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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 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Dusty Environment Classification and Testing: Dust Mitigation Slide Cleaning Material Study

During the Apollo missions many mechanisms, equipment, and surfaces were contaminated by lunar dust and often negatively affected. The methods used to clear these devices of dust proved ineffective, which led to premature failure in some cases. Systems being designed for upcoming missions to the Moon will need to address the performance degradation risk of dust contamination. Surfaces at risk include thermal control surfaces, solar cells, camera and sensor optics, seals, metal joints and tools, and space suit assemblies. To improve state of the art dust mitigation approaches, the dust mitigation team at NASA Glenn Re-search Center (GRC) explored the effects imposed on substrates during cleaning activities in the presence of lunar dust. The Uniform Dust Deposition System (UDDS) was used to conduct a study of various cleaning techniques on different substrates. Test substrates and cleaning media were selected to represent a wide range of structural and functional materials. Substrates included orthofabric, thermal radiator coating, aluminum, quartz glass, silicone rubber, aluminized Mylar, and FEP. Cleaning materials included cloth wipes, tapes, a brush, and a pliable cleaner concept. Cleaning material / substrate pairs were rated on cleaning efficiency, substrate damage, cleaning material longevity, and ease of use. The best performing cleaning method varied based on application.

dust mitigation↗
NASA NTRSDate not supplied

Hybrid Modeling for Complex Systems Health Management

The research work presents application of hybrid physics-informed machine learning to a representative electric powertrain for unmanned aerial vehicles. The model is composed of physics-derived and empirical equations, integrated with connected networks that are strategically placed within the model to substitute equations that are subject to large uncertainty. Polynomial fit driven by heuristics or empirical observations can be substituted by more flexible networks that can minimize the error between model predictions and observations without being restricted to a predefined functional form. This modeling strategy allows training of networks deep inside the model and unknown parameters in a single learning stage. The powertrain model consists of Li-ion batteries, electronic speed controller with pulse-width modulation, and brush-less DC motor with connected propeller. Results obtained from combination of laboratory and simulation tests are discussed in this work.

PINNS↗
NASA NTRSDate not supplied

Quantifying SAGE II (1984-2005) and SAGE III/ISS (2017-2022) Observations of Smoke in the Stratosphere

The Stratospheric Aerosol and Gas Experiment (SAGE II) operated for over 20 years (1984-2005) and collected near global observations of aerosol extinction coefficient from the upper troposphere to about 40 km. SAGE III has flown aboard the International Space Station (ISS) since 2017 and has collected comparable aerosol measurements during this period. The SAGE II record is dominated by recovery from El Chichón (1982) and the Pinatubo eruption of 1991 with a few smaller volcanic events that are detectable in the data set. In addition, a number of pyrocumulus events injected smoke into the lower stratosphere with magnitudes that are comparable to the smaller volcanic events. The shorter SAGE III/ISS record is qualitatively different than SAGE II’s with a number of small to moderate volcanic eruptions in both low and high latitudes (e.g., Ambae in 2018 and Raikoke in 2020) as well several smoke events including the two largest events seen by SAGE-like instruments: the BC pyrocumulus event in 2017 and the Australian brush fires of 2020/2021. In this paper, I will review the detection and quantification of the magnitude of these smoke events with a particular focus on the differences between the two data periods.

Smoke↗
NASA NTRSDate not supplied

Quantifying SAGE II (1984-2005) and SAGE III/ISS (2017-2022) Observations of Smoke in the Stratosphere

The Stratospheric Aerosol and Gas Experiment (SAGE II) operated for over 20 years (1984-2005) and collected near global observations of aerosol extinction coefficient from the upper troposphere to about 40 km. SAGE III has flown aboard the International Space Station (ISS) since 2017 and has collected comparable aerosol measurements during this period. The SAGE II record is dominated by recovery from El Chichón (1982) and the Pinatubo eruption of 1991 with a few smaller volcanic events that are detectable in the data set. In addition, a number of pyrocumulus events injected smoke into the lower stratosphere with magnitudes that are comparable to the smaller volcanic events. The shorter SAGE III/ISS record is qualitatively different than SAGE II’s with a number of small to moderate volcanic eruptions in both low and high latitudes (e.g., Ambae in 2018 and Raikoke in 2020) as well several smoke events including the two largest events seen by SAGE-like instruments: the BC pyrocumulus event in 2017 and the Australian brush fires of 2020/2021. In this talk, I will review the detection and quantification of the magnitude of these smoke events with a particular focus on the differences between the two data periods.

Smoke Stratosphere SAGE↗
NASA NTRSDate not supplied

Quantifying SAGE II (1984-2005) and SAGE III/ISS (2017-2022) Observations of Smoke in the Stratosphere

The Stratospheric Aerosol and Gas Experiment (SAGE II) operated for over 20 years (1984-2005) and collected near global observations of aerosol extinction coefficient from the upper troposphere to about 40 km. SAGE III has flown aboard the International Space Station (ISS) since 2017 and has collected comparable aerosol measurements during this period. The SAGE II record is dominated by recovery from El Chichón (1982) and the Pinatubo eruption of 1991 with a few smaller volcanic events that are detectable in the data set. In addition, a number of pyrocumulus events injected smoke into the lower stratosphere with magnitudes that are comparable to the smaller volcanic events. The shorter SAGE III/ISS record is qualitatively different than SAGE II’s with a number of small to moderate volcanic eruptions in both low and high latitudes (e.g., Ambae in 2018 and Raikoke in 2020) as well several smoke events including the two largest events seen by SAGE-like instruments: the BC pyrocumulus event in 2017 and the Australian brush fires of 2020/2021. In this talk, I will review the detection and quantification of the magnitude of these smoke events with a particular focus on the differences between the two data periods.

SAGE↗
NASA NTRS2024

Per- and Polyfluoroalkyl Substances Confirmatory Sampling Report, South Repeater Building (SWMU 121), Kennedy Space Center, Florida

This Per- and Polyfluoroalkyl Substances (PFAS) Confirmatory Sampling (CS) Report was prepared by AECOM Technical Services, Inc. (AECOM) for the National Aeronautics and Space Administration (NASA) under Contract 80KSC019D0010, Task Order 80KSC021F0096. The purpose of this report is to document CS activities at the South Repeater Building, Solid Waste Management Unit (SWMU) 121, formerly known as the Area 3 Repeater Building (A3RB). A Phase I SWMU Assessment and Confirmatory Sampling Report (NASA 2019) and a Phase II and III SWMU Assessment and Confirmatory Sampling Report (NASA 2022b) were previously submitted detailing Center-Wide assessment activities performed at the John F. Kennedy Space Center (KSC) in Florida that identified 33 locations of concern and 19 areas of potential concern at KSC associated with the storage, use, or release of materials containing PFAS. A review of the analytical results from investigation derived waste samples collected in 2020 from the South Repeater Building area indicated concentrations of perfluorooctanesulfonic acid (PFOS) were above Florida Department of Environmental Protection (FDEP) provisional Groundwater Cleanup Target Levels of 70 nanograms per liter (ng/L) at a concentration of 1,750 ng/L. Following this review, the KSC Fire Chief was contacted; the Chief recalled fighting a brush fire in 1998 in the area, during which an unknown volume of aqueous film-forming foam was used to extinguish the fire. The Phase II and Phase III SWMU Assessment Report recommended this area proceed to CS. Historical results in this area are provided in Appendix A . PFAS CS activities were contracted at the South Repeater Building. Initial CS activities were conducted in accordance with the PFAS Assessment and Mitigation Work Plan (AECOM 2022), which was submitted to the NASA Remediation Project Management team and accepted by the team on November 1 and 8, 2021. The objectives of the PFAS CS were to: - - Confirm and begin to assess the extent of PFAS affected media in the South Repeater Building area. - - Identify locations for groundwater, soil, surface water, and soil core sampling. - - Qualitatively characterize the migration potential of released PFAS to environmental media (soil, groundwater, and surface water). The following activities were completed to meet the PFAS CS objectives: - - Installation of monitoring wells via direct push technology (DPT) and rotosonic techniques - - Groundwater, soil, and surface water sampling - - Collection of soil cores to evaluate site lithology - - Development of initial PFAS plume characterization

PFAS↗
NASA NTRS2022

Dusty Environment Classification and Testing: Dust Mitigation Slide Wipes & Tapes

During the Apollo missions many mechanisms, equipment, and surfaces were contaminated by lunar dust and often negatively affected. The methods used to clear these devices of dust proved ineffective, which led to premature failure in some cases. Systems being designed for upcoming missions to the Moon will need to address the performance degradation risk of dust contamination. Surfaces at risk include thermal control surfaces, solar cells, camera and sensor optics, seals, metal joints and tools, and space suit assemblies. To improve state of the art dust mitigation approaches, the dust mitigation team at NASA Glenn Research Center (GRC) explored the effects imposed on substrates during cleaning activities in the presence of lunar dust. The Uniform Dust Deposition System (UDDS) was used to conduct a study of various cleaning techniques on different substrates. Test substrates and cleaning media were selected to represent a wide range of structural and functional materials. Substrates included orthofabric, thermal radiator coating, aluminum, quartz glass, silicone rubber, aluminized Mylar, and FEP. Cleaning materials included cloth wipes, tapes, a brush, and a pliable cleaner concept. Cleaning material / substrate pairs were rated on cleaning efficiency, substrate damage, cleaning material longevity, and ease of use. The best performing cleaning method varied based on application.

lunar simulant↗
NASA NTRS1962

Collected Papers on Instability of Shell Structures - 1962

Shell structures are important components of airplanes, missiles, and space vehicles, but present capabilities for predicting the local and general instability of many such structures are inadequate. A large effort continues to be devoted to the stability analysis of shell structures, and considerable progress has been made. Results are slowly disseminated, however, and many engaged in research are not fully cognizant of the problems and practices of the vehicle designers who utilize research results. Therefore, an NASA SYMPOSIUM ON INSTABILITY OF SKELL STRUCTURES was organized by the Langley Research Center with sessions held there on October 24 and 25, 1962. Participants were limited to persons contributing papers and to certain officials of the U.S. Government. This symposium was planned to provide those persons concerned with shell instability at research laboratories, at educational institutions, and in the aerospace industry with a comprehensive view of the present state of the art, including the voids in present knowledge, important current problems, and the most fruitful directions for future theoretical and experimental research on the instability of all types of shell structures. Individuals actively engaged in research on shell stability or design were invited to contribute written papers for inclusion in a compilation to be distributed to the participants prior to the symposium. A few papers were selected by a steering committee for oral presentation at the symposium. Provision was made, also, for a discussion of all papers.

MISSILE↗
NASA NTRS1962

SOME SHELL STABILITY PROBLEMS IN MISSILE AND SPACE VEHICLE ANALYSIS

A brief discussion is presented of three structural shell stability studies in progress at Lockheed Missiles & Space Company: the stabilizing influence of solid propellants, the effect of cushion stiffness on buckling under cushion loading, and the snap-through buckling of axially loaded cylinders. Recent analytical results are compared with test data. Also included is a brief description of a few shell stability problems of present interest to LMSC for which satisfactory methods of analysis are not available.

MISSILE↗
NASA NTRS1974

A guide for performing system safety analysis

A general guide is presented for performing system safety analyses of hardware, software, operations and human elements of an aerospace program. The guide describes a progression of activities that can be effectively applied to identify hazards to personnel and equipment during all periods of system development. The general process of performing safety analyses is described; setting forth in a logical order the information and data requirements, the analytical steps, and the results. These analyses are the technical basis of a system safety program. Although the guidance established by this document cannot replace human experience and judgement, it does provide a methodical approach to the identification of hazards and evaluation of risks to the system.

Brush, J. M.↗
NASA NTRS1986

Investigation of potential driver modules and transmission lines for a high frequency power system on the space station

The objective was to assess the feasibility of using the Series Resonant inverter as the driver module for the high frequency power system on the Space Station. This study evaluates the performance of the Series Resonant driver when it was operated with a dc input voltage and run through a series of tests to determine its start-up performance, response to load changes, load regulation, and efficiency. Also, this study compares the Series Resonant driver to another kind of driver that uses a Power Transistor snubber. An investigation of the various types of transmission lines is initiated. In particular, a simplified approach is utilized to describe the optimal transmission line.

Brush, H. T.↗
NASA NTRS1986

Investigation of potential driver modules and transmission lines for a high frequency power system on the space station

The feasibility of using Series Resonant Inverter as the driver module for high frequency power system on the Space Station was assessed. The performance of the Series Resonant Inverter that was used in the testing of the single-phase, 2.0-kw resonant AC power system breadboard is summarized. The architecture is descirbed and the driver modules of the 5.0 kw AC power system breadboard are analyzed. An investigation of the various types of transmission lines is continued. Measurements of equivalent series resistor and inductor and equivalent parallel capacitors are presented. In particular, a simplified approach is utilized to describe the optimal transmission line.

Brush, Harold T.↗
NASA NTRS1988

Microgravity robotics technology program

A research program to develop technology for robots operating in the microgravity environment of the space station laboratory is described. These robots must be capable of manipulating payloads without causing them to experience harmful levels of acceleration, and the motion of these robots must not disturb adjacent experiments and operations by transmitting reactions that translate into damaging effects throughout the laboratory. Solutions to these problems, based on both mechanism technology and control strategies, are discussed. Methods are presented for reduction of robot base reactions through the use of redundant degrees of freedom, and the development of smoothly operating roller-driven robot joints for microgravity manipulators is discussed.

Rohn, Douglas A.↗
NASA NTRS1988

Microgravity manipulator demonstration

A test rig is being developed that will be used to demonstrate and evaluate approaches to limiting manipulator base reactions in microgravity environments. The demonstration will include a 4-degrees-of-freedom arm, control computing facilities, and a base reaction measurement system.

Brush, Andrew S.↗
NASA NTRS1989

Development and testing of a 20-kHz component test bed

A history of the General Dynamics Space Systems Division 20 kHz Breadboard is presented including its current configuration and its role in the Space Station Freedom (SSF) program. Highlights and results are presented on a series of tests conducted on the 20 kHz Breadboard. The first test presented is the 20 kHz Breadboard Acceptance test. This test verified the operation of the delivered Breadboard and also characterized the main components of the system. Next, an indepth efficiency testing effort is presented. The tests attempted to apportion all the power losses in the 20 kHz Breadboard Main Invert Units. Distortion test data is presented showing the distortion characteristics of a Mapham inverter. Lastly, current work on the 20 kHz Breadboard is presented including Main Inverter Unit paralleling tests. Conclusions are summarized and references given.

Button, Robert M.↗