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Concept: Human spaceflight


As multiple spacefaring nations contemplate extended manned missions to Mars and the Moon, health risks could be elevated as travel goes beyond the Earth’s protective magnetosphere into the more intense deep space radiation environment. The primary purpose of this study was to determine whether mortality rates due to cardiovascular disease (CVD), cancer, accidents and all other causes of death differ in (1) astronauts who never flew orbital missions in space, (2) astronauts who flew only in low Earth orbit (LEO), and (3) Apollo lunar astronauts, the only humans to have traveled beyond Earth’s magnetosphere. Results show there were no differences in CVD mortality rate between non-flight (9%) and LEO (11%) astronauts. However, the CVD mortality rate among Apollo lunar astronauts (43%) was 4-5 times higher than in non-flight and LEO astronauts. To test a possible mechanistic basis for these findings, a secondary purpose was to determine the long-term effects of simulated weightlessness and space-relevant total-body irradiation on vascular responsiveness in mice. The results demonstrate that space-relevant irradiation induces a sustained vascular endothelial cell dysfunction. Such impairment is known to lead to occlusive artery disease, and may be an important risk factor for CVD among astronauts exposed to deep space radiation.

Concepts: Mortality rate, Atherosclerosis, Earth's magnetic field, Earth, Blood vessel, Moon, Endothelium, Human spaceflight


Manned space flight induces a reduction in immune competence among crew and is likely to cause deleterious changes to the composition of the gastrointestinal, nasal, and respiratory bacterial flora, leading to an increased risk of infection. The space flight environment may also affect the susceptibility of microorganisms within the spacecraft to antibiotics, key components of flown medical kits, and may modify the virulence characteristics of bacteria and other microorganisms that contaminate the fabric of the International Space Station and other flight platforms. This review will consider the impact of true and simulated microgravity and other characteristics of the space flight environment on bacterial cell behavior in relation to the potential for serious infections that may appear during missions to astronomical objects beyond low Earth orbit.

Concepts: Bacteria, Antibiotic, Microorganism, International Space Station, Space exploration, Human spaceflight, Spaceflight, Satellite


The International Space Station (ISS) is a unique built environment due to the effects of microgravity, space radiation, elevated carbon dioxide levels, and especially continuous human habitation. Understanding the composition of the ISS microbial community will facilitate further development of safety and maintenance practices. The primary goal of this study was to characterize the viable microbiome of the ISS-built environment. A second objective was to determine if the built environments of Earth-based cleanrooms associated with space exploration are an appropriate model of the ISS environment.

Concepts: Carbon dioxide, Natural environment, International Space Station, Space exploration, Mir, Human spaceflight, Outer space, Space Shuttle


This paper demonstrates the significant utility of deploying non-traditional biological techniques to harness available volatiles and waste resources on manned missions to explore the Moon and Mars. Compared with anticipated non-biological approaches, it is determined that for 916 day Martian missions: 205 days of high-quality methane and oxygen Mars bioproduction with Methanobacterium thermoautotrophicum can reduce the mass of a Martian fuel-manufacture plant by 56%; 496 days of biomass generation with Arthrospira platensis and Arthrospira maxima on Mars can decrease the shipped wet-food mixed-menu mass for a Mars stay and a one-way voyage by 38%; 202 days of Mars polyhydroxybutyrate synthesis with Cupriavidus necator can lower the shipped mass to three-dimensional print a 120 m(3) six-person habitat by 85% and a few days of acetaminophen production with engineered Synechocystis sp. PCC 6803 can completely replenish expired or irradiated stocks of the pharmaceutical, thereby providing independence from unmanned resupply spacecraft that take up to 210 days to arrive. Analogous outcomes are included for lunar missions. Because of the benign assumptions involved, the results provide a glimpse of the intriguing potential of ‘space synthetic biology’, and help focus related efforts for immediate, near-term impact.

Concepts: Solar System, Mars, Moon, Spacecraft, Space exploration, Human spaceflight, NASA, Robotic spacecraft


On May 5, 1961, astronaut Alan Shepard became the first American to fly in space. Although National Aeronautics and Space Administration (NASA) had discounted the need for him to urinate, Shepard did, in his spacesuit, short circuiting his electronic biosensors. With the development of the pressure suit needed for high-altitude and space flight during the 1950s, technicians had developed the means for urine collection. However, cultural mores, combined with a lack of interagency communication, and the technical difficulties of spaceflight made human waste collection a difficult task. Despite the difficulties, technicians at NASA created a successful urine collection device that John Glenn wore on the first Mercury orbital flight on February 20, 1962. With minor modifications, male astronauts used this system to collect urine until the Space Shuttle program. John Glenn’s urine collection device is at the National Air and Space Museum and has been on view to the public since 1976.

Concepts: Spacecraft, International Space Station, Space exploration, Human spaceflight, NASA, Outer space, Space Shuttle, John Glenn


A number of ophthalmic findings including optic disc edema, globe flattening, and choroidal folds have been observed in several astronauts after long-duration space flights. The authors report the first astronaut with previously documented postflight ophthalmic abnormalities who developed new pathological changes after a repeat long-duration mission.

Concepts: Force, Human spaceflight, Spaceflight, Flight, Rocket, Astronaut


The success of interplanetary human spaceflight will depend on many factors, including the behavioral activity levels, sleep, and circadian timing of crews exposed to prolonged microgravity and confinement. To address the effects of the latter, we used a high-fidelity ground simulation of a Mars mission to objectively track sleep-wake dynamics in a multinational crew of six during 520 d of confined isolation. Measurements included continuous recordings of wrist actigraphy and light exposure (4.396 million min) and weekly computer-based neurobehavioral assessments (n = 888) to identify changes in the crew’s activity levels, sleep quantity and quality, sleep-wake periodicity, vigilance performance, and workload throughout the record-long 17 mo of mission confinement. Actigraphy revealed that crew sedentariness increased across the mission as evident in decreased waking movement (i.e., hypokinesis) and increased sleep and rest times. Light exposure decreased during the mission. The majority of crewmembers also experienced one or more disturbances of sleep quality, vigilance deficits, or altered sleep-wake periodicity and timing, suggesting inadequate circadian entrainment. The results point to the need to identify markers of differential vulnerability to hypokinesis and sleep-wake changes during the prolonged isolation of exploration spaceflight and the need to ensure maintenance of circadian entrainment, sleep quantity and quality, and optimal activity levels during exploration missions. Therefore, successful adaptation to such missions will require crew to transit in spacecraft and live in surface habitats that instantiate aspects of Earth’s geophysical signals (appropriately timed light exposure, food intake, exercise) required for temporal organization and maintenance of human behavior.

Concepts: Time, Psychology, Behavior, Human behavior, Circadian rhythm, Spacecraft, Space exploration, Human spaceflight



Understanding the effects of spaceflight on microbial communities is crucial for the success of long-term, manned space missions. Surface-associated bacterial communities, known as biofilms, were abundant on the Mir space station and continue to be a challenge on the International Space Station. The health and safety hazards linked to the development of biofilms are of particular concern due to the suppression of immune function observed during spaceflight. While planktonic cultures of microbes have indicated that spaceflight can lead to increases in growth and virulence, the effects of spaceflight on biofilm development and physiology remain unclear. To address this issue, Pseudomonas aeruginosa was cultured during two Space Shuttle Atlantis missions: STS-132 and STS-135, and the biofilms formed during spaceflight were characterized. Spaceflight was observed to increase the number of viable cells, biofilm biomass, and thickness relative to normal gravity controls. Moreover, the biofilms formed during spaceflight exhibited a column-and-canopy structure that has not been observed on Earth. The increase in the amount of biofilms and the formation of the novel architecture during spaceflight were observed to be independent of carbon source and phosphate concentrations in the media. However, flagella-driven motility was shown to be essential for the formation of this biofilm architecture during spaceflight. These findings represent the first evidence that spaceflight affects community-level behaviors of bacteria and highlight the importance of understanding how both harmful and beneficial human-microbe interactions may be altered during spaceflight.

Concepts: Bacteria, Pseudomonas aeruginosa, Spacecraft, International Space Station, Space exploration, Mir, Human spaceflight, Space Shuttle


This investigation was designed to measure aerobic capacity (VO2peak) during and after long-duration International Space Station (ISS) missions. Astronauts (9 M, 5 F: 49 ± 5 yr, 77.2 ± 15.1 kg, 40.6 ± 6.4 ml/kg/min [mean ±SD]) performed peak cycle tests ~90 days before flight, 15 days after launch (FD15), every ~30 days in-flight, and on recovery days 1 (R+1), R+10, and R+30. Expired metabolic gas fractions, ventilation and heart rate (HR) were measured. Data were analyzed using mixed-model linear regression. The main findings of this study were that VO2peak decreased early in-flight (~17%) then gradually increased during flight but never returned to preflight levels. VO2peak was lower on R+1 and R+10 than preflight, but recovered by R+30. Peak HR was not different from preflight at any time during or following flight. A sustained decrease in VO2peak during and/or early postflight was not a universal finding in this study, as 7 astronauts were able to attain their preflight VO2peak levels either at some time during flight or on R+1. Four of these astronauts performed in-flight exercise at higher intensities compared to those who experienced a decline in VO2peak, and three had low aerobic capacities prior to flight. These data indicate that, while VO2peak may be difficult to maintain during long-duration ISS missions, aerobic deconditioning is not an inevitable consequence of long-duration spaceflight.

Concepts: Measurement, Exercise physiology, International Space Station, Space exploration, Mir, Human spaceflight, Rocket, Space station