Long-term Space Research Articles

Ground-based passive generation of Solar Particle Event spectra: Planning and manufacturing of a 3D-printed modulator

The generation of space radiation on Earth is essential to study and predict the effects of radiation on space travelers, electronics, or materials during future long-term space missions. Next to the heavy ions of the galactic cosmic rays, solar particle events play a major role concerning the radiation risk in space, which consist of intermediate-energy protons with broad spectra and energies up to a few hundred MeV. This work describes an approach for the ground-based generation of solar particle events. As a proof of principle, a passive beam modulator with a specific funnel-shaped periodic structure was designed and is used to convert a monoenergetic proton beam into a spectral proton energy distribution, mimicking a solar particle event from August 1972, which is known as one of the strongest recorded SPE events. The required proton beam of 220 MeV can be generated at many existing particle accelerators at research or particle therapy facilities. The planning, manufacturing and testing of the modulator is described step by step. Its correct manufacturing and the characteristics of the solar particle event simulator are tested experimentally and by means of Monte Carlo simulations. Future modulators will follow the same concept with minor adjustments such as a larger lateral extension. As of now, the presented beam modulator is available to the research community to conduct experiments at GSI for exposure under solar particle event conditions. In addition, researchers can use and apply the described concept to design and print their individualized modulator to reproduce any desired solar particle event spectrum or request the presented modulator geometry from the authors.

Experimental Studies on Thermal Oxidation and Laser Ignition Properties of Al-Mg-Li Powders.

Powder ramjets are a kind of vehicle propulsion system with high specific impulse and efficiency. They provide significant benefits in terms of extended propulsion and thrust adjustment. The pursuit of a highly reactive fuel appropriate for powder ramjets is likely to stimulate advancements in innovative propulsion systems, which are crucial for deep space exploration and long-term space missions. This work presents experimental studies on the thermal oxidation and laser ignition performance of aluminum-magnesium-lithium powders at atmospheric pressure. TG-DSC curves of powders in three heating rates were obtained. The ignition processes and ignition delay times were recorded by a CO2 laser ignition experiment system at a laser power of 10~60 W. The results show that at a lower heating rate of 10 K/min, the powder's thermal hysteresis is less, and the powder energy released in stage I is more concentrated. However, the degree of heat release concentration approached a similar level at heating rates of 30 K and 50 K. The ignition delay time decreased as the laser flux density increased. When the laser flux density exceeds 80 W/cm2, the effect of laser power on the ignition delay time decreases. At atmospheric pressure, the mathematical relationship between ignition delay time and laser flux density is given. Finally, the powder ignition processes at different laser powers are represented graphically.

Long-term spaceflight composite stress induces depressive behaviors in model rats through disrupting hippocampus synaptic plasticity.

Long-term spaceflight composite stress (LSCS) can cause adverse effects on human systems, including the central nervous system, which could trigger anxiety and depression. This study aimed to identify changes in hippocampus synaptic plasticity under LSCS. The present study simulated the real long-term space station environment by conducting a 42-day experiment that involved simulating microgravity, isolation, noise, circadian rhythm disruptions, and low pressure. The mood and behavior of the rats were assessed by behavior test. Transmission electron microscopy and patch-clamp were used to detect the changes in synapse morphology and electrophysiology, and finally, the expression of NMDA receptor channel proteins was detected by western blotting. The results showed that significant weight loss, anxiety, and depressive behaviors in rats were observed after being exposed to LSCS environment for 42 days. The synaptic structure was severely damaged, manifested as an obvious decrease in postsynaptic density thickness and synaptic interface curvature (p < 0.05; p < 0.05, respectively). Meanwhile, LTP was significantly impaired (p < 0.0001), and currents in the NMDAR channel were also significantly reduced (p < 0.0001). Further analysis found that LSCS decreased the expression of two key subtype proteins on this channel. These results suggested that LSCS-induced depressive behaviors by impairing synaptic plasticity in rat hippocampus.

Substrate and fertigation management modulate microgreens production, quality and resource efficiency

Long-term space missions will require a self-sustaining food production system to meet the crew’s nutritional and health needs. For this purpose, plant-based food production systems with elevated resource efficiency are required, based on advanced agricultural technologies that produce phytonutrient-rich crops. In addition to the resource requirements for crop production on Earth, volume and time efficiency become essential factors to consider for food production in space. Microgreens represent a promising candidate for space farming as they have a high harvest index, short cultivation cycle, and high nutritional potential. However, the development of specific technical protocols for growing microgreens in space is essential since different agronomic inputs, such as substrates and fertigation, can modulate productivity, quality and resource efficiency of microgreens cultivation. The current work examines the effects of different substrates (coconut fiber and cellulose sponge) and nutrient solution (NS) management strategies (quarter strength Hoagland and half strength Hoagland/osmotic water) on the production of two species of microgreens [Raphanus sativus cv. Saxa 2 (Radish); Brassica oleracea var. capitata f. sabauda cv. Vertus (Savoy cabbage)]. The appraisal focused on (i) biomass production and quality, and (ii) sizing of space facilities devoted to the production of phytonutrients required for the astronauts’ wellbeing. In our study, the interaction among species, substrate and NS significantly affected the accumulation of fructose, sucrose, total soluble non-structural carbohydrates and nitrate as well as the daily production of total ascorbic acid and, in turn, the required microgreens serving to supply its adequate daily intake. Species-substrate interaction effects on fresh yield, dry yield, dry matter, anthocyanins, TPC, β-carotene and sulfate content as well as the cultivation surface required to produce the adequate daily intake of ascorbic acid (AscA) were assessed. Substrate-NS interaction modulated the anthocyanins, violaxanthin and sulfate contents independently of species. On the other hand, single factor effects were identified with respect to the accumulation of lutein, chlorophylls, glucose, and starch. Therefore, the management of microgreens cultivation in terms of NS and substrate is an effective tool to meet the phytochemical requirements of the crew.

Simplified equations for object trajectories in rotating space habitats and space juggling

Rotating space habitats provide artificial gravity as a physiological countermeasure for long-term space habitation, though the lived experience of a person in these habitats requires further investigation. Movement planning will require adaptation to the Coriolis and centrifugal forces. The multicultural arts of juggling may offer potential psycho-physiological countermeasures for some individuals and provide interesting insights into movement planning and arts in both microgravity and rotating habitats. Previously developed equations of motion for thrown objects in rotating habitats have not been centered within the lived rotating environment. Here, I show a set of simplified equations for object trajectories in rotating environments and their underlying mathematical framework. The full set of possible trajectories for objects thrown in rotating environments is provided and a simplified approach to the Coriolis and centrifugal force differential equation using complex algebra is demonstrated. Experimentation reported in this article was conducted on parabolic flights and an analog weightlessness and rotating apparatus. Near the surface of the Earth, thrown objects travel along parabolas. In rotating space environments, thrown objects will travel along a set of mathematical curves known as roulettes, created by a fixed circle and rolling line with generator point connected to the line. These roulette trajectories will be the everyday experience of every person living in a rotating space habitat, always.

Effects of gamma radiation on engineered tomato biofortified for space agriculture by morphometry and fluorescence-based indices.

Future long-term space missions will focus to the solar system exploration, with the Moon and Mars as leading goals. Plant cultivation will provide fresh food as a healthy supplement to astronauts' diet in confined and unhealthy outposts. Ionizing radiation (IR) are a main hazard in outer space for their capacity to generate oxidative stress and DNA damage. IR is a crucial issue not only for human survival, but also for plant development and related value-added fresh food harvest. To this end, efforts to figure out how biofortification of plants with antioxidant metabolites (such as anthocyanins) may contribute to improve their performances in space outposts are needed. MicroTom plants genetically engineered to express the Petunia hybrida PhAN4 gene, restoring the biosynthesis of anthocyanins in tomato, were used. Seeds and plants from wild type and engineered lines AN4-M and AN4-P2 were exposed to IR doses that they may experience during a long-term space mission, simulated through the administration of gamma radiation. Plant response was continuously evaluated along life cycle by a non-disturbing/non-destructive monitoring of biometric and multiparametric fluorescence-based indices at both phenotypic and phenological levels, and indirectly measuring changes occurring at the primary and secondary metabolism level. Responses to gamma radiation were influenced by the phenological stage, dose and genotype. Wild type and engineered plants did not complete a seed-to-seed cycle under the exceptional condition of 30 Gy absorbed dose, but were able to cope with 0.5 and 5 Gy producing fruits and vital seeds. In particular, the AN4-M seeds and plants showed advantages over wild type: negligible variation of fluorimetric parameters related to primary metabolism, no alteration or improvement of yield traits at maturity while maintaining smaller habitus than wild type, biosynthesis of anthocyanins and maintained levels of these compounds compared to non-irradiated controls of the same age. These findings may be useful in understanding phenotypic effects of IR on plant growth in space, and lead to the exploitation of new breeding efforts to optimize plant performances to develop appropriate ideotypes for future long-term space exploration extending the potential of plants to serve as high-value product source.

Rational and design of the REMOTE trial: An exploratory, pilot study to analyze REtinal MicrOcirculaTion in wEightlessness.

"Spaceflight associated neuro-ocular syndrome" (SANS) represents a challenging health condition in modern space medicine. Forty-eight percent of astronauts are diagnosed with SANS after long-term space missions. The pathophysiological mechanism seems to be multifactorial, and yet remains unknown. In this proof-of-concept study we plan to investigate retinal microcirculatory changes in weightlessness and aim to identify their role in the development of SANS. Healthy individuals will take part in a parabolic flight campaign, which recreates fractioned total weightlessness periods. The airplane is specifically equipped, and designed for the execution of parabolic flight maneuvers and scientific research in microgravity. Retinal microcirculation will be assessed with a modified fundus camera, which allows dynamic vessel analysis. We will additionally measure intra-ocular pressure and hemodynamic changes during each phase of the flight. Blood samples will be analyzed at baseline, one hour and 24 hours after exposure to weightlessness. This pilot study aims to investigate the feasibility of retinal microcirculation assessment during varying gravity. Results of this study may generate insights whether venous stasis in the eye, surrogated by the dilatation of retinal vessels and increase in intraocular pressure as signs of venous insufficiency, may potentially contribute to the development of SANS.

Why moral bioenhancement in future space missions may not be a good idea: The perspective of feminist bioethics of space exploration

Moral bioenhancement for future space missions, like radical forms of biomedical human enhancements in general, seems at first glance a reasonable idea. This is due to the harsh conditions of the space environment, as well as the high cost and difficulty of implementing long-term and long-distance space missions. However, it turns out that this most controversial type of human enhancement, which is biomodification of morality, can also bring many risks for such a demanding environment as that of future long-distance space missions. The object of this paper is to polemicize the philosophy of moral bioenhancement proposed by Henri Huttunen and Oskari Sivula and to supplement their point of view with important but missing contexts.

Metabolomics Profile of the Secretome of Space-Flown Oligodendrocytes.

Intracranial hypertension (ICP) and visual impairment intracranial pressure (VIIP) are some of the sequels of long-term space missions. Here we sought to determine how space microgravity (µG) impacts the metabolomics profile of oligodendrocyte progenitors (OLPs), the myelin-forming cells in the central nervous system. We report increased glutamate and energy metabolism while the OLPs were in space for 26 days. We also show that after space flight, OLPs (SPC OLPs) display significantly increased mitochondrial respiration and glycolysis. These data are in agreement with our previous work using simulated microgravity. In addition, our global metabolomics approach allowed for the discovery of endogenous metabolites secreted by OLPs while in space that are significantly modulated by microgravity. Our results provide, for the first time, relevant information about the energetic state of OLPs while in space and after space flight. The functional and molecular relevance of these specific pathways are promising targets for therapeutic intervention for humans in long-term space missions to the moon, Mars and beyond.

Sustainable wastewater treatment and reuse in space

Exploring the vast extraterrestrial space is an inevitable trend with continuous human development. Water treatment and reuse are crucial in the limited and closed space that is available in spaceships or long-term use space bases that will be established in the foreseeable future. Dedicated water treatment technologies have experienced iterative development for more than 60 years since the first manned spaceflight was successfully launched. Herein, we briefly review the related wastewater characteristics and the history of water treatment in space stations, and we focus on future challenges and perspectives, aiming at providing insights for optimizing wastewater treatment technologies and closing the water cycle in future.

A surface-enhanced Raman scattering-based competitive lateral flow assay for on-orbit rapid detection of bone loss biomarker CTX I

The complexity of space environment will lead to a series of health problems, especially the bone loss caused by weightlessness is one of the key medical problems limiting long-term manned space flight. However, the size and energy constraints of the aircraft make conventional bone loss detection methods impractical. Hence, it is necessary to establish on-orbit bone loss detection methods to ensure the health of astronauts. As one of NASA's recommended methods, the lateral flow assay (LFA) would be an ideal tool to solve this problem. Herein, a surface-enhanced Raman based molecular probe was designed and integrated with LFA to detect carboxy-terminal cross-linked telopeptides of type I collagen (CTX I) with high sensitivity and specificity, and the limit of detection was 232 pg/mL. This method was not interference by the serum matrix or other targets, and the storage life of LFA was up to 6 months at 4 °C. Compared with the method previously reported, SERS-based LFA was an ideal detection method with simple operation, convenient and time saving. It is also expected to be chosen as a potential analytical tool to detect bone loss for long-term on-orbit, and guarantee the health of astronauts.

Effects of Microgravity on Astronaut Physiology in Long-Term Space Missions and Proposed Countermeasures

The interest in long-term space travel (&gt;6 months) has gained popularity in the space community. This began in the 1970s with multiple short-term missions exploring the Moon and Mars to understand true habitability and early developments of long-term space settlements. With new missions being proposed by major pioneers in aerospace, such as NASA, SpaceX, and JAXA, scientists are concerned with human health, especially the long-term effects. Long-term settlements have been hypothesized to have major short-term and long-term detriments to multiple physiological systems, most notably musculoskeletal, cardiovascular, and neurophysical. This is due to the effects of microgravity; however, more experimentation must be conducted to understand these effects sufficiently. So far, scientists have linked microgravity to decreased osteoblastic differentiation, rapid bone loss, and increased risk of kidney stone formation in the musculoskeletal system. Additionally, the cardiovascular system is impacted by space anemia, which is hypothesized to be reversible but may induce detrimental effects. Finally, microgravity affects the vestibular system significantly, especially spatial recognition. Countermeasures have been proposed to reduce these effects, like inducing artificial gravity, administrating bisphosphonates and other drugs/therapies, and utilizing tactile aids. The long-term effect of microgravity is still an emerging topic of space research, and much more research must be conducted through various programs like the Artificial Gravity Bed Rest Study with the European Space Agency (AGBRESA) to understand long-term results better.

Adjuvant pharmacological strategies for the musculoskeletal system during long-term space missions.

Despite two hours of daily exercise training, muscle wasting and bone loss are still present after 6-month missions to the international space station. Some crew members lose bone much faster than others. In preparation for Moon and Mars, space agencies are therefore reviewing their countermeasure portfolios. Here, we discuss the potential of current pharmacological strategies. Bone loss in space is fueled by bone resorption. Alendronate, an oral bisphosphonate, reduced bone losses in experimental bed rest and space. However, gastrointestinal side effects precluded its further utilization in space. Zoledronate (a potent bisphosphonate), denosumab (RANKL antagonist) and romosozumab (sclerostin antagonist) are all administered via injection. They effectively suppress bone resorption and are routinely prescribed against osteoporosis. Their serious adverse effects, namely osteonecrosis of the jaw and atypical femur fractures occur very rarely when the usage is limited to one or two years. Hence, utilization of one of these compounds may outweigh the bone risks of space travelling, in particular in those with high bone resorption rates. Muscle wasting in space is likely due to hampered muscle protein synthesis. Even though this might theoretically be countered by the synthesis-boosting effects of anabolic steroids, the practical grounds for such recommendation are currently weak. Moreover, they reveal their full potential only when combined with an anabolic exercise stimulus, e.g. via strength training. It therefore seems that a combination of exercise and pharmacological countermeasures should be considered for musculoskeletal health on the way to Moon and Mars and back.

Magnetically-Induced Buoyancy for Efficient Electrochemical Oxygen Production in Microgravity

The realization of long-term space travels and the establishment of a lunar research platform are challenged by the lack of technological device architectures for efficient, stable and continuous oxygen production. One obstacle is that the near-absence of buoyancy in microgravity results in hindered gas bubble desorption at the electrode-electrolyte interface, causing lower efficiencies for electrolyser systems when operating in space.1,2 The significantly reduced buoyancy force also has severe complications for phase separation, which is a crucial process for a variety of space technologies also including heat transfer, fuel production and removal of carbon dioxide from cabin air. Multiple approaches have been studied in the past to induce phase separation such as creating centrifugal force fields. These approaches lack however efficiency, stability and robustness.3,4 In our recent work, we demonstrate the use of magnetic polarisation to artificially induce buoyancy in the electrolytic oxygen evolution half-cell reaction and thus significantly increasing the overall half-cell efficiency. This was carried out in a series of experiments at the Bremen Drop Tower, Center of Space Technology and Microgravity (ZARM, Germany), where short-term microgravity conditions of 9.2 s were achieved.5,6. Chronoamperometric and cyclic voltammetry measurements on high-activity RuOx electrocatalyst structures on a Ti substrate were undertaken with and without a magnet in close proximity to the electrode to closely monitor the electrochemical performance in a three-electrode potentiostatic arrangement and to demonstrate the magnetic effect on gas bubble desorption during free fall. It was observed that current densities for the electrodes at a potential of +1.49 V vs RHE were significantly higher in the presence of a magnet. We conclude that magnetic phase separation can be utilised in electrolytic systems in reduced gravitational environments to efficiently detach oxygen bubbles from the electrode surface and operate the devices at higher efficiencies, providing a key advancement for future oxygen production in space missions.2,3,5 References Cheng, W.-H.; Richter, M. H.; May, M. M.; Ohlmann, J.; Lackner, D.; Dimroth, F.; Hannappel, T.; Atwater, H. A.; Lewerenz, H.-J. (2018). Monolithic Photoelectrochemical Device for Direct Water Splitting with 19% Efficiency. ACS Energy Lett., 3, 1795−1800.Saravanabavan, S.; Coulthard, C. T.; Kaur, M.; Brinkert, K. (2022). Catalysis in Space Environments. doi.org/10.1002/9783527830909.ch7 In: Hessel V., Stoudemire J., H. Miyamoto & I. D. Fisk (Eds.). In Space Manufacturing and Resources.Wiley-VCH. ISBN: 978-3-527-83091-6Romero-Calvo, Á.; Akay, Ö.; Schaub, H.; Brinkert, K. (2022). Magnetic phase separation in microgravity. npj Microgravity 8 (32). doi.org/10.1038/s41526-022-00212-9.Harvey, A.; Ramshaw, C.; Reay, D. A. Process Intensification: Engineering for Efficiency. Sustainability and Flexibility. 2nd edition. Butterworth- Heinemann; 201Brinkert, K.; Richter, M. H.; Akay, Ö.; Liedtke, J.; Giersig, M.; Fountaine, K. T.; Lewerenz, H. J. (2018). Efficient solar hydrogen production in microgravity environment. Commun. 9(2527). doi: 10.1038/s41467-018-04844-yhttps://www.zarm.uni-bremen.de/fileadmin/user_upload/drop_tower/Users_Manual_0412.pdf

Synergistic Microfluidic and Optical Performance Enhancements of Photoelectrodes for Space Applications

The realisation of long-term space missions as well as lunar habitats require reliable and efficient oxygen and chemical producing devices e.g., for life support, fuel generation and in-situ resource utilisation (ISRU). We have recently demonstrated that integrated semiconductor-electrocatalyst systems can be operated in microgravity environments generated for 9.2 s at the Bremen Drop Tower (Center of Applied Space Technology and Microgravity, ZARM) at terrestrial efficiencies, thus opening the possibility of utilising these photoelectrochemical (PEC) devices for chemical synthesis in space. 1,2 , 3 Our findings reveal that by altering the electrocatalyst surface morphology through nanostructuring, we can introduce catalytic hot-spots on the photoelectrode which - through their hydrophilic nature - can also enhance gas bubble detachment in microgravity and thus circumvent the near-absence of buoyancy.1,3 We have found that the surface hydrophilicity and electrocatalyst loading require however careful balancing as the most effective nanostructures for gas bubble desorption can also result in less catalyst material on the photoelectrode surface, which in turn leads to a non-optimal PEC device performance.Here, we present a combined theoretical and experimental microfluidic, optical and photoelectrocatalytic performance analysis of photoelectrodes with integrated, nanostructured electrocatalysts, aiming at providing a guideline for an optimal design for microgravity applications. Focusing on the hydrogen evolution reaction (HER) and a well-investigated photoabsorber for this reaction, p-type InP, we firstly built an optoelectronic model in COMSOL Multiphysics in pursuit of quantifying the optical performance enhancements of Rh and Pt electrocatalyst nanostructures such as nanopyramids, nanowires and sub-wavelength aperture holes.4 We then developed a microfluidic model using the same nanostructure geometries to predict the hydrophilicity of the device surface and subsequently, the gas bubble contact angle. The best-performing nanostructured photoelectrodes predicted in our models where then manufactured, photoelectrochemically tested and fully optically and spectroscopically characterised. Predicted local electric field enhancements through catalytic hotspot formation were moreover experimentally validated using scanning electrochemical cell microscopy (SECCM). Our findings indicate that our developed optoelectronic and microfluidic models can be utilised to design a theoretical framework for identifying ideal electrocatalyst nanostructures for microgravity applications.References Brinkert K, et al. Efficient solar hydrogen generation in microgravity environment. Nature Communications 9, (2018). Brinkert K, Mandin P. Fundamentals and future applications of electrochemical energy conversion in space. npj Microgravity 8, (2022). Akay Ö, et al. Releasing the Bubbles: Nanotopographical Electrocatalyst Design for Efficient Photoelectrochemical Hydrogen Production in Microgravity Environment. Advanced Science 9, 2105380 (2022). Tembhurne S, Haussener S. Integrated Photo-Electrochemical Solar Fuel Generators under Concentrated Irradiation. Journal of The Electrochemical Society 163, H988 (2016). Pan Y, Huang S, Li F, Zhao X, Wang W. Coexistence of superhydrophilicity and superoleophobicity: theory, experiments and applications in oil/water separation. Journal of Materials Chemistry A 6, 15057-15063 (2018).

Flips: Fluidic Integration of Printed Sensors

As NASA’s manned exploration programs advance toward more challenging missions including Martian spaceflight and long-term space habitation, novel technologies must be adapted for astronaut health monitoring and diagnostics. Among the technologies currently under development, In-Space Manufacturing (ISM) is an attractive approach because it mitigates the need to include multiple prefabricated sensors in spaceflight payloads instead allowing production of sensors on an as-needed basis by additive manufacturing techniques such as 3D-printing and inkjet printing. Several examples of ISM sensors have been demonstrated recently. However, liquid sample handling in microgravity environments produces several challenges, and consequently all liquid handling must be contained in a closed environment to prevent sample loss and contamination of crew quarters. Here we demonstrate the development of an ISM-compatible manifold for the fluidic integration of printed sensors (FLIPS). Our approach to the development of the FLIPS manifold is to identify components that cannot be manufactured using ISM techniques, and to fabricate all other components using flight-heritage 3D-printing and CNC cutting. FLIPS includes a mounted peristaltic pump and switch valve with measurements performed on off-the-shelf screen-printed carbon electrodes. We demonstrate the performance of the manifold with a model redox species (ferrocene carboxylic acid). Finally, we show the potential application as an integrated healthcare diagnostic system by detection of a renal health biomarker, alkaline phosphatase.This capability is necessary to ensure the success of ISM sensors for liquid samples and allows further customization of sensor architectures. The FLIPS platform demonstrates the applicability of ISM to complex fluid handling that will be adopted in future NASA missions.

Reviewing the state of biosensors and lab-on-a- chip technologies: opportunities for extreme environments and space exploration.

The space race is entering a new era of exploration, in which the number of robotic and human missions to various places in our solar system is rapidly increasing. Despite the recent advances in propulsion and life support technologies, there is a growing need to perform analytical measurements and laboratory experiments across diverse domains of science, while keeping low payload requirements. In this context, lab-on-a-chip nanobiosensors appear to be an emerging technology capable of revolutionizing space exploration, given their low footprint, high accuracy, and low payload requirements. To date, only some approaches for monitoring astronaut health in spacecraft environments have been reported. Although non-invasive molecular diagnostics, like lab-on-a-chip technology, are expected to improve the quality of long-term space missions, their application to monitor microbiological and environmental variables is rarely reported, even for analogous extreme environments on Earth. The possibility of evaluating the occurrence of unknown or unexpected species, identifying redox gradients relevant to microbial metabolism, or testing for specific possible biosignatures, will play a key role in the future of space microbiology. In this review, we will examine the current and potential roles of lab-on-a-chip technology in space exploration and in extreme environment investigation, reporting what has been tested so far, and clarifying the direction toward which the newly developed technologies of portable lab-on-a-chip sensors are heading for exploration in extreme environments and in space.

Long-term space climate monitoring

Long-term space climate monitoring

Circadian regulation in aging: Implications for spaceflight and life on earth.

Alterations in the circadian system are characteristic of aging on Earth. With the decline in physiological processes due to aging, several health concerns including vision loss, cardiovascular disorders, cognitive impairments, and muscle mass loss arise in elderly populations. Similar health risks are reported as "red flag" risks among astronauts during and after a long-term Space exploration journey. However, little is known about the common molecular alterations underlying terrestrial aging and space-related aging in astronauts, and controversial conclusions have been recently reported. In light of the regulatory role of the circadian clock in the maintenance of human health, we review here the overlapping role of the circadian clock both on aging on Earth and spaceflight with a focus on the four most affected systems: visual, cardiovascular, central nervous, and musculoskeletal systems. In this review, we briefly introduce the regulatory role of the circadian clock in specific cellular processes followed by alterations in those processes due to aging. We next summarize the known molecular alterations associated with spaceflight, highlighting involved clock-regulated genes in space flown Drosophila, nematodes, small mammals, and astronauts. Finally, we discuss common genes that are altered in terms of their expression due to aging on Earth and spaceflight. Altogether, the data elaborated in this review strengthen our hypothesis regarding the timely need to include circadian dysregulation as an emerging hallmark of aging on Earth and beyond.

Stem Cells and Exosome Applications for Cutaneous Wound Healing: From Ground to Microgravity Environment.

The increasing number of astronauts entering microgravity environments for long-term space missions has resulted in serious health problems, including accidental injury and trauma. Skin, as the largest organ and outermost layer of the human body, has the ability to self-renew and withstand a variety of harmful biological and environmental influences. Recent spaceflight experiments and simulated studies have begun to concern the effects of microgravity on the growth of skin cells and the process of cutaneous wound healing. However, the mechanisms of the adverse effects of microgravity on skin cells and potential intervention measures are still limited. Stem cells and their exosomes provide unique opportunities for the cutaneous wound healing as they have been used to improve skin repair. This review discusses the effects of microgravity on wound healing, from cell morphological changes to molecular level alterations. Furthermore, the current research on wound healing treatment utilizing stem cells and their exosomes on the ground is summarized. Finally, this review proposes promising therapeutic strategies using stem cells or exosomes for wound healing in the microgravity environment. Graphical Abstract.