Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “SEI”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Versatile dynamic isotope power systems for the exploration of space

Dynamic, isotope-heated power systems are needed to carry out the exploration of space and are major elements identified by NASA for the Space Exploration Initiative (SEI). The Dynamic Isotope Power System (DIPS) Demonstration Program is aimed at establishing the advanced technology as well as the system designs and hardware for the SEI and other exploratory missions. Several conceptual designs of DIPS systems have been developed to provide compact, reliable, and long-lived power systems.

Johnson, Richard A.↗
NASA NTRS1993

In-space operations for lunar and Mars space transfer vehicles

The objective of this paper is to discuss the in-space operations required to process the lunar and Mars mission vehicles envisioned for the Space Exploration Initiative (SEI). Recent studies, which have examined the degree to which on-orbit operations change as a function of the Earth-to-orbit (ETO) launch vehicle size, identified a common set of on-orbit vehicle processing tasks, and generated functional requirements for in-space processing nodes are summarized in this paper. Timelines for on-orbit processing of two different lunar transfer vehicles (LTV's) were developed to compare a 'current practice,' labor-intensive EVA approach to ones utilizing telerobotics and advanced automation. LTV aerobrake concepts ranging from simple deployment to considerable assembly are compared. Similar timelines for the on-orbit processing of a nuclear Mars transfer vehicle (MTV) are also presented. Aerobrakes can be processed in a timely manner and should not be ruled out for SEI missions. The 'tall pole' time interval for on-orbit vehicle initial processing is the delivery of elements to orbit, not the processing tasks.

Raper, James L., Sr.↗
NASA NTRS1990

Space Exploration Initiative

An overview of President Bush's Space Exploration Initiative (SEI) and it's three main components, Space Station Freedom, a Permanent Lunar Base, and a Manned Mission to Mars is provided. Computer simulations of the Space Station Freedom and Permanent Lunar Base are shown, and an animated sequence describes a Mars mission where heavy lift vehicle will bring components of a Mars Spacecraft into orbit, where it will be put together by astronauts using a robotic arm. The Mars spacecraft is shown orbiting Mars and discharging a lander to the surface, carrying human explorers. The video also details the SEI's Outreach Program, designed to garner interest in and ideas for Space Exploration.

Source record↗
NASA NTRS1993

Rover requirements for the planet surface segment of the space exploration initiative

Annotated requirements for rovers to be used for the First Lunar Outpost (FLO) of the Space Exploration Initiative (SEI) and for Mars missions are presented. The requirements are presented in the form of functions as opposed to performance. SEI surface systems will be required to execute many roving vehicle functions ranging from transporting humans to recovery and transporting raw materials to a processing plant. Some of the roving vehicles will be highly automated. These automation functions may include the following: teleoperated site survey and certification; teleoperation for repair; autonomous operations for resource location and mining; autonomous navigation and terrain traverse; and telerobotic scientific investigations. These requirements are complex, contradictory, and will be costly if they are not carefully analyzed and properly allocated to conceptual elements. Of greatest importance will be the iterative analysis of requirements and synergistic utilization of vehicle elements.

Roberts, Barney B.↗
NASA NTRS1991

Planetary protection issues and future Mars missions

A primary scientific theme for the Space Exploration Initiative (SEI) is the search for life, extant or extinct, on Mars. Because of this, concerns have arisen about Planetary Protection (PP), the prevention of biological cross-contamination between Earth and other planets during solar system exploration missions. A recent workshop assessed the necessity for, and impact of, PP requirements on the unmanned and human missions to Mars comprising the SEI. The following ground-rules were adopted: (1) Information needed for assessing PP issues must be obtained during the unmanned precursor mission phase prior to human landings. (2) Returned Mars samples will be considered biologically hazardous until proven otherwise. (3) Deposition of microbes on Mars and exposure of the crew to martian materials are inevitable when humans land. And (4) Human landings are unlikely until it is demonstrated that there is no harmful effect of martian materials on terrestrial life forms. These ground-rules dictated the development of a conservative PP strategy for precursor missions. Key features of the proposed strategy include: to prevent forward-contamination, all orbiters will follow Mars Observer PP procedures for assembly, trajectory, and lifetime. All landers will follow Viking PP procedures for assembly, microbial load reduction, and bio-shield. And, to prevent back-contamination, all sample return missions will have PP requirements which include fail-safe sample sealing, breaking contact chain with the martian surface, and containment and quarantine analysis in Earth-based laboratory. In addition to deliberating on scientific and technical issues, the workshop made several recommendations for dealing with forward and back-contamination concerns from non-scicntific perspectives.

Devincenzi, D. L.↗
NASA NTRS1990

Taguchi Approach to Design Optimization for Quality and Cost: An Overview

Calibrations to existing cost of doing business in space indicate that to establish human presence on the Moon and Mars with the Space Exploration Initiative (SEI) will require resources, felt by many, to be more than the national budget can afford. In order for SEI to succeed, we must actually design and build space systems at lower cost this time, even with tremendous increases in quality and performance requirements, such as extremely high reliability. This implies that both government and industry must change the way they do business. Therefore, new philosophy and technology must be employed to design and produce reliable, high quality space systems at low cost. In recognizing the need to reduce cost and improve quality and productivity, Department of Defense (DoD) and National Aeronautics and Space Administration (NASA) have initiated Total Quality Management (TQM). TQM is a revolutionary management strategy in quality assurance and cost reduction. TQM requires complete management commitment, employee involvement, and use of statistical tools. The quality engineering methods of Dr. Taguchi, employing design of experiments (DOE), is one of the most important statistical tools of TQM for designing high quality systems at reduced cost. Taguchi methods provide an efficient and systematic way to optimize designs for performance, quality, and cost. Taguchi methods have been used successfully in Japan and the United States in designing reliable, high quality products at low cost in such areas as automobiles and consumer electronics. However, these methods are just beginning to see application in the aerospace industry. The purpose of this paper is to present an overview of the Taguchi methods for improving quality and reducing cost, describe the current state of applications and its role in identifying cost sensitive design parameters.

Unal, Resit↗
NASA NTRS1991

The Space Exploration Initiative: a challenge to advanced life support technologies: keynote presentation

President Bush has enunciated an unparalleled, open-ended commitment to human exploration of space called the Space Exploration Initiative (SEI). At the heart of the SEI is permanent human presence beyond Earth orbit, which implies a new emphasis on life science research and life support system technology. Proposed bioregenerative systems for planetary surface bases will require carefully designed waste processing elements whose development will lead to streamlined and efficient and efficient systems for applications on Earth.

Ecological Systems, Closed↗
NASA NTRS2002

Improved performance and safety of lithium ion cells with the use of fluorinated carbonate-based electrolytes

There has been increasing interest in developing lithium-ion electrolytes that possess enhanced safety characteristics, while still able to provide the desired stability and performance. Toward this end, our efforts have been focused on the development of lithium-ion electrolytes which contain partially and fully fluorinated carbonate solvents. The advantage of using such solvents is that they possess the requisite stability demonstrated by the hydrocarbon-based carbonates, while also possessing more desirable physical properties imparted by the presence of the fluorine substituents, such as lower melting points, increased stability toward oxidation, and favorable SEI film forming Characteristics on carbon. Specifically, we have demonstrated the beneficial effect of electrolytes which contain the following fluorinated carbonate-based solvents: methyl 2,2,2-trifluoroethyl carbonate (MTFEC), ethyl-2,2,2 trifluoroethyl carbonate (ETFEC), propyl 2,2,2-trifluoroethyl carbonate (PTFEC), methyl-2,2,2,2',2',2' -hexafluoro-i-propyl carbonate (MHFPC), ethyl- 2,2,2,2',2',2' -hexafluoro-i-propyl carbonate (EHFPC), and di-2,2,2-trifluoroethyl carbonate (DTFEC). These solvents have been incorporated into multi-component ternary and quaternary carbonate-based electrolytes and evaluated in lithium-carbon and carbon-LiNio.8Coo.202 cells (equipped with lithium reference electrodes). In addition to determining the charge/discharge behavior of these cells, a number of electrochemical techniques were employed (i.e., Tafel polarization measurements, linear polarization measurements, and electrochemical impedance spectroscopy (EIS)) to further characterize the performance of these electrolytes, including the SEI formation characteristics and lithium intercalatiodde-intercalation kinetics. In addition to their evaluation in experimental cells, cyclic voltammetry (CV) and conductivity measurements were performed on select electrolyte formulations to further our understanding of the trends in stability and ionic mobility imparted by different alkyl substituents in linear carbonates.

li-ion batteries fluorinated carbonate electrolyte↗
NASA NTRS2007

A Synopsis of Interfacial Phenomena in Lithium-Based Polymer Electrolyte Electrochemical Cells

The interfacial regions between electrode materials, electrolytes and other cell components play key roles in the overall performance of lithium-based batteries. For cell chemistries employing lithium metal, lithium alloy or carbonaceous materials (i.e., lithium-ion cells) as anode materials, a "solid electrolyte interphase" (SEI) layer forms at the anode/electrolyte interface, and the properties of this "passivating" layer significantly affect the practical cell/battery quality and performance. A thin, ionically-conducting SEI on the electrode surface can beneficially reduce or eliminate undesirable side reactions between the electrode and the electrolyte, which can result in a degradation in cell performance. The properties and phenomena attributable to the interfacial regions existing at both anode and cathode surfaces can be characterized to a large extent by electrochemical impedance spectroscopy (EIS) and related techniques. The intention of the review herewith is to support the future development of lithium-based polymer electrolytes by providing a synopsis of interfacial phenomena that is associated with cell chemistries employing either lithium metal or carbonaceous "composite" electrode structures which are interfaced with polymer electrolytes (i.e., "solvent-free" as well as "plasticized" polymer-binary salt complexes and single ion-conducting polyelectrolytes). Potential approaches to overcoming poor cell performance attributable to interfacial effects are discussed.

Baldwin, Richard S.↗
NASA NTRS2012

Fundamental Investigation of Silicon Anode in Lithium-Ion Cells

Silicon is a promising and attractive anode material to replace graphite for high capacity lithium ion cells since its theoretical capacity is ~10 times of graphite and it is an abundant element on Earth. However, there are challenges associated with using silicon as Li-ion anode due to the significant first cycle irreversible capacity loss and subsequent rapid capacity fade during cycling. Understanding solid electrolyte interphase (SEI) formation along with the lithium ion insertion/de-insertion kinetics in silicon anodes will provide greater insight into overcoming these issues, thereby lead to better cycle performance. In this paper, cyclic voltammetry and electrochemical impedance spectroscopy are used to build a fundamental understanding of silicon anodes. The results show that it is difficult to form the SEI film on the surface of a Si anode during the first cycle; the lithium ion insertion and de-insertion kinetics for Si are sluggish, and the cell internal resistance changes with the state of lithiation after electrochemical cycling. These results are compared with those for extensively studied graphite anodes. The understanding gained from this study will help to design better Si anodes, and the combination of cyclic voltammetry with impedance spectroscopy provides a useful tool to evaluate the effectiveness of the design modifications on the Si anode performance.

Wu, James J.↗
NASA NTRS2016

Final Mission and Navigation Design for the 2016 Mars InSight Mission

Project Overview: NASA’s 12th Discovery Program mission that will place a single geophysical lander on Mars to study its deep interior using seismic (tidal, marsquake, and impact), rotational, and thermal measurements -First mission to unveil the composition, structure and thermal state of martian crust, mantle and core; Rebuild of the Phoenix flight system, upgraded with Juno/GRAIL avionics -Phoenix cruise stage: 3-axis stabilized, 3.2 square meter UTJ (Ultra Triple-Junction) solar array, X-band telecom -Phoenix aeroshell (heat shield, backshell, parachute) -Phoenix lander: radar, pulsed thrusters, legs, payload deck, 5.1 square meter UTJ solar arrays, two redundant Li-ion batteries, UHF (Ultra High Frequency)/X-band telecom -Dual string: Internally or functionally-redundant equipment; Science Payload -SEIS (Seismic Experiment for Interior Structure) / CNES (Centre National d’Etudes Spatiales); Three-axis seismometry, to measure seismic waves traveling through the interior -HP3 (Heat Flow and Physical Properties Probe) / DLR (German Aerospace Center) -Subsurface heat probe, to measure the heat flux from the interior - RISE (Rotation and Interior Structure Experiment) / JPL (Jet Propulsion Laboratory) -Radiometric geodesy, to determine precession & nutation of the planet’s rotation axis. 2016 Disclaimer: The InSight launch in 2016 was suspended due to critical issues with the Seismic Experiment for Interior Structure (SEIS) instrument that could not be fixed prior to the planned launch period. This presentation and its corresponding paper represent the state of the design for the 2016 mission. No attempt has been made to reflect the latest developments. [2018 Note: InSight (Mars Lander) was later launched and arrived on Mars on Nov. 26, 2018.]

Abilleira, F.↗
NASA NTRS2017

InSight System Acoustic Requirement Evolution

The InSight Mars lander is to be launched to Mars in 2018 on a rocket, contained within an aeroshell designed for Mars entry. The primary mission objective is to deliever an ultra-sensitive seismometer to the Martian surface for scientific investigations. The preliminary InSight PF acoustic requirement (the heritage Phoenix environment, 139.8 dB overall SPL maximum expected environment) was reduced significantly when the Launch vehicle was selected as the InSight launch vehicle (134.5 dB overall SPL maximum expected environment). This reduction would have resulted in a very low Lander Deck random vibration at SEIS, and other instruments inside the aeroshell, during the system Protoflight (PF) acoustic test with questionable workmanship value. To mitigate this concern JPL and Launch vehicle contractor agreed to increase the InSight PF acoustic test requirement to enhance workmanship testing for science instruments and assemblies inside the aeroshell. The actual InSight system acoustic test vibration responses at the SEIS instrument are compared to the predicted responses.

O'Connell, Michael↗
NASA NTRS2021

Robotics Instrument Deployment System Surface Operations for the InSight Mars Lander

This paper describes NASA’s first successful precision robotics instrument placement and release on another astronomical body since Apollo. This operations breakthrough enabled NASA’s InSight lander to detect the first known ‘marsquake’, a faint trembling of Mars’s surface on 6th April 2019, 128 Martian days after landing on Mars on the 26th November 2018. This is the first quake detected on an astronomical body other than Earth or the Moon. This paper describes the operations of the Robotics Instrument Deployment Systems (IDS) that successfully deployed the InSight science payload to the surface of Mars. The payload includes a seismometer (SEIS), Wind and Thermal Shield (WTS) and Heat Flow and Physical Properties Package (HP3), enabling scientists to perform the first comprehensive surface-based geophysical investigation of Mars’ interior structure. In addition, the paper describes the IDS planning and command sequence generation process used for the successful deployment of SEIS, WTS and HP3 on the surface of Mars. The paper concludes with recommendations based on the experience gained from InSight IDS operations. This includes identified technology gaps in the operations of in-situ manipulators for planetary exploration.

Yen, Jeng↗
NASA NTRSDate not supplied

Variable Pressure - Scanning Electron Microscopy (VP-SEM)

Variable Pressure (or Environmental) Scanning Electron Microscopy (VP-SEM) combined with Energy Dispersive X-ray Spectroscopy (EDS) is one of the most powerful methods for characterizing the sub-micron topography and chemical composition of uncoated samples. Terrestrially, VP-SEM is extensively used to non-destructively study geologic and manufactured materials with high spatial resolution (tens of nanometers) and large depth-of-field. An SEM offers a geologist a first survey of microscopic mineral phases via secondary electron imaging (SEI), which provides a topographic look at a sample, as well as backscattered electron (BEI) imaging, which contrasts the phases present based on their geochemistry (atomic number). A VP-SEM utilizes a gas in the sample chamber as a charge dissipation and signal amplification method, allowing analysis of a sample without preparation in the form of a conductive coating. A miniaturized VP-SEM operating in-situ on a lander or rover would be able to use the CO2-rich Martian atmosphere (e.g., Nier et al., 1976; Williams 2016) as an imaging medium for this purpose. Adaptation of a VP-SEM for in-situ Mars surface studies will provide a new imaging capability (via SEI) that is at least an order of magnitude higher resolution than the Mars Hand Lens Imager (MAHLI) on the Mars Science Laboratory (Williams et al., 2015), and equal to or better than the achieved resolution of the Atomic Force Microscope on the Phoenix Mars lander (Pike et al., 2011). In addition, the MVP-SEM is capable of BSI and simultaneous chemical analysis of the imaged region. In this sense, the MVP-SEM can be regarded as an instrument suite that will provide a new set of information not achievable by any other instrument. The Miniaturized Variable Pressure Scanning Electron Microscope (MVP-SEM) was designed, built, and benchtop tested by a team at NASA’s Marshall Space Flight Center and Jet Propulsion Laboratory (JPL), Jacobs Space Exploration Group, Applied Physics Technologies, Inc. (AP-Tech), and Creare LLC, working with a team of technical and science collaborators. Benchtop testing was successful, proving concept feasibility. To date, the MVP-SEM has achieved an imaging resolution of <100 nm in the lab, and with continued optimization, even better performance (~50 nm resolution) is possible. Use in-situ on the lunar or other planetary surfaces would require some redesign to optimize instrument performance, but such an instrument would be equally useful.

Variable Pressure Scanning Electron Microscopy↗
NASA NTRSDate not supplied

Miniature Variable Pressure - Scanning Electron Microscopy (MVP-SEM)

Variable Pressure (or Environmental) Scanning Electron Microscopy (VP-SEM) combined with Energy Dispersive X-ray Spectroscopy (EDS) is one of the most powerful methods for characterizing the sub-micron topography and chemical composition of uncoated samples. Terrestrially, VP-SEM is extensively used to non-destructively study geologic and manufactured materials with high spatial resolution (tens of nanometers) and large depth-of-field. An SEM offers a geologist a first survey of microscopic mineral phases via secondary electron imaging (SEI), which provides a topographic look at a sample, as well as backscattered electron (BEI) imaging, which contrasts the phases present based on their geochemistry (atomic number). A VP-SEM utilizes a gas in the sample chamber as a charge dissipation and signal amplification method, allowing analysis of a sample without preparation in the form of a conductive coating. A miniaturized VP-SEM operating in-situ on a lander or rover would be able to use the CO2-rich Martian atmosphere (e.g., Nier et al., 1976; Williams 2016) as an imaging medium for this purpose. Adaptation of a VP-SEM for in-situ Mars surface studies will provide a new imaging capability (via SEI) that is at least an order of magnitude higher resolution than the Mars Hand Lens Imager (MAHLI) on the Mars Science Laboratory (Williams et al., 2015), and equal to or better than the achieved resolution of the Atomic Force Microscope on the Phoenix Mars lander (Pike et al., 2011). In addition, the MVP-SEM is capable of BSI and simultaneous chemical analysis of the imaged region. In this sense, the MVP-SEM can be regarded as an instrument suite that will provide a new set of information not achievable by any other instrument. The Miniaturized Variable Pressure Scanning Electron Microscope (MVP-SEM) was designed, built, and benchtop tested by a team at NASA’s Marshall Space Flight Center and Jet Propulsion Laboratory (JPL), Jacobs Space Exploration Group, Applied Physics Technologies, Inc. (AP-Tech), and Creare LLC, working with a team of technical and science collaborators. Benchtop testing was successful, proving concept feasibility. To date, the MVP-SEM has achieved an imaging resolution of <100 nm in the lab, and with continued optimization, even better performance (~50 nm resolution) is possible. Use in-situ on the lunar or other planetary surfaces would require some redesign to optimize instrument performance, but such an instrument would be equally useful.

Variable Pressure Scanning Electron Microscopy↗
NASA NTRS1989

An SSE approach to reusability

The SSE project has engineering analysis and design efforts under way for the development of the SSE reusability library management system. An ad hoc committee on reuse has been meeting for several months identifying design considerations and learning about Ruben Prieto-Diaz faceted classification, CAMP domain analysis, SPC activities, SEI activities, and SPS activities. A standard format was developed for the Ada prologue for reusable components (both specification and body). The SSE reusability process can be viewed as a transformation process with minimized losses and difficulties.

Badal, David L.↗
NASA NTRS1990

Lunar orbiting microwave beam power system

A microwave beam power system using lunar orbiting solar powered satellite(s) and surface rectenna(s) was investigated as a possible energy source for the Moon's surface. The concept has the potential of reduced system mass by placing the power source in orbit. This can greatly reduce and/or eliminate the 14 day energy storage requirement of a lunar surface solar system. Also propellants required to de-orbit to the surface are greatly reduced. To determine the practicality of the concept and the most important factors, a zero-th order feasibility analysis was performed. Three different operational scenarios employing state of the art technology and forecasts for two different sets of advanced technologies were investigated. To reduce the complexity of the problem, satellite(s) were assumed in circular equatorial orbits around the Moon, supplying continuous power to a single equatorial base through a fixed horizontal rectenna on the surface. State of the art technology yielded specific masses greater than 2500 kg/kw, well above projections for surface systems. Using advanced technologies the specific masses are on the order of 100 kg/kw which is within the range of projections for surface nuclear (20 kg/kw) and solar systems (500 kg/kw). Further studies examining optimization of the scenarios, other technologies such as lasers transmitters and nuclear sources, and operational issues such as logistics, maintenance and support are being carried out to support the Space Exploration Initiative (SEI) to the Moon and Mars.

Fay, Edgar H.↗
NASA NTRS1989

The winds of O-stars. II - The terminal velocities of stellar winds of O-type stars

The SEI method (Lamers et al., 1987) is used to obtain P Cygni profiles of the UV resonance lines of C IV, N V, and S IV and of the subordinate UV lines of N IV and C III observed in the spectra of 27 O-type stars. Theoretical profiles which include the turbulence effects agree well with the observations, and they can account for the deep absorption troughs, the shape of the violet absorption wings, and the wavelength of the emission peak. The resulting terminal velocities of the stellar winds are found to be systematically lower by about 400 km/s than previous estimates obtained using the Sobolev approximation (Castor and Lamers, 1979), suggesting that the narrow absorption components, observed in the UV resonance lines of O and B stars, reach the terminal velocity of the winds.

Groenewegen, M. A. T.↗