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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.

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At least 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

Orbit Determination Issues for Libration Point Orbits

Libration point mission designers require knowledge of orbital accuracy for a variety of analyses including station keeping control strategies, transfer trajectory design, and formation and constellation control. Past publications have detailed orbit determination (OD) results from individual libration point missions. This paper collects both published and unpublished results from four previous libration point missions (ISEE (International Sun-Earth Explorer) -3, SOHO (Solar and Heliospheric Observatory), ACE (Advanced Composition Explorer) and MAP (Microwave Anisotropy Probe)) supported by Goddard Space Flight Center's Guidance, Navigation & Control Center. The results of those missions are presented along with OD issues specific to each mission. All past missions have been limited to ground based tracking through NASA ground sites using standard range and Doppler measurement types. Advanced technology is enabling other OD options including onboard navigation using seaboard attitude sensors and the use of the Very Long Baseline Interferometry (VLBI) measurement Delta Differenced One-Way Range (DDOR). Both options potentially enable missions to reduce coherent dedicated tracking passes while maintaining orbital accuracy. With the increased projected loading of the DSN (Deep Space Network), missions must find alternatives to the standard OD scenario.

Beckman, Mark↗
NASA NTRS2002

Orbit Determination Issues for Libration Point Orbits

Libration point mission designers require knowledge of orbital accuracy for a variety of analyses including station keeping control strategies, transfer trajectory design, and formation and constellation control. Past publications have detailed orbit determination (OD) results from individual notation point missions. This paper collects both published and unpublished results from four previous notation point missions (ISEE-3, SOHO, ACE and MAP) supported by Goddard Space Flight Center's Guidance, Navigation & Control Center. The results of those missions are presented along with OD issues specific to each mission. All past missions have been limited to ground based tracking through NASA ground sites using standard marine and Doppler measurement types. Advanced technology is enabling other OD options including onboard navigation using onboard attitude sensors and the use of the Very Long Baseline Interferometry (VLBI) measurement Delta Differenced One-Way Range (DDOR). Both options potentially enable missions to reduce coherent dedicated tracking passes while maintaining orbital accuracy. With the increased projected loading of the DSN, missions must find alternatives to the standard OD scenario.

Beckman, Mark↗
NASA NTRS1995

ACTS on-orbit multibeam antenna pattern measurements

The Advanced Communication Technology (ACTS) is a key to NASA's goal of developing high-risk, advanced communications technology using multiple frequency bands to support the nation's future communication needs. Using the multiple, dynamic hopping spot beams and advanced on board switching and processing systems, ACTS will open a new era in communications satellite technology. One of the key technologies to be validated as part of the ACTS program is the multibeam antenna (MBA) with rapidly reconfigurable hopping and fixed spot beams to serve users equipped with small-aperture terminals within the coverage areas. The MBA test program is designed to evaluate the on-orbit ACTS antenna performance. The main parameters measured are beam shape, beam center location and gain.

Acosta, R.↗
NASA NTRS1977

Sensing the earth's environment from space: User needs and technology opportunities

The specific measurements and data needs of users of remotely sensed environmental data were identified in a number of studies supported by NASA in cooperation with industry, universities, and the operational government agencies involved. The present capabilities of space and aircraft sensors, data systems, and satellite support systems were assessed and compared with the trends in the supporting technology. Areas of high benefit in which there is a large gap between the efforts underway and the need are identified. The problems in narrowing these gaps are briefly discussed.

Nagler, R. G.↗
NASA NTRS1989

Global tropospheric chemistry: Chemical fluexes in the global atmosphere

In October 1987, NSF, NASA, and NOAA jointly sponsored a workshop at Columbia University to assess the experimental tools and analysis procedures in use and under development to measure and understand gas and particle fluxes across this critical air-surface boundary. Results are presented for that workshop. It is published to summarize the present understanding of the various measurement techniques that are available, identify promising new technological developments for improved measurements, and stimulate thinking about this important measurement challenge.

Lenschow, Donald H.↗
NASA NTRS1992

Strategic directions and mechanisms in technology transfer

An outline summarizing the Working Panel discussion related to strategic directions for technology transfer is presented. Specific topics addressed include measuring success, management of technology, innovation and experimentation in the tech transfer process, integration of tech transfer into R&D planning, institutionalization of tech transfer, and policy/legislative resources.

Mackin, Robert↗
NASA NTRSDate not supplied

Verification and Validation of Safety-Critical Aircraft Systems Operating under Off-Nominal, Contingency, and Emergency Conditions

Verification and validation (V&V) of safety-critical technologies developed for loss of control (LOC) prevention and recovery and other aviation safety concerns pose significant challenges. Aircraft LOC can result from a wide spectrum of hazards, often occurring in combination, which cannot be fully replicated during evaluation. Technologies developed for LOC prevention and recovery must therefore be effective under a wide variety of hazardous and uncertain conditions, and the verification and validation of these technologies must provide some measure of assurance that the new vehicle safety technologies do no harm (i.e., that they themselves do not introduce new safety risks). V&V technologies must also enable the identification of system limitations and constraints, as well as enable the identification of safe and unsafe operating conditions (and their boundaries). Additionally, the V&V of complex, increasingly autonomous systems is a fundamental concern. Scalable, reproducible and cost-effective techniques for the assurance of safety critical systems during their design and operation is a key barrier to fielding new systems or updating current systems. Moreover, these techniques need to provide artifacts that enable a comprehensive evidence-based approach to certification. This briefing summarizes research performed under NASA’s Aviation Safety Program and follow-on research for the V&V of safety-critical aircraft system technologies developed for LOC prevention and recovery and increasingly autonomous systems, and for a broad assurance capability in both current and emerging aviation applications. Note that, in this briefing, the term “validation” refers to a confirmation that the system implementation (e.g., algorithms etc.) is performing the intended function(s), as well as an affirmation of effectiveness in these functions. “Verification” refers to a confirmation that the system implementation in the software and hardware meets its (hopefully validated) specifications (e.g., correctly executes algorithms as designed).

Validation↗
NASA NTRS2015

Technology Advancement for Active Remote Sensing of Carbon Dioxide from Space Using the ASCENDS CarbonHawk Experiment Simulator: First Results

The ASCENDS CarbonHawk Experiment Simulator (ACES) is a newly developed lidar developed at NASA Langley Research Center and funded by NASA's Earth Science Technology Office (ESTO) Instrument Incubator Program (IIP) that seeks to advance technologies critical to measuring atmospheric column carbon dioxide (CO2) mixing ratios in support of the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission. The technology advancements targeted include: (1) increasing the power-aperture product to approach ASCENDS mission requirements by implementing multi-aperture telescopes and multiple co-aligned laser transmitters; (2) incorporating high-efficiency, high-power Erbium-Doped Fiber Amplifiers (EDFAs); (3) developing and incorporating a high-bandwidth, low-noise HgCdTe detector and transimpedence amplifier (TIA) subsystem capable of long-duration autonomous operation on Global Hawk aircraft, and (4) advancing algorithms for cloud and aerosol discrimination. The ACES instrument architecture is being developed for operation on high-altitude aircraft and will be directly scalable to meet the ASCENDS mission requirements. These technologies are critical towards developing not only spaceborne instruments but also their airborne simulators, with lower platform requirements for size, mass, and power, and with improved instrument performance for the ASCENDS mission. ACES transmits five laser beams: three from commercial EDFAs operating near 1.57 microns, and two from the Exelis oxygen (O2) Raman fiber laser amplifier system operating near 1.26 microns. The three EDFAs are capable of transmitting up to 10 watts average optical output power each and are seeded by compact, low noise, stable, narrow-linewidth laser sources stabilized with respect to a CO2 absorption line using a multi-pass gas absorption cell. The Integrated-Path Differential Absorption (IPDA) lidar approach is used at both wavelengths to independently measure the CO2 and O2 column number densities and retrieve the average column CO2 mixing ratio. The ACES receiver uses three fiber-coupled 17.8-cm diameter athermal telescopes. The transmitter assembly consists of five fiber-coupled laser collimators and an associated Risley prism pair for each laser to co-align the outgoing laser beams and to align them with the telescope field of view. The backscattered return signals collected by the three telescopes are combined in a fiber bundle and sent to a single low noise detector. The detector/TIA development has improved the existing detector subsystem by increasing its bandwidth to 4.7 MHz from 500 kHz and increasing the duration of autonomous, service-free operation periods from 4 hours to >24 hours. The new detector subsystem enables the utilization of higher laser modulation rates, which provides greater flexibility for implementing advanced thin-cloud discrimination algorithms as well as improving range-determination resolution and error reduction. The cloud/aerosol discrimination algorithm development by Langley and Exelis features a new suite of algorithms for the minimization/elimination of bias errors in the return signal induced by the presence of intervening thin clouds. Multiple laser modulation schemes are being tested in an effort to significantly mitigate the effects of thin clouds on the retrieved CO2 column amounts. Full instrument development concluded in the spring of 2014. After ground range tests of the instrument, ACES successfully completed six test flights on the Langley Hu-25 aircraft in July, 2014, and recorded data at multiple altitudes over land and ocean surfaces with and without intervening clouds. Preliminary results from these test flights will be presented in this paper.

Obland, Michael D.↗
NASA NTRS2006

Advanced Chemical Propulsion

Advanced Chemical Propulsion (ACP) provides near-term incremental improvements in propulsion system performance and/or cost. It is an evolutionary approach to technology development that produces useful products along the way to meet increasingly more demanding mission requirements while focusing on improving payload mass fraction to yield greater science capability. Current activities are focused on two areas: chemical propulsion component, subsystem, and manufacturing technologies that offer measurable system level benefits; and the evaluation of high-energy storable propellants with enhanced performance for in-space application. To prioritize candidate propulsion technology alternatives, a variety of propulsion/mission analyses and trades have been conducted for SMD missions to yield sufficient data for investment planning. They include: the Advanced Chemical Propulsion Assessment; an Advanced Chemical Propulsion System Model; a LOx-LH2 small pumps conceptual design; a space storables propellant study; a spacecraft cryogenic propulsion study; an advanced pressurization and mixture ratio control study; and a pump-fed vs. pressure-fed study.

Alexander, Leslie, Jr.↗
NASA NTRSDate not supplied

ACES Instrument

During the Atmospheric Carbon and Transport–America (ACT–America) suborbital mission (ACT-America) Mission Spring 2018 campaign, ASCENDS CarbonHawk Experiment Simulator (ACES), an intensity modulated continuous wave (IMCW) lidar system funded by NASA’s Science Mission Directorate, measured differential optical depths leading to partial-column CO2 lidar retrievals while flying aboard the C-130 aircraft across North America striving to advance technology critical to measuring column carbon dioxide mixing ratios (XCO2) remotely. ACES was developed by NASA Langley Research Center in the aims to have an active remote sensing system able to accurately measure XCO2 from space independent of the presence of sunlight, land surface type, and even through thin clouds. Differential absorption optical depth measurements made during the fourth campaign of ACT-America in Spring of 2018 were processed, analyzed and compared to on board in situ derived differential optical depth CO2 measurements.

XCO2↗
NASA NTRSDate not supplied

Dust Ejecta RADAR Technology (DERT): A Millimeter Wave Doppler Radar to Measure Plume Surface Interaction Ejecta Velocities

A novel method to measure the velocity of ejecta generated by the impingement of rocket plumes on a lunar or planetary surface is presented. Dust Ejecta RADAR Technology (DERT), is a Millimeter Wave Doppler Radar sensor that provides a unique dataset based on direct measurements of ejecta particle velocities during plume-surface interactions, which will help inform risk assessments associated with impacts by high-speed ejecta particles. DERT has measured velocities of a pendulum (~1 m/s), a rotating strip (60 m/s), projected regolith simulant BP-1 (~250 m/s) and rifle rounds (~820 m/s). Signal-to-noise ratios of up to 60 dB with regolith simulant BP-1 have been demonstrated with a CW 94 GHz unit. Data collected from DERT will inform the development of high-fidelity computational models of plume-surface interaction effects and will help address NASA Strategic Knowledge Gaps related to characterizing entry, descent and landing effects, and the risks associated with high-speed ejecta on the lander and lunar surface assets. Recent efforts to develop DERT as a flight instrument are presented as well as the development of a Lunar Regolith Ejecta Simulator (LuRES) system to calibrate DERT.

PSI↗
NASA NTRS1974

Instruments for measuring radiant thermal fluxes

An absolute two-sided radiometer, designed on the principle of replacing absorbed radiant energy with electrical energy, is described. The sensitive element of the detector is a thermoelectric transducer of thermal flux. The fabrication technology, methods of measurement, technical characteristics, and general operation of the instrument are presented.

Gerashenko, O. A.↗
NASA NTRS2004

Space Technology 5: Enabling Future Micro-Sat Constellation Science Missions

The Space Technology 5 (ST-5) Project is part of NASA s New Millennium Program. ST-5 will consist of a constellation of three micro-satellites, each approximately 25 kg in mass. The mission goals are to demonstrate the research-quality science capability of the ST-5 spacecraft; to operate the three spacecraft as a constellation; and to design, develop and flight-validate three capable micro-satellites with new technologies. ST-5 is designed to measurably raise the utility of small satellites by providing high functionality in a low mass, low power, and low volume package. The whole of ST-5 is greater than the sum of its parts: the collection of components into the ST-5 spacecraft allows it to perform the functionality of a larger scientific spacecraft on a micro-satellite platform. The ST-5 mission was originally designed to be launched as a secondary payload into a Geosynchronous Transfer Orbit (GTO). Recently, the mission has been replanned for a Pegasus XL dedicated launch into an elliptical polar orbit. A three-month flight demonstration phase, beginning in March 2006, will validate the ability to perform science measurements, as well as the technologies and constellation operations. ST- 5 s technologies and concepts will then be transferred to future micro-sat science missions.

Carlisle, Candace C.↗
NASA NTRS2004

Space Technology 5: Enabling Future Micro-Sat Constellation Science Missions

The Space Technology 5 (ST-5) Project is part of NASA s New Millennium Program. ST-5 will consist of a constellation of three micro-satellites, each approximately 25 kg in mass. The mission goals are to demonstrate the research-quality science capability of the ST-5 spacecraft, to operate the three spacecraft as a constellation; and to design, develop and flight-validate three capable micro-satellites with new technologies. ST-5 is designed to measurably raise the utility of small satellites by providing high functionality in a low mass, low power, and low volume package. The whole of ST-5 is greater than the sum of its parts: the collection of components into the ST-5 spacecraft allows it to perform the functionality of a larger scientific spacecraft on a micro-satellite platform. The ST-5 mission was originally designed to be launched as a secondary payload into a Geosynchronous Transfer Orbit (GTO). Recently, the mission has been replanned for a Pegasus XL dedicated launch into an elliptical polar orbit. A three-month flight demonstration phase, beginning in March 2006, will validate the ability to perform science measurements, as well as the technologies and constellation operations. ST- 5 s technologies and concepts will then be transferred to future micro-sat science missions.

Carlisle, Candace C.↗
NASA NTRS2012

Decision Gate Process for Assessment of a Technology Development Portfolio

The NASA Dust Management Project (DMP) was established to provide technologies (to TRL 6 development level) required to address adverse effects of lunar dust to humans and to exploration systems and equipment, which will reduce life cycle cost and risk, and will increase the probability of sustainable and successful lunar missions. The technology portfolio of DMP consisted of different categories of technologies whose final product is either a technology solution in itself, or one that contributes toward a dust mitigation strategy for a particular application. A Decision Gate Process (DGP) was developed to assess and validate the achievement and priority of the dust mitigation technologies as the technologies progress through the development cycle. The DGP was part of continuous technology assessment and was a critical element of DMP risk management. At the core of the process were technology-specific criteria developed to measure the success of each DMP technology in attaining the technology readiness levels assigned to each decision gate. The DGP accounts for both categories of technologies and qualifies the technology progression from technology development tasks to application areas. The process provided opportunities to validate performance, as well as to identify non-performance in time to adjust resources and direction. This paper describes the overall philosophy of the DGP and the methodology for implementation for DMP, and describes the method for defining the technology evaluation criteria. The process is illustrated by example of an application to a specific DMP technology.

Kohli, Rajiv↗
NASA NTRS2012

Decision Gate Process for Assessment of a NASA Technology Development Portfolio

The NASA Dust Management Project (DMP) was established to provide technologies (to Technology Readiness Level (TRL) 6) required to address adverse effects of lunar dust to humans and to exploration systems and equipment, to reduce life cycle cost and risk, and to increase the probability of sustainable and successful lunar missions. The technology portfolio of DMP consisted of different categories of technologies whose final product was either a technology solution in itself, or one that contributes toward a dust mitigation strategy for a particular application. A Decision Gate Process (DGP) was developed to assess and validate the achievement and priority of the dust mitigation technologies as the technologies progress through the development cycle. The DGP was part of continuous technology assessment and was a critical element of DMP risk management. At the core of the process were technology-specific criteria developed to measure the success of each DMP technology in attaining the technology readiness levels assigned to each decision gate. The DGP accounts for both categories of technologies and qualifies the technology progression from technology development tasks to application areas. The process provided opportunities to validate performance, as well as to identify non-performance in time to adjust resources and direction. This paper describes the overall philosophy of the DGP and the methodology for implementation for DMP, and describes the method for defining the technology evaluation criteria. The process is illustrated by example of an application to a specific DMP technology.

Kohli, Rajiv↗
NASA NTRS2019

A 20 Year Retrospective of The Advanced Noise Control Fan - Contributions to Turbofan Noise Research

The Advanced Noise Control Fan (neé Active Noise Control Fan - ANCF) was utilized in the design, test, and evaluation for technical risk mitigation of most of the innovative fan noise reduction technologies developed by NASA over the past 20 years. The ANCF is a low-speed, ducted fan, testbed for measuring and understanding fan-generated aeroacoustics, duct propagation, and radiation to the farfield. It is considered a low Technology Readiness Level testbed. The international aeroacoustics research community employed the ANCF to facilitate advancement of multiple noise reduction and measurement technologies, and for code validation. From 1994 to 2016, it was located in the NASA Glenn Research Center’s Aero-Acoustic Propulsion Laboratory. In 2016 the ANCF was transferred to the University of Notre Dame where it is expected to continue to positively impact ducted fan aeroacoustic research and provide STEM support. This paper summarizes the capabilities and contributions of the ANCF to the field by documenting its history. Limited data is presented, focusing on a description of the configurations, goals, and objectives of representative ANCF tests. This provides an overview of the progress of aeroacosustic research as implemented on the ANCF, as well as a background for its continued usage.

Fan Noise↗