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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

Improved Dynamic Modeling of the Cascade Distillation Subsystem and Analysis of Factors Affecting Its Performance

The Cascade Distillation Subsystem (CDS) is a rotary multistage distiller being developed to serve as the primary processor for wastewater recovery during long-duration space missions. The CDS could be integrated with a system similar to the International Space Station Water Processor Assembly to form a complete water recovery system for future missions. A preliminary chemical process simulation was previously developed using Aspen Custom Modeler® (ACM), but it could not simulate thermal startup and lacked detailed analysis of several key internal processes, including heat transfer between stages. This paper describes modifications to the ACM simulation of the CDS that improve its capabilities and the accuracy of its predictions. Notably, the modified version can be used to model thermal startup and predicts the total energy consumption of the CDS. The simulation has been validated for both NaC1 solution and pretreated urine feeds and no longer requires retuning when operating parameters change. The simulation was also used to predict how internal processes and operating conditions of the CDS affect its performance. In particular, it is shown that the coefficient of performance of the thermoelectric heat pump used to provide heating and cooling for the CDS is the largest factor in determining CDS efficiency. Intrastage heat transfer affects CDS performance indirectly through effects on the coefficient of performance.

Perry, Bruce 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 NTRS2008

Renewed Mapping of the Nepthys Mons Quadrangle (V-54), Venus

After a long hiatus due to competing tasks with the PI, mapping of Venus' Nepthys Mons Quadrangle (V-54, 300-330degE, 25-50degS) has been resumed, with planned submission late in 2008 or early 2009. Major goals are to determine the style of volcanism and tectonism over time, the evolution of shield volcanoes, the evolution of coronae, the characteristics of plains volcanism, and what these observations tell us about the general geologic history of Venus. This abstract largely repeats earlier progress reports, with some updates to show GEMS that the PI intends to complete this task in the near future. Methods: Geologic units and structures have been mapped onto hardcopy FMAPs and then transferred to the 1:5 million-scale map base (Figure 1). Pseudostereo anaglyphs have proved an indispensable tool and have resulted in a virtual complete revision of previously mapped areas [1,2]. At FMAP scale, structural trends and inferred ages are broken out using different symbols and colors. These are in the process of being transferred to a 1:5 million-scale structure map separate from the geologic map. The geologic units, structures, impact craters, coronae, and volcanoes are being arranged in time-stratigraphic sequences as the mapping progresses.

Bridges, Nathan T.↗
NASA NTRS1987

Using bibliographic databases in technology transfer

When technology developed for a specific purpose is used in another application, the process is called technology transfer--the application of an existing technology to a new use or user for purposes other than those for which the technology was originally intended. Using Bibliographical Databases in Technology Transfer deals with demand-pull transfer, technology transfer that arises from need recognition, and is a guide for conducting demand-pull technology transfer studies. It can be used by a researcher as a self-teaching manual or by an instructor as a classroom text. A major problem of technology transfer is finding applicable technology to transfer. Described in detail is the solution to this problem, the use of computerized, bibliographic databases, which currently contain virtually all documented technology of the past 15 years. A general framework for locating technology is described. NASA technology organizations and private technology transfer firms are listed for consultation.

Huffman, G. David↗
NASA NTRS1989

Numerically efficient algorithm for model development of high-order systems

A technique for estimating transfer functions in partial fraction expansion form from frequency response data for a high-order system is presented. The problem formulation avoids many of the numerical difficulties associated with high-order polynomials and has the advantage of having the option to fix the camping and frequency of a mode, if known, during the estimation process. The resulting transfer function(s) may be converted to Jordan-Form time domain equations directly. During the implementation of this technique, a frequency and amplitude normalizing window was developed that maximized the efficiency of the optimization algorithm. The combination of estimating the transfer function in factored form, the ability to fix preciously determined parameters and the effectiveness of the normalizing window led to a progressive approach to synthesizing transfer functions from frequency response data for high-order systems.

Parada, L. O.↗
NASA NTRSDate not supplied

Exploring the Low-Thrust Transfer Design Space in an Ephemeris Model via Multi-Objective Reinforcement Learning

Multi-Reward Proximal Policy Optimization (MRPPO) is a multi-objective reinforcement learning algorithm used to train multiple policies to uncover solutions within a multi-objective solution space. MRPPO is used in this paper to train policies to construct low-thrust transfers for a SmallSat from the vicinity of !2 to an !5 short period orbit in the Sun-Earth-Moon system. First, the policies are trained in this scenario in the circular restricted three-body problem. This information is used to initialize the policies before training in a higher-fidelity ephemeris model; a process known as transfer learning. The recovered segments of the solution space will be compared to fundamental dynamical structures to both examine the results of MRPPO in this complex design scenario and explore the effectiveness of transfer learning.

Christopher J Sullivan↗
NASA NTRSDate not supplied

Exploring the Low-Thrust Transfer Design Space in an Ephemeris Model via Multi-Objective Reinforcement Learning

Multi-Reward Proximal Policy Optimization (MRPPO) is a multi-objective reinforcement learning algorithm used to train multiple policies to uncover solutions within a multi-objective solution space. MRPPO is used in this paper to train policies to construct low-thrust transfers for a SmallSat from the vicinity of L2 to an L5 short period orbit in the Sun-Earth-Moon system. First, the policies are trained in this scenario in the circular restricted three-body problem. This information is used to initialize the policies before training in a higher-fidelity ephemeris model; a process known as transfer learning. The recovered segments of the solution space will be compared to fundamental dynamical structures to both examine the results of MRPPO in this complex design scenario and explore the effectiveness of transfer learning.

Christopher J. Sullivan↗
NASA NTRS2022

Exploring the Low-Thrust Transfer Design Space in an Ephemeris Model via Multi-Objective Reinforcement Learning

Multi-Reward Proximal Policy Optimization (MRPPO) is a multi-objective reinforcement learning algorithm used to train multiple policies to uncover solutions within a multi-objective solution space. MRPPO is used in this paper to train policies to construct low-thrust transfers for a SmallSat from the vicinity of 𝐿2 to an 𝐿5 short period orbit in the Sun-Earth-Moon system. First, the policies are trained in this scenario in the circular restricted three-body problem. This information is used to initialize the policies before training in a higher-fidelity ephemeris model; a process known as transfer learning. The recovered segments of the solution space will be compared to fundamental dynamical structures to both examine the results of MRPPO in this complex design scenario and explore the effectiveness of transfer learning.

Mashiku, Alinda K.↗
NASA NTRS1995

Shuttle to space station transfer of the materials exposure facility

The Materials Exposure Facility (MEF) is being proposed by LaRC as the first long-term space materials exposure facility with real-time interaction with materials experiments in actual conditions of orbital space flight. The MEF is proposed as a Space Station external payload dedicated to technology advancement in spacecraft materials and coatings research. This paper will define a set of potential logistics for removing the MEF from the Shuttle cargo bay and the process required for transferring the MEF to a specific external payload site on Space Station Freedom (SSF). The SSF UF-2 configuration is used for this study. The kinematics and ability to successfully perform the appropriate MEF maneuvers required were verified. During completion of this work, the Space Station was redesigned and the International Space Station Alpha (ISSA) configuration evolved. The transfer procedure for SSF was valid for ISSA; however, a verification of kinematics and clearances was essential. Also, SSF and ISSA robotic interfaces with the Orbiter were different.

Shannon, David T., Jr.↗
NASA NTRS1980

A probabilistic approach to radiative energy loss calculations for optically thick atmospheres - Hydrogen lines and continua

An approximate probabilistic radiative transfer equation and the statistical equilibrium equations are simultaneously solved for a model hydrogen atom consisting of three bound levels and ionization continuum. The transfer equation for L-alpha, L-beta, H-alpha, and the Lyman continuum is explicitly solved assuming complete redistribution. The accuracy of this approach is tested by comparing source functions and radiative loss rates to values obtained with a method that solves the exact transfer equation. Two recent model solar-flare chromospheres are used for this test. It is shown that for the test atmospheres the probabilistic method gives values of the radiative loss rate that are characteristically good to a factor of 2. The advantage of this probabilistic approach is that it retains a description of the dominant physical processes of radiative transfer in the complete redistribution case, yet it achieves a major reduction in computational requirements.

Canfield, R. C.↗
NASA NTRS1988

Computerized monitoring and control of experiments in space

The computer subsystem of the Villanova University GAS (Get Away Special) experiment apparatus is discussed. The function of the computer subsystem is to provide data acquisition and control system support to the experiments. The computer subsystem will provide high availability, low power consumption and highly reliable data retention. The general layout of the subsystem provides for redundant processing units, control modules, and multiple data acquisition modules. Each of the two redundant processing units will be composed of a microprocessor, control logic, PROM, RAM, non-volitile memory, timers, self-check logic and data ports to the data acquisition and control modules. One unit will control the experiment while the other shadows the primary unit operation. The data acquisition module gathers data from the experiment. The data is transfered to the processing unit in digital form. The control module validates the data, decodes it and executes the command.

Janisch, Thomas V.↗
NASA NTRS1991

Comparison of spectroscopic properties of Tm and Ho in YAG and YLF crystals

The paper compares the cross-relaxation, energy transfer and loss processes in Tm- and Ho-doped YAG and YLF as a function of temperature, Tm concentration, and excitation power. Significant differences in the behavior of Tm and Tm,Ho in YAG and YLF crystals were found. The cross-relaxation rates of Tm(6 pct) are faster in YLF (about 5 microsec) than YAG (about 10 microsec). The energy transfer rates between Tm and Ho are faster in YLF than YAG. The time it takes for the maximum intensity of 1.7-micron emission to drop 10 percent is 25 microsec for YLF:Tm(6 pct),Ho(0.6 pct) and 65 microsec YAG:Tm(6 pct),Ho(0.5 pct). The losses occurring with increasing pump power for 2.1-micron emission of the above samples are 30 percent less in YLF than YAG. These qualitative differences point to YLF as a valuable 2-micron laser host material.

Armagan, G.↗
NASA NTRS1994

A realistic model of evaporation for a liquid droplet

An intuitive delineation along with dimensional considerations and experimental evidences are presented to show that in a general case, the evaporation of a liquid droplet undergoes three regimes through the process. Initially, the heat transfer inside the evaporating droplets is conduction controlled; then, in the second stage, convective heat transfer may take over; finally, the convections subside, and the process returns to conduction controlled mode.

Chai, An-Ti↗
NASA NTRS2005

Bacillus subtilis spore survival and expression of germination-induced bioluminescence after prolonged incubation under simulated Mars atmospheric pressure and composition: implications for planetary protection and lithopanspermia

Bacterial endospores in the genus Bacillus are considered good models for studying interplanetary transfer of microbes by natural or human processes. Although spore survival during transfer itself has been the subject of considerable study, the fate of spores in extraterrestrial environments has received less attention. In this report we subjected spores of a strain of Bacillus subtilis, containing luciferase resulting from expression of an sspB-luxAB gene fusion, to simulated martian atmospheric pressure (7-18 mbar) and composition (100% CO(2)) for up to 19 days in a Mars simulation chamber. We report here that survival was similar between spores exposed to Earth conditions and spores exposed up to 19 days to simulated martian conditions. However, germination-induced bioluminescence was lower in spores exposed to simulated martian atmosphere, which suggests sublethal impairment of some endogenous spore germination processes.

Mars↗
NASA NTRS2017

A Overview of New Technologies Driving Innovation in the Airborne Science Community

Following a more than a century of scientific aircraft and ballooning there is a sense that a renaissance of sorts is at hand in the aviation industry. The advent of incredibly miniaturized autopilots, inertial navigation systems, GPS antennae, and payloads has sparked a revolution in manned and unmanned aircraft. Improved SATCOM and onboard computing has enabled realtime data processing and improved transfer of data on and off the aircraft, making flight planning and data collection more efficient and effective. Electric propulsion systems are scaling up to larger and larger vehicles as evidenced by the NASA GL-10, which is leading to a new X-plane and is leading to renewed interest in personal air vehicles. There is also significant private and government investments in the development of High Altitude, Long Endurance (HALE) aircraft. This presentation will explore how such developments are likely to improve our ability to observe earth systems processes from aircraft by providing an overview of current NASA Airborne Science capabilities, followed by a brief discussion of new technologies being applied to Airborne Science missions, and then conclude with an overview of new capabilities on the horizon that are likely to be of interest to the Earth Science community.

airborne science↗
NASA NTRS2017

An Overview of New Technologies Driving Innovation in the Airborne Science Community

Following a more than a century of scientific aircraft and ballooning there is a sense that a renaissance of sorts is at hand in the aviation industry. The advent of incredibly miniaturized autopilots, inertial navigation systems, GPS antennae, and payloads has sparked a revolution in manned and unmanned aircraft. Improved SATCOM and onboard computing has enabled realtime data processing and improved transfer of data on and off the aircraft, making flight planning and data collection more efficient and effective. Electric propulsion systems are scaling up to larger and larger vehicles as evidenced by the NASA GL-10, which is leading to a new X-plane and is leading to renewed interest in personal air vehicles. There is also significant private and government investments in the development of High Altitude, Long Endurance (HALE) aircraft. This presentation will explore how such developments are likely to improve our ability to observe earth systems processes from aircraft by providing an overview of current NASA Airborne Science capabilities, followed by a brief discussion of new technologies being applied to Airborne Science missions, and then conclude with an overview of new capabilities on the horizon that are likely to be of interest to the Earth Science community.

airborne science↗
NASA NTRS1990

Signalling design and architecture for a proposed mobile satellite network

In a frequency-division/demand-assigned multiple-access (FD/DAMA) architecture, each mobile subscriber must make a connection request to the Network Management Center before transmission for either open-end or closed-end services. Open-end services are for voice calls and long file transfer and are processed on a blocked-call-cleared basis. Closed-end services are for transmitting burst data and are processed on a first-come first-served basis. This paper presents the signalling design and architecture for non-voice services of an FD/DAMA mobile satellite network. The connection requests are made through the recently proposed multiple channel collision resolution scheme which provides a significantly higher throughput than the traditional slotted ALOHA scheme. For non-voice services, it is well known that retransmissions are necessary to ensure the delivery of a message in its entirety from the source to destination. Retransmission protocols for open-end and closed-end data transfer are investigated. The signal structure for the proposed network is derived from X-25 standards with appropriate modifications. The packet types and their usages are described in this paper.

Yan, T.-Y.↗