Can the Biophilia Hypothesis Be Applied to Long-Duration Human Space Flight? A Mini-Review

The International Space Station (ISS) has around 3–5 crew members on-board at all times, and they normally stay on the ISS for about 5–7months in duration. Since March 2020, 170 long-duration space missions have occurred on the ISS. Thus, long-duration space missions are an integral part of space exploration and will only continue to expand in duration as missions to the Moon and Mars are on the horizon. However, long-duration space missions present several challenges to human crew members. Most of these challenges have been associated with physiological adaptation to microgravity, including motion sickness, muscle atrophy, and cardiovascular deconditioning. While not as well-studied, another major factor to consider when planning long-duration space missions is the psychological impact of the environment on the astronauts. Astronauts living in space will be unable to access natural landscapes and other environments found to have restorative effects on psychological stress and overall well-being. On top of being unable to access these restorative natural environments, astronauts will also be exposed to the stressful, unfamiliar environment of space. The purpose of this mini-review is to first summarize the literature related to stressors associated with space. Next, an overview of the large breadth of literature on the biophilia hypothesis and restorative environments will be provided, as these may serve as relatively simple and cost-effective solutions to mitigate the stress faced during long-duration space missions. Lastly, considerations related to the design of such environments in a space capsule as well as future directions will be presented.

Simulated Space Environmental Factors of Weightlessness, Noise and Low Air Pressure Differentially Affect the Circadian Rhythm and Gut Microbiome

Backgroundhe circadian clock extensively regulates physiology and behavior. In space, the astronauts encounter many environmental factors that are dramatically different from those on earth, however, the effects of these factors on circadian rhythms and the mechanisms remain largely unknown. The present study aimed to investigate the changes in the mouse circadian rhythm and gut microbiome under simulated space capsule conditions, including microgravity, noise and low atmospheric pressure.ResultsNoise and low atmospheric pressure were loaded in the capsule while the conditions in the animal room remained constant. The mice in the capsule showed disturbed locomotor rhythms and faster adaptation to a 6-h phase advance. RNA sequencing of hypothalamus samples revealed that microgravity simulated by hind limb unloading (HU) and exposure to noise and low atmospheric pressure led to decreases in the quantities of differentially expressed genes (DEGs), including circadian clock genes. Changes in the rhythmicity of genes implicated in pathways of cardiovascular deconditioning and more concentrated circadian phases were found under HU or noise and low atmospheric pressure. Furthermore, 16S rRNA sequencing revealed dysbiosis in the gut microbiome, and noise and low atmospheric pressure may repress the temporal discrepancy in the microbiome community structure induced by microgravity. Changes in diel oscillation were observed in a number of gut bacteria with critical physiological consequences in metabolism and immunodefense.ConclusionsOur data demonstrate that in addition to microgravity, exposure to noise and low atmospheric pressure affect the robustness of circadian rhythms and the community structure of the gut microbiome, and these factors may interfere with each other in their adaptation to respective conditions. These findings are important to further our understanding of the alteration of circadian rhythms in the space complex environment.

Design and Selection Criteria of Main Parachute for Re entry Space Payload

Parachutes are used as a decelerator in the re-entry, descent, and landing of space recovery payloads, providingstability and desired descent rate for a safe landing. The selection of the main parachute is the most critical andimportant part of the space module recovery system. Parachute size is restricted by the required landing speed,materials, and weight of the payload. Parachute materials are selected based on the various forces experienced bythe parachute. An investigation has been carried out to design a parachute system which gives less impact velocity, less angle of oscillation and less impact load for the landing of a crew module. Therefore, in this paper, selection criteria for the main parachute have been discussed considering recovery of re-entry space payload of 500 kg (unmanned) and 3500 kg (manned) class. Based on analysis carried out on the parachute size, canopy filling time, velocity reduction, peak deceleration, and opening shock, authors have proposed a unique type of solid canopy with slots (slots of the minimum area equivalent to geometry porosity) for the main parachute rather than a complex ringsail or disk-band type canopy. With this new concept, the parachute has been designed, developed and qualified through testing, trials and maiden flight of space capsule in LEO and is propose to use in the next manned space mission program.

Error Modeling in Distance and Rotation for Self-Calibration of Space Robots on Orbit

Vibration and impact of launching, inner and outer pressure difference, and thermal deformation of the space capsule will change the transformation between the pose measurement system and the space robot base. It will be complicated, even hard, to measure and calculate this transformation accurately. Therefore, an error modeling method considering both the distance error and the rotation error of the end-effector is proposed for self-calibration of the space robot on orbit, in order to avoid the drawback of frame transformation. Moreover, according to linear correlation of the columns of the identification matrix, unrecognizable parameters in the distance and rotation error model are removed to eliminate singularity in robot kinematic calibration. Finally simulation tests on a 7-DOF space robot are conducted to verify the effectiveness of the proposed method.