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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

Mars ISRU for Production of Mission Critical Consumables - Options, Recent Studies, and Current State of the Art

In 1978, a ground breaking paper titled, "Feasibility of Rocket Propellant Production on Mars" by Ash, Dowler, and Varsi discussed how ascent propellants could be manufactured on the Mars surface from carbon dioxide collected from the atmosphere to reduce launch mass. Since then, the concept of making mission critical consumables such as propellants, fuel cell reactants, and life support consumables from local resources, commonly known as In-Situ Resource Utilization (ISRU), for robotic and human missions to Mars has been studied many times. In the late 1990's, NASA initiated a series of Mars Human Design Reference Missions (DRMs), the first of which was released in 1997. These studies primarily focused on evaluating the impact of making propellants on Mars for crew ascent to Mars orbit, but creating large caches of life support consumables (water & oxygen) as a backup for regenerative life support systems for long-duration surface stays (>500 days) was also considered in Mars DRM 3.0. Until science data from the Mars Odyssey orbiter and subsequent robotic missions revealed that water may be widely accessable across the surface of Mars, prior Mars ISRU studies were limited to processing Mars atmospheric resources (carbon dioxide, nitrogen, argon, oxygen, and water vapor). In December 2007, NASA completed the Mars Human Design Reference Architecture (DRA) 5.0 study which considered water on Mars as a potential resource for the first time in a human mission architecture. While knowledge of both water resources on Mars and the hardware required to excavate and extract the water were very preliminary, the study concluded that a significant reduction in mass and significant enhancements to the mission architecture were possible if Mars water resources were utilized. Two subsequent Mars ISRU studies aimed at reexamining ISRU technologies, processing options, and advancements in the state-of-the-art since 2007 and to better understand the volume and packaging associated with Mars ISRU systems further substantiated the preliminary results from the Mars DRA 5.0 study. This paper will provide an overview of Mars ISRU consumable production options, the analyses, results, and conclusions from the Mars DRA 5.0 (2007), Mars Collaborative (2013), and Mars ISRU Payload for the Supersonic Retro Propulsion (2014) mission studies, and the current state-of-the-art of Mars ISRU technologies and systems. The paper will also briefly discuss the mission architectural implications associated with Mars resource and ISRU processing options.

Sanders, G. B.↗
NASA NTRS1982

Dynamics of magnetosphere-ionosphere coupling including turbulent transport

A two dimensional two-fluid MHD model including anomalous resistivity was used to investigate the dynamics of magnetosphere-ionosphere coupling. When a field-aligned current is generated on auroral field lines, the disturbance propagates towards the ionosphere in the form of a kinetic Alfven wave. When the current exceeds a critical value, microscopic turbulence is produced, which modifies the propagation of the Alfven wave. This process is modeled by a nonlinear collision frequency, which increases with the excess of the drift velocity over the critical value. Turbulence leads to absorption and reflection of the Alfven wave, partially decoupling the generator from the ionosphere. The approach to a steady-state is strongly dependent on the presence or absence of the turbulence. The current is self-limiting, since a current in excess of critical causes a diffusion of the magnetic field perturbation and a reduction of current.

Lysak, R. L.↗
NASA NTRS2006

Towards an Airframe Noise Prediction Methodology: Survey of Current Approaches

In this paper, we present a critical survey of the current airframe noise (AFN) prediction methodologies. Four methodologies are recognized. These are the fully analytic method, CFD combined with the acoustic analogy, the semi-empirical method and fully numerical method. It is argued that for the immediate need of the aircraft industry, the semi-empirical method based on recent high quality acoustic database is the best available method. The method based on CFD and the Ffowcs William- Hawkings (FW-H) equation with penetrable data surface (FW-Hpds ) has advanced considerably and much experience has been gained in its use. However, more research is needed in the near future particularly in the area of turbulence simulation. The fully numerical method will take longer to reach maturity. Based on the current trends, it is predicted that this method will eventually develop into the method of choice. Both the turbulence simulation and propagation methods need to develop more for this method to become useful. Nonetheless, the authors propose that the method based on a combination of numerical and analytical techniques, e.g., CFD combined with FW-H equation, should also be worked on. In this effort, the current symbolic algebra software will allow more analytical approaches to be incorporated into AFN prediction methods.

Farassat, Fereidoun↗
NASA NTRS2019

New Test Rig to Measure Alternating Current Losses of Both Low and High Critical Temperature Superconductors

This paper presents the design, development, operation, and test capabilities of a proposed superconducting coil testbed to measure alternating current (AC) losses at the NASA Glenn Research Center. Superconducting AC losses are important in the design of electric stators and rotors, power transmission lines, transformers, fault current limiters, magnets, and superconducting energy storage (not batteries). The new liquid-hydrogen-based rig will allow superconducting testing across a wide range of test parameters, including injected current up to 400 A, frequency (0 to 400 Hz), magnetic field (0 to 0.6 T), phase angle between induced voltage and injected current (–180° to 180°), coil coolant temperature (18 to 28 K), and AC power loss (5 to 30 W). While the target application of interest is 20 K superconducting MgB2 (the only superconductor that can presently be made with low losses) stator coils for future electric machines, the rig can accommodate test articles (TAs) with straight wire, tape, cables, coils of any shape, any allowable combination of superconducting wire and fluid (e.g., yttrium barium copper oxide (YBCO) coils and liquid nitrogen), and AC or direct current (DC) testing. The new spin rig builds upon the existing Air Force spin rig through a more flexible mode of fluid control, a wider gap space (up to 10.2 cm) for TAs, and the ability to accommodate TAs over a wider range of operating temperatures (18 to 95 K) using liquid hydrogen, gaseous helium, or liquid nitrogen as the working fluid, thus supporting direct cooled machines below 77 K.

liquid hydrogen↗
NASA NTRS1982

Double layer formation during current sheet disruptions in a reconnection experiment

When the current density in the center of a neutral sheet is increased to a critical value spontaneous current disruptions are observed. The release of stored magnetic field energy results in a large inductive voltage pulse which drops off inside the plasma in the form of a potential double layer. Particles are energized, microinstabilities are generated, the plasma is thinned, and the current flow is redirected. These laboratory observations qualitatively support recent models of magnetic substorms and solar flares.

Stenzel, R. L.↗
NASA NTRS2013

Plasma Ion Composition Measurements for Europa

Jupiter magnetospheric interactions and surface composition, both important to subsurface ocean detection for the Galilean icy moons Europa, Ganymede, and Callisto, can be measured using plasma ion mass spectrometry on either an orbiting spacecraft or one designed for multiple flybys of these moons. Detection of emergent oceanic materials at the Europa surface is more likely than at Ganymede and Callisto. A key challenge is to resolve potential intrinsic Europan materials from the space weathering patina of iogenic species implanted onto the sensible surface by magnetospheric interactions. Species resolved measurements of pickup ion currents are also critical to extraction of oceanic induced magnetic fields from magnetospheric interaction background dominated by these currents. In general the chemical astrobiological potential of Europa should be determined through the combination of surface, ionospheric, and pickup ion composition measurements. The requisite Ion Mass Spectrometer (IMS) for these measurements would need to work in the high radiation environment of Jupiter's magnetosphere between the orbits of Europa and Ganymede, and beyond. A 3D hybrid model of the moon magnetosphere interaction is also needed to construct a global model of the electric and magnetic fields, and the plasma environment, around Europa. Europa's ionosphere is probably usually dominated by hot pickup ions with 100-1000 eV temperatures, excursions to a "classical" cold ionosphere likely being infrequent. A field aligned ionospheric wind driven by the electron polarization electric field should arise and be measurable.

Plasma↗
NASA NTRS1986

A simple kinetic theory of auroral arc scales

A kinetic theory of the origins of the auroral arc scale spectrum is presented in this paper. The conceptual basis of the theory is current conservation in a turbulent plasma at the magnetospheric equatorial region in which a field-aligned current is generated and the local electrostatic potential structure is forced to adjust to the presence of the field-aligned current. This simple model uses an ad hoc Ohm's law relationship between the perpendicular current and the perpendicular electric field, but with a negative conductance in the generator region so that J(perpendicular) x E(perpendicular) is less than 0. An exact solution of a simple model of the concept yields a bistatic auroral generator for which multiple-arc formation is predicted if the field-aligned current exceeds a critical value. The predicted scale spectrum is inversely proportional to the square root of the field-aligned current strength spectrum.

Chiu, Y. T.↗
NASA NTRS2007

Human Factors in the Design of the Crew Exploration Vehicle (CEV)

NASA s Space Exploration vision for humans to venture to the moon and beyond provides interesting human factors opportunities and challenges. The Human Engineering group at NASA has been involved in the initial phases of development of the Crew Exploration Vehicle (CEV), Orion. Getting involved at the ground level, Human Factors engineers are beginning to influence design; this involvement is expected to continue throughout the development lifecycle. The information presented here describes what has been done to date, what is currently going on, and what is expected in the future. During Phase 1, prior to the contract award to Lockheed Martin, the Human Engineering group was involved in generating requirements, conducting preliminary task analyses based on interviews with subject matter experts in all vehicle systems areas, and developing preliminary concepts of operations based on the task analysis results. In addition, some early evaluations to look at CEV net habitable volume were also conducted. The program is currently in Phase 2, which is broken down into design cycles, including System Readiness Review, Preliminary Design Review, and Critical Design Review. Currently, there are ongoing Human Engineering Technical Interchange Meetings being held with both NASA and Lockheed Martin in order to establish processes, desired products, and schedules. Multiple design trades and quick-look evaluations (e.g. display device layout and external window size) are also in progress. Future Human Engineering activities include requirement verification assessments and crew/stakeholder evaluations of increasing fidelity. During actual flights of the CEV, the Human Engineering group is expected to be involved in in-situ testing and lessons learned reporting, in order to benefit human space flight beyond the initial CEV program.

Whitmore, Mihriban↗
NASA NTRS1983

Simulation of auroral current sheet equilibria and associated V-shaped potential structures

Results from numerical simulations of auroral current sheet equilibria and associated V-shaped potential structures are presented. It is shown that with allowance for both hot magnetospheric ion and cold ionospheric ion populations, the perpendicular potential drop, Phi(m), associated with a non-neutral auroral current sheet is critically controlled by the temperature of the 'heated' ionospheric ions. The heating is caused by the wave turbulence excited by the auroral current sheet. In the presence of heated ionospheric ions, a relatively large variation in the temperature of the hot magnetospheric ion population causes a very small variation in the potential drop Phi(m). The perpendicular potential drop acts to produce a V-shaped double layer with multiple potential steps parallel to the magnetic field when a zero potential boundary condition is imposed at the ionospheric boundary. Outside the V-shaped potential structure, ionospheric return currents develop self-consistently.

Singh, N.↗
NASA NTRS1983

Dynamics of magnetosphere-ionosphere coupling including turbulent transport

The dynamics of magnetosphere-ionosphere coupling has been investigated by means of a two-dimensional two-fluid MHD model including anomalous resistivity. When field-aligned current is generated on auroral field lines, the disturbance propagates toward the ionosphere in the form of a kinetic Alfven wave. When the current exceeds a critical value, microscopic turbulence is produced, which modifies the propagation of the Alfven wave. This process is modeled by a nonlinear collision frequency, which increases with the excess of the drift velocity over the critical value. The system evolves toward an electrostatic structure, with the perpendicular electric field having a shorter scale than the field-aligned current. The approach to a steady state is strongly dependent on the presence or absence of the turbulence and on the boundary conditions imposed in the generator. As current is increased or scale size is decreased, the turbulent region reflects and absorbs most of the Alfven wave energy, decoupling the generator from the ionosphere.

Lysak, R. L.↗
NASA NTRS2003

Certification Processes for Safety-Critical and Mission-Critical Aerospace Software

This document is a quick reference guide with an overview of the processes required to certify safety-critical and mission-critical flight software at selected NASA centers and the FAA. Researchers and software developers can use this guide to jumpstart their understanding of how to get new or enhanced software onboard an aircraft or spacecraft. The introduction contains aerospace industry definitions of safety and safety-critical software, as well as, the current rationale for certification of safety-critical software. The Standards for Safety-Critical Aerospace Software section lists and describes current standards including NASA standards and RTCA DO-178B. The Mission-Critical versus Safety-Critical software section explains the difference between two important classes of software: safety-critical software involving the potential for loss of life due to software failure and mission-critical software involving the potential for aborting a mission due to software failure. The DO-178B Safety-critical Certification Requirements section describes special processes and methods required to obtain a safety-critical certification for aerospace software flying on vehicles under auspices of the FAA. The final two sections give an overview of the certification process used at Dryden Flight Research Center and the approval process at the Jet Propulsion Lab (JPL).

Nelson, Stacy↗
NASA NTRS2003

Certification Processes for Safety-Critical and Mission-Critical Aerospace Software

This document is a quick reference guide with an overview of the processes required to certify safety-critical and mission-critical flight software at selected NASA centers and the FAA. Researchers and software developers can use this guide to jumpstart their understanding of how to get new or enhanced software onboard an aircraft or spacecraft. The introduction contains aerospace industry definitions of safety and safety-critical software, as well as, the current rationale for certification of safety-critical software. The Standards for Safety-Critical Aerospace Software section lists and describes current standards including NASA standards and RTCA DO-178B. The Mission-Critical versus Safety-Critical software section explains the difference between two important classes of software: safety-critical software involving the potential for loss of life due to software failure and mission-critical software involving the potential for aborting a mission due to software failure. The DO-178B Safety-critical Certification Requirements section describes special processes and methods required to obtain a safety-critical certification for aerospace software flying on vehicles under auspices of the FAA. The final two sections give an overview of the certification process used at Dryden Flight Research Center and the approval process at the Jet Propulsion Lab (JPL).

Nelson, Stacy↗
NASA NTRS2015

JSC Advanced Curation: Research and Development for Current Collections and Future Sample Return Mission Demands

Curation of NASA's astromaterials sample collections is a demanding and evolving activity that supports valuable science from NASA missions for generations, long after the samples are returned to Earth. For example, NASA continues to loan hundreds of Apollo program samples to investigators every year and those samples are often analyzed using instruments that did not exist at the time of the Apollo missions themselves. The samples are curated in a manner that minimizes overall contamination, enabling clean, new high-sensitivity measurements and new science results over 40 years after their return to Earth. As our exploration of the Solar System progresses, upcoming and future NASA sample return missions will return new samples with stringent contamination control, sample environmental control, and Planetary Protection requirements. Therefore, an essential element of a healthy astromaterials curation program is a research and development (R&D) effort that characterizes and employs new technologies to maintain current collections and enable new missions - an Advanced Curation effort. JSC's Astromaterials Acquisition & Curation Office is continually performing Advanced Curation research, identifying and defining knowledge gaps about research, development, and validation/verification topics that are critical to support current and future NASA astromaterials sample collections. The following are highlighted knowledge gaps and research opportunities.

Fries, M. D.↗
NASA NTRS2002

Commercial Research and Development: Power to Explore, Opportunities from Discovery

The technical and economic goals of commercial use of space are laudable, and are addressed as a high priority by almost every national space program and most major aerospace companies the world over. Yet, the focus of most organizational agendas and discussions tends to focus on one or two very narrow enabling aspects of this potentially large technological and economic opportunity. While government sponsored commercial launch activities and private space platforms are an integral part of efforts to leverage the commercial use of space, these activities are possibly one of the smallest parts of creating, a viable and sustainable market for the commercial use of space. Most of the current programs usually do not appropriately address some of the critical issues of the current, already interested, potential space user communities. Current programs place the focus of the majority of the user requirements on the vehicle payload weight and mass performance considerations as the primary payload economical factor in providing a commercial market with a stimulating price for gaining access to the space environment. The larger user challenges of transformation from Earth-based research and development approaches to space environment approaches are not addressed early enough in programs to impact the new business considerations of potential users. Currently, space-based research and development user activities require a large user investment in time, in development of new areas of support expertise, in development of new systems, in risk of schedule to completion, and in long term capital positioning. The larger opportunities for stimulating a strong market driven interest in commercial use of space that could result from the development of vehicle payload "leap ahead technologies" for users are being missed, and there is a real risk of limiting the potentially broader market base to support a more technologically advanced and economically lucrative outcome. A major driving force for strengthening the commercial space activities is not only the technological advances in launch vehicle, or newer satellites, but the myriad of enabling payloads technologies that could, as a goal, result in an almost transparent facilitation to regular CD a, -n access to space and microgravity environments by the future users from the existing Earth-based research and development organizations market segments. Rather than focusing only on developing high lift performance launch vehicles and then developing payloads to fit them, the real focus from a business model perspective should to be on the customer payloads requirements, and on designing launch vehicles and platforms systems for a space transportation and facility infrastructure to support all aspects of the business model for the user market. To harness the full potential of space commercialization, new efforts need to be made to comprehensively examine all the critical business model areas for commercial research, development, and manufacturing in space so as to identify specific products and efforts; to determine how such operations must be both similar to and different from current Earth-based activities; to evaluate the enabling technological devices, processes and efforts so that like efforts can be addressed in a synergistic fashion for maximum user cost effectiveness; to delineate the services that are both needed and can be provided by such activities; and to use this information to drive design and development of space commercialization efforts and policy.

Casas, Joseph C.↗
NASA NTRS2017

Electric Potential and Electric Field Imaging with Dynamic Applications: 2017 Research Award Innovation

The technology and methods for remote quantitative imaging of electrostatic potentials and electrostatic fields in and around objects and in free space is presented. Electric field imaging (EFI) technology may be applied to characterize intrinsic or existing electric potentials and electric fields, or an externally generated electrostatic field may be used for illuminating volumes to be inspected with EFI. The baseline sensor technology (e-Sensor) and its construction, optional electric field generation (quasi-static generator), and current e- Sensor enhancements (ephemeral e-Sensor) are discussed. Critical design elements of current linear and real-time two-dimensional (2D) measurement systems are highlighted, and the development of a three dimensional (3D) EFI system is presented. Demonstrations for structural, electronic, human, and memory applications are shown. Recent work demonstrates that phonons may be used to create and annihilate electric dipoles within structures. Phonon induced dipoles are ephemeral and their polarization, strength, and location may be quantitatively characterized by EFI providing a new subsurface Phonon-EFI imaging technology. Initial results from real-time imaging of combustion and ion flow, and their measurement complications, will be discussed. These new EFI capabilities are demonstrated to characterize electric charge distribution creating a new field of study embracing areas of interest including electrostatic discharge (ESD) mitigation, crime scene forensics, design and materials selection for advanced sensors, combustion science, on-orbit space potential, container inspection, remote characterization of electronic circuits and level of activation, dielectric morphology of structures, tether integrity, organic molecular memory, atmospheric science, and medical diagnostic and treatment efficacy applications such as cardiac polarization wave propagation and electromyography imaging.

Generazio, Ed↗
NASA NTRS2017

Electric Potential and Electric Field Imaging with Dynamic Applications & Extensions

The technology and methods for remote quantitative imaging of electrostatic potentials and electrostatic fields in and around objects and in free space is presented. Electric field imaging (EFI) technology may be applied to characterize intrinsic or existing electric potentials and electric fields, or an externally generated electrostatic field made be used for volumes to be inspected with EFI. The baseline sensor technology (e-Sensor) and its construction, optional electric field generation (quasi-static generator), and current e- Sensor enhancements (ephemeral e-Sensor) are discussed. Critical design elements of current linear and real-time two-dimensional (2D) measurement systems are highlighted, and the development of a three dimensional (3D) EFI system is presented. Demonstrations for structural, electronic, human, and memory applications are shown. Recent work demonstrates that phonons may be used to create and annihilate electric dipoles within structures. Phonon induced dipoles are ephemeral and their polarization, strength, and location may be quantitatively characterized by EFI providing a new subsurface Phonon-EFI imaging technology. Results from real-time imaging of combustion and ion flow, and their measurement complications, will be discussed. Extensions to environment, Space and subterranean applications will be presented, and initial results for quantitative characterizing material properties are shown. A wearable EFI system has been developed by using fundamental EFI concepts. These new EFI capabilities are demonstrated to characterize electric charge distribution creating a new field of study embracing areas of interest including electrostatic discharge (ESD) mitigation, manufacturing quality control, crime scene forensics, design and materials selection for advanced sensors, combustion science, on-orbit space potential, container inspection, remote characterization of electronic circuits and level of activation, dielectric morphology of structures, tether integrity, organic molecular memory, atmospheric science, weather prediction, earth quake prediction, and medical diagnostic and treatment efficacy applications such as cardiac polarization wave propagation and electromyography imaging.

Generazio, Ed↗
NASA NTRS1994

Shadowgraphy of transcritical cryogenic fluids

The future of liquid-rocket propulsion depends heavily on continued development of high pressure liquid oxygen/hydrogen systems that operate near or above the propellant critical states; however, current understanding of transcritical/supercritical injection and combustion is yet lacking. The Phillips Laboratory and the United Technologies Research Center are involved in a collaborative effort to develop diagnostics for and make detailed measurements of transcritical droplet vaporization and combustion. The present shadowgraph study of transcritical cryogenic fluids is aimed at providing insight into the behavior of liquid oxygen or cryogenic stimulants as they are injected into a supercritical environment of the same or other fluids. A detailed history of transcritical injection of liquid nitrogen into gaseous nitrogen at reduced pressures of 0.63 (subcritical) to 1.05 (supercritical) is provided. Also, critical point enhancement due to gas phase solubility and mixture effects is investigated by adding helium to the nitrogen system, which causes a distinct liquid phase to re-appear at supercritical nitrogen pressures. Liquid oxygen injection into supercritical argon or nitrogen, however, does not indicate an increase in the effective critical pressure of the system.

Woodward, R. D.↗