Getting sloshed in outer space

We document some basic facts about how liquids behave in the low gravity of outer space and how this poses challenges to space scientists and engineers who need to design and test systems that handle fluids in outer space while working in the 1-g environment on Earth. N Ananthkrishnan is Director, Coral Digital Technologies (P) Ltd, a Bangalore-based company working in the area of multidisciplinary simulation and system integration of aerospace, naval and surface vehicles, and in the design and development of autonomous unmanned/micro air vehicles.     

Development of a space cold atom clock

Atomic clocks with cold atoms play important roles in the field of fundamental physics as well as primary frequency standards. Operating such cold atom clocks in space paves the way for further exploration in fundamental physics, for example dark matter and general relativity. We developed a space cold atom clock (SCAC), which was launched into orbit with the Space Lab TG-2 in 2016. Before it deorbited with TG-2 in 2019, the SCAC had been working continuously for almost 3 years. During the period in orbit, many scientific experiments and engineering tests were performed. In this article, we summarize the principle, development and in-orbit results. These works provide the basis for construction of a space-borne time-frequency system in deep space.     

模拟微重力对玉米根尖细胞核的影响

用水平旋转的方法模拟微重力环境来处理正萌发的玉米种子,探讨微重力条件对玉米根尖细胞核结构的影响．结果表明,在微重力的作用下,根尖分生区细胞出现较多的异形核及微核,同时还发现大量的异位核;在36h内,随着处理时间的增长,出现异形核、微核、异位核的频率增高,当处理时间进一步增长时,异形核、微核、异位核的出现频率有下降趋势．结论：模拟微重力对植物细胞核的形态、结构具有明显的诱变作用．     

Development of mouse preimplantation embryos in space

The development of life beyond planet Earth is a long-standing quest of the human race, but whether normal mammalian embryonic development can occur in space is still unclear. Here, we show unequivocally that preimplantation mouse embryos can develop in space, but the rate of blastocyst formation and blastocyst quality are compromised. Additionally, the cells in the embryo contain severe DNA damage, while the genome of the blastocysts developed in space is globally hypomethylated with a unique set of differentially methylated regions. The developmental defects, DNA damage and epigenetic abnormalities can be largely mimicked by the treatment with ground-based low-dose radiation. However, the exposure to simulated microgravity alone does not cause major disruptions of embryonic development, indicating that radiation is the main cause for the developmental defects. This work advances the understanding of embryonic development in space and reveals long-term extreme low-dose radiation as a hazardous factor for mammalian reproduction.     

Efficacy of manual versus free-weight training to improve maximal strength and performance for microgravity conditions

We tested a simple and compact device designed for manual resistance training in conditions of microgravity (Self-Powered Rope Trainer Duo (SPoRT Duo)) to increase muscle performance. Twenty-four participants (20.8 ± 2.1 years) were randomly assigned to a manual resistance group (n = 12) and a free-weight group (n = 12). Participants performed eight exercises (three sets; 8–12 efforts) either with free weights or the SPoRT Duo twice a week for 6 weeks. Maximal isometric force of trunk flexion, back extension and chest press increased (P at least 0.01, d at least 0.52) both in the manual resistance group (18.4% ± 15.0%; 32.7% ± 22.7%; 15.3% ± 9.7%) and free-weight group (18.0% ± 13.9%; 26.6% ± 28.9%; 13.3% ± 7.6%). The change in maximal isometric force of wide grip row in both groups (d at best 0.38) did not reach statistical significance (P at best 0.08). The squat one-repetition-maximum increased in the manual resistance group (29.8% ± 22.1%) and the free-weight group (32.4% ± 26.6%). Jump height, determined by a jump-and-reach test, increased in the free-weight group (9.8% ± 13.2%) but not in the manual resistance group (2.0% ± 8.5%). Manual resistance training was equally effective in increasing strength as traditional resistance training with free weights. This apparatus is a useful addition to current in-flight exercise systems.     

The brain in micro- and hypergravity: The effects of changing gravity on the brain electrocortical activity

Abstract

Understanding the effects of increased and decreased gravity on central nervous system is essential for developing proper physical and cognitive countermeasures to assure safe and effective space missions and human survival in space. This short review covers the available literature on the brain electrocortical activity effects of decreased and increased gravitational force comparing to the 1g Earth conditions. Among all neuroimaging methods such as functional magnetic resonance imaging (fMRI), positron-emission tomography (PET), diffusion tensor imaging (DTI), the electroencephalography (EEG) was found to be suitable method to monitor brain electrocortical activity in the extreme environments. Due to complexity and high cost of space flight missions, ground-based models have been employed to simulate microgravity effects on human body. Surprisingly, there is very limited number of publications reporting gravity-dependent EEG spectral changes. With increased gravity there are initially increased EEG activity in higher frequencies and at around 4g appears loss of consciousness with accompanying slowing of EEG due to hypoxia. In microgravity, the most prevalent changes in EEG are faster frequencies such as alpha and beta. The results from simulated microgravity (bed rest) are pointing to changes in theta and alpha, representing signs of cortical inhibition. The changes in EEG activity in space flight are attributed to a decreased sensorimotor input while in parabolic flights short and fast transitions from hyper to microgravity presumably reflect lower arousal levels and emotional processes in microgravity. Thus, based on limited research about gravity-related changes in EEG from different environments it is difficult to draw any unequivocal conclusions. Additional systematic studies about electrocortical activity in space and parabolic flights, as well as longer bed rest studies are needed in order to advance knowledge about brain functioning in extreme conditions such as space flights.     

微重力条件下腔体内竖板火蔓延的三维非稳态数值模拟

本文用数值求解基本控制微分方程组的方法研究了微重力条件下腔体内部固体可燃物表面火焰传播的三维非稳态过程。建立的理论模型考虑了气相有限速率化学反应，以及固相的传热和热解过程，阐明了微重力场中固体表面火蔓延过程可燃表面热解的“表面燃料喷射”效应的重要作用，并建立了相应的数学处理方法。数值模拟的结果反映了微重力大小对竖板火蔓延过程形成重要影响的特点，结果基本合理。     

美国国际空间站的经历与探索及对我国的启示

建设空间站是人类探索外层空间的重要步骤。美、俄、欧、日、加等国联合运营的国际空间站将于2010年建成,并延续到2020年。中国的载人空间站将于2020年升空。本文回顾了空间站的主要历史,概述了美国在国际空间站上10年(1998—2008)的工作,分析了空间站可能对人类做出的贡献,介绍了美国新政府对载人航天任务的新选择,最后借鉴国外发展空间站的经验教训,提出了我国研制空间站应注意的问题。     

微重力科学实验卫星——“实践十号”

北京时间2016年4月6日1时38分04秒,酒泉卫星发射中心,"长征"二号丁运载火箭成功发射,在559秒后将中国科学卫星系列第二颗星——"实践十号"返回式科学实验卫星送入高度约250 km的圆轨道,卫星发射取得圆满成功。"实践十号"卫星在太空运行15天,装载着19项科学设施,共28项实验。实验内容涉及微重力流体物理、微重力燃烧、空间材料科学、空间辐射生物效应、重力生物学效应和空间生物技术6大方向。卫星的返回舱装载着全部9项生物学设备以及空间材料科学多功位炉和流体物理中的输运系数测量装置;而留轨舱中装载着其他8项微重力科学设施。     

空间微重力环境地面气动模拟系统设计

本论文提出了在地面采用气动方式模拟空间微重力环境下实验系统方案,该实验系统用于验证空间机器人的捕获性能。本验证系统由模拟目标星实验模型、气浮平台、双目视觉系统、通讯系统、电机系统,传感器系统、信号调理系统六个子系统组成。本论文首先阐述了系统各个子系统的设计方案,其次讨论了基于层次递减式控制系统结构,最后重点研究了模拟目标星在垂直地面方向上的漂浮运动控制算法,仿真和实验结果验证了该控制算法是有效的。