Combustion of clear cast polymethylmethacrylate (PMMA) samples 10 cm long by either 1 or 2 cm wide with thicknesses ranging from 1-5 mm was investigated in opposed flow. Tests included both one sided and two sided burns. The samples were burned in a flow duct within the Microgravity Science Glovebox (MSG) on the International Space Station (ISS) to ensure true microgravity conditions. The experiment took place in opposed flow with a varying oxygen concentration (uncontrolled) and varying flow;velocities (controlled). Flames are recorded on two cameras and later tracked to determine spread rate.;Assuming a linear profile between oxygen concentration at the start and the end of each test we made graphs of oxygen concentration vs. time for each test. From these we created flammability maps showing the flame behavior at different oxygen concentrations and flow velocities. Additionally we have conducted an extinction analysis, plotting the oxygen concentration against the flow velocity at;the time of extinction with respect to type of test (one sided or two sided).;Currently we are modeling combustion of flat PMMA;samples in microgravity using Fire Dynamic Simulator (FDS 5.5.3). The entire modeling for BASS-II is done in DNS mode because of the laminar conditions and small domain. The model employs the same test sample and MSG geometry as the experiment. The model predicts a higher flame spread rate than that observed in experiments. So we look to modify the chemical kinetics and materials;properties to improve the model. Also we plan to do a domain study and grid sensitivity analysis in future.
Research Containing: Hardware
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.
Evaluation of rodent spaceflight in the NASA animal enclosure module for an extended operational period (up to 35 days)
The National Aeronautics and Space Administration Animal Enclosure Module (AEM) was developed as a self-contained rodent habitat for shuttle flight missions that provides inhabitants with living space, food, water, ventilation, and lighting, and this study reports whether, after minimal hardware modification, the AEM could support an extended term up to 35 days for Sprague-Dawley rats and C57BL/6 female mice for use on the International Space Station. Success was evaluated based on comparison of AEM housed animals to that of vivarium housed and to normal biological ranges through various measures of animal health and well-being, including animal health evaluations, animal growth and body masses, organ masses, rodent food bar consumption, water consumption, and analysis of blood contents. The results of this study confirmed that the AEMs could support 12 adult female C57BL/6 mice for up to 35 days with self-contained RFB and water, and the AEMs could also support 5 adult male Sprague-Dawley rats for 35 days with external replenishment of diet and water. This study has demonstrated the capability and flexibility of the AEM to operate for up to 35 days with minor hardware modification. Therefore, with modifications, it is possible to utilize this hardware on the International Space Station or other operational platforms to extend the space life science research use;of mice and rats.
The ionizing radiation environment on the International Space Station: performance vs. expectations for avionics and materials
The role of structural shielding mass in the design, verification, and in-flight performance of International Space Station (ISS), in both the natural and induced orbital ionizing radiation (IR) environments, is reported.
The set of materials interactions with the space flight environment that have produced the largest impacts on the verification and acceptance of flight hardware and on flight operations of the International Space Station (ISS) Program during the May 2000 to May 2002 time frame are described in this paper. In-flight data, flight crew observations, and the results of ground-based test and analysis directly supporting programmatic and operational decision-making are reported.
The International Space Station (ISS) presents a significant acoustics challenge considering all of the modules and equipment that make it an on-orbit laboratory workshop and home with long-term crew occupation. This challenge is further complicated by the fact that there are numerous suppliers of ISS hardware, including the international partners. This paper addresses how ISS acoustics are managed to ensure a safe and habitable environment by establishing requirements, providing oversight and design support, sharing lessons learned and information, testing for hardware compliance, predicting future acoustic levels, and performing on-orbit measurements and monitoring of actual acoustic levels. ISS acoustic requirements are classified in three categories by the type of hardware involved: modules; payloads, and Government Furnished Equipment. The current status of overall ISS acoustics for each of these hardware categories will be discussed. In addition, examples will be discussed where NASA design support was used to aid in obtaining compliance, where difficulties were encountered, and where areas of concern were addressed.
Apparatus and methods for separating a fluid are provided. The apparatus can include a separator and a collector having an internal volume defined at least in part by one or more surfaces narrowing toward a bottom portion of the volume. The separator can include an exit port oriented toward the bottom portion of the volume. The internal volume can receive a fluid expelled from the separator into a flow path in the collector and the flow path can include at least two directional transitions within the collector.
The present suite of advanced space plant cultivation facilities require a significant level of resources to launch and maintain in flight. The facilities are designed to accommodate a broad size range of plant species and are, therefore, not configured to support the specific growth requirements of small plant species such as Arabidopsis thaliana at maximum efficiency with respect to mass and power. The facilities are equally not configured to support automated plant harvesting or tissue processing procedures, but rely on crew intervention and time. The recent reorganization of both spaceflight opportunities and allocation of limited in-flight resources demand that experiments be conducted with optimal efficiency. The emergence of A. thaliana as a dominant space flight model organism utilized in research on vegetative and reproductive phase biology provides strong justification for the establishment of a dedicated cultivation system for this species. This paper presents work on the design of a small plant cultivation facility directed at supporting research on the vegetative growth phase of A. thaliana . The design of the facility is based on the use of existing space flight hardware, and configured to support the fully automated germination of seed, cultivation of plants, and final termination of plant growth by chemical fixation and preservation of plant tissue.