Astronauts are at risk of losing 1.0% to 1.5% of their bone mass for every month they spend in space despite their adherence to diets and exercise regimens designed to protect their musculoskeletal systems. This loss is the result of microgravity-related impairment of osteocyte and osteoblast function and the consequent upregulation of osteoclast-mediated bone resorption. This review describes the ontogeny of osteoclast hematopoietic stem cells and the contributions macrophage colony stimulating factor, receptor activator of the nuclear factor-kappa B ligand, and the calcineurin pathways make in osteoclast differentiation and provides details of bone formation, the osteoclast cytoskeleton, the immune regulation of osteoclasts, and osteoclast mechanotransduction on Earth, in space, and under conditions of simulated microgravity. The article discusses the need to better understand how osteoclasts are able to function in zero gravity and reviews current and prospective therapies that may be used to treat osteoclast-mediated bone disease.

This study investigates funding within the US human spaceflight program in the timeperiod from 2004 to 2012. The approach taken employed the “potential well” model from physical science. The potential well model constrains any physical body trapped within it, and similarly a political “funding well” will constrain all programmatic decision-making. Two potential well models are employed, one represents classical physics while the other represents quantum physics. Since each model results in motion with certain properties, it can be seen if funding decisions also exhibit similar properties. In physics, the bifurcation between the classical world of aggregate bodies and the quantum world of individual particles is an indicator of deeper physical principles. This study seeks to explore whether this bifurcation exists in the political world as well. If so, it would help explain space policy evolution from 2004 to 2012, and provide evidence concerning the usefulness of physical models for discovering further trends in social science, including political science. The study of a bifurcation in space policy political decision-making resulted in an unclear relationship since some properties were found to be similar to their physical counterpart, some were found to be different, and one property, the quantization of funding into discrete increments, was absent from political decision-making. Further studies are required to explore this bifurcation in greater detail. However, the potential well did prove to be a powerful model in explaining the evolution of human spaceflight policy in 2004 to 2012 as it provided a framework to explain dynamics that may have otherwise remained unclear

Yes / Background: Understanding and countering the well-established negative health consequences of spaceflight remains a primary challenge preventing safe deep space exploration. Targeted/personalized therapeutics are at the forefront of space medicine strategies, and cross-species molecular signatures now define the 'typical' spaceflight response. However, a lack of direct genotype-phenotype associations currently limits the robustness and, therefore, the therapeutic utility of putative mechanisms underpinning pathological changes in flight. Methods: We employed the worm Caenorhabditis elegans as a validated model of space biology, combined with 'NemaFlex-S' microfluidic devices for assessing animal strength production as one of the most reproducible physiological responses to spaceflight. Wild-type and dys-1 (BZ33) strains (a Duchenne muscular dystrophy (DMD) model for comparing predisposed muscle weak animals) were cultured on the International Space Station in chemically defined media before loading second-generation gravid adults into NemaFlex-S devices to assess individual animal strength. These same cultures were then frozen on orbit before returning to Earth for next-generation sequencing transcriptomic analysis. Results: Neuromuscular strength was lower in flight versus ground controls (16.6% decline, p

<p>Although decades of experience in human spaceflight have produced and refined a wealth of operational knowledge, the unique challenges posed to long-term extraterrestrial surface habitats will require new approaches to mission design. The key objectives of this thesis are to develop an understanding of 1) how to use simulation to study these habitats and 2) how to make contingency plans for these habitats under complex, changing conditions. In order to accurately represent the challenges posed, we identify the common qualities of mission architectures that are likely to be present in near-future habitats. These qualities are used to formulate sample crew schedules that contribute to developing realistic models for meaningful research. We discuss the development of such models and demonstrate the suitability of simulation to enable the design and study of resilient space habitats. Simulation can be used as a tool to understand the challenges and consequences associated with decision making, as well as the importance of resilient design choices in a hazard-prone environment. We then identify aspects of vulnerability in space habitat mission operations, the subfactors that influence changes in habitat vulnerability, and the effects of each identified category of vulnerability. These ‘vulnerability factors’ are subsystem availability, environmental conditions, safety control options, and recent events. Each vulnerability factor has several subfactors that influence its change during a mission.</p> <p><br></p> <p>The set of vulnerability factors is significant because each captures some category of behavior in surface habitats that changes over time and impacts the likelihood or consequences of risks to the habitat. We use these vulnerability factors to formulate six research questions which can be addressed via simulation-based research. A simulation set plan is developed to highlight the significant concepts at play in each research question. Finally, we conduct trials and analyses of these questions via simulation by injecting faults into a modular coupled virtual testbed for space habitats. The results of the simulations are used to develop lists of key implications for each vulnerability factor in practice. In addition, the lessons learned over the course of simulation set design and the usage of the simulation tool are discussed to support future simulation-based research efforts. We conclude by summarizing the major findings and potential for future work in the area.</p>

The concept of using the vibration transmitted through the structure of space systems whilst they are in flight for monitoring purposes is proposed and analysed.The performed patent review seems to indicate that this technique is not currently used despite being, in principle, a good way to obtain valuable knowledge about the spacecraft’s condition. Potential sources of vibration were listed and some of them were down-selected via a trade-off analysis for implementation in a numerical model of a CubeSat structure. Models were proposed for the sources chosen and implemented in the Ansys Workbench software, along with a simplified structure designed to be representative of a generic picosatellite mission.The results confirmed very different amplitude and frequency ranges for the sources of interest, which would make it difficult to monitor them with one type of sensor.Basic system requirements for accelerometer operating under space conditions were derived and commercial sources were identified as already having the technologies needed.The conclusion was a positive evaluation of the overall concept, although revising negatively the initial expectations for its performance due to the diversity encountered in the sources.

The most pressing barriers between reality and the dream of the first African astronaut in space are a lack of resources, cooperation, and support. However, Nigeria presently suffers from the threat of famine, intercommunal violence, and population displacement as a result of terrorism and food insecurity. The reliance upon humanitarian aid from countries such as the United States and international NGOs creates a question of whether Nigeria should even be considering exploration of space. It can be said that any investment into space should instead be granted to displaced people, water and food security, and cracking down on terrorism. Why should a developing country go to space? And what benefits would human space flight provide to people struggling on earth? Economically, the benefits of sending an African into orbit reap effects such as a significant return in investment for the space sector of the continent. Socially, cultural and national pride, international respect, and historical reverence are certainly guaranteed by this accomplishment. There is always a risk in human space flight, be it political or economic investment. There is the risk that the country would be scrutinized for looking to the stars instead of to their own conflict-riddled soil. There is the risk that if a mission fails, money will be wasted and lives needlessly lost. There is a risk that success in the sky will be short-lived, or that political corruption may collapse the foundations of this venture. However, where there is risk, there is also opportunity. There is an opportunity to create stronger diplomatic relationships with other space-interested nations who seek to invest in Africa as a launching point for their own expeditions. There is an opportunity to begin an economic and cultural legacy of African-based space exploration, a legacy that provides secure jobs and education to African citizens and invites international investment and interest. And of course, there is opportunity to put the first African astronaut into space. Conclusively, the quickest and most cost-efficient method to launch an African astronaut into space is by international collaboration on a lunar mission, a space station, or low-earth orbit. This, however, is a short-term solution. For a long-lasting investment into space, the true answer is to create a continental space agency for Africa that would permit its countries to embark on space-faring journeys at their own will. Reliance on foreign countries can solidify or promote diplomatic relations, but it will not improve the local situation in Africa. This requires the collaboration of involved African countries as well as a feasible economic plan to maintain such an organization. The ownership of African spaceports, with the provision of access to partnering countries, would give the continent leverage in international affairs, grant jobs to African citizens, and grant a prosperous stake in the future colonization and exploration of space.

No description available.

Au cours de ma thèse, j'ai étudié l'impact des stress associés aux vols spatiaux sur l'immunité humorale du pleurodèle et de la souris. Chez le pleurodèle adulte, j'ai d'abord étudié l'utilisation des gènes VH lors de la synthèse des chaînes lourdes d'anticorps suite à une immunisation pendant 5 mois à bord de Mir (expérience Genesis en 1999). J'ai ensuite étudié le processus de maturation de l'affinité des anticorps chez ces mêmes animaux. Ce processus s'effectue par l'apparition d'hypermutations somatiques dans les segments variables des gènes d'anticorps. Ces travaux ont permis de montrer que les segments VH sont utilisés différemment sur Terre et dans Mir et que la fréquence des hypermutations est diminuée suite au vol. Ensuite, j'ai étudié l'impact des stress rencontrés lors d'un autre vol spatial sur la synthèse des premiers anticorps (IgM) chez le pleurodèle en développement (expérience AMPHIBODY en 2006). Le taux d'IgM étant modifié suite à cette expérience, nous avons recréé sur Terre chacun des stress rencontrés en vol (microgravité, hypergravité, choc thermique, radiations, perturbation du rythme circadien et confinement) afin de connaître le(s) stress responsable(s) de cette modification. Ainsi, seule la gravité modifiée affecte l'expression des IgM. Enfin, j'ai étudié l'impact de l'hypergravité (2G et 3G) sur la réponse au stress et le système immunitaire de la souris. Nous avons mis en évidence une réponse physiologique et comportementale au stress à 3G mais pas à 2G. Pourtant, des modifications du système immunitaire sont constatées dès 2G. Cela montre qu'une modification de la gravité, associée ou non à une réponse au stress, affecte le système immunitaire / During my PhD, I studied the impact of spaceflight-associated stresses on Pleurodeles waltl and Mus musculus humoral immunity. In adult P. waltl immunized during 5 months onboard the Mir space station (Genesis experiment in 1999), I first determined how individual VH genes are used. Then, I studied antibodies affinity maturation in these animals. This maturation implies the introduction of somatic hypermutations (SHM) in DNA encoding the variable segments of antibodies genes. These two pieces of work have shown that variable segments of heavy chain gene are differently used and that SHM frequency is reduced when immunization occurs in space. Then, I studied antibodies production during animal development onboard the international space station (ISS) (AMPHIBODY experiment in 2006). The antibodies production being increased in larvae that developed in the ISS, we recreated in the laboratory each stress encountered during the spaceflight (hypergravity, microgravity, heat shock associated to the re-entry in the atmosphere, radiations, perturbation of circadian rhythm and confinement) to determine their impact on IgM heavy chain transcription. This allowed to observe that only gravity changes affect this transcription. Finally, I studied the impact of hypergravity (2G and 3G) on the murine immune system. I observed physiological and behavioural stress responses in mice exposed to 3G but not in 2G mice. However, immune system alterations were observed in both the 2G and 3G groups, suggesting that gravity modifications, associated or not with stress responses, are responsible for immune system modifications

One countermeasure to cardiovascular spaceflight deconditioning being tested is the application of intermittent artificial gravity provided by centripetal acceleration of a human via centrifuge. However, artificial gravity protocols have not been optimized for the cardiovascular system, or any other physiological system for that matter. Before artificial gravity protocols can be optimized for the cardiovascular system, cardiovascular responses to the variables of artificial gravity need to be quantified. The research presented in this document is intended to determine how the artificial gravity variables, radius (gravity gradient) and lower limb exercise, affect cardiovascular responses during centrifugation. Net fluid (blood) shifts between body segments (thorax, abdomen, upper leg, lower leg) will be analyzed to assess the cardiovascular responses to these variables of artificial gravity, as well as to begin to understand potential mechanism(s) underlying the beneficial orthostatic tolerance response resulting from artificial gravity training. Methods: Twelve healthy males experienced the following centrifuge protocols. Protocol A: After 10 minutes of supine control, the subjects were exposed to rotational 1 Gz at radius of rotation 8.36 ft (2.54 m) for 2 minutes followed by 20 minutes alternating between 1 and 1.25 Gz. Protocol B: Same as A, but lower limb exercise (70% V02max) preceded ramps to 1.25 Gz. Protocol C: Same as A but radius of rotation 27.36 ft (8.33 m). Results: While long radius without exercise presented an increased challenge for the cardiovascular system compared to short radius without exercise, it is likely at the expense of more blood “pooling” in the abdominal region. Whereas short radius with exercise provided a significant response compared to short radius without exercise. More fluid loss occurred from the thorax and with the increased fluid loss from the thorax blood did not “pool” in the abdominal region but instead was essentially “mobilized” to the upper and lower leg. The exercise fluid shift profile presented in this document is applicable to not only artificial gravity protocol design but also proposes a mechanistic reason as to why certain artificial gravity protocols are more effective than others in increasing orthostatic tolerance.

The desire to send humans to Mars will require a change in the way that extravehicular activity (EVA) is performed; in-space crews (including those within a vehicle or habitat monitoring others conducting EVA) will need to be more autonomous and that will require them to monitor large amounts of information in order to ensure crew safety and mission success. The amount of information to perceive and process will overwhelm unassisted intra-vehicular (IV) crewmembers, meaning that automation will need to be developed to support these crews on Mars while EVA is performed (Mishkin, Lee, Korth, & LeBlanc, 2007). This dissertation seeks to identify the information requirements for the performance of scientific EVA and determine which information streams will need to be allocated to in-space crew and which are the most effective streams to automate. The first study uses Mars rover operations as a homology—as defined by von Bertalanffy (1968)—to human scientific exploration. Mars rover operations personnel were interviewed using a novel method to identify the information requirements to perform successful science on Mars, how that information is used, and the timescales on which those information streams operate. The identified information streams were then related to potential information streams relevant to human exploration in order to identify potential function allocation or automated system development areas. The second study focused on one identified mission-critical information stream for human space exploration: monitoring astronaut status physiologically. Heart rate, respiration rate, and heart rate variability measurements were recorded from participants as they performed field science tasks (potentially tasks that are similar to those that will be performed by astronauts on Mars). A statistical method was developed to analyze this data in order to determine whether or not physiological responses to different tasks were statistically different, and whether any of those differences followed consistent patterns. A potential method to automate the monitoring of physiological data was also described. The results of this work provide a more detailed outline of the information requirements for EVA on Mars and can be used as a starting point for others in the exploration community to further develop automation or function allocation to support astronauts as they explore Mars.