Extent of Exposure

Extent of Exposure -- Risk in Space and Space Analogues is a text by Regina Peldszus and Alex Salam. It is part of the Blowup Reader 7 (2013).

Extent of Exposure

Antarctic winter isolation. Photo by Alex Salam.

Living and working in space entails significant physical and behavioural risks, whether in the context of conducting experiments on board an orbital platform today, or in the future, the remote-control of lunar mining equipment, extravehicular activity to service satellites, or the collection of samples on a planetary surface. Once the violent G-forces of the launch have been ridden out, the crew faces a hostile environment humanshave not evolved to inhabit. Acute environmental stressors can be mediated through the use of technology: the immediate habitat can be made to provide adequate pressure, a breathable atmosphere, protection from extreme temperatures and radiation, and countermeasures can be taken against physiological deconditioning due to reduced gravity. More latent aspects of the human condition kick in however as mission duration increases. Technological and medical issues and emergencies—from muscle atrophy to power cuts, mood decrements or appendicitis—are exacerbated through extreme isolation and remoteness: conditions that not only foster some of these stressors and expedite their consequences, but also render their counteracting more difficult. With no possibility of re-supply or rescue, the crew ultimately relies entirely on itself.

In order to cope, crews are trained and prepared for many eventualities, and missions are planned and designed to minimize these risks. Yet, where do we get experience and data from beforeexposing crews to the actual space environment? Strategies can be based on insights and evidence from previous missions but when emergencies have occurred, it has been technically and logistically taxing to collect data on these incidents or developments. At the same time, it is challenging for the analyst or planner to access the space environment to experience, research and design for it.

If we cannot access the setting to immerse ourselves, our training subjects, or our technologies in it, then how can we tackle the risks, particularly in view of future scenarios that are incomparable to historical missions to date? It is to this end that, since the advent of human spaceflight, a range of testbeds has evolved (Bishop, 2011). With different degrees of fidelity and complexity in set-up and operation, these range from bed rest studies, parabolic flights, and neutral buoyancy facilities where some of the physical aspects of the space environment can be mimicked, to isolation chambers in research complexes, undersea habitats, and remote duty bases in polar regions that evoke the isolation and confinement of extended, remote missions. Whole landscapes become laboratories—like Antarctica (Sandal et al., 2006)—as they offer somewhat controlled conditions within which to observe the complexities and subtleties of human behaviour and performance, as they unfold over durations of thirteen to seventeen months.

No single analogue alone can recreate the different conditions of space in their entirety and elicit the associated set of physical and psychological changes, but each of them excels at mimicking one or more aspects. In conjunction, and together with evidence from previous missions, they offer insights into the impact of the hostile space environment, and the effects of both technical failures and medical emergencies on physical and psychological health.


Human physiology is adapted to the Earth’s gravitational, atmospheric, and geomagnetic fields. In space, in the absence of these, the human body undergoes a series of changes.

Nausea and vomiting are often the first symptoms upon transition to reduced gravity. These occur due to a mismatch between the visual and the vestibular systems. This is initially accompanied by facial swelling, nasal congestion, and headaches as body fluids redistribute themselves. In parabolic flight, a specially adapted plane flies a series of parabolic trajectories in order to recreate twenty-second blocks of near-weightlessness. This allows us to study these early changes and adaptations that occur in a microgravity environment. The body fluid redistribution from the legs to the head, a syndrome described as ‘puffy face-bird legs’ syndrome, is thought to lead to increased pressure within the skull and brain tissue, resulting eventually in visual impairment. Some months of six-degree head-down tilted bed rest here on Earth mimics, to a degree, these fluid shifts.

Over time, even intensive daily exercise programmes cannot prevent muscle and bone loss. Changes in muscle volume and architecture are not limited to skeletal muscle, but also affect the heart. The decrease in blood volume that occurs as a result of fluid redistribution, in combination with cardiac atrophy, leads to the inability to maintain blood pressure when standing upon return to Earth (or any environment with greater than micro-gravity) and, as a consequence, fainting. This puts astronauts at risk of serious fractures, a situation that could be life-threatening during planetary surface missions. The psychological and practical impact of an injured or dead crewmember on the rest of the team would be significant. Along the way, astronauts are also exposed to elevated radiation levels that can lead to cancer, cataracts and central nervous system dysfunction. The levels and types of radiation encountered in space are particularly difficult to recreate and study on Earth. By the end of an extended, long distance space mission, an initially healthy astronaut may risk returning as a weak, fragile, partially blind, cognitively impaired shell of his or her former self.


Spaceflight also involves significant psychologicalstress and elevations in stress hormones, potentially leading to cognitive and behavioural decrements. To a degree, most stressors in space can be related to extreme isolation and confinement—a setting that, from a behavioural perspective, humans, as a highly social species, are not well adapted to. Humans depend on meaningful social contact and support; inadequacy or lack thereof has a significant impact on our mental and physical well-being. When confined to small habitable volumes in monotonous sensory conditions for prolonged periods of time with only a handful of other people, humans may experience changes in behaviour. These will, to a certain extent, be driven by the effects of stress hormones on specific brain structures and functions. We know from animal studies that stress hormones affect areas of the brain such as the hippocampus (involved in memory), the amygdala (involved in threat detection), and the pre-frontal cortex (involved in complex decision-making and moderating social behaviour) (Lupien et al., 2009). However, to what extent stress and stress hormones affect human behaviour under conditions akin to spaceflight, and how best to counteract and prevent any adverse changes, is currently unknown.

Several facilities on Earth allow for the recreation of the levels of isolation and confinement felt in space, for instance in chamber facilities, such as Mars500 at the Institute of Biomedical Problems in Moscow. Antarctic research stations have an advantage over chamber studies however, in that they carry an element of actual danger, and evacuation can often take months, making these more real analogues. This can make a significant difference to the amount of stress experienced. The lack of acute danger in chamber studies (beyond a fire in the module), and the possibility that one can ultimately open the hatch if required, results in participants experiencing significantly less anxiety and other psychiatric complaints than Antarctic personnel (Sandal et al., 1996). In his account of the Belgian Antarctic Expedition in the late 19th century, surgeon Frederick Cook was already describing the effects of the long, dark, lonely Antarctic winter on the crew:

‘The curtain of blackness which has fallen over the outer world of icy desolation has also descended upon the inner world of our souls. Around the tables, in the laboratory, and in the forecastle, men are sitting about sad and dejected, lost in dreams of melancholy from which, now and then, one arouses with an empty attempt at enthusiasm… Each man is intent on being left alone to take what comfort he can from memories of happier days, though such effort usually leaves him more hopelessly oppressed by the sense of utter desertion and loneliness.’ (Cook, 1909)

In an extreme scenario, severe stress in an isolated setting could unmask latent psychiatric illness, which could have the potential to cause severe disruption to the crew and the mission. In 1955 for example, during the establishment of the main United States Antarctic station, one of the crew members developed a full blown acute psychosis that ultimately required him to be sedated for the remainder of the Antarctic winter (Stuster, 1996).


While health decrements gradually accumulate, the crew is also completely dependent on their habitat and its life support systems for protection from outside influences. The habitat acts as a safe haven from solar flares that can irradiate the astronaut, but is, itself, vulnerable to decompression due to micrometeorites that could puncture its hull and pose a significant and immediate risk to life. With limited or periodically no external supply, most habitats are quasi closed-loop environments where resources are recycled and conserved; they are self-contained units and have to function reliably. When the habitat system fails, the crew’s trust in technology is challenged.

During the Mars500 study, the crew had to wait out a twenty-seven hour power cut. Their module started heating up as the ventilation system had stopped working, the food in the freezer was close to spoiling, and there was hardly any light to work to fix the problem. Being aware that this was a planned failure injected by the team of scientists running the simulation, the crew felt uncomfortable, yet knew that they were in reality safely inside the research facility. When the same thing happened at Concordia research station—the second most isolated base in Antarctica—the sense of danger became much more tangible. A power failure during the Antarctic winter meant no light, no hot food, no heating, and for the habitat to face external temperatures of up to minus eighty-four degrees. Despite the incident being short (although the crew did not, of course, know how long it would go on for), the impact on the mood of some crewmembers was significant, with several experiencing a lasting sense of anxiety (Salam, 2012).

When medical doctor and US astronaut Jerry Linenger witnessed a power failure during his 132-day stay aboard the Russian space station MIR, his diary entry evokes the sense of being truly cut loose:

‘Last night it got really, really, really dark… We lost all electrical power…this was un-Earthly dark. Darker than any dark I had ever seen…the word "dark" is not adequate to describe what I saw. And silent. So silent.’ (Linenger, 2000)


Potential illnesses, latent behavioural changes, traumatic injuries, and life support system failures may all require support and attention from the ground. Providing adequate medical care in any remote environment, on site or through telemedicine applications, such as to polar stations and underwater laboratories like NEEMO (NASA Extreme Environment Mission Operations),can represent a critical challenge. In space, this is compounded by the fact that performing medical procedures, especially surgery, in reduced gravity can be technically demanding, and equipment, consumables (such as medication or blood reserves), and the volume needed to operate in are all limited. In any case, not every medical contingency can be planned for. The expertise of the crew medical officer will also be a limiting factor in the level of care that can be provided. Although training in surgery, anaesthetics, medicine, and psychiatry can be provided pre-departure, no doctor can be proficient in all of these fields. At distances far from Earth, there will be no real-time communication and advice for guidance. And despite assistance from non-medical crew members cross-trained in a certain amount of emergency medical care, there are potentially life-threatening situations in which a crew medical officer will have to diagnose and treat him or herself. In 1961, Leonid Ivanovich Rogozov, while stationed at the Russian Novolazarevskaya Antarctic station, developed appendicitis. Unfortunately for Rogozov, he was the station doctor, and had no choice but to perform an appendectomy on himself. One of his crewmates later commented:

‘When Rogozov had made the incision and was manipulating his own innards as he removed the appendix, his intestine gurgled, which was highly unpleasant for us; it made one want to turn away, flee, not look—but I kept my head and stayed. Artemev and Teplinsky also held their places, although it later turned out they had both gone quite dizzy and were close to fainting.’ (Rogozov & Bermel, 2009)


Operating on oneself, living through a power cut, a fire, the decompression of a space station, or attending to the breakdown of a colleague on a polar base, these all represent extreme situations in already extreme settings. When possible mission scenarios are ‘played out’ in the confines of a research analogue however, a central question emerges: how far will we allow the participant to be exposed to dangerous or stressful situations or conditions?

It is worth remembering that participants do self-select to take part in simulations and polar operations, and are aware of the associated risks. Studies in isolation chambers are especially bound by guidelines on ethics in research involving human participants. The participant may interrupt or leave the experiment at any time, but this is a hard decision to make when studies are highly publicized in the media and represent multilateral collaborations. Beyond choosing to leave a study, emergencies may require the participants to be removed for their own health. As much as it would be intriguing to observe and practice the real response of the crew to an emergency in a simulator, the cost of acquiring this type of data outweighs the potential benefit of it—and real operations, of course, already offer a string of exceptionally severe scenarios that can be debriefed and examined in retrospect, or remotely in real-time.

As simulation techniques evolve, even if one could recreate the space environment with high fidelity, this would continue to raise ethical questions as to whether it is appropriate to expose test subjects to broad and significant risks to health and life. Ultimately, this question also surfaces in the context of spaceflight per se, and the levels of risk we consider acceptable. 


Bishop, S. L. (2011), 'From Earth Analogs to Space: Getting There from Here', in Vakoch, D. A. (Ed.), Psychology of Space Exploration: Contemporary Research in Historical Perspective. NASA SP-2011-4411. Washington, DC: National Aeronautics & Space Administration, 47-78.

Cook, F. A. (1909), Through the first Antarctic night, 1898-1899: a narrative of the voyage of the" Belgica" among newly discovered lands and over an unknown sea about the South pole. Chicago: Doubleday & McClure.

Gunderson, E. K. E. (1973), Group Compatibility in Restricted Environments. Report No. 6724. Washington, D.C.: Bureau of Medicine and Surgery Department of the Navy.

Linenger, J. M. (2000), Off The Planet: Surviving Five Perilous Months Aboard the Space Station MIR. New York: McGraw Hill.

Lupien, S. J., McEwen, B. S., Gunnar, M. R., & Heim, C. (2009), Effects of stress throughout the lifespan on the brain, behaviour and cognition. Nature Reviews Neuroscience, 10(6), 434-445.

Rogozov V., Bermel N. (2009), Auto-appendectomy in the Antarctic: case report. British Medical Journal, 339, b4965.

Sandal, G. M., Vaernes, R., Bergan, T., Warncke, M., & Ursin, H. (1996), Psychological reactions during polar expeditions and isolation in hyperbaric chambers. Aviation, space, and environmental medicine Journal, University of Bergen, Norway.

Sandal, G. M., Leon, G. R., Palinkas, L. (2006), Human challenges in polar and space environments. Reviews in Environmental Sciences and Biotechnology. 5(2-3), 281-296.

Salam, A. P. (2012), 'Exploration Class Missions on Earth: Lessons Learnt from Life in Extreme Antarctic Isolation and Confinement', in Choker, A., Stress Challenges and Immunity in Space: From Mechanisms to Monitoring and Preventive Strategies. Berlin/ Heidelberg: Springer, 425-439.

Stuster, J. W. (1996), Bold endeavors: Lessons from polar and space exploration. Annapolis MD: Naval Institute Press.


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