rss_2.0Sciendo RSS Feed for Gravitational and Space Researchhttps://sciendo.com/journal/GSRhttps://www.sciendo.comhttps://sciendo-parsed.s3.eu-central-1.amazonaws.com/6471e18d215d2f6c89db3e9c/cover-image.jpghttps://sciendo.com/journal/GSR140216https://sciendo.com/article/10.2478/gsr-2023-0001<abstract> <title style='display:none'>Abstract</title> <p>In long-duration space missions, crops will supplement the astronaut diet. One proposed crop type is microgreens, the young seedlings of edible plants that are known for their high nutritional levels, intense flavors, colorful appearance, and variety of textures. While these characteristics make microgreens promising for space crop production, their small size presents a unique challenge within the microgravity environment. To address this challenge, a microgreen planting box was developed to improve microgreen harvest techniques both in 1 g and in microgravity without concern for contamination by roots. Using this microgreen planting box, three parabolic flights were conducted where two different bagging methods (attached and manual) and three different microgreen cutting methods (Guillotine, Pepper Grinder, Scissors) were tested. In flight, the microgreens were contained within a glovebox and footage of all microgreen harvests was recorded. Statistical and trade analyses revealed that the combination of Cutting &amp; Bagging method that performed the best was the Pepper Grinder with attached bagging. This was based on the following criteria: (1) average execution time, (2) microgreen debris, (3) biomass yield, (4) root debris, (5) microgreens left on the hardware, (6) number of seedlings growing under the lids, (7) hardware failure, and (8) perceived ease of use. This process allowed us to identify weaknesses and strengths of all hardware types and helped us identify major points of improvement within the hardware design to harvest microgreens in microgravity. Future directions include microgreen harvests in analog environments and further development of microgreen Cutting &amp; Bagging method.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2023-00012023-10-31T00:00:00.000+00:00https://sciendo.com/article/10.2478/gsr-2021-0002<abstract> <title style='display:none'>Abstract</title> <p>The increasing availability of flights on suborbital rockets creates new avenues for the study of spaceflight effects on biological systems, particularly of the transitions between hypergravity and microgravity. This paper presents an initial comparison of the responses of Arabidopsis thaliana to suborbital and atmospheric parabolic flights as an important step toward characterizing these emerging suborbital platforms and their effects on biology. Transcriptomic profiling of the response of the Arabidopsis ecotype Wassilewskija (WS) to the aggregate suborbital spaceflight experiences in Blue Origin New Shepard and Virgin Galactic SpaceShipTwo revealed that the transcriptomic load induced by flight differed between the two flights, yet was biologically related to traditional parabolic flight responses. The sku5 skewing mutant and 14-3-3κ:GFP regulatory protein overexpression lines, flown in the Blue Origin and parabolic flights, respectively, each showed altered intra-platform responses compared to WS. An additional parabolic flight using the F-104 Starfighter showed that the response of 14-3-3κ:GFP to flight was modulated in a similar manner to the WS line. Despite the differing genotypes, experimental workflows, flight profiles, and platforms, differential gene expression linked to remodeling of central metabolic processes was commonly observed in the flight responses. However, the timing and directionality of differentially expressed genes involved in the conserved processes differed among the platforms. The processes included carbon and nitrogen metabolism, branched-chain amino acid degradation, and hypoxic responses. The data presented herein highlight the potential for various suborbital platforms to contribute insights into biological responses to spaceflight, and further suggest that in-flight fixation during suborbital experiments will enhance insights into responses during each phase of flight.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2021-00022021-01-29T00:00:00.000+00:00https://sciendo.com/article/10.2478/gsr-2021-0009<abstract> <title style='display:none'>Abstract</title> <p>Improvement of cryogenic fluid storage and transfer technology for in-space propulsion and storage systems is required for long-term space missions. Screened channel liquid acquisition devices (LADs) have long been used with storable propellants to deliver vapor-free liquid during engine restart and liquid transfer processes. The use of LADs with cryogenic fluids is problematic due to low temperatures associated with cryogenic fluids. External heat leaks will cause vapor bubbles to form within the LADs that are difficult to remove in the existing designs. A tapered LAD channel has been proposed to reliably remove vapor bubbles within the device without costly thrusting maneuvers or active separation systems. A model has been developed to predict bubble movement within tapered LAD channels, and subsequent ground testing was completed with a simulant fluid to provide model validation data. Suborbital microgravity testing of tapered LAD technology was recently completed with two different simulant fluids and demonstrated that the concept can passively expel vapor bubbles within the channel. Two additional suborbital flights have been funded to further develop this technology by investigating the performance of larger scale versions of the design.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2021-00092021-06-26T00:00:00.000+00:00https://sciendo.com/article/10.2478/gsr-2021-0001<abstract> <title style='display:none'>Abstract</title> <p>Small, airless bodies are covered by a layer of regolith composed of particles ranging from μm-size dust to cm-size pebbles that evolve under conditions very different than those on Earth. Flight-based microgravity experiments investigating low-velocity collisions of cm-size projectiles into regolith have revealed that certain impact events result in a mass transfer from the target regolith onto the surface of the projectile. The key parameters that produce these events need to be characterized to understand the mechanical behavior of granular media, which is composed of the surfaces of small bodies. We carried out flight and ground-based research campaigns designed to investigate these mass transfer events. The goals of our experimental campaigns were (1) to identify projectile energy thresholds that influence mass transfer outcomes in low-energy collision events between cm-size projectiles and μm-size regolith, (2) to determine whether these mass transfer events required a microgravity environment to be observed, and (3) to determine whether the rebound portion of these collision events could be replicated in a laboratory drop tower environment. We found that (1) mass transfer events occurred for projectile rebound accelerations &lt;7.8 m/s² and we were unable to identify a corresponding impact velocity threshold, (2) mass transfer events require a microgravity environment, and (3) ourdrop tower experiments were able to produce mass transfer events. However, drop tower experiments do not exactly reproduce the free-particle impacts and rebound of the long-duration microgravity experiments and yielded systematically lower amounts of the overall mass transferred.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2021-00012021-01-29T00:00:00.000+00:00https://sciendo.com/article/10.2478/gsr-2021-0005<abstract> <title style='display:none'>Abstract</title> <p>Blue Origin's New Shepard launch vehicle made its first flight above the Kármán Line, returning safely to Earth in November 2015. At the time when this paper is being written (February 2021), the system has conducted 14 flights, including 10 with research and education payloads aboard. More than 100 payloads have exercised a wide range of capabilities and interfaces, from small cubesat-form factor student payloads to large custom payloads of nearly 100 kg. Investigations have spanned a wide range of high-altitude and microgravity research objectives, as well as raising technology readiness level (TRL) on diverse hardware. This paper summarizes New Shepard's payload missions to date, and presents standardized and custom accommodations, both in the shirtsleeve cabin and directly exposed to the space environment.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2021-00052021-03-20T00:00:00.000+00:00https://sciendo.com/article/10.2478/gsr-2021-0006<abstract> <title style='display:none'>Abstract</title> <p>The Orbital Syngas/Commodity Augmentation Reactor (OSCAR) project investigated hardware and engineering development for waste conversion operations related to trash deconstruction and repurposing for long duration space missions. Operations of the trash-to-gas system were investigated to compare microgravity (μg) and Earth gravity environments. The OSCAR system has been demonstrated in other μg platforms, but here the performance and results on the Blue Origin New Shepard Suborbital Vehicle are discussed. The OSCAR suborbital operation demonstrated the introduction of trash into a high temperature reactor for solid to gas conversion, ignition of mixed trash feedstock, combustion during μg, and subsequent gas collection processes in a flight automated sequence. An oxygen (O₂)- and steam-rich environment was created within the reactor for ignition conditions, and the product gases were quantified to verify the reaction product composition. This paper focuses on the chemistry processes of the reactor, and gas and solid product analysis of the μg and gravity conditions. The gas production, reactor thermal profile, and mass and carbon conversion results validated confidence in the system design to continue the advancement of this technology for future spaceflight implementations.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2021-00062021-05-24T00:00:00.000+00:00https://sciendo.com/article/10.2478/gsr-2021-0007<abstract> <title style='display:none'>Abstract</title> <p>The Spaceflight Associated Neuro-ocular Syndrome (SANS) is hypothesized to be associated with microgravity-induced fluid shifts. There is a need for an animal model of SANS to investigate its pathophysiology. We used the rat hindlimb suspension (HS) model to examine the relationship between the assumed cephalad fluid shifts, intraocular (IOP) pressure and the molecular responses in the retina to the prolonged change in body posture. Long evans rats were subjected to HS up to 90 days. Animals completing 90-day suspension were further studied for recovery periods up to 90 additional days in normal posture. With respect to baseline, the average IOP increase in HS animals and the rate of change varied by cohort. Transcriptomics evidence supported a response to HS in the rat retina that was affected by age and sex. Several molecular networks suggested stress imposed by HS affected the retinal vasculature, oxidative and inflammation status, pigmented epithelium and glia. The CSNK1A1-TP53 pathway was implicated in the response in all cohorts. Sex-specific genes were involved in cytoprotection and may explain sex-dependent vulnerabilities to certain eye diseases. These results support the hypothesis that changes in the biology of the retina subjected to simulated microgravity involve both the neural and vascular retina.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2021-00072021-09-18T00:00:00.000+00:00https://sciendo.com/article/10.2478/gsr-2021-0003<abstract> <title style='display:none'>Abstract</title> <p>Multiple private companies are building suborbital reusable launch vehicles possessing vastly different designs. Many of these companies originally focused on space tourism; however, revolutionary applications for scientific and engineering research as well as technology demonstrations and instrument development are emerging. The dramatic reduction in cost over traditional launch systems as well as a guaranteed (and rapid) safe payload return enable many new launch vehicle applications. These new capabilities will essentially move the laboratory environment up to the edge of space. To make use of these novel launch vehicles, the John Hopkins University Applied Physics Laboratory has established a Commercial Suborbital Program with a core system (JANUS) to support and enable many future suborbital missions. This program has already conducted six suborbital flight missions to establish vehicle interfaces and analyze the suitability and limits of each flight environment. Additionally, this program has also been selected by the NASA Flight Opportunities Program for five additional operational suborbital missions. Here we present the results of our completed missions as well as descriptions of future selected missions scheduled for 2021–2023.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2021-00032021-01-29T00:00:00.000+00:00https://sciendo.com/article/10.2478/gsr-2021-0004<abstract> <title style='display:none'>Abstract</title> <p>The Modal Propellant Gauging (MPG) experiment has demonstrated sub-1% gauging accuracy under laboratory conditions on both flight hardware and subscale tanks. Recently, MPG was adapted for flight on Blue Origin's New Shepard vehicle and has flown twice, achieving equilibrated, zero-g surface configurations of propellant simulant at three different fill fractions. Flight data from MPG missions on New Shepard P7 and P9 show agreement between known and measured propellant levels of 0.3% for the fill fractions investigated in the present study. Two approaches for estimating zero-g propellant mass are described here. Both approaches rely on measuring shifts in modal frequencies of a tank excited by acoustic surface waves and subject to fluid mass loading by the propellant. In the first approach, shifts in the lowest mode frequency (LMF) are measured and associated with liquid fill-level changes. In the second approach, 1-g modal spectra at a range of known fill levels are used in a cross-correlation calculation to predict fill levels associated with a zero-g modal spectrum. Flight data for both approaches are consistent with finite element predictions using a simple fluid–structure interaction model. In both settled and unsettled microgravity environments, MPG meets or exceeds NASA Roadmap goals for in-space propellant mass gauging.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2021-00042021-02-26T00:00:00.000+00:00https://sciendo.com/article/10.2478/gsr-2021-0011<abstract> <title style='display:none'>Abstract</title> <p>With benefits such as environmentally safe treatment methods to stimulate growth, to increase plant yield, and improve disinfection efficiency, literature on the field of plasma treatment of seeds is growing. Generalized variables and success criteria have not been well correlated between studies, so this review paper serves to connect plasma and agriculture technologies to coordinate future efforts in this growing area of research. The authors have particular interest due to space agriculture, where seeds are sanitized before being sent into space for crop production. In order to supply a spectrum of nutritional needs, it is necessary to provide a variety of crops and ensure biological decontamination before the seeds are being sent into space. Traditional seed sanitization methods are not viable for all seed types, so exploration of other options is needed to expand the astronaut diet on long-duration space missions. This review paper brings together the current state-of-the-art reported literature to aide in understanding plasma seed application apparatus, seed or crop performance pertaining to germination, growth, water interactions, inactivation of bacteria, and surface sanitization results. These recent works include evolving research themes for potential seed treatment sanitization processes for various seed types to ensure the viability of plants for future growth in microgravity crop production systems.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2021-00112021-12-24T00:00:00.000+00:00https://sciendo.com/article/10.2478/gsr-2021-0010<abstract> <title style='display:none'>Abstract</title> <p>In preparation of a flight experiment, ground-based studies for optimizing the growth of radishes (Raphanus sativus) were conducted at the ground-based Advanced Plant Habitat (APH) unit at the Kennedy Space Center (KSC), Florida. The APH provides a large, environmentally controlled chamber that has been used to grow various plants, such as Arabidopsis, wheat, peppers, and now radish. In support of National Aeronautics and Space Administration (NASA)'s goals to provide astronauts with fresh vegetables and fruits in a confined space, it is important to extend the cultivation period to produce substantial biomass. We selected Raphanus sativus cv. Cherry Belle as test variety both for preliminary tests and flight experiments because it provides edible biomass in as few as four weeks, has desirable secondary metabolites (glucosinolates), is rich in minerals, and requires relatively little space. We report our strategies to optimize the growth substrate, watering regimen, light settings, and planting design that produces good-sized radishes, minimizes competition, and allows for easy harvesting. This information will be applicable for growth optimization of other crop plants that will be grown in the APH or other future plant growth facilities.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2021-00102021-08-23T00:00:00.000+00:00https://sciendo.com/article/10.2478/gsr-2021-0013<abstract> <title style='display:none'>Abstract</title> <p>As human exploration extends further into deep space, it is critical to understand the cellular impacts of spaceflight in order to ensure the safety of future astronauts. Extended exposure to cosmic radiation and microgravity has been shown to cause genetic damage and impair cellular DNA repair mechanisms, which together can lead to genomic instability. In particular, microsatellite instability (MSI), in which dysfunction in DNA mismatch repair (MMR) causes alterations in tandemly repeated “microsatellite” sequences, is a manifestation of genomic instability that has been associated with certain cancers. In this study, we establish the feasibility of an on-orbit multiplex polymerase chain reaction (PCR)-based assay to detect mutations in cancer-related microsatellites. Multiplex PCR was used to amplify five quasimonomorphic microsatellites in space and on Earth from both wild-type and MMR-deficient human cell lines. These data provide proof of concept of simultaneous amplification of multiple DNA sequences in space, expanding in-flight research and health-monitoring capabilities.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2021-00132021-12-31T00:00:00.000+00:00https://sciendo.com/article/10.2478/gsr-2021-0008<abstract> <title style='display:none'>Abstract</title> <p>Microgravity experiment modules for living organisms have been instrumental to space research, yet their design remains complex and costly. As the private space sector enables more widely available payloads for researchers, it is increasingly necessary to design experimental modules innovatively so that they are proportionately accessible. To ease this bottleneck, we developed a rapid fabrication methodology for producing custom modules compatible with commercial payload slots. Our method creates a unified housing geometry, based on a given component layout, which is fabricated in a digital design and subtractive manufacturing process from a single lightweight foam material. This module design demonstrated a 25–50% reduction in chassis weight compared with existing models, and is extremely competitive in manufacturing time, simplicity, and cost. To demonstrate the ability to capture data on previously limited areas of space biology, we apply this methodology to create an autonomous, video-enabled module for sensing and observing queen and retinue bees aboard the Blue Origin New Shepard 11 (NS-11) suborbital flight. To explore whether spaceflight impacts queen fitness, results used high-definition visual data enabled by the module's compact build to analyze queen-worker regulation under microgravity stress (n = 2, with controls). Overall, this generalizable method for constructing experimental modules provides wider accessibility to space research and new data on honey bee behavior in microgravity.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2021-00082021-06-01T00:00:00.000+00:00https://sciendo.com/article/10.2478/gsr-2021-0014<abstract> <title style='display:none'>Abstract</title> <p>For long-term space missions, it is necessary to understand how organisms respond to changes in gravity. Plant roots are positively gravitropic; the primary root grows parallel to gravity's pull even after being turned away from the direction of gravity. We examined if this gravitropic response varies depending on the time of day reorientation occurs. When plants were reoriented in relation to the gravity vector or placed in simulated microgravity, the magnitude of the root gravitropic response varied depending on the time of day the initial change in gravity occurred. The response was greatest when plants were reoriented at dusk, just before a period of rapid growth, and were minimal just before dawn as the plants entered a period of reduced root growth. We found that this variation in the magnitude of the gravitropic response persisted in constant light (CL) suggesting the variation is circadian-regulated. Gravitropic responses were disrupted in plants with disrupted circadian clocks, including plants overexpressing Circadian-clock Associated 1 (CCA1) and <italic>elf3</italic>-2, in the reorientation assay and on a 2D clinostat. These findings indicate that circadian-regulated pathways modulate the gravitropic responses, thus, highlighting the importance of considering and recording the time of day gravitropic experiments are performed.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2021-00142021-12-31T00:00:00.000+00:00https://sciendo.com/article/10.2478/gsr-2021-0012<abstract> <title style='display:none'>Abstract</title> <p>Spaceflight offers vast possibilities for expanding human exploration, whereas it also bears unique health risks. One of these risks is immune dysfunction, which can result in the reactivation of latent pathogens and increased susceptibility to infections. The ability to monitor the function of the immune system is critical for planning successful long-term space travel. T lymphocytes are immune cells that develop in the thymus and circulate in the blood. They can detect foreign, infected, or cancerous cells through T cell receptors (TCRs). The assembly of TCR gene segments, to produce functional TCR genes, can be monitored by measuring the presence of TCR excision circles (TRECs), circular fragments of DNA that are by-products of this assembly process mediated by the V(D)J recombination machinery. In this study, we used polymerase chain reaction (PCR) on the International Space Station (ISS) to detect TRECs in murine peripheral blood. We were able to detect TRECs in the blood of normal healthy mice of different ages, with an efficiency comparable to that achieved in ground controls. As expected, we were unable to detect TRECs in the blood of immunodeficient mice. These results are the first step in optimizing a specific, rapid, safe, and cost-effective PCR-based assay to measure the integrity of mammalian immune systems during spaceflight.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2021-00122021-12-31T00:00:00.000+00:00https://sciendo.com/article/10.2478/gsr-2020-0001<abstract><title style='display:none'>Abstract</title><p>In this work, we report on the construction, training and functional assessment of an electronic nose (called ‘E-Nose’) that is capable of monitoring the microbial contamination onboard space ships under microgravity conditions. To this end, a commercial electronic nose was modified to allow for the sampling of microbial volatile organic compounds (MVOCs) emitted from relevant bacterial and fungi species. Training of the modified ‘E-Nose’ was performed by establishing an MVOC database consisting of two Gram-positive bacteria strains (Bacillus subtilis and Staphylococcus warneri) and two fungi strains (Aspergillus versicolor and Penicillium expansum). All these strains are known to exist onboard the International Space Station (ISS) and to form important parts of its microbial contamination. All cultures were grown on four kinds of structural materials also in use onboard the ISS. The MVOCs emitted during the different growth phases of these cultures were monitored with an array of ten different metal oxide gas sensors inside the ‘E-Nose’. Principal component analysis of the array data revealed that B. subtilis and S. warneri form separate clusters in an optimized score plot, while the two fungi strains of A. versicolor and P. expansum form a large common cluster, well discriminated against to the bacteria clusters.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2020-00012020-06-17T00:00:00.000+00:00https://sciendo.com/article/10.2478/gsr-2020-0002<abstract><title style='display:none'>Abstract</title><p>NASA is planning to launch robotic landers to the Moon as part of the Artemis lunar program. We have proposed sending a greenhouse housed in a 1U CubeSat as part of one of these robotic missions. A major issue with these small landers is the limited power resources that do not allow for a narrow temperature range that we had on previous spaceflight missions with plants. Thus, the goal of this project was to extend this temperature range, allowing for greater flexibility in terms of hardware development for growing plants on the Moon. Our working hypothesis was that a mixture of ecotypes of <italic>Arabidopsis thaliana</italic> from colder and warmer climates would allow us to have successful growth of seedlings. However, our results did not support this hypothesis as a single genotype, Columbia (Col-0), had the best seed germination, growth, and development at the widest temperature range (11–25 °C). Based on results to date, we plan on using the Columbia ecotype, which will allow engineers greater flexibility in designing a thermal system. We plan to establish the parameters of growing plants in the lunar environment, and this goal is important for using plants in a bioregenerative life support system needed for human exploration on the Moon.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2020-00022020-05-26T00:00:00.000+00:00https://sciendo.com/article/10.2478/gsr-2020-0004<abstract><title style='display:none'>Abstract</title><p>Recycling systems aboard spacecraft are currently limited to approximately 80% water recovery from urine. To address challenges associated with odors, contamination, and microgravity fluid flow phenomena, current systems use toxic pretreatment chemicals, filters, and rotary separators. Herein, a semipassive and potentially contaminant- and biofouling-free approach to spacecraft urine processing is developed by combining passive liquid–gas separation, nanophotonic pasteurization, and noncontact Leidenfrost droplet distillation. The system aims to achieve &gt;98% water recovery from wastewater streams in zero, Lunar, Martian, and terrestrial gravitational environments. The surfaces of the phase separator are coated with carbon black nanoparticles that are irradiated by infrared light-emitting diodes (LEDs) producing hyperlocal heating and pasteurization during urine collection, separation, and storage. For the prescribed flow rate and timeline, the urine is then introduced into a heated 8.5-m-long helical hemicircular aluminum track. The low pitch and the high temperature of the track combine to establish weakly gravity-driven noncontact Leidenfrost droplet distillation conditions. In our technology demonstrations, salt-free distillate and concentrated brine are successfully recovered from saltwater feed stocks. We estimate equivalent system mass metrics for the approach, which compare favorably to the current water recovery system aboard the International Space Station.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2020-00042020-07-14T00:00:00.000+00:00https://sciendo.com/article/10.2478/gsr-2020-0003<abstract><title style='display:none'>Abstract</title><p>Cell culture on orbit is complicated by numerous operational constraints, including g-loads on the ascent, vibrations, transit time to International Space Station, and delays in experiment initiation. Cryopreserving cells before launch would negate these factors. However, defrosting these cells is problematic, since the traditional method of employing a water bath is not possible. We here describe a unique apparatus designed to accomplish this in a microgravitational environment. This apparatus resulted in rapid defrost of cryopreserved cell cultures and allowed successful tissue culture operations on the station for periods of up to 21 days.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2020-00032020-06-14T00:00:00.000+00:00https://sciendo.com/article/10.2478/gsr-2019-0005<abstract><title style='display:none'>Abstract</title><p>To investigate the effect of macromolecular transport and the incorporation of protein aggregate impurities in growing crystals, experiments were performed on the International Space Station (ISS) and compared with control experiments performed in a 1G laboratory environment. Crystal growth experiments for hen egg-white lysozyme (HEWL) and <italic>Plasmodium falciparum</italic> glutathione <italic>S</italic>-transferase (<italic>Pf</italic>GST) were monitored using the ISS Light Microscopy Module (LMM). Experiments were performed applying the liquid–liquid counter diffusion crystallization method using rectangular, optically transparent capillaries. To analyze the quantity of impurity incorporated into growing crystals, stable fluorescently labeled protein aggregates were prepared and subsequently added at different percent concentrations to nonlabeled monomeric protein suspensions. For HEWL, a covalent cross-linked HEWL dimer was fluorescently labeled, and for <italic>Pf</italic>GST, a stable tetramer was prepared. Crystallization solutions containing different protein aggregate ratios were prepared. The frozen samples were launched on 19.02.2017 via SpaceX-10 mission and immediately transferred to a -80°C freezer on the ISS. Two series of crystallization experiments were performed on ISS, one during 26.02.2017 to 10.03.2017 and a second during 16.06.2017 to 23.06.2017. A comparison of crystal growth rate and size showed different calculated average growth rates as well as different dimensions for crystals growing in different positions along the capillary. The effect of macromolecular mass transport on crystal growth in microgravity was experimentally calculated. In parallel, the percentage of incorporated fluorescent aggregate into the crystals was monitored utilizing the fluorescent LMM and ground-based fluorescent microscopes.</p></abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/gsr-2019-00052019-09-10T00:00:00.000+00:00en-us-1