npj Microgravity最新文献

The MISSE-Seed project was designed to investigate the effects of space exposure on seed quality and storage. The project tested the Multipurpose Materials International Space Station Experiment-Flight Facility (MISSE-FF) hardware as a platform for exposing biological samples to the space environment outside the International Space Station (ISS). Furthermore, it evaluated the capability of a newly designed passive sample containment canister as a suitable exposure unit for biological samples for preserving their vigor while exposing to the space environment to study multi-stressor effects. The experiment was launched to the ISS on Northrup Grumman (NG)-15. The exposure lasted eight months outside the ISS in the MISSE-FF at the Zenith position. The specimens consisted of eleven seed varieties. Temperature dataloggers and thermoluminescent dosimeters were included in each container to record environmental data. We presented here the hardware and experimental design, environmental profiles, and seed survival from post-flight germination tests.

The importance of gravity for human motor control is well established, but it remains unclear how the central nervous system accounts for gravitational changes to perform complex motor skills. We tested the hypothesis that microgravity and hypergravity have distinct effects on the neuromuscular control of reaching movements compared to normogravity. To test the influence of gravity levels on sensorimotor planning and control, participants (n = 9) had to reach toward visual targets during parabolic flights. Whole-body kinematics and muscular activity were adjusted in microgravity, allowing arm reaching to be as accurate as in normogravity. However, we observed in hypergravity a systematic undershooting, which likely resulted from a lack of reorganization of muscle activations. While new studies are necessary to clarify whether hypergravity impairs the internal model of limb dynamics, our findings provide new evidence that hypergravity creates a challenge that the human sensorimotor system is unable to solve in the short term.

Systemic mitochondrial dysfunction, dopamine loss, sustained structural changes in the basal ganglia including reduced tyrosine hydroxylase, and altered gait- these effects observed in space-flown animals and astronauts mirrors Parkinson's disease (PD). Evidence of mitochondrial changes in space-flown human cells, examined through the lens of PD, suggests that spaceflight-induced PD-like molecular changes are important to monitor during deep space exploration. These changes, may potentially elevate the risk of PD in astronauts.

The effects of galactic cosmic radiation on reproductive physiology remain largely unknown. We determined the impact of near-continuous low-dose-rate Californium-252 neutron irradiation (1 mGy/day) as a space-relevant analog on litter size and number of resorptions at embryonic day (E) 12.5 (n = 19 radiated dams, n = 20 controls) and litter size, number of resorptions, fetal growth, and placental signaling and transcriptome (RNA sequencing) at E18.5 (n = 21 radiated dams, n = 20 controls) in pregnant mice. A significantly increased early resorption rate and decreased placental weight were observed in irradiated mice. There were no statistically significant differences in litter size, fetal weight, length, or malformation rate between the groups. Near-continuous radiation had no significant effects on the mechanistic target of rapamycin (mTOR), endoplasmic reticulum stress or inflammatory signaling, rate of double-stranded DNA breaks, and had minimal effects on gene expression in the placenta. These data suggest that near-continuous, low-level galactic cosmic radiation has a limited impact on pregnancy outcomes.

Men and women have different cardiovascular responses to spaceflight; however, few studies have focused on direct comparisons between sexes. We investigated the mechanisms of aortic stiffening in socially and sexually mature 20-week-old male and female Sprague Dawley (SD) rats exposed to hindlimb unloading (HLU) for 14 days. Pulse wave velocity (PWV) was greater in the aortic arch of females after HLU versus control females (n = 6-8). HLU had no effect on aortic PWV in males (n = 5-6). Aortic α smooth muscle actin, myosin, collagen, elastin, and collagen-to-elastin ratio were not different in rats of either sex following HLU. The levels of G protein-coupled estrogen receptor (GPER) were lower in the aorta of SD females exposed to HLU compared with female controls but were not altered in males. HLU females also had lower aortic PPARγ, increased oxidative stress markers, and diastolic dysfunction compared with control females. GPER agonist G1 prevented the increase in PWV and 8-hydroxy-2'-deoxyguanosine without altering PPARγ or p47phox in HLU females (n = 4 in each group) suggesting that lower GPER may contribute to arterial stiffening in the setting of simulated microgravity. This study highlights sex-specific vascular adaptations to the state of simulated microgravity.

Directional solidification experiments of Al-3.5 wt.% Si and Al-10 wt.% Cu alloys were conducted under gravity and microgravity conditions using a 50-m-high drop tube. The solidification morphology of the two alloys is mainly columnar dendrites and equiaxed dendrites, respectively. The dendrite arm spacing (DAS), eutectic content, grain size, and compositional distribution of both alloys exhibit distinct characteristics under gravity and microgravity conditions. The study introduces an innovative perspective by taking solute density and its redistribution behavior into account when discussing the gravity effects during the directional solidification of alloys. The results indicate that the way gravity works on the solidification behavior of alloys depends strongly on the redistribution behavior and density of solute as well as crystallization modes, such as columnar grain or equiaxed grain. These findings are helpful in clarifying the coupling mechanism of gravity and relevant factors on the solidification of alloys, not only contributing to understanding the effect of gravity on solidification better but also offering valuable guidance for eliminating solidification segregation and producing high-performance alloys.

With the rapid growth of China's space industry, long-term manned space missions face challenges from the complex space environment, posing risks to human health. Aerospace medicine, a key field, addresses these risks by researching the impacts of space on biochemical changes, cognitive abilities, and immune systems. This article reviews China's aerospace medicine research, summarizing efforts from various institutions and offering insights for future developments in the field.

Spaceflight-associated neuro-ocular syndrome (SANS) has been well documented in astronauts. However, its pathogenesis is not fully understood. New findings indicate the impaired outflow of the optic nerve cerebrospinal fluid may participate or contribute to some changes in SANS. In this perspective, we generated a hypothesis that the outflow of cerebrospinal fluid through the optic nerve sheath may be impaired under micro-gravity and then may potentially lead to SANS-related alterations.

Colloidal solids (COLIS) is a state-of-the-art light scattering setup developed for experiments onboard the International Space Station (ISS). COLIS allows for probing the structure and dynamics of soft matter systems on a wide range of length scales, from a few nm to tens of microns, and on time scales from 100 ns to tens of hours. In addition to conventional static and dynamic light scattering, COLIS includes depolarized dynamic light scattering, a small-angle camera, photon correlation imaging, and optical manipulation of thermosensitive samples through an auxiliary near-infrared laser beam, thereby providing a unique platform for probing soft matter systems. We demonstrate COLIS through ground tests on standard Brownian suspensions, and on protein, colloidal glasses, and gel systems similar to those to be used in future ISS experiments.

Astronauts in space often experience sleep loss. In the AGBRESA (Artificial Gravity Bed Rest) study, we examined 24 participants (mean age ± SD, 33 ± 9 years) during two months of 6^o head-down tilt (HDT) bed rest, which is a well-established spaceflight analogue. Polysomnography was recorded during baseline (BDC-9), HDT (nights 1, 8, 30 and 58) and recovery (R, nights 1 and 12). Mixed ANOVAs with post-hoc step-down Bonferroni adjustment indicated that compared to BDC-9, arousals were increased, while sleep duration, N3, and sleep efficiency were all decreased during HDT. Significant quadratic associations between sleep duration and quality with time into HDT did not indicate adaptive improvements during the course of HDT. While sleep duration recovered quickly after the end of bed rest, participants still displayed protracted sleep fragmentation. We conclude that physiological changes caused by exposure to microgravity may contribute to persistent sleep deficits experienced during real space missions.