US Astronauts Research Articles

The role of oxygen and the Goldilocks range in the development of cataracts induced by space radiation in US astronauts

This article explores the role that oxygen levels in US spacecraft from 1961 to 1998 have on the development of cataracts induced by space radiation in astronauts and whether oxygen levels are well accounted for in experimental studies examining cataractogenesis. The first epidemiological report in 2001 linked an increased risk of the primary types of cataracts, and nuclear cataract alone, for astronauts with higher lens doses. However, later studies of US astronauts in 2009 and 2012 reported a higher risk of cortical cataract and posterior subcapsular cataract, but not for nuclear cataract. Firstly, it is postulated that the high oxygen level atmospheres of spacecraft employed before 1976 were a factor in promoting nuclear cataract. The high oxygen levels of hyperbaric oxygen therapy are reportedly associated with nuclear cataract, and the low intraocular oxygen levels of diabetic patients are possibly linked to their higher risk of posterior subcapsular cataract and cortical cataract. Secondly, it is hypothesized that the normal hypoxic environment of the lens and lens epithelial cells (LECs), and all stem/progenitor cells in general, have an optimal Goldilocks range of oxygen levels. Too high a lenticular oxygen level increases oxidative stress and radiosensitivity due to the oxygen effect. Whereas too low an oxygen tension also increases oxidative stress and disrupts LEC differentiation. Even so, a focused literature search of the PubMed database of in vitro experiments with LECs shows that studies rarely account for the hypoxic state of the normal lens, whether ionizing radiation is a factor or not. It is therefore recommended that ocular physioxic levels should therefore be considered when designing in vitro studies to better understand the progression of cataractogenesis on long-duration missions to the Moon and Mars.

SATELLITE OCEANOGRAPHY: HARNESSING THE TECHNOLOGICAL REVOLUTION

In 43 years since the first civilian ocean satellite, the Seasat, observations of the world’s oceans have progressed a lot. From color photographies taken by US astronauts during the first manned spaceflight programs back in the 60s to nano and picosatellites nowadays, Satellite Oceanography (SO) has allowed near real-time support capabilities for operational Oceanography and climate change studies. These outcomes can improve and contribute to the growth of the blue economy local, national and international by limiting the negative impact of climate change and the potential risks for aquaculture, fisheries, and environmental protection. Moreover, SO increases maritime situational awareness and surveillance for civilian purposes, accessing shipping routes, tracking illegal activities, and piracy. Therefore, the objective of this manuscript is to share some of the historical technical facts and needs that push SO observations and sensors forward to understanding our oceans and how they interact with our planet.
 Keywords: Nasa, Seasat, NOAA TIROS-N, Swot, CubeSats

Modeling Occupational Fingernail Onycholysis Disorders in the Population of US Astronauts Who Have Engaged in Extravehicular Activity.

Spacesuits are designed to be reliable personal spacecraft that preserve the life and well-being of the astronaut from the extremes of space. However, materials, operating pressures, and suit design requirements often result in a risk of musculoskeletal discomfort and injury to various areas of the body. In particular, this investigation looked at fingernails and their risk of developing onycholysis. An onycholysis literature review was followed by a retrospective analysis of injury characteristics, astronaut suited training and spaceflight events, hand anthropometry, glove sizing, and astronaut demographics. Multiple logistic regression was used to assess the likelihood of onycholysis occurrence by testing potential risk variables against the dataset compiled from the retrospective data mining. The duration of event exposure, type of glove used, distance (delta) between the fingertip and the tip of the glove, sex, and age were found to be significantly related to occurrence of onycholysis (whether protective or injurious). An initial risk formula (model) for onycholysis was developed as a result of this investigation. In addition to validation through a future study, further improvement to this onycholysis equation and spacesuit discomfort and injury in general can be aided by future investigations that lead to better definition of the threshold between safe and risky exposure for each type of risk factor. This work described a potential method that can be used for EVA spacesuit glove onycholysis injury risk analysis for either iterative glove design or between glove comparisons, such as during a product downselect process.

Novel Computerized Method for Automated Determination of Ventilatory Threshold and Respiratory Compensation Point.

Introduction: The ventilatory threshold (named as VT1) and the respiratory compensation point (named as VT2) describe prominent changes of metabolic demand and exercise intensity domains during an incremental exercise test.Methods: A novel computerized method based on the optimization method was developed for automatically determining VT1 and VT2 from expired air during a progressive maximal exercise test. A total of 109 peak cycle tests were performed by members of the US astronaut corps (74 males and 35 females). We compared the automatically determined VT1 and VT2 values against the visual subjective and independent analyses of three trained evaluators. We also characterized VT1 and VT2 and the respective absolute and relative work rates and distinguished differences between sexes.Results: The automated compared to the visual subjective values were analyzed for differences with t test, for agreement with Bland–Altman plots, and for equivalence with a two one-sided test approach. The results showed that the automated and visual subjective methods were statistically equivalent, and the proposed approach reliably determined VT1 and VT2 values. Females had lower absolute O2 uptake, work rate, and ventilation, and relative O2 uptake at VT1 and VT2 compared to men (p ≤ 0.04). VT1 and VT2 occurred at a greater relative percentage of their peak VO2 for females (67 and 88%) compared to males (55 and 74%; main effect for sex: p < 0.001). Overall, VT1 occurred at 58% of peak VO2, and VT2 occurred at 79% of peak VO2 (p < 0.0001).Conclusion: Improvements in determining of VT1 and VT2 by automated analysis are time efficient, valid, and comparable to subjective visual analysis and may provide valuable information in research and clinical practice as well as identifying exercise intensity domains of crewmembers in space.

Cancer incidence and mortality in the USA Astronaut Corps, 1959–2017

ObjectivesCancer incidence and mortality are important outcomes in the surveillance of long-term astronaut health. We compare cancer incidence rates, cancer-specific mortality rates, and cancer case-fatality ratios in US astronauts with...

Moonshot: Affordable, Simple, Flight Hardware for the Artemis-1 Mission and Beyond

Artemis is a NASA initiative to return US astronauts to the moon and beyond. Artemis includes a robust science program. A key to space-based biological science is the ability to construct high quality, efficacious scientific hardware cheaply and in a short time frame. We report the design and fabrication of affordable new flight hardware to support the growth of Chlamydomonas reinhardtii, a single-cell green alga on the Artemis-1 mission. Chlamydomonas reinhardtii, produces two products of great interest to space travel - lipids as a source of bioproducts and hydrogen a source of fuel. We will use this hardware to grow a library of mutant strains to identify Chlamydomonas reinhardtii genes that optimize survival and fuel production during exposure to the combined impacts of space radiation and microgravity in the cosmic space environment beyond the van Allen belts. Using fitness as a readout a library of mapped insertion mutant strains will be grown competitively during exposure to space radiation and microgravity. This report describes the hardware and the science verification test that validates its utility for missions ahead. This hardware can be easily adapted to a broad range of uses and microbes and its low cost will make space science affordable and practical.

Risk and fun: Dan Kiley’s interior landscape for the Ford Foundation

In December 1968, from aboard the Apollo 8 spacecraft, US astronaut Bill Anders photographed a radiant blue earth floating above the gray lunar horizon. Although the primary objective of the Apollo...

Contrapositive logic suggests space radiation not having a strong impact on mortality of US astronauts and Soviet and Russian cosmonauts

Space travelers are exposed to unique forms of ionizing radiation that pose potentially serious health hazards. Prior analyses have attempted to quantify excess mortality risk for astronauts exposed to space radiation, but low statistical power has frustrated inferences. If exposure to deep space radiation were causally linked to deaths due to two particular causes, e.g., cancer and cardiovascular disease, then those cause-specific deaths would not be statistically independent. In this case, a Kaplan-Meier survival curve for a specific cause that treats deaths due to competing causes as uninformative censored events would result in biased estimates of survival probabilities. Here we look for evidence of a deleterious effect of historical exposure to space radiation by assessing whether or not there is evidence for such bias in Kaplan-Meier estimates of survival probabilities for cardiovascular disease and cancer. Evidence of such bias may implicate space radiation as a common causal link to these two disease processes. An absence of such evidence would be evidence that no such common causal link to radiation exposure during space travel exists. We found that survival estimates from the Kaplan-Meier curves were largely congruent with those of competing risk methods, suggesting that if ionizing radiation is impacting the risk of death due to cancer and cardiovascular disease, the effect is not dramatic.

Impact Of Long-acting Reversible Contraceptives On Bone Density During Simulated Microgravity

Hormonal contraception is routinely used by premenopausal women, including female astronauts, to suppress ovarian function and menstrual cycling. Combined oral contraceptive pill (COC, ethinyl estradiol and progestin) use leads to a suppression of bone turnover and reduced bone mineral density (BMD) gain with long-term exercise. Long-acting, reversible contraceptives (LARC, progestin-only) provide many practical advantages over COC. With increasing numbers of women in the US astronaut corps, we risk sending female crew members into microgravity without a clear understanding of the impact of LARC use on bone health. PURPOSE: We hypothesize that LARC use will blunt decreases in BMD associated with hindlimb unloading (HU). METHODS: Virgin female Sprague-Dawley rats (n=26; 4-mo-old) were singly housed and randomly assigned to placebo and LARC groups, via a slow-release etonogestrel pellet (0.00ug/d vs. 0.30ug/d) implanted under the skin. Animals were further randomized into ambulatory and HU subgroups (n=6-7/subgroup), with HU initiated a week following pellet insertion and lasting for 6 weeks. Pre/post HU, proximal tibia metaphysis (PTM) were scanned in vivo with peripheral quantitative computed tomography (pQCT). Univariate and repeated measures 2-way ANOVA were used. RESULTS: There was a time*loading group interaction (p<0.01) for body weight and food consumption. HU animals weighed less over the last 4 weeks of the study but consumed more food over 6 weeks of HU vs. ambulatory animals. Soleus wet weights were significantly lower in HU compared to ambulatory animals (p<0.001). There was a main effect of time for (p<0.001) PTM total, cancellous, and cortical volumetric BMD and total and cortical areas. For marrow area at the PTM there was a time*loading group interaction (p=0.044), such that over time the HU animals had a decrease in marrow area compared to the ambulatory animals. No impact of LARC on these outcomes was detected. CONCLUSIONS: Early results indicate that LARC use does not alter the PTM bone response to mechanical unloading of simulated microgravity assessed by in vivo pQCT. This work is supported by the Translational Research Institute for Space Health through Cooperative Agreement NNX16AO69A.

Drug Interactions in Space: a Cause for Concern?

Crewmembers aboard the International Space Station (ISS) have free access to an increasing number of medications within medical kits. The aim of the current study was to assess the number, severity and reliability of potential drug-drug interactions (DDIs) involving those medications. We evaluated the information obtained from clinical decision support systems. Searches for potential DDIs were applied to published lists of medications available to US astronauts in medical kits aboard the ISS. A total of 311 potential DDIs were identified by Lexi-Interact, of which approximately half were recognized by Micromedex as well. Major, moderate and minor interactions consisted 23.5%, 68.5% and 8.0% of entries, respectively. The reliability of 71.1% of alerts was fair. Commonly used drugs, including zolpidem and zaleplon, were involved in multiple potential interactions that were classified as major based on additive CNS depression. Most potential DDIs likely to be encountered in space are unestablished even in terrestrial medicine and their assignment is based on class-effects. Yet, some drug combinations may be associated with clinically-relevant consequences. Future DDI rating should be adjusted to space-related outcomes. Until that happens, it would be advisable to avoid non-established drug combinations in space when possible.

Alterations in Nitric Oxide‐Mediated Signals in Coronary Arteries Following Spaceflight

Proportional cardiovascular disease mortality rates are not different between US astronauts that have flown in low Earth orbit (LEO) and those that have never flown orbital missions in space. While these data suggest that spaceflight (SF) in LEO holds nominal long‐term cardiovascular health consequences, to date the acute effect of SF on coronary artery function has not been explored. The purpose of this study was to examine murine coronary artery contractile, dilatory, and mechanical properties following SF in LEO aboard the International Space Station (ISS). Twenty C57BL/6J mice were housed in a specially designed rodent habitat and were launched to the ISS aboard a Falcon 9 rocket (Space‐X CRS‐12). Following ~33 days of SF in LEO, the Dragon capsule containing the mice splashed down in the Pacific Ocean. Within 33–41 hours of returning to Earth, the left anterior descending (LAD) coronary arteries were cleared of surrounding cardiac tissue and mounted in a Danish Myotech wire myograph. LADs were then exposed to agonists that allowed for the examination of endothelial (EC) and smooth muscle cell (SMC) function. Vivarium controls (VC), consisting of mice housed in conventional vivarium cages, and habitat controls (HC), which were housed in the same type cages as those flown on orbit and maintained under similar pCO2, temperature, humidity, and light conditions, were used for comparison. The passive pressure‐diameter relationship was not different between SF and either control. SMC‐dependent vasoconstriction to U46619, a thromboxane receptor agonist, was significantly greater in HC versus SF at only a single dose, while vasoconstriction to isosmotic KCl was unaltered. LADs from SF mice preconstricted with U46619 exhibited similar EC‐dependent vasodilation to the muscarinic receptor agonist acetylcholine when compared to VC and HC. Acetylcholine and ADPβS (a P2Y1 receptor agonist)‐mediated vasodilation were completely absent in all LADs preconstricted with KCl in the presence of the nitric oxide synthase inhibitor, L‐NAME. In vessels preconstricted with U46619 vasodilation to the EC‐dependent vasodilator ADPβS was similar between SF and both controls, with SF LADs exhibiting less dependence on nitric oxide (NO)‐mediated mechanisms as observed in the presence of L‐NAME. LADs from SF mice exhibited a right‐ward shift to the NO donor and SMC‐dependent vasodilator, DEA NONOate. Collectively, these data suggest that subtle changes in LAD function occur following spaceflight in LEO. In particular, NO‐mediated signals were the most affected, as indicated by decreased SMC sensitivity to exogenous NO. In addition, while the magnitude of vasodilation to ADPβS was unchanged, SF animals exhibited less dependence on NO‐mediated signals. These ADPβS responses suggest a shift away from the canonical NO‐mediated pathway of vasodilation. These data represent the first examination of coronary artery function following SF and suggest that function is well maintained due to subtle mechanistic adaptations.Support or Funding InformationThis work was supported by NASA Space Biology grant NNX16AC28G.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Self-Reported Skin Changes by a Selected Number of Astronauts after Long-Duration Mission on ISS as Part of the Skin B Project

Background: One of the most challenging and important factors of manned space missions is to keep astronauts healthy on orbit. In a study on 46 ISS crew members who were on 6-month (average) missions, skin rashes were the most self-reported event. Furthermore, among notable events, 40% were classified as skin rashes/hypersensitivities. Thus, especially skin conditions during space travel are of major clinical interest and require further research. Aims: The aim of the study was to determine skin conditions in space flight among US and European astronauts, especially taking into account the terrestrial skin conditions as well as on-orbit skin care habits. Methods: A preflight questionnaire was given to the astronauts asking about their terrestrial skin care habits and skin conditions/atopy before launch. In addition, they were asked to fill out a postflight questionnaire asking about their on-orbit skin care routine and whether any special observations regarding the skin were made during flight. Results: A total of 23 skin symptoms were recorded by 8 nonatopic astronauts (mean age: 41 years) during the mission. The symptoms were peeling (21.74%), rash (17.39%), dryness (13.04%), severe dryness (8.70%), reddening (8.70%), itchiness (8.70%), bruising (4.35%), skin sensitivity (4.34%), bumps (4.35%), acne (4.35%) and slow healing of contusions and lacerations (4.35%). Especially the hands and feet were affected by skin problems. As a result of this examination, it was shown that the skin symptoms correlate with poor hygiene on orbit, whereas the factor “environment” on the ISS plays a minor role. Surprisingly, 2 astronauts even experienced positive effects on their skin. Conclusion: Based on these preliminary data, it is important to pay more attention to skin hygiene and maintenance in space.

Russian space agency to investigate Soyuz rocket crash

A Russian cosmonaut and a US astronaut are safe after their rocket, bound for the International Space Station, malfunctioned. A Russian cosmonaut and a US astronaut are safe after their rocket, bound for the International Space Station, malfunctioned.

Trump tells NASA to return to the Moon

US astronauts last visited the lunar surface in the 1970s. US astronauts last visited the lunar surface in the 1970s.

Get the girl to check the numbers

In 1962, the first US astronaut to go into orbit entrusted one person with his life, the mathematician and space pioneer Katherine Johnson

Personalized Cancer Risk Assessments for Space Radiation Exposures.

Individuals differ in their susceptibility to radiogenic cancers, and there is evidence that this inter-individual susceptibility extends to HZE ion-induced carcinogenesis. Three components of individual risk: sex, age at exposure, and prior tobacco use, are already incorporated into the NASA cancer risk model used to determine safe days in space for US astronauts. Here, we examine other risk factors that could potentially be included in risk calculations. These include personal and family medical history, the presence of pre-malignant cells that could undergo malignant transformation as a consequence of radiation exposure, the results from phenotypic assays of radiosensitivity, heritable genetic polymorphisms associated with radiosensitivity, and postflight monitoring. Inclusion of these additional risk or risk reduction factors has the potential to personalize risk estimates for individual astronauts and could influence the determination of safe days in space. We consider how this type of assessment could be used and explore how the provisions of the federal Genetic Information Non-discrimination Act could impact the collection, dissemination and use of this information by NASA.

Adjustment of lifetime risks of space radiation-induced cancer by the healthy worker effect and cancer misclassification.

Background. The healthy worker effect (HWE) is a source of bias in occupational studies of mortality among workers caused by use of comparative disease rates based on public data, which include mortality of unhealthy members of the public who are screened out of the workplace. For the US astronaut corp, the HWE is assumed to be strong due to the rigorous medical selection and surveillance. This investigation focused on the effect of correcting for HWE on projected lifetime risk estimates for radiation-induced cancer mortality and incidence.Methods. We performed radiation-induced cancer risk assessment using Poisson regression of cancer mortality and incidence rates among Hiroshima and Nagasaki atomic bomb survivors. Regression coefficients were used for generating risk coefficients for the excess absolute, transfer, and excess relative models. Excess lifetime risks (ELR) for radiation exposure and baseline lifetime risks (BLR) were adjusted for the HWE using standardized mortality ratios (SMR) for aviators and nuclear workers who were occupationally exposed to ionizing radiation. We also adjusted lifetime risks by cancer mortality misclassification among atomic bomb survivors.Results. For all cancers combined (“Nonleukemia”), the effect of adjusting the all-cause hazard rate by the simulated quantiles of the all-cause SMR resulted in a mean difference (not percent difference) in ELR of 0.65% and mean difference of 4% for mortality BLR, and mean change of 6.2% in BLR for incidence. The effect of adjusting the excess (radiation-induced) cancer rate or baseline cancer hazard rate by simulated quantiles of cancer-specific SMRs resulted in a mean difference of in the all-cancer mortality ELR and mean difference of in the mortality BLR. Whereas for incidence, the effect of adjusting by cancer-specific SMRs resulted in a mean change of for the all-cancer BLR. Only cancer mortality risks were adjusted by simulated quantiles for misclassification, and results indicate a mean change of 1.1% for all-cancer mortality ELR, while the mean change in the all-cancer PC was approximately 4% for males and 6% for females.Conclusions. The typical life table approach for projecting lifetime risk of radiation-induced cancer mortality and incidence for astronauts and radiation workers can be improved by adjusting for HWE while simulating the uncertainty of input rates, input excess risk coefficients, and bias correction factors during multiple Monte Carlo realizations of the life table.

Alterations in Lumbar Paraspinal Muscle Structure after Long Duration Spaceflight and Recovery

Spaceflight results in moderate to severe lumbar pain in some astronauts. Moreover, the incidence of herniated nucleus pulposus is about four times greater in US astronauts, as compared to matched controls. In addition, it is unclear if exercise countermeasures during their International Space Station (ISS) missions prevent lumbar paraspinal muscle deconditioning. PURPOSE: To quantify functional paraspinal muscle cross sectional area before, immediately after, and 30-days after 6-month ISS missions. METHODS: To date complete data sets of three astronauts were available for this MRI paraspinal muscle cross sectional area study. Functional cross-sectional area (FCSA) was measured in four lumbar paraspinal muscles (multifidus, erector spinae, quadratus lumborum, and psoas) at lumbar vertebral level 3/4. The FCSA was measured by setting a threshold to isolate altered lean muscle. RESULTS: Long duration spaceflight produced a significant mean 15.1% decrease (p=0.023) in total lumbar paraspinal muscle (multifidus, erector spinae, quadratus lumborum, and psoas) FCSA of the three crewmemebers, as compared to before flight (Table 1). In addition, approximately 63% of this FCSA loss recovered by 30-days after their ISS mission and was not significantly different from before flight (p=0.152). CONCLUSION: These early data indicate that the exercises conducted by these crewmembers did not mitigate decrements in lumbar paraspinal muscle FCSA during spaceflight. However, post-flight recovery activities resulted in a 63% recovery 30-days after their mission. Therefore, these data suggest that spaceflight induced back pain and elevated disc herniation risk may be partly related to reduced dynamic trunk stability linked to atrophied lumbar paraspinal muscles. Supported by NASA grant # NNX13AM89G (to ARH) and NSBRI through NASA NCC 9-58 (to BRM).

High-Intensity Resistive and Rowing Exercises Do Not Prevent Orthostatic Intolerance after 70 Days of Bed Rest

More than 60% of US astronauts participating in Mir and early International Space Station missions (>5 months) were unable to complete a 10-min 80 head-up tilt test on landing day. This high incidence of post-spaceflight orthostatic intolerance may be related to limitations of the in-flight exercise hardware that prevented high-intensity training. PURPOSE: To determine whether a countermeasure program that included intense lower-body resistive and rowing exercises designed to prevent cardiovascular and musculoskeletal deconditioning during 70 d of 6 head-down-tilt bed rest (BR), a spaceflight analog, also would protect against post-BR orthostatic intolerance. METHODS: Sixteen men participated in this study and performed either no exercise (Control, n=10) or an intense exercise protocol with resistive and aerobic components (Exercise, n=6). On 3 d/wk, Exercise subjects performed supine lower-body resistive exercise and a 30-min continuous bout of upright seated rowing (≥75% max heart rate) separated by 4 hr. On 3 other d/wk, Exercise subjects performed high-intensity interval rowing. Orthostatic intolerance was assessed using a 15-min 80 head-up tilt test performed 2 d before (BR-2) and on the last day of BR (BR70). Plasma volume was measured using a carbon monoxide rebreathing technique on BR-3 and before rising on the first recovery day (BR+0). RESULTS: After 70 d of BR, tilt tolerance time significantly decreased 34±31% (mean ±SD) in the Control subjects (BR-2: 15.0±0.0, BR70: 9.9±4.6 min) and by 56±16% in Exercise subjects (BR-2: 12.2±4.7, BR70: 4.9±1.9 min), with no difference between groups. Plasma volume also decreased from pre to post-BR in both groups (Control: -0.56±0.40, Exercise: -0.48±0.33 L), with no between group differences. CONCLUSIONS: Despite the combination of high intensity aerobic with resistive exercise during prolonged BR, orthostatic intolerance and plasma volume losses were evident, similar to previously results observed in shorter duration BR that used less comprehensive exercise protocols. These data suggest the need to continue to investigate novel or combinations of countermeasures, including periodic orthostatic stress, fluid repletion, and/or lower-body compression garments to minimize orthostatic intolerance following spaceflight.

Lumbar Paraspinal Muscle Atrophy during Long Duration Spaceflight

Spaceflight results in significant lumbar pain and muscle atrophy in astronauts. The rate of disc herniation is about four times greater in US astronauts than in matched controls. Muscles are vital spine stabilizers, and trunk muscle atrophy is associated with chronic back pain. Yet, it is unclear whether current countermeasures during 6‐month International Space Station (ISS) missions prevent lumbar paraspinal muscle atrophy.PURPOSETo quantify paraspinal muscle functional cross sectional area (FCSA) before, immediately after, and 30‐days after 6‐month ISS missions.METHODSTo date, complete paraspinal MRI data for three astronauts were available. FCSA was measured in four lumbar paraspinal muscles (multifidus, erector spinae, quadratus lumborum, and psoas) at lumbar vertebral level 3/4. FCSA was measured by setting a threshold to isolate lean muscle.RESULTSLong duration spaceflight produced a significant 15.1% decrease (p=0.023) in total lumbar paraspinal muscle FCSA, as compared to before flight (Table 1). Subsequently 63.3% of FCSA loss was recovered by 30‐days post flight and was not significantly different from before flight (p=0.152).imageCONCLUSIONDespite low sample size, paraspinal muscle atrophy is not prevented by current countermeasures on 6‐month ISS missions. However, recovery activities resulted in a 63% recovery 30‐days post flight. This suggests spaceflight induced back pain and disc herniation risk may be partly related to reduced dynamic trunk stability linked to atrophied lumbar paraspinal muscles.Project supported by NASA grant # NNX13AM89G (to ARH) and NSBRI through NASA NCC 9‐58 (to BRM).