Volume 6 (2018): Issue 2 (December 2018)

International Space Station crewmembers experience microgravity, resulting in musculoskeletal losses. It remains unclear how much mechanical loading during disuse is sufficient to mitigate disuse-induced bone loss. We examined 75 minutes of weight-bearing per day on disuse-induced bone loss during hindlimb unloading (HU). Female C57BL/6J mice, 17 weeks (n=10/group), were exposed to HU for 28 days or were ambulatory controls (CC). Half of the HU animals were continuously unloaded while the remainder were removed from tail suspension for ~75 min/day for cage activity weight-bearing (HU+WB). HU and HU+WB led to total body mass and bone mineral density loss. HU+WB mitigated HU-induced losses in total body fat and lean mass and, in the distal femur, prevented losses in μCT measures of cancellous bone volume and microarchitecture. These findings support the robust impact of short durations of normal loading on preventing or mitigating HU-induced bone loss.

This work investigates the suitability of membrane aerated biological reactors (MABRs) for biological treatment of a space-based waste stream consisting of urine, hygiene/grey water, and humidity condensate within an overall water recycling system. Water represents a critical limiting factor for human habitation and travel within space; thus, water recycling systems are essential. Biological treatment of wastewater provides a more efficient sustainable means of stabilizing the waste stream within water recycling system architectures in comparison to current chemical stabilization processes that utilize harsh chemicals, which represent both a hazardous and an unsustainable approach. To assess the capabilities of MABRs for providing microgravity compatible biological treatment and verify long duration operation and integration with desalination processes, two full-scale MABR systems were challenged with various loading rates and operational scenarios during sustained operation for over 1 year. The MABRs were able to maintain 196 g-C/m³-d and 194 g-N/m³-d volumetric conversion rates. Additionally the systems were able to handle intermittent loading and recover rapidly from system hibernation periods of up to 27 days. Overall, the use of MABRs within a wastewater treatment system architecture provides several potential benefits including minimizing the use of toxic chemical pretreatment solutions and providing an effluent solution that is easier to desalinate and dewater.

Passive cyclonic gas-liquid separators (PCGLSs) are commonly used in microgravity conditions where gravity settling separation is difficult or impossible. In this study, displacement-current phase tomography (DCPT) is used to measure various features of the gas-liquid flow inside of a PCGLS. The liquid holdup, liquid angular velocity, and gas core size are investigated. The liquid holdup is also measured in a gas-liquid flow that simulates the injection flow for a PCGLS. It is found that the gas core contracts and expands in a periodic motion as air is injected with water. This motion becomes more noticeable as the air flow rate is increased. It is also found that the liquid layer angular velocity has a positive linear trend with the air flow rate under constant water flow rates. A basic linear relation is derived to relate the liquid angular velocity to the air and water flow rates. All DCPT and electrical capacitance phase tomography (ECVT) results closely match the visual confirmation methods used for each flow feature.

In spaceflight experiments, model organisms are used to assess the effects of microgravity on specific biological systems. In many cases, only one biological system is of interest to the Principal Investigator. To maximize the scientific return of experiments, the remaining spaceflight tissue is categorized, documented, and stored in the biobank at NASA Ames Research Center, which is maintained by the Ames Life Science Data Archive (ALSDA). The purpose of this study is to evaluate the state of a sample set of tissues from the ALSDA biobank. Garnering information – such as downstream functional analysis for the generation of omics datasets – from tissues is, in part, dependent on the state of sample preservation. RNA integrity number (RIN) values have been calculated for rodent liver tissues that were part of scientific payloads returned from the International Space Station (ISS). Rat livers from Spacelab Life Sciences 1 (SLS-1) and mouse livers from Commercial Biomedical Test Module 3 (CBTM-3), Rodent Research 1 (RR1), and Rodent Research 3 (RR3) were tested. It was found that mean RIN values from CBTM-3, RR1, and RR3 were suitable for downstream functional analysis (RIN > 5) while the mean RIN value for SLS-1 was not (RIN = 2.5 ± 0.1). Information from this study lays the foundation for future efforts in determining the types of assays that are most appropriate for different tissues in the ALSDA biobank and similar preservation facilities, which would aid in shaping the design of experiments.

The Cosmic Ray Exposure Sequencing Science (CRESS) payload system was a proof of concept experiment to assess the genomic impact of space radiation on seeds. CRESS was designed as a secondary payload for the December 2016 high-altitude, long-duration south polar balloon flight carrying the Boron and Carbon Cosmic Rays in the Upper Stratosphere (BACCUS) experiment. Investigation of the biological effects of Galactic Cosmic Radiation (GCR), particularly those of ions with High-Z and Energy (HZE), was of interest due to the genomic damage this type of radiation inflicts. The biological effects of radiation above Antarctica (ANT) were studied using Arabidopsis thaliana seeds and compared to a simulation of GCR at Brookhaven National Laboratory (BNL) and to laboratory control seeds. The CRESS payload was broadly designed to 1U CubeSat specifications (10 cm × 10 cm × 10 cm, ≤1.33 kg), maintained 1 atm internal pressure, and carried an internal cargo of 580,000 seeds and twelve CR-39 Solid-State Nuclear Track Detectors (SSNTDs). Exposed BNL and ANT M₀ seeds showed significantly reduced germination rates and elevated somatic mutation rates when compared to non-irradiated controls, with the BNL mutation rate also being higher than that of ANT. Genomic DNA from plants presenting distinct aberrant phenotypes was evaluated with whole-genome sequencing using PacBio SMRT technology, which revealed an array of structural genome variants in the M₀ and M₁ plants. This study was the first whole-genome characterization of space-irradiated seeds and demonstrated both the efficiency and efficacy of Antarctic long-duration balloons for the study of space radiation effects on eukaryote genomes.

Long term spaceflight is associated with the loss of skeletal muscle mass and function. The Molecular Muscle Experiment (MME) seeks to identify the causes of muscle decline in space and test potential therapies to attenuate this in the microscopic worm, Caenorhabditis elegans. This is the first UK-led experiment in the almost two-decade history of the International Space Station. We therefore intend to complete significant and widespread educational outreach activities to promote interest in science, technology, engineering, and math (STEM), and to increase engagement with our space life science experiment. This paper describes three education outreach activities relating to MME that are suitable for use in the classroom: (i) observing normal and mutant worms; (ii) observing the effect of unloading (simulation of microgravity); and (iii) handling spaceflight hardware. Activity packs are provided at a starter and advanced level to support these activities. This paper also provides three posters that may be used as learning resources for educators. These posters provide information on: (i) why worms are used for research; (ii) spaceflight human physiology; and (iii) the specifics of the MME. Details of further planned engagement activities are outlined to increase the awareness of the MME.