of mission stress and the lack of complete treatment capabilities on board the spacecraft, which could result in the manifestation of more severe symptoms than those usually associated with the same disease in the terrestrial environment. Also, the situation is potentially hazardous for the other crewmembers because the small, closed, ecological system of the spacecraft is conducive to disease transmission. Even if the disease is not transmitted, the safety of the other crewmembers may be jeopardized by the loss of the capabilities of the crewmember who is ill. Such an occurrence will be more serious and potentially hazardous as the durations of crewed missions increase and as operational procedures become more complex. Not only do the health and safety of the crewmembers become critical, but the probability of mission success is lessened if the illness occurs during flight. Aborting a mission to return an ill crewmember before mission goals are completed is costly and potentially dangerous."
Impact on science and medicine
Astronauts are not the only ones who benefit from space medicine research. Several medical products have been developed that are space spinoffs, that is practical applications for the field of medicine arising out of the space program. Because of joint research efforts between NASA, the National Institutes on Aging (a part of the National Institutes of Health), and other aging-related organizations, space exploration has benefited a particular segment of society, seniors. Evidence of aging related medical research conducted in space was most publicly noticeable during STS-95 (See below).
Pre-Mercury through Apollo
- Radiation therapy for the treatment of cancer: In conjunction with the Cleveland Clinic, the cyclotron at Glenn Research Center in Cleveland, Ohio was used in the first clinical trials for the treatment and evaluation of neutron therapy for cancer patients.
- Foldable walkers: Made from a lightweight metal material developed by NASA for aircraft and spacecraft, foldable walkers are portable and easy to manage.
- Personal alert systems: These are emergency alert devices that can be worn by individuals who may require emergency medical or safety assistance. When a button is pushed, the device sends a signal to a remote location for help. To send the signal, the device relies on telemetry technology developed at NASA.
- CAT and MRI scans: These devices are used by hospitals to see inside the human body. Their development would not have been possible without the technology provided by NASA after it found a way to take better pictures of the Earth's moon.
- Muscle stimulator device: This device is used for ½ hour per day to prevent muscle atrophy in paralyzed individuals. It provides electrical stimulation to muscles which is equal to jogging three miles per week. Christopher Reeve used these in his therapy.
- Orthopedic evaluation tools: Equipment to evaluate posture, gait and balance disturbances was developed at NASA, along with a radiation-free way to measure bone flexibility using vibration.
- Diabetic foot mapping: This technique was developed at NASA's center in Cleveland, Ohio to help monitor the effects of diabetes in feet.
- Foam cushioning: Special foam used for cushioning astronauts during liftoff is used in pillows and mattresses at many nursing homes and hospitals to help prevent ulcers, relieve pressure, and provide a better night's sleep.
- Kidney dialysis machines: These machines rely on technology developed by NASA in order to process and remove toxic waste from used dialysis fluid.
- Talking wheelchairs: Paralyzed individuals who have difficulty speaking may use a talking feature on their wheelchairs which was developed by NASA to create synthesized speech for aircraft.
- Collapsible, lightweight wheelchairs: These wheelchairs are designed for portability and can be folded and put into trunks of cars. They rely on synthetic materials that NASA developed for its air and space craft
- Surgically implantable heart pacemaker: These devices depend on technologies developed by NASA for use with satellites. They communicate information about the activity of the pacemaker, such as how much time remains before the batteries need to be replaced.
- Implantable heart defibrillator: This tool continuously monitors heart activity and can deliver an electric shock to restore heartbeat regularity.
- EMS communications: Technology used to communicate telemetry between Earth and space was developed by NASA to monitor the health of astronauts in space from the ground. Ambulances use this same technology to send information—like EKG readings—from patients in transport to hospitals. This allows faster and better treatment.
- Weightlessness therapy: The weightlessness of space can allow some individuals with limited mobility on Earth—even those normally confined to wheelchairs—the freedom to move about with ease. Physicist Stephen Hawking took advantage of weightlessness in NASA's Vomit Comet aircraft in 2007. This idea also led to the development of the Anti-Gravity Treadmill from NASA technology.
The Advanced Diagnostic Ultrasound in Microgravity Study is funded by the National Space Biomedical Research Institute and involves the use of ultrasound among Astronauts including former ISS Commanders Leroy Chiao and Gennady Padalka who are guided by remote experts to diagnose and potentially treat hundreds of medical conditions in space. This study has a widespread impact and has been extended to cover professional and Olympic sports injuries as well as medical students. It is anticipated that remote guided ultrasound will have application on Earth in emergency and rural care situations. Findings from this study were submitted for publication to the journal Radiology aboard the International Space Station; the first article submitted in space.
- Artificial gravity
- Effect of spaceflight on the human body
- Fatigue and sleep loss during spaceflight
- Intervertebral disc damage and spaceflight
- List of microorganisms tested in outer space
- Mars analog habitat
- Medical treatment during spaceflight
- Microgravity University
- Reduced-gravity aircraft
- Renal stone formation in space
- Spaceflight osteopenia
- Spaceflight radiation carcinogenesis
- Space food
- Space nursing
- Space Nursing Society
- Team composition and cohesion in spaceflight missions
- Visual impairment due to intracranial pressure
- "International Space Station Medical Monitoring (ISS Medical Monitoring)". 3 December 2013. Retrieved January 13, 2014.
- Chang, Kenneth (January 27, 2014). "Beings Not Made for Space". New York Times. Retrieved January 27, 2014.
- Mann, Adam (July 23, 2012). "Blindness, Bone Loss, and Space Farts: Astronaut Medical Oddities". Wired. Retrieved July 23, 2012.
- Dunn, Marcia (October 29, 2015). "Report: NASA needs better handle on health hazards for Mars". AP News. Retrieved October 30, 2015.
- Staff (October 29, 2015). "NASA's Efforts to Manage Health and Human Performance Risks for Space Exploration (IG-16-003)" (PDF). NASA. Retrieved October 29, 2015.
- Andrew Walker (21 November 2005). "Project Paperclip: Dark side of the Moon". BBC News. Retrieved 2012-04-25.
- "Former Nazi removed from Space Hall of Fame". NBC News. Associated Press. 2006-05-19. Retrieved 2006-05-19.
- Link, Mae Mills (1965). Space Medicine in Project Mercury (NASA Special Publication). NASA SP (Series). Washington, D.C.: Scientific and Technical Information Office, National Aeronautics and Space Administration. OCLC 1084318604. NASA SP-4003. Retrieved 17 February 2019.
- Griffin, Andrew (2 October 2018). "Travelling to Mars and deep into space could kill astronauts by destroying their guts, finds Nasa-funded study – Previous work has shown that astronauts could age prematurely and have damaged brain tissue after long journeys". The Independent. Retrieved 2 October 2018.
- Strickland, Ashley (15 November 2019). "Astronauts experienced reverse blood flow and blood clots on the space station, study says". CNN News. Retrieved 22 November 2019.
- Marshall-Goebel, Karina; et al. (13 November 2019). "Assessment of Jugular Venous Blood Flow Stasis and Thrombosis During Spaceflight". JAMA Network Open. 2 (11): e1915011. doi:10.1001/jamanetworkopen.2019.15011. PMID 31722025.
- Platts, S. H., Stenger, M. B., Phillips, T. R., Brown, A. K., Arzeno, N. M., Levine, B., & Summers, R. (2009). Evidence Based Review: Risk of Cardiac Rhythm Problems During Spaceflight.
- Ackles, KN (1973). "Blood-Bubble Interaction in Decompression Sickness". Defence R&D Canada (DRDC) Technical Report. DCIEM-73-CP-960. Retrieved 23 May 2010.
- Nevills, Amiko (2006). "Preflight Interview: Joe Tanner". NASA. Retrieved 26 June 2010.
- Webb, James T; Olson, RM; Krutz, RW; Dixon, G; Barnicott, PT (1989). "Human tolerance to 100% oxygen at 9.5 psia during five daily simulated 8-hour EVA exposures". Aviation, Space, and Environmental Medicine. 60 (5): 415–21. doi:10.4271/881071. PMID 2730484.
- Francis, T James R; Mitchell, Simon J (2003). "10.6: Manifestations of Decompression Disorders". In Brubakk, Alf O; Neuman, Tom S (eds.). Bennett and Elliott's physiology and medicine of diving (5th Revised ed.). United States: Saunders. pp. 578–584. ISBN 978-0-7020-2571-6. OCLC 51607923.
- Berghage, Thomas E; Vorosmarti Jr, James; Barnard, EEP (1978). "Recompression treatment tables used throughout the world by government and industry". US Naval Medical Research Center Technical Report. NMRI-78-16. Retrieved 25 May 2010.
- Marx, John (2010). Rosen's emergency medicine: concepts and clinical practice (7th ed.). Philadelphia, PA: Mosby/Elsevier. ISBN 978-0-323-05472-0.
- Thalmann, Edward D (March–April 2004). "Decompression Illness: What Is It and What Is The Treatment?". Divers Alert Network. Archived from the original on 13 June 2010. Retrieved 3 August 2010.
- US Navy Diving Manual, 6th revision. United States: US Naval Sea Systems Command. 2006. Retrieved 2008-05-26.
- Brubakk, A. O.; Neuman, T. S. (2003). Bennett and Elliott's physiology and medicine of diving, 5th Rev ed. United States: Saunders Ltd. p. 800. ISBN 978-0-7020-2571-6.
- Vogt, L., Wenzel, J., Skoog, A. I., Luck, S., & Svensson, B. (1991). European EVA decompression sickness risks. Acta astronautica, 23, 195–205.
- Newman, D., & Barrat, M. (1997). Life support and performance issues for extravehicular activity (EVA). Fundamentals of Space Life Sciences, 2.
- Robichaud, R.; McNally, M. E. (January 2005). "Barodontalgia as a differential diagnosis: symptoms and findings". Journal of the Canadian Dental Association. 71 (1): 39–42. PMID 15649340. Retrieved 2008-07-19.
- Kay, E (2000). "Prevention of middle ear barotrauma". Doc's Diving Medicine. staff.washington.edu. Retrieved 13 January 2017.
- Kaplan, Joseph. Alcock, Joe (ed.). "Barotrauma Medication". emedicine.medscape.com. Retrieved 15 January 2017.
- Clark, J. B. (2008). Decompression-related disorders: pressurization systems, barotrauma, and altitude sickness. In Principles of Clinical Medicine for Space Flight (pp. 247–271). Springer, New York, NY.
- Hidir, Y., Ulus, S., Karahatay, S., & Satar, B. (2011). A comparative study on efficiency of middle ear pressure equalization techniques in healthy volunteers. Auris Nasus Larynx, 38(4), 450–455.
- Pierson, D.L., Stowe, R.P., Phillips, T.M., Lugg, D.J. and Mehta, S.K., 2005. Epstein–Barr virus shedding by astronauts during space flight. Brain, Behavior, and Immunity, 19(3), pp.235–242.
- Cogoli, A., 1996. Gravitational physiology of human immune cells: a review of in vivo, ex vivo and in vitro studies. Journal of gravitational physiology: a journal of the International Society for Gravitational Physiology, 3(1), pp.1–9.
- Kim W, et al. (April 29, 2013). "Spaceflight Promotes Biofilm Formation by Pseudomonas aeruginosa". PLOS ONE. 8 (4): e6237. Bibcode:2013PLoSO...862437K. doi:10.1371/journal.pone.0062437. PMC 3639165. PMID 23658630.
- Staff (15 March 2019). "Dormant viruses activate during spaceflight -- NASA investigates - The stress of spaceflight gives viruses a holiday from immune surveillance, putting future deep-space missions in jeopardy". EurekAlert!. Retrieved 16 March 2019.
- Caspermeyer, Joe (23 September 2007). "Space flight shown to alter ability of bacteria to cause disease". Arizona State University. Retrieved 14 September 2017.
- Dvorsky, George (13 September 2017). "Alarming Study Indicates Why Certain Bacteria Are More Resistant to Drugs in Space". Gizmodo. Retrieved 14 September 2017.
- Dose, K.; Bieger-Dose, A.; Dillmann, R.; Gill, M.; Kerz, O.; Klein, A.; Meinert, H.; Nawroth, T.; Risi, S.; Stridde, C. (1995). "ERA-experiment "space biochemistry"". Advances in Space Research. 16 (8): 119–129. Bibcode:1995AdSpR..16..119D. doi:10.1016/0273-1177(95)00280-R. PMID 11542696.
- Vaisberg, Horneck G.; Eschweiler, U.; Reitz, G.; Wehner, J.; Willimek, R.; Strauch, K. (1995). "Biological responses to space: results of the experiment "Exobiological Unit" of ERA on EURECA I". Adv. Space Res. 16 (8): 105–18. Bibcode:1995AdSpR..16..105V. doi:10.1016/0273-1177(95)00279-N. PMID 11542695.
- BioMed Central (22 November 2018). "ISS microbes should be monitored to avoid threat to astronaut health". EurekAlert!. Retrieved 25 November 2018.
- Singh, Nitin K.; et al. (23 November 2018). "Multi-drug resistant Enterobacter bugandensis species isolated from the International Space Station and comparative genomic analyses with human pathogenic strains". BMC Microbiology. 18 (1): 175. doi:10.1186/s12866-018-1325-2. PMC 6251167. PMID 30466389.
- Harrison, Y; Horne, JA (Jun 1998). "Sleep loss impairs short and novel language tasks having a prefrontal focus". Journal of Sleep Research. 7 (2): 95–100. doi:10.1046/j.1365-2869.1998.00104.x. PMID 9682180.
- Durmer, JS; Dinges, DF (Mar 2005). "Neurocognitive consequences of sleep deprivation" (PDF). Seminars in Neurology. 25 (1): 117–29. doi:10.1055/s-2005-867080. PMC 3564638. PMID 15798944. Archived from the original (PDF) on 2012-06-17.
- Banks, S; Dinges, DF (15 August 2007). "Behavioral and physiological consequences of sleep restriction". Journal of Clinical Sleep Medicine. 3 (5): 519–28. PMC 1978335. PMID 17803017.
- Whitmire, A.M.; Leveton, L.B; Barger, L.; Brainard, G.; Dinges, D.F.; Klerman, E.; Shea, C. "Risk of Performance Errors due to Sleep Loss, Circadian Desynchronization, Fatigue, and Work Overload" (PDF). Human Health and Performance Risks of Space Exploration Missions: Evidence reviewed by the NASA Human Research Program. p. 88. Retrieved 17 May 2012.
- Shi, S. J., Platts, S. H., Ziegler, M. G., & Meck, J. V. (2011). Effects of promethazine and midodrine on orthostatic tolerance. Aviation, Space, and Environmental Medicine, 82(1), 9–12.
- Sibonga, J. D., Evans, H. J., Sung, H. G., Spector, E. R., Lang, T. F., Oganov, V. S., ... & LeBlanc, A. D. (2007). Recovery of spaceflight-induced bone loss: bone mineral density after long-duration missions as fitted with an exponential function. Bone, 41(6), 973–978.
- Williams, D., Kuipers, A., Mukai, C., & Thirsk, R. (2009). Acclimation during space flight: effects on human physiology. Canadian Medical Association Journal, 180(13), 1317–1323.
- Hawkey, A. (2007). Low magnitude, high frequency signals could reduce bone loss during spaceflight. Journal of the British Interplanetary Society, 60, 278–284.
- Mader, T. H.; et al. (2011). "Optic Disc Edema, Globe Flattening, Choroidal Folds, and Hyperopic Shifts Observed in Astronauts after Long-duration Space Flight". Ophthalmology. 118 (10): 2058–2069. doi:10.1016/j.ophtha.2011.06.021. PMID 21849212.
- Puiu, Tibi (November 9, 2011). "Astronauts' vision severely affected during long space missions". zmescience.com. Retrieved February 9, 2012.
- "Male Astronauts Return With Eye Problems (video)". CNN News. 9 Feb 2012. Retrieved 2012-04-25.
- Space Staff (13 March 2012). "Spaceflight Bad for Astronauts' Vision, Study Suggests". Space.com. Retrieved 14 March 2012.
- Kramer, Larry A.; et al. (13 March 2012). "Orbital and Intracranial Effects of Microgravity: Findings at 3-T MR Imaging". Radiology. 263 (3): 819–827. doi:10.1148/radiol.12111986. PMID 22416248.
- Howell, Elizabeth (3 November 2017). "Brain Changes in Space Could Be Linked to Vision Problems in Astronauts". Seeker. Retrieved 3 November 2017.
- Fong, MD, Kevin (12 February 2014). "The Strange, Deadly Effects Mars Would Have on Your Body". Wired. Retrieved 12 February 2014.
- Cherry, Jonathan D.; Frost, Jeffrey L.; Lemere, Cynthia A.; Williams, Jacqueline P.; Olschowka, John A.; O'Banion, M. Kerry (2012). "Galactic Cosmic Radiation Leads to Cognitive Impairment and Increased Aβ Plaque Accumulation in a Mouse Model of Alzheimer's Disease". PLOS ONE. 7 (12): e53275. Bibcode:2012PLoSO...753275C. doi:10.1371/journal.pone.0053275. PMC 3534034. PMID 23300905.
- Staff (January 1, 2013). "Study Shows that Space Travel is Harmful to the Brain and Could Accelerate Onset of Alzheimer's". SpaceRef. Retrieved January 7, 2013.
- Cowing, Keith (January 3, 2013). "Important Research Results NASA Is Not Talking About (Update)". NASA Watch. Retrieved January 7, 2013.
- Roberts, Donna R.; et al. (2 November 2017). "Effects of Spaceflight on Astronaut Brain Structure as Indicated on MRI". New England Journal of Medicine. 377 (18): 1746–1753. doi:10.1056/NEJMoa1705129. PMID 29091569.
- Foley, Katherine Ellen (3 November 2017). "Astronauts who take long trips to space return with brains that have floated to the top of their skulls". Quartz. Retrieved 3 November 2017.
- "Beckman physiological and cardiovascular monitoring system". Science History Institute. Retrieved 31 July 2019.
- "When Space Makes You Dizzy". NASA. 2002. Archived from the original on 2009-08-26. Retrieved 2012-04-25.
- Kerr, Richard (31 May 2013). "Radiation Will Make Astronauts' Trip to Mars Even Riskier". Science. 340 (6136): 1031. doi:10.1126/science.340.6136.1031. PMID 23723213.
- Zeitlin, C.; et al. (31 May 2013). "Measurements of Energetic Particle Radiation in Transit to Mars on the Mars Science Laboratory". Science. 340 (6136): 1080–1084. Bibcode:2013Sci...340.1080Z. doi:10.1126/science.1235989. PMID 23723233.
- Chang, Kenneth (30 May 2013). "Data Point to Radiation Risk for Travelers to Mars". New York Times. Retrieved 31 May 2013.
- Gelling, Cristy (June 29, 2013). "Mars trip would deliver big radiation dose; Curiosity instrument confirms expectation of major exposures". Science News. 183 (13): 8. doi:10.1002/scin.5591831304. Retrieved July 8, 2013.
- "Soviet cosmonauts burnt their eyes in space for USSR's glory". Pravda.Ru. 17 Dec 2008. Retrieved 2012-04-25.
- John A. Caldwell, Jr., Nicholas K. Smythe, III, J. Lynn Caldwell, Kecia K. Hall, David N. Norman, Brian F. Prazinko, Arthur Estrada, Philip A. Johnson, John S. Crowley, Mary E. Brock (June 1999). "The Effects of Modafinil on Aviator Performance During 40 Hours of Continuous Wakefulness" (PDF). U.S. Army Aeromedical Research Laboratory. Retrieved 2012-04-25.CS1 maint: multiple names: authors list (link)
- "Space Nursing Society". Retrieved 5 December 2011.
- Perrin, MM (Sep 1985). "Space nursing. A professional challenge". Nurs Clin North Am. 20 (3): 497–503. PMID 3851391.
- Emanuelli, Matteo (2014-03-17). "Evolution of NASA Medical Kits: From Mercury to ISS". Space Safety Magazine. Retrieved 28 April 2015.
- Gray, Tara. "John H. Glenn Jr". NASA History Program Office. Archived from the original on January 28, 2016. Retrieved December 9, 2016.
- Wooley, Bennie (1972). "Apollo Experience Report- Protection of Life and Health" (PDF). NASA Technical Note: 20.
- Gahbauer, R., Koh, K. Y., Rodriguez-Antunez, A., Jelden, G. L., Turco, R. F., Horton, J., ... & Roberts, W. (1980). Preliminary results of fast neutron treatments in carcinoma of the pancreas.
- Goldin, D. S. (1995). Keynote address: Second NASA/Uniformed Services University of Health Science International Conference on Telemedicine, Bethesda, Maryland. Journal of medical systems, 19(1), 9–14.
- "Hawking takes zero-gravity flight". BBC. 2007-04-27. Retrieved 2018-02-03.
- "Advanced Diagnostic Ultrasound in Microgravity (ADUM)". Nasa.gov. 2011-11-08. Retrieved 2012-02-10.
- Sishir Rao, BA, Lodewijk van Holsbeeck, BA, Joseph L. Musial, PhD, Alton Parker, MD, J. Antonio Bouffard, MD, Patrick Bridge, PhD, Matt Jackson, PhD and Scott A. Dulchavsky, MD, PhD (May 1, 2008). "A Pilot Study of Comprehensive Ultrasound Education at the Wayne State University School of Medicine". Journal of Ultrasound in Medicine. 27 (5): 745–749. doi:10.7863/jum.2008.27.5.745. PMID 18424650. Archived from the original on December 17, 2013. Retrieved 2012-04-25.CS1 maint: multiple names: authors list (link)
- E. Michael Fincke, MS, Gennady Padalka, MS, Doohi Lee, MD, Marnix van Holsbeeck, MD, Ashot E. Sargsyan, MD, Douglas R. Hamilton, MD, PhD, David Martin, RDMS, Shannon L. Melton, BS, Kellie McFarlin, MD and Scott A. Dulchavsky, MD, PhD (February 2005). "Evaluation of Shoulder Integrity in Space: First Report of Musculoskeletal US on the International Space Station". Radiology. 234 (2): 319–322. doi:10.1148/radiol.2342041680. PMID 15533948.CS1 maint: multiple names: authors list (link)
- Altitude Decompression Sickness Susceptibility, MacPherson, G; Aviation, Space, and Environmental Medicine, Volume 78, Number 6, June 2007, pp. 630–631(2)
- Decision Analysis in Aerospace Medicine: Costs and Benefits of a Hyperbaric Facility in Space, John-Baptiste, A; Cook, T; Straus, S; Naglie, G; et al. Aviation, Space, and Environmental Medicine, Volume 77, Number 4, April 2006, pp. 434–443(10)
- Incidence of Adverse Reactions from 23,000 Exposures to Simulated Terrestrial Altitudes up to 8900 m, DeGroot, D; Devine JA; Fulco CS; Aviation, Space, and Environmental Medicine, Volume 74, Number 9, September 2003, pp. 994–997(4)