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The relationship between altitude and atmospheric pressure. As the elevation increases from sea level the atmospheric pressure decreases. The range of the earth’s atmosphere is 101 kPa at sea level to near 0 kPa at 30,000 m.
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Atmospheric pressure is a variable that has been often manipulated in the trade space surrounding the design and engineering of space exploration vehicles and extraterrestrial habitats. Low pressures were used to reduce structural engineering and launch mass throughout the early human space program; moreover, low pressures will certainly be conside...
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... adapted and colonized a vast variety of environments and many of those environments contain extremes of one parameter or another; however, extreme terrestrial altitude has escaped colonization by higher life forms because of a suite of parameters that together prevent habitability. Atmospheric pressure is one of the major parameters that limit life to lower earth altitudes. An almost bewildering myriad of environmental parameters have been presented to Terran life forms during the process of evolutionary change. Life has ____________________ * Correspondence to: Robert J. Ferl The current atmospheric attributes of the Earth’s surface are the culmination of the physics of our planet and the impact of over a billion years of biology and geology. Biology has evolved and expanded into a wide range of environments, including those that press the limits of terrestrial altitudes, where physiology is limited by the extremes of temperature, moisture and atmospheric pressure that are the intrinsic components of terrestrial high altitudes (Figure 1). Indeed, it is only where all three of these extremes converge that we see an absence of life on our planet. On tropical mountains mammals and large plants (e.g. hyraxes and giant lobelias of Kilimanjaro) are found no higher than altitudes of 5000 m (Njiro, 2005) and herbaceous plants no higher than 5600 m (Körner, 2003). Yet even these altitude limits are dependent upon other environmental variables. For example, the upper limit of forests in tropical mountains may be 4000 m, yet that same limit can be less than 2000 m in more temperate latitudes (Körner and Paulsen, 2004). In addition, for mammals and birds, the limits of typical habitation appear to be delimitated as much by easy access to food and available oxygen as by temperature, moisture and atmospheric pressure. For humans, this habitation limit is around 4200 m in the latitude of the Himalayas, where the village of Kibber, India, is located (Table 1). In general, human excursions to higher altitudes and lower pressures requires supplemental oxygen – though oxygen alone cannot alleviate all difficulties for humans at low pressures and high altitudes (Maggiorini et al., 2001; Bartsch et al., 2005). In natural environments, plant growth at high altitudes is more limited by temperature than pressure; the 5600 m limit on Kilimanjaro is not imposed by the atmospheric pressure but rather by the fact the ground freezes every night. Laboratory experiments indicate that if plants are kept from freezing and are provided with adequate water, they can be maintained at pressures far less than that present at the summit of Kilimanjaro (e.g. Mansell et al., 1968; Gale, 1973; Boston, 1981; Rule and Staby, 1981; Andre and Richaux, 1986; Musgrave et al., 1988a; Andre and Massimino, 1992; Daunicht and Brinkjans, 1992; Ohta et al., 1993; Corey et al., 1996; Iwabuchi et al., 1996; Corey et al., 2000; Ferl et al., 2002; Goto et al., 2002; He et al., 2003; Paul et al., 2004). It is only in artificial environments, such as those of the human spaceflight program, that atmospheric pressure becomes a variable independent of the temperature, moisture and gas composition concerns that accompany terrestrial altitudes. In the contained, closed, and engineered volumes of extraterrestrial habitats and vehicles, challenges are created by the need to contain atmospheric pressure against the vacuum of space. Hence, atmospheric pressure has been independently manipulated to levels well beyond the limits imposed by altitude conditions on Earth. The idea that plants can be successfully cultured in very low atmospheric pressures for the purposes of advanced life support in non-terrestrial environments has serious implications for attaining the goal of taking humans to new planetary surfaces. A primary and long-term goal of sustaining life in remote space locations is to minimize the amount of mass, and therefore energy, required to launch and maintain life support systems. Furthermore, if one considers maximizing the use of local resources, then it would be desirable to make use of ambient light, which makes it necessary to have a structure with maximum transparency. This then leads to the question of what materials would be both sufficiently transparent and sufficiently strong to contain a plant growth atmosphere that would sustain a higher pressure than the near vacuum present on the Moon or the low pressure atmosphere on the Martian surface. At present there are no materials that would be generally accepted as sufficiently transparent, lightweight, and strong enough to meet all of these criteria at a full earth normal pressure. However, reducing the pressure within a plant habitat would consequently reduce the intrinsic strength required for such structures and materials, reducing the mass of material that must be lifted from the Earth’s surface, and potentially allowing the capture of ambient light as a resource. In this review we present a brief history of the various atmospheric pressures and gas compositions that have been used within the human-habitable vehicles of the space programs, with an eye toward the possible atmospheric configurations that might be used in future vehicles and habitats. This narration is followed by a general discussion of the uses of low pressure atmospheres in plant biology applications. These two threads will be integrated with a discussion of experiments focused specifically on low pressure atmospheres in plant space biology applications. We will then develop an argument that low atmospheric pressures present a serious environmental challenge to plants, a challenge that requires an adaptive response and redirection of metabolic resources. Understanding of this response is enhanced by analysis of the gene expression changes that take place as plants respond and adapt. Much like response and adaptation to other environmental stresses, such understanding can lead to both a definition of the current limits of terrestrial plants as well as a ...
Citations
... Astronauts face unique hazards from spaceflight, including ionizing radiation, altered gravitational fields, altered day-night cycles, confined isolation, hostile closed environments, distance-duration from Earth 1 , planetary dust-regolith 2,3 and extreme temperatures and atmospheres 4,5 . As astronauts experience these hazards, the body responds by adapting and deconditioning, with the potential for synergistic effects as the exposures persist 1,2,6 . ...
Human exploration of deep space will involve missions of substantial distance and duration. To effectively mitigate health hazards, paradigm shifts in astronaut health systems are necessary to enable Earth-independent healthcare, rather than Earth-reliant. Here we present a summary of decadal recommendations from a workshop organized by NASA on artificial intelligence, machine learning and modelling applications that offer key solutions toward these space health challenges. The workshop recommended various biomonitoring approaches, biomarker science, spacecraft/habitat hardware, intelligent software and streamlined data management tools in need of development and integration to enable humanity to thrive in deep space. Participants recommended that these components culminate in a maximally automated, autonomous and intelligent Precision Space Health system, to monitor, aggregate and assess biomedical statuses.
... Controlled studies that manipulate pressure and oxygen composition independently indicate altered gene expression under hypobaric conditions, which is only partially alleviated under normoxia (Zhou et al., 2017). Understanding plant growth under hypobaria is relevant to space agriculture, where hypobaric environments may reflect a favorable engineering choice for plant growth habitats, and in terrestrial crop breeding, enabling expansion of cultivation into marginal terrain and environments Paul and Ferl, 2007;Wheeler, 2010). Current evidence suggests that alteration in pressure generally has little effect on plant development. ...
Human space exploration cannot occur without reliable provision of nutritious and palatable food to sustain physical and mental well-being. This ultimately will depend upon efficient production of food in space, with on-site manufacturing on space stations or the future human colonies on celestial bodies. Extraterrestrial environments are by their nature foreign, and exposure to various kinds of plant stressors likely cannot be avoided. But this also offers opportunities to rethink food production as a whole. We are used to the boundaries of the Earth ecosystem such as its standard temperature range, oxygen and carbon dioxide concentrations, plus diel cycles of light, and we are unfamiliar with liberating ourselves from those boundaries. However, space research, performed both in true outer space and with mimicked space conditions on Earth, can help explore plant growth from its ‘first principles’. In this sense, this perspective paper aims to highlight fundamental opportunities for plant growth in space, with a new perspective on the subject. Conditions in space are evidently demanding for plant growth, and this produces “stress”. Yet, this stress can be seen as positive or negative. With the positive view, we discuss whether plant production systems could proactively leverage stresses instead of always combatting against them. With an engineering view, we focus, in particular, on the opportunities associated with radiation exposure (visible light, UV, gamma, cosmic). Rather than adapting Earth conditions into space, we advocate on rethinking the whole issue; we propose there are opportunities to exploit space conditions, commonly seen as threats, to benefit space farming.
... Space biology research focuses on answering fundamental mechanistic questions about how molecular, cellular, tissue, and whole organismal life responds to the space environment. Biological stressors of spaceflight include ionizing radiation, altered gravitational fields, accelerated day-night cycles, confined isolation, hostile-closed environments, distance-duration from Earth 1 , planetary dust-regolith 2 , and extreme temperatures/atmospheres 3,4 . Moreover, spaceflight stressors are likely compounded and amplified with increasing time in space and distance from Earth 1,5 . ...
Space biology research aims to understand fundamental effects of spaceflight on organisms, develop foundational knowledge to support deep space exploration, and ultimately bioengineer spacecraft and habitats to stabilize the ecosystem of plants, crops, microbes, animals, and humans for sustained multi-planetary life. To advance these aims, the field leverages experiments, platforms, data, and model organisms from both spaceborne and ground-analog studies. As research is extended beyond low Earth orbit, experiments and platforms must be maximally autonomous, light, agile, and intelligent to expedite knowledge discovery. Here we present a summary of recommendations from a workshop organized by the National Aeronautics and Space Administration on artificial intelligence, machine learning, and modeling applications which offer key solutions toward these space biology challenges. In the next decade, the synthesis of artificial intelligence into the field of space biology will deepen the biological understanding of spaceflight effects, facilitate predictive modeling and analytics, support maximally autonomous and reproducible experiments, and efficiently manage spaceborne data and metadata, all with the goal to enable life to thrive in deep space.
... Astronauts face hazards unique to spaceflight such as ionizing radiation, altered gravitational fields, accelerated day-night cycles, confined isolation, hostile-closed environments, distance-duration from Earth 1 , planetary dust-regolith 2 , and extreme temperatures/atmospheres 3,4 . As astronauts experience these hazards, the body responds by adapting and deconditioning over the duration of the exposure with the potential for synergistic effects as the exposures persist 1,5 . ...
Human space exploration beyond low Earth orbit will involve missions of significant distance and duration. To effectively mitigate myriad space health hazards, paradigm shifts in data and space health systems are necessary to enable Earth-independence, rather than Earth-reliance. Promising developments in the fields of artificial intelligence and machine learning for biology and health can address these needs. We propose an appropriately autonomous and intelligent Precision Space Health system that will monitor, aggregate, and assess biomedical statuses; analyze and predict personalized adverse health outcomes; adapt and respond to newly accumulated data; and provide preventive, actionable, and timely insights to individual deep space crew members and iterative decision support to their crew medical officer. Here we present a summary of recommendations from a workshop organized by the National Aeronautics and Space Administration, on future applications of artificial intelligence in space biology and health. In the next decade, biomonitoring technology, biomarker science, spacecraft hardware, intelligent software, and streamlined data management must mature and be woven together into a Precision Space Health system to enable humanity to thrive in deep space.
... The results of our experiments also show that three species showed substantial growth at 80 mbar and 160 mbar (Supplementary Figures 27, 28), well below the 200-300 mbar lower limit generally proposed for flexible materials on Mars, and well below the value thought to be the limit for vascular plant growth (Hublitz et al., 2004;Paul and Ferl, 2006;Richards et al., 2006). Under these conditions of very low pressure (80 mbar), the growth rates of the cultures C. brevispina, D. salina, and C. vulgaris were relatively slow (with doubling times of ∼5-9 days, although these are comparable to C. brevispina growth under optimum conditions (Harrold et al., 2018). ...
With long-term missions to Mars and beyond that would not allow resupply, a self-sustaining Bioregenerative Life Support System (BLSS) is essential. Algae are promising candidates for BLSS due to their completely edible biomass, fast growth rates and ease of handling. Extremophilic algae such as snow algae and halophilic algae may also be especially suited for a BLSS because of their ability to grow under extreme conditions. However, as indicated from over 50 prior space studies examining algal growth, little is known about the growth of algae at close to Mars-relevant pressures. Here, we explored the potential for five algae species to produce oxygen and food under low-pressure conditions relevant to Mars. These included Chloromonas brevispina, Kremastochrysopsis austriaca, Dunaliella salina, Chlorella vulgaris, and Spirulina plantensis. The cultures were grown in duplicate in a low-pressure growth chamber at 670 ± 20 mbar, 330 ± 20 mbar, 160 ± 20 mbar, and 80 ± 2.5 mbar pressures under continuous light exposure (62–70 μmol m–2 s–1). The atmosphere was evacuated and purged with CO2 after sampling each week. Growth experiments showed that D. salina, C. brevispina, and C. vulgaris were the best candidates to be used for BLSS at low pressure. The highest carrying capacities for each species under low pressure conditions were achieved by D. salina at 160 mbar (30.0 ± 4.6 × 105 cells/ml), followed by C. brevispina at 330 mbar (19.8 ± 0.9 × 105 cells/ml) and C. vulgaris at 160 mbar (13.0 ± 1.5 × 105 cells/ml). C. brevispina, D. salina, and C. vulgaris all also displayed substantial growth at the lowest tested pressure of 80 mbar reaching concentrations of 43.4 ± 2.5 × 104, 15.8 ± 1.3 × 104, and 57.1 ± 4.5 × 104 cells per ml, respectively. These results indicate that these species are promising candidates for the development of a Mars-based BLSS using low pressure (∼200–300 mbar) greenhouses and inflatable structures that have already been conceptualized and designed.
... Though designed primarily for investigations on cyanobacterial behavior under atmospheres relevant to Mars-specific BLSS, Atmos can be used for other studies related to the physiology of microorganisms (as well as small plants) at low pressure. This area bears relevance to fields such as in-habitat BLSS, planetary protection, habitability, ecopoiesis, and aerobiology (Paul and Ferl, 2007;Schwendner and Schuerger, 2020;Verseux, 2020a). We intend for our device to support the astrobiology and BLSS communities through collaborative projects. ...
The leading space agencies aim for crewed missions to Mars in the coming decades. Among the associated challenges is the need to provide astronauts with life-support consumables and, for a Mars exploration program to be sustainable, most of those consumables should be generated on site. Research is being done to achieve this using cyanobacteria: fed from Mars's regolith and atmosphere, they would serve as a basis for biological life-support systems that rely on local materials. Efficiency will largely depend on cyanobacteria's behavior under artificial atmospheres: a compromise is needed between conditions that would be desirable from a purely engineering and logistical standpoint (by being close to conditions found on the Martian surface) and conditions that optimize cyanobacterial productivity. To help identify this compromise, we developed a low-pressure photobioreactor, dubbed Atmos, that can provide tightly regulated atmospheric conditions to nine cultivation chambers. We used it to study the effects of a 96% N 2 , 4% CO 2 gas mixture at a total pressure of 100 hPa on Anabaena sp. PCC 7938. We showed that those atmospheric conditions (referred to as MDA-1) can support the vigorous autotrophic, diazotrophic growth of cyanobacteria. We found that MDA-1 did not prevent Anabaena sp. from using an analog of Martian regolith (MGS-1) as a nutrient source. Finally, we demonstrated that cyanobacterial biomass grown under MDA-1 could be used for feeding secondary consumers (here, the heterotrophic bacterium E. coli W). Taken as a whole, our results suggest that a mixture of gases extracted from the Martian atmosphere, brought to approximately one tenth of Earth's pressure at sea level, would be suitable for photobioreactor modules of cyanobacterium-based life-support systems. This finding could greatly enhance the viability of such systems on Mars.
... Tactical and high altitude aviators confront inescapable physiological hazards of hypobaric hypoxia, venous gas emboli and decompression sickness (Paul & Ferl, 2006). A fractional inspired oxygen (F I,O 2 ) concentration of 100% confers resiliency against those risks (Ciarlone et al. 2019;Tarver & Cooper, 2020). ...
Key points
Extreme aviation is accompanied by ever‐present risks of hypobaric hypoxia and decompression sickness. Neuroprotection against those hazards is conferred through fractional inspired oxygen (FI,O2) concentrations of 60–100% (hyperoxia).
Hyperoxia reduces global cerebral perfusion (gCBF), increases reactive oxygen species within the brain and leads to cell death within the hippocampus. However, an understanding of hyperoxia's effect on cortical activity and concomitant levels of cognitive performance is lacking. This limits our understanding of whether hyperoxia could lower the brain's threshold of tolerance to physiological stressors inherent to extreme aviation, such as high gravitational forces.
This study aimed to quantify the impact of hyperoxia upon global cerebral perfusion (gCBF), cognitive performance and cortical electroencephalography (EEG).
Hyperoxia evoked a rapid reduction in gCBF, yet cognitive performance and vigilance were enhanced. EEG measurements revealed enhanced alpha power, suggesting less desynchrony, within the cortical temporal regions.
Collectively, this work suggests hyperoxia‐induced brain hypoperfusion is accompanied by enhanced cognitive processing and cortical arousal.
Abstract
Extreme aviators continually inspire hyperoxic gas to mitigate risk of hypoxia and decompression injury. This neuroprotection carries a physiological cost: reduced cerebral perfusion (CBF). As reduced CBF may increase vulnerability to ever‐present physiological challenges during extreme aviation, we defined the magnitude and duration of hyperoxia‐induced changes in CBF, cortical electrical activity and cognition in 30 healthy males and females. Magnetic resonance imaging with pulsed arterial spin labelling provided serial measurements of global CBF (gCBF), first during exposure to 21% inspired oxygen (FI,O2) followed by a 30‐min exposure to 100% FI,O2. High‐density EEG facilitated characterization of cortical activity during assessment of cognitive performance, also measured during exposure to 21% and 100% FI,O2. Acid‐base physiology was measured with arterial blood gases. We found that exposure to 100% FI,O2 reduced gCBF to 63% of baseline values across all participants. Cognitive performance testing at 21% FI,O2 was accompanied by increased theta and beta power with decreased alpha power across multiple cortical areas. During cognitive testing at 100% FI,O2, alpha activity was less desynchronized within the temporal regions than at 21% FI,O2. The collective hyperoxia‐induced changes in gCBF, cognitive performance and EEG were similar across observed partial pressures of arterial oxygen (PaO2), which ranged between 276–548 mmHg, and partial pressures of arterial carbon dioxide (PaCO2), which ranged between 34–50 mmHg. Sex did not influence gCBF response to 100% FI,O2. Our findings suggest hyperoxia‐induced reductions in gCBF evoke enhanced levels of cortical arousal and cognitive processing, similar to those occurring during a perceived threat.
... Here the focus is on bacteria, with occasional comparisons with fungi or eukaryotic microalgae. The reader interested in plants under hypobaria is referred to a review by Paul and Ferl (2006). ...
Biological life-support systems could greatly increase the sustainability of crewed missions to the Moon or Mars. Understanding how bacteria react to hypobaria is critical to their optimization: if enclosed within crewed compartments, microbial modules may be exposed to the lower-than-Earth atmospheric pressure considered for future space vehicles and habitats and, if deployed outside, they would best rely on a low pressure to minimize both engineering constraints and risks of leakage. Bacterial behavior at low pressures is of relevance to other fields as well, both within astrobiology (e.g., habitability and planetary protection) and outside of it (e.g., aerobiology and food preservation). Unfortunately, while microbial survival under vacuum has been largely investigated, little work has focused on metabolism at low but growth-permissive pressures. Nonetheless, recent studies brought some insights. Limits were outlined: a few bacterial species can grow just above water’s triple point, more can multiply down to around 25 mbar, and shifting pressure within 100 mbar to 1 bar seems not to largely affect growth of most species when the partial pressures of metabolizable gases are not limiting. Some mediating mechanisms have been proposed: hypobaria can affect bacteria by desiccation, via a reduced availability of specific gases, and through various other physico-chemical effects, interdependent and dependent on other environmental factors. A limited number of studies also gave insights into how bacteria cope with low pressure, and how much they can adapt to it. But, overall, much remains to be discovered on bacterial growth under hypobaric conditions.
... Average annual relative humidity (%) across the South Asian countries ranges from <25% to 100% across the South Asia (3). South Asian region has wider altitudinal variations ranging from sea level to 4000m above sea level (5) which additionally leads to variations in air pressure of different regions, since altitude and atmospheric pressure are negatively correlated (6). These climatic immoderations are challenging for human well-being, and climate change amplifies these challenges (2). ...
Background: The review of literature suggests that there is a dearth of meta-analytical study that examines the role of Atmospheric Variability on the prevalence of mental disorders in South Asia. Aims &Objectives: Therefore, the present study explores the moderating role of variability in temperature, air pressure, humidity, and rainfall on the prevalence of Common Psychiatric Disorders in South Asia. Material & Methods: Databases of several web sources, namely, EBSCOhost, PubMed, PsycINFO, and Google Scholar were explored for the studies that had previously observed the prevalence of psychiatric morbidity in South Asian countries. Further, articles were also examined manually. Initially, geographical locations (i.e. latitude, longitude, and altitude) of surveyed places were determined. Based on these locations, historical atmospheric data were retrieved. Meta-regression analysis was computed using R-software with 'metafor' package. Results: The present Meta-analysis included 32 epidemiological studies consisting of 110402 persons reported a total morbidity in 7935 persons across seven countries of South Asia. Yearly rainfall (z=2.8260, p<0.01), yearly variability in temperature (z=3.7160, p<0.001), yearly variability in humidity (z=-2.4031, p<0.05) appear to have a significant influence on the prevailing patterns of common psychiatric disorders. However, yearly variability in atmospheric pressure did not have a significant influence on the prevalence of mental disorders (z= 1.0364, p>0.300). Conclusion: Discomfort weather conditions such as yearly temperature variability, excessive rainfall, and yearly variability in humidity have a significant role in the occurrence and maintenance of different psychiatric disorders in South Asia.
... Fortunately, the adaptation process to high altitude takes place within a few weeks and participants should be acclimated to their new environment for their first measurement [104,184]. Nevertheless, high altitude at Concordia station is a good model of hypoxia and hypobaria conditions encountered during space missions [201]. ...
Since the Moon race in the 60s, human kind has continuously been orbiting Earth. However, before we can envision a permanent settlement on the Moon and explore our solar system, human physiology adaptation challenges need to be answered. Adequate sleep quantity and quality are required for good cognitive performances and chronic sleep restriction comes with a high cost. Sleep quality and sleep quantity are regulated by two interacting processes, the homeostatic and the circadian process. Electroencephalographic (EEG) theta activity (5-7Hz) during wakefulness reflects both the homeostatic and the circadian process. The circadian influence can be seen by a diurnal oscillation of theta activity. The homeostatic component, on the other hand, builds up with the time awake. Theta activity is therefore considered a sleep pressure marker and was associated with alertness and subjective daytime sleepiness. Intracranial recordings in rats showed that an increase of sleep pressure was also linked to neuronal "off" periods during wakefulness, similar to what can be recorded during slow waves sleep. These local sleep-like events during wakefulness have also been studied in the human EEG as markers of sleep pressure and widespread local sleep-like events are thought to be responsible for the decrease in cognitive performances under high sleep pressure conditions. Sleep quality and quantity in space will be key for maintaining astronaut’s cognitive functions and improving missions’ success rate. Even though astronauts are allocated enough time to sleep, a decrease of sleep quantity was reported on the International Space Station (ISS). Furthermore, for proper dissipation of sleep pressure, the quality of sleep is also important. In space, sleep quality might be impacted by external factors such as microgravity, isolation, confinement, circadian misalignment, chronic stress, temperature, light and noise disturbances. Besides space missions, analogue missions are opportunities to study human acclimatisation to space-like environment. Concordia station in Antarctica is one of the most remote human outpost on Earth. Studies conducted in Antarctica suggested that isolation, high altitude and constant darkness might disturb sleep in a similar fashion as on the ISS. In this thesis we investigated sleep pressure markers on the ISS. Then, to disentangle the effects of space environmental factors, we studied sleep pressure markers during a space analogue mission on Earth. Additionally, we studied sleep pressure's impact on cognitive performances and we explored novel countermeasures to enable human deep space travel. In this regard, we subdivided our work into three lines of research with three associated research papers.
