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  • Spacecraft Propulsion and Power  (12)
  • Aerospace Medicine  (9)
  • 2015-2019  (4)
  • 2000-2004  (17)
  • 1
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    Erythroid cell growth and differentiation in vitro in the simulated microgravity environment of the NASA rotating wall vessel bioreactor (2001)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Prolonged exposure of humans and experimental animals to the altered gravitational conditions of space flight has adverse effects on the lymphoid and erythroid hematopoietic systems. Although some information is available regarding the cellular and molecular changes in lymphocytes exposed to microgravity, little is known about the erythroid cellular changes that may underlie the reduction in erythropoiesis and resultant anemia. We now report a reduction in erythroid growth and a profound inhibition of erythropoietin (Epo)-induced differentiation in a ground-based simulated microgravity model system. Rauscher murine erythroleukemia cells were grown either in tissue culture vessels at 1 x g or in the simulated microgravity environment of the NASA-designed rotating wall vessel (RWV) bioreactor. Logarithmic growth was observed under both conditions; however, the doubling time in simulated microgravity was only one-half of that seen at 1 x g. No difference in apoptosis was detected. Induction with Epo at the initiation of the culture resulted in differentiation of approximately 25% of the cells at 1 x g, consistent with our previous observations. In contrast, induction with Epo at the initiation of simulated microgravity resulted in only one-half of this degree of differentiation. Significantly, the growth of cells in simulated microgravity for 24 h prior to Epo induction inhibited the differentiation almost completely. The results suggest that the NASA RWV bioreactor may serve as a suitable ground-based microgravity simulator to model the cellular and molecular changes in erythroid cells observed in true microgravity.
    Keywords: Aerospace Medicine
    Type: In vitro cellular & developmental biology. Animal (ISSN 1071-2690); Volume 37; 2; 79-83
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Thermal Analysis of the Fastrac Chamber/Nozzle (2001)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: This paper will describe the thermal analysis techniques used to predict temperatures in the film-cooled ablative rocket nozzle used on the Fastrac 60K rocket engine. A model was developed that predicts char and pyrolysis depths, liner thermal gradients, and temperatures of the bondline between the overwrap and liner. Correlation of the model was accomplished by thermal analog tests performed at Southern Research, and specially instrumented hot fire tests at the Marshall Space Flight Center. Infrared thermography was instrumental in defining nozzle hot wall surface temperatures. In-depth and outboard thermocouple data was used to correlate the kinetic decomposition routine used to predict char and pyrolysis depths. These depths were anchored with measured char and pyrolysis depths from cross-sectioned hot-fire nozzles. For the X-34 flight analysis, the model includes the ablative Thermal Protection System (TPS) material that protects the overwrap from the recirculating plume. Results from model correlation, hot-fire testing, and flight predictions will be discussed.
    Keywords: Spacecraft Propulsion and Power
    Type: The Tenth Thermal and Fluids Analysis Workshop; NASA/CP-2001-211141
    Format: application/pdf
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  • 3
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    Ion Propulsion Subsystem Environmental Effects on Deep Space 1: Initial Results from the IPS Diagnostics Subsystem (2000)
    In:  Other Sources
    Details
    Publication Date: 2018-06-08
    Keywords: Spacecraft Propulsion and Power
    Type: Deep Space 1 Technology Validatation Symposium; Pasadena, CA; United States
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  • 4
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    Ion Propulsion Subsystem Environmental Effects on DS1: Initial Results from the IPS Diagnostics Subsystem (2000)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Spacecraft Propulsion and Power
    Type: DS1 Technology Validation Symposium; Pasadena, CA; United States
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  • 5
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    Restoring Redundancy to the Wilkinson Microwave Anisotrophy Probe Propulsion System (2004)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: The Wilkinson Microwave Anisotropy Probe is a follow-on to the Differential Microwave Radiometer instrument on the Cosmic Background Explorer. Attitude control system engineers discovered sixteen months before launch that configuration changes after the critical design review had resulted in a significant migration of the spacecraft's center of mass. As a result, the spacecraft no longer had a viable backup control mode in the event of a failure of the negative pitch-axis thruster. A tiger team was formed and identified potential solutions to this problem, such as adding thruster-plume shields to redirect thruster torque, adding or removing mass from the spacecraft, adding an additional thruster, moving thrusters, bending thruster nozzles or propellant tubing, or accepting the loss of redundancy. The project considered the impacts on mass, cost, fuel budget, and schedule for each solution, and decided to bend the propellant tubing of the two roll-control thrusters to allow the pair to be used for backup control in the negative pitch axis. This paper discusses the problem and the potential solutions, and documents the hardware and software changes and verification performed. Flight data are presented to show the on-orbit performance of the propulsion system and lessons learned are described.
    Keywords: Spacecraft Propulsion and Power
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  • 6
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    Propulsion Options for the Global Precipitation Measurement Core Satellite (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This study was conducted to evaluate several propulsion system options for the Global Precipitation Measurement (GPM) core satellite. Orbital simulations showed clear benefits for the scientific data to be obtained at a constant orbital altitude rather than with a decay/reboost approach. An orbital analysis estimated the drag force on the satellite will be 1 to 12 mN during the five-year mission. Four electric propulsion systems were identified that are able to compensate for these drag forces and maintain a circular orbit. The four systems were the UK-10/TS and the NASA 8 cm ion engines, and the ESA RMT and RITl0 EVO radio-frequency ion engines. The mass, cost, and power requirements were examined for these four systems. The systems were also evaluated for the transfer time from the initial orbit of 400 x 650 km altitude orbit to a circular 400 km orbit. The transfer times were excessive, and as a consequence a dual system concept (with a hydrazine monopropellant system for the orbit transfer and electric propulsion for drag compensation) was examined. Clear mass benefits were obtained with the dual system, but cost remains an issue because of the larger power system required for the electric propulsion system. An electrodynamic tether was also evaluated in this trade study.
    Keywords: Spacecraft Propulsion and Power
    Type: AIAA Joint Propulsion Conference; Jul 20, 2003 - Jul 23, 2003; Huntsville, AL; United States
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  • 7
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    The MAP Propulsion Subsystem (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper describes the requirements, design, integration, test, performance, and lessons learned of NASA's Microwave Anisotropy Probe (MAP) propulsion subsystem. MAP was launched on a Delta-II launch vehicle from NASA's Kennedy Space Center on June 30, 2001. Due to instrument thermal stability requirements, the Earth-Sun L2 Lagrange point was selected for the mission orbit. The L2 trajectory incorporated phasing loops and a lunar gravity assist. The propulsion subsystem's requirements are to manage momentum, perform maneuvers during the phasing loops to set up the lunar swingby, and perform stationkeeping at L2 for 2 years. MAP's propulsion subsystem uses 8 thrusters which are located and oriented to provide attitude control and momentum management about all axes, and delta-V in any direction without exposing the instrument to the sun. The propellant tank holds 72 kg of hydrazine, which is expelled by unregulated blowdown pressurization. Thermal management is complex because no heater cycling is allowed at L2. Several technical challenges presented themselves during I and T, such as in-situ weld repairs and in-situ bending of thruster tubes to accommodate late changes in the observatory CG. On-orbit performance has been nominal, and all phasing loop, mid-course correction, and stationkeeping maneuvers have been successfully performed to date.
    Keywords: Spacecraft Propulsion and Power
    Type: AIAA-2002-4156 , AIAA/ASME/SAE/ASEE 38th Joint Propulsion Conference; Jul 07, 2002 - Jul 10, 2002; Indianapolis, IN; United States
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  • 8
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    Calcium and Bone Homeostasis During 4-6 Months Space Flight (2000)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: Bone and calcium homeostasis are altered by weightlessness. We previously reported calcium studies on three subjects from the first joint US/Russian mission to Mir. We report here data on an additional three male subjects, whose stays on Mir were 4 (n= 1) and 6 (n=2) mos. Data were collected before, during, and after the missions. Inflight studies were conducted at 2-3 mos. Endocrine and biochemical indices were measured, along with 3-wk calcium tracer studies. Percent differences are reported compared to preflight. Ionized calcium was unchanged (2.8 +/-2.1 %) during flight. Calcium absorption was variable inflight, but was decreased after landing. Vitamin D stores were decreased 35 +/-24% inflight, similar to previous reports. Serum PTH was decreased 59 +/-9% during flight (greater than we previously reported), while 1,25(OH)(sub 2)-Vitamin D was decreased in 2 of 3 subjects. Markers of bone resorption (e.g., crosslinks) were increased in all subjects. Bone-specific alkaline phosphatase was decreased (n=1) or unchanged (n=2), while osteocalcin was decreased 34 +/-23%. Previously presented data showed that inflight bone loss is associated with increased resorption and unchanged/decreased formation. The data reported here support these earlier findings. These studies will help to extend our understanding of space flight-induced bone loss, and of bone loss associated with diseases such as osteoporosis or paralysis.
    Keywords: Aerospace Medicine
    Type: Experimental Biology; Apr 15, 2000 - Apr 18, 2000; San Diego, CA; United States
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  • 9
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    Analysis of Surface Charging for a Candidate Solar Sail Mission Using NASCAP-2K (2004)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: The characterization of the electromagnetic interaction for a solar sail in the solar wind environment, and identification of viable charging mitigation strategies, is a critical solar sail mission design task, as spacecraft charging has important implications both for science applications and for sail lifetime. To that end, we have performed surface charging calculations of a candidate 150-meter-class solar sail spacecraft for the 0.5 AU solar polar orbit and a 1.0 AU L1 orbit. We construct a model of the spacecraft with candidate materials having appropriate electrical properties using Object Toolkit and perform the spacecraft charging analysis using NASCAP-2k, the NASA/AFRL sponsored spacecraft charging analysis tool. We use nominal and atypical solar wind environments appropriate for the 0.5 AU and 1.0 AU missions to establish current collection of solar wind ions and electrons. In addition, we include a geostationary orbit case to demonstrate a bounding example of extreme (negative) charging of a solar sail spacecraft in the geostationary orbit environment. Results from the charging analysis demonstrate that minimal differential potentials (and resulting threat of electrostatic discharge) occur when the spacecraft is constructed entirely of conducting materials, as expected. Examples with dielectric materials exposed to the space environment exhibit differential potentials ranging from a few volts to extreme potentials in the kilovolt range.
    Keywords: Spacecraft Propulsion and Power
    Type: 9th Spacecraft Charging Technology Conference; Apr 04, 2005 - Apr 08, 2005; Tsukuba; Japan
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  • 10
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    The Visual Impairment Intracranial Pressure Syndrome in Long Duration NASA Astronauts: An Integrated Approach (2015)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: The Visual Impairment Intracranial Pressure (VIIP) syndrome is currently NASA's number one human space flight risk. The syndrome, which is related to microgravity exposure, manifests with changes in visual acuity (hyperopic shifts, scotomas), changes in eye structure (optic disc edema, choroidal folds, cotton wool spots, globe flattening, and distended optic nerve sheaths). In some cases, elevated cerebrospinal fluid pressure has been documented postflight reflecting increased intracranial pressure (ICP). While the eye appears to be the main affected end organ of this syndrome, the ocular affects are thought to be related to the effect of cephalad fluid shift on the vascular system and the central nervous system. The leading hypotheses for the development of VIIP involve microgravity induced head-ward fluid shifts along with a loss of gravity-assisted drainage of venous blood from the brain, both leading to cephalic congestion and increased ICP. Although not all crewmembers have manifested clinical signs or symptoms of the VIIP syndrome, it is assumed that all astronauts exposed to microgravity have some degree of ICP elevation in-flight. Prolonged elevations of ICP can cause long-term reduced visual acuity and loss of peripheral visual fields, and has been reported to cause mild cognitive impairment in the analog terrestrial population of Idiopathic Intracranial Hypertension (IIH). These potentially irreversible health consequences underscore the importance of identifying the factors that lead to this syndrome and mitigating them.
    Keywords: Aerospace Medicine
    Type: JSC-CN-34816 , American Society for Gravitational and Space Research Meeting; Nov 10, 2015 - Nov 14, 2015; Alexandria, VA; United States
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