DECLIC is a multi-user facility to investigate critical fluids behaviour and directional solidification of transparent alloys, developed in the frame of a joint NASA/CNES research program. The instrument is a miniaturized thermo optical laboratory in which one can plug inserts containing the materials to be studied.
Research Containing: Microgravity
The Importance of Caveolin-1 as Key-Regulator of Three-Dimensional Growth in Thyroid Cancer Cells Cultured under Real and Simulated Microgravity Conditions
We recently demonstrated that the CAV1 gene was down-regulated, when poorly differentiated thyroid FTC-133 cancer cells formed spheroids under simulated microgravity conditions. Here, we present evidence that the caveolin-1 protein is involved in the inhibition of spheroid formation, when confluent monolayers are exposed to microgravity. The evidence is based on proteins detected in cells and their supernatants of the recent spaceflight experiment: "NanoRacks-CellBox-Thyroid Cancer". The culture supernatant had been collected in a special container adjacent to the flight hardware incubation chamber and stored at low temperature until it was analyzed by Multi-Analyte Profiling (MAP) technology, while the cells remaining in the incubation chamber were fixed by RNAlater and examined by mass spectrometry. The soluble proteins identified by MAP were investigated in regard to their mutual interactions and their influence on proteins, which were associated with the cells secreting the soluble proteins and had been identified in a preceding study. A Pathway Studio v.11 analysis of the soluble and cell-associated proteins together with protein kinase C alpha (PRKCA) suggests that caveolin-1 is involved, when plasminogen enriched in the extracellular space is not activated and the vascular cellular adhesion molecule (VCAM-1) mediated cell-cell adhesion is simultaneously strengthened and activated PRKCA is recruited in caveolae, while the thyroid cancer cells do not form spheroids.
Recent space flight experiments have provided many new insights into the role of gravity in plant growth and development. Scientists have been taking seeds and plants into space for decades in an effort to understand how the stressful environment of space affects them. The resultant data have yielded significant advances in the development of advanced life-support systems for long-duration space flight and a better understanding of the fundamental role of gravity in directing the growth and development of plants. Experiments have improved as new spaceflight hardware and technology paved the way for progressively more insightful and rigorous plant research in space. The International Space Station (ISS) provided an opportunity for scientists to both monitor and control their experiments in real-time. Experiments on the ISS have provided valuable insights into endogenous growth responses, light-responses, and transcriptomic and proteomic changes that occur in the microgravity environment. In recent years most studies of plants in space have used Arabidopsis thaliana, but the single-celled, Ceratopteris richardii spore is also a valuable model system that has been used to understand plant gravity response. Experiments using these fern spores have revealed a dynamic and gravity-responsive trans-cell Ca2+ current that directs polarization of these spores, and a possible role of extracellular nucleotides in establishing or contributing to this current. As technology continues to improve, space flight experiments will provide many new insights into the role and effects of gravity on plant growth and development.
Viability of the lichen Xanthoria elegans and its symbionts after 18 months of space exposure and simulated Mars conditions on the ISS
The lichen Xanthoria elegans has been exposed to space conditions and simulated Mars-analogue conditions in the lichen and fungi experiment (LIFE) on the International Space Station (ISS). After several simulations and short space exposure experiments such as BIOPAN, this was the first long-term exposure of eukaryotic organisms to the hostile space conditions of the low Earth orbit (LEO). The biological samples were integrated in the EXPOSE-E facility and exposed for 1.5 years outside the ISS to the combined impact of insolation, ultraviolet (UV)-irradiation, cosmic radiation, temperatures and vacuum conditions of LEO space. Additionally, a subset of X. elegans samples was exposed to simulated Martian environmental conditions by applying Mars-analogue atmosphere and suitable solar radiation filters. After their return to Earth the viability of the lichen samples was ascertained by viability analysis of LIVE/DEAD staining and confocal laser-scanning microscopy, but also by analyses of chlorophyll a fluorescence. According to the LIVE/DEAD staining results, the lichen photobiont showed an average viability rate of 71%, whereas the even more resistant lichen mycobiont showed a rate of 84%. Post-exposure viability rates did not significantly vary among the applied exposure conditions. This remarkable viability is discussed in the context of particular protective mechanisms of lichens such as anhydrobiosis and UV-screening pigments.
Microgravity experiments burning cast PMMA cylindrical rods in axial flow have been conducted aboard the International Space Station in the Microgravity Science Glovebox (MSG) facility using the Burning and Suppression of Solids (BASS) flow duct, as part of the BASS-II experiment. Twenty-four concurrent-flow tests were performed, focusing on finding flammability limits as a function of oxygen and flow speed. The oxygen was varied by using gaseous nitrogen to vitiate the working volume of the MSG. The speed of the flow parallel to the rod was varied using a fan at the entrance to the duct. Both blowoff and quenching limits were obtained at several oxygen concentrations. Each experiment ignited the rod at the initially hemispherical stagnation tip of the rod, and allowed the flame to develop and heat the rod at a sufficient flow to sustain burning. For blowoff limit tests, the astronaut quickly turned up the flow to obtain extinction. Complementary 5.18-second Zero Gravity Facility drop tests were conducted to compare blowoff limits in short and long duration microgravity. For quenching tests, the flow was incrementally turned down and the flame allowed to stabilize at the new flow condition for at least the solid-phase response time before changing it again. Quenching was observed when the flow became sufficiently weak that the flame could no longer provide adequate heat flux to compensate for the heat losses (conduction into the rod and radiation). A surface energy balance is presented that shows the surface radiative loss exceeds the conductive loss into the rod near the limit. The flammability boundary is shown to represent a critical Damkohler number, expressed in terms of the reaction rate divided by the stretch rate. For the blowoff branch, the boundary exhibits a linear dependence on oxygen concentrationandstretchrate,indicatingthatthetemperatureatblowoffmustbefairlyconstant. Forthe quenching branch, the dominance of the exponential nature of the Arrhenius kinetics reaction rate indicates that the temperature is critical.
Results from on-board CSA-CP and CDM Sensor Readings during the Burning and Suppression of Solids– II (BASS-II) Experiment in the Microgravity Science Glovebox (MSG)
For the first time on ISS, BASS-II utilized MSG working volume dilution with gaseous nitrogen (N2). We developed a perfectly stirred reactor model to determine the N2 flow time and flow rate to obtain the desired reduced oxygen concentration in the working volume for each test. We calibrated the model with CSA-CP oxygen readings offset using the Mass Constituents Analyzer reading of the ISS ambient atmosphere data for that day. This worked out extremely well for operations, and added a new vital variable, ambient oxygen level, to our test matrices. The main variables tested in BASS-II were ambient oxygen concentration, ventilation flow velocity, and fuel type, thickness, and geometry.;BASS-II also utilized the on-board CSA-CP for oxygen and carbon monoxide readings, and the CDM for carbon dioxide readings before and after each test. Readings from these sensors allow us to evaluate the completeness of the combustion. The oxygen and carbon dioxide readings before and after each test were analyzed and compared very well to stoichiometric ratios for a one step gas-phase reaction. The CO versus CO2 followed a linear trend for some datasets, but not for all the different geometries of fuel and flow tested. We calculated the heat release rates during each test from the oxygen consumption and burn times, using the constant 13.1 kJ of heat released per gram of oxygen consumed. The results showed that the majority of the tests had heat release rates well below 100 Watts. Lastly, the global equivalence ratio for the tests is estimated to be fuel rich: 1.3 on average using mass loss and oxygen consumption data.
Characterization of fungi isolated from the equipment used in the International Space Station or Space Shuttle
As a part of a series of studies regarding the microbial biota in manned space environments, fungi were isolated from six pieces of equipment recovered from the Japanese Experimental Module "KIBO" of the International Space Station and from a space shuttle. Thirty-seven strains of fungi were isolated, identified and investigated with regard to morphological phenotypes and antifungal susceptibilities. The variety of fungi isolated in this study was similar to that of several previous reports. The dominant species belonged to the genera Penicillium, Aspergillus and Cladosporium, which are potential causative agents of allergy and opportunistic infections. The morphological phenotypes and antifungal susceptibilities of the strains isolated from space environments were not significantly different from those of reference strains on Earth.
This paper will explore the opportunities and challenges in developing the commercial market in LEO through the ISS program and all its facets, including operations, mission support activities, utilization, and contracting. The role of NASA-funded research in the vertical translation of basic research in space to practical application in the market or to other government service agencies will also be addressed. Other aspects, including government regulation, investment and tax incentives, and possible roles of various government agencies will also be explored. Of particular importance, the role of private industry, currently in the supply business, in the development of the demand for LEO capabilities and services beyond the federal government will be highlighted. In conclusion, this paper will address the prospects in reaching the goal of commercializing LEO starting from where we are today in human spaceflight and the International Space Station.
Reduced gravity combustion experiments were performed aboard the International Space Station with individual methanol and n-heptane droplets that had initial diameters in the 1.2-5.0 mm size range. Experiments were performed with air-inert mixtures at 0.1 and 0.07 MPa and about 298 K, where the monatomic gases helium and xenon were separately used as the added inert. These two gases have the same thermodynamic properties on a molar basis, but their transport properties are significantly different, allowing investigation of transport property effects such as Lewis number variations on combustion phenomena. The results indicate that ambient gas transport properties play an important role in determining limiting oxygen indices as well as burning rates and radiant heat output histories of flames. However, comparison with drop tower data suggests that initial droplet diameters may not play a significant role in determining limiting oxygen index values.
Effects of cooling temperature on heat pipe evaporator performance using an ideal fluid mixture in microgravity
The effect of cooling temperature on heat pipe performance has generally received little consideration. In this paper, we studied the performance of a Constrained Vapor Bubble (CVB) heat pipe using a liquid mix- ture of 94 vol%-pentane and 6 vol%-isohexane at different cooling temperatures in the microgravity envi- ronment of the International Space Station (ISS). Using a one-dimensional (1-D) heat transfer model developed in our laboratory, the heat transfer coefficient of the evaporator section was calculated and shown to decrease with increasing cooler temperature. Interestingly, the decreasing trend was not the same across the cooler settings studied in the paper. This trend corresponded with the change in the tem- perature profile along the cuvette. When the cooling temperature went from 0 to 20 C, the temperature of the cuvette decreased monotonically from the heater end to the cooler end and the heat transfer coef- ficient decreased slowly from 456 to 401 (W m 2 K 1) (at a rate of 2.75 W m 2 K 2). However, when the cooling temperature increased from 25 to 35 C, a minimum point formed in the temperature profile, and the heat transfer coefficient dramatically decreased from 355 to 236 (W m 2 K 1) (at a rate of 11.9 W m 2 K 2). A similar change in decreasing trend was observed in the pressure gradient and liquid velocity profile. The reduced heat pipe performance at high cooling temperatures was consistent with the reduced evaporation which was indicated by the decreasing internal heat transfer and the increasing liq- uid film thickness along the cuvette as seen in the surveillance images. The result obtained is important for future heat pipe design because we now have a better understanding of the working temperature ranges of these devices.