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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 433 records · Page 24

Lunar transfer vehicle design issues with electric propulsion systems

This paper describes parametric design studies of electric propulsion lunar transfer vehicles. In designing a lunar transfer vehicle, selecting the 'best' operating points for the design parameters allows significant reductions in the mass in low earth orbit (LEO) for the mission. These parameters include the specific impulse, the power level, and the propulsion technology. Many of the decisions regarding the operating points are controlled by the propulsion and power system technologies that are available for the spacecraft. The relationship between these technologies is discussed and analyzed here. It is found that both ion and MPD propulsion offer significant LEO mass reductions over O2/H2 for lunar transfer vehicle missions. The recommended operating points for the lunar transfer vehicle are an I(sp) of 5000 lb(f)-s/lb(m) and a 1 MW power level. For large lunar missions, krypton may be the best choice for ion propulsion.

Palaszewski, Bryan↗

An Overview of the Formation and Attitude Control System for the Terrestrial Planet Finder Formation Flying Interferometer

The Terrestrial Planet Finder formation flying Interferometer (TPF-I) will be a five-spacecraft, precision formation operating near the second Sun-Earth Lagrange point. As part of technology development for TPF-I, a formation and attitude control system (FACS) is being developed that achieves the precision and functionality needed for the TPF-I formation and that will be demonstrated in a distributed, real-time simulation environment. In this paper we present an overview of FACS and discuss in detail its formation estimation, guidance and control architectures and algorithms. Since FACS is currently being integrated into a high-fidelity simulation environment, component simulations demonstrating algorithm performance are presented.

Scharf, Daniel P.↗

The Fate of Trace Contaminants in a Crewed Spacecraft Cabin Environment

Trace chemical contaminants produced via equipment offgassing, human metabolic sources, and vehicle operations are removed from the cabin atmosphere by active contamination control equipment and incidental removal by other air quality control equipment. The fate of representative trace contaminants commonly observed in spacecraft cabin atmospheres is explored. Removal mechanisms are described and predictive mass balance techniques are reviewed. Results from the predictive techniques are compared to cabin air quality analysis results. Considerations are discussed for an integrated trace contaminant control architecture suitable for long duration crewed space exploration missions.

Perry, Jay L.↗

Conjunction Assessment and Deconfliction Paradigm for Co-Located Satellite Constellations With on-Spacecraft “Autonomous” Flight Dynamics Control

Satellite constellations that employ on-spacecraft flight dynamics and conjunction assessment (CA) approaches face particular challenges. First, they must arrange to obtain and upload to the constellation satellite close approach information, such as Conjunction Data Messages, so that their on-board systems will have the data they need to make informed CA decisions. Second, given current latencies in obtaining CA screening information, such systems often cannot obtain dedicated screenings of their proposed maneuvers before they are executed. Third, they usually cannot engage in real time with owner/operators (O/Os) with whom they may come into conjunction, relying instead on pre-arranged courses of action that may or may not fit a given situation well. Despite these difficulties, it is nonetheless possible, as operators such as SpaceX have demonstrated, to operate safely using on-board CA calculations, in the presence of a largely collaborative operating environment. The situation breaks down, however, when two constellations that operate with such a paradigm are placed in the same orbital region and will experience conjunctions with each other. Each may have a vague idea of where the other’s satellites are, or perhaps even a somewhat precise idea if they exchange O/O ephemerides, but neither will know the other’s more immediate maneuver intentions, especially for situations in which they are in a high-risk conjunction with each other and a mitigation maneuver is required. As there is no formalized way for these automated systems to ascertain each other’s intentions for this type of conjunction, it is quite possible that each spacecraft may choose a maneuver that results in the two objects’ colliding. An opportunity to develop a solution to this problem was presented by the NASA “Starling” project, a small experimental constellation developed to demonstrate autonomous satellite control and constellation reconfiguration and for which a launch was obtained that, serendipitously, will place this constellation close to the SpaceX Starlink constellation. Because the NASA constellation is experimental, an extended mission part of the mission has been negotiated to implement and test mechanisms for resolving the problem of co-located constellations with on-board flight dynamics control. For the last eighteen months, a consortium among NASA Ames (the Starling satellite providers), NASA CARA (the Agency organization responsible for conjunction assessment), Space X, and the Department of Commerce (in observer status) has met regularly to assemble a concept of operations for a robust solution to this problem and has developed a prototype ground node that will serve as a needed CA screening and information dispensary. The approach and methods, as well as the active employment of the developed ground node, will be tested both in simulation before actual use and then in actual spacecraft operations, which are anticipated to begin in January 2024. This paper will describe the co-located autonomously-controlled constellation problem and the developed solution in detail, outlining what ground node (i.e., government) infrastructure and features are required, what particular capabilities are needed by the constellations themselves in order to make use of this deconfliction paradigm, and the migration path forward to allow such a capability set to be incorporated by the Department of Commerce’s space traffic coordination system.

Conjunction Assessment↗

On the use of distributed sensing in control of large flexible spacecraft

Distributed processing technology is being developed to process signals from distributed sensors using distributed computations. Thiw work presents a scheme for calculating the operators required to emulate a conventional Kalman filter and regulator using such a computer. The scheme makes use of conventional Kalman theory as applied to the control of large flexible structures. The required computation of the distributed operators given the conventional Kalman filter and regulator is explained. A straightforward application of this scheme may lead to nonsmooth operators whose convergence is not apparent. This is illustrated by application to the Mini-Mast, a large flexible truss at the Langley Research Center used for research in structural dynamics and control. Techniques for developing smooth operators are presented. These involve spatial filtering as well as adjusting the design constants in the Kalman theory. Results are presented that illustrate the degree of smoothness achieved.

Montgomery, Raymond C.↗

Results from teleoperated free-flying spacecraft simulations in the Martin Marietta space operations simulator lab

To augment the capabilities of the Space Transportation System, NASA has funded studies and developed programs aimed at developing reusable, remotely piloted spacecraft and satellite servicing systems capable of delivering, retrieving, and servicing payloads at altitudes and inclinations beyond the reach of the present Shuttle Orbiters. Since the mid 1970's, researchers at the Martin Marietta Astronautics Group Space Operations Simulation (SOS) Laboratory have been engaged in investigations of remotely piloted and supervised autonomous spacecraft operations. These investigations were based on high fidelity, real-time simulations and have covered a wide range of human factors issues related to controllability. Among these are: (1) mission conditions, including thruster plume impingements and signal time delays; (2) vehicle performance variables, including control authority, control harmony, minimum impulse, and cross coupling of accelerations; (3) maneuvering task requirements such as target distance and dynamics; (4) control parameters including various control modes and rate/displacement deadbands; and (5) display parameters involving camera placement and function, visual aids, and presentation of operational feedback from the spacecraft. This presentation includes a brief description of the capabilities of the SOS Lab to simulate real-time free-flyer operations using live video, advanced technology ground and on-orbit workstations, and sophisticated computer models of on-orbit spacecraft behavior. Sample results from human factors studies in the five categories cited above are provided.

Hartley, Craig S.↗

Smarter Software For Enhanced Vehicle Health Monitoring and Inter-Planetary Exploration

The existing philosophy for space mission control was born in the early days of the space program when technology did not exist to put significant control responsibility onboard the spacecraft. NASA relied on a team of ground control experts to troubleshoot systems when problems occurred. As computing capability improved, more responsibility was handed over to the systems software. However, there is still a large contingent of both launch and flight controllers supporting each mission. New technology can update this philosophy to increase mission assurance and reduce the cost of inter-planetary exploration. The advent of model-based diagnosis and intelligent planning software enables spacecraft to handle most routine problems automatically and allocate resources in a flexible way to realize mission objectives. The manifests for recent missions include multiple subsystems and complex experiments. Spacecraft must operate at longer distances from earth where communications delays make earthbound command and control impractical. NASA's Ames Research Center (ARC) has demonstrated the utility of onboard diagnosis and planning with the Remote Agent experiment in 1999. KSC has pioneered model-based diagnosis and demonstrated its utility for ground support operations. KSC and ARC are cooperating in research to improve the state of the art of this technology. This paper highlights model-based reasoning applications for Moon and Mars missions including in-situ resource utilization and enhanced vehicle health monitoring.

Larson, William E.↗

Operational Health Physics for Radiation Source Payloads

Spacecraft payloads processed at the Kennedy Space Center (KSC) frequently include ionizing and nonionizing radiation sources that require controls to protect the health of the workers involved in the ground operations. At KSC, a robust radiation protection program ensures that radiation hazards are identified, and appropriate controls are implemented using a radiation use authorization (RUA) process and Radiation Protection Committee review and approval. The Health Physics Office provides monitoring and oversight to ensure compliance. A brief overview of health physics activities in support of the Mars 2020 mission will be described to illustrate the overall management of radiation sources during payload ground processing.

Kurt R Geber↗

Mission Operations Data Analysis Tools for Mars Observer Guidance and Control

The focus of this paper is on the data analysis tools for the Mars Observer Attitude and Articulation Control Subsystem (AACS). Four different categories of analysis tools are presented, with details offered for specific tools. These same tools, and extensions thereof, have been adopted by the Galileo mission operations, and are being designed into Cassini and other future spacecraft mission operations.

mission↗

Air-bearing spin facility for measuring energy dissipation

The air-bearing spin facility was developed to determine experimentally the effect of energy dissipation upon the motion of spinning spacecraft. The facility consists of an air-bearing spin table, a telemetry system, a command system, and a ground control station. The air-bearing spin table was designed to operate in a vacuum chamber. Tests were run on spacecraft components such as fuel tanks, nutation dampers, reaction wheels, and active nutation damper systems. Each of these items affected the attitude of a spinning spacecraft. An experimental approach to determine these effects was required because the dissipation of these components could not be adequately analyzed. The results of these experiments have been used, with excellent results, to predict spacecraft motion.

Peterson, R. L.↗

Automated support for system's engineering and operations - The development of new paradigms

Technological developments in spacecraft ground operations are reviewed. The technological, operations-oriented, managerial, and economic factors driving the evolution of the Mission Operations Control Center (MOCC), and its predecessor the Operational Control Center are examined. The functional components of the various MOCC subsystems are outlined. A brief overview is given of the concepts behind the The Knowledge-Based Software Engineering Environment, the Generic Spacecraft Analysis Assistant, and the Knowledge From Pictures tool.

Truszkowski, Walt↗

STF-1 Ground Operations - Automating the Planning, Scheduling, Assessment and Data Processing/Reduction for a Small Satellite

On December 16, 2018, a 3-U CubeSat named STF-1 launched as West Virginia's first spacecraft. This event marked the culmination of a run-up to launch involving the production of the spacecraft, creation/configuration of command and control infrastructure, and the evolution of its co-creation, the NASA Operational Simulator for Small Satellites (NOS3). This event also marked the beginning of a new phase: operations. While plans, procedures, and infrastructure were already in place or started for operations, many lessons were learned during the operations phase, especially during early operations (first month/commissioning phase). Additional plans, procedures, and infrastructure, especially related to communication planning and automated data processing, were created and developed to fill needs for the operation of the STF-1 mission.This paper and presentation will overview the STF-1 operations team's solutions to addressing the many needs of operating a low-earth orbiting CubeSat mission with a single ground antenna that is shared and scheduled with several other missions. The STF-1 operations team deployed a combination of virtualization technologies, ground station technology solutions, collaboration software, custom planning software solutions, and existing ground antenna scheduling solutions to create an effective and efficient CubeSat operations environment. The end-solution satisfied the operations stakeholders, which include NASA, its industry partner TMC2 Technologies, and four independent professor-student teams at West Virginia University.

Suder, Mark↗

Simulation of an Electromechanical Spin Motor System of a Control Moment Gyroscope

A two-phase brushless DC motor (BDCM) with pulse-width modulated (PWM) voltage drive is simulated to control the flywheel speed of a control moment gyroscope (CMG). An overview of a double-gimballed control moment gyroscope (DGCMG) assembly is presented along with the CMG torque effects on the spacecraft. The operating principles of a two-phase brushless DC motor are presented and the system's electro-mechanical equations of motion are developed for the root-mean-square (RMS) currents and wheel speed. It is shown that the system is an extremely "stiff" set of first-order equations for which an implicit Euler integrator is required for a stable solution. An adaptive proportional voltage controller is presented which adjusts the PWM voltages depending on several control modes for speed, current, and torque. The simulation results illustrate the interaction between the electrical system and the load dynamics and how these influence the overall performance of the system. As will be shown, the CMG spin motor model can directly provide electrical power use and thermal power output to spacecraft subsystems for effective (average) calculations of CMG power consumption.

Inampudi, Ravi↗

Automating satellite operations at the NASA Goddard Space Flight Center

A second generation of graphical expert systems are under development at NASA's Goddard Space Flight Center (GSFC) to support real-time operations in the satellite control centers. Built with a new domain-specific expert system development tool named the Generic Spacecraft Analyst Assistant (GenSAA), these systems have been deployed to assist with a variety of satellite operations functions.

Hughes, Peter M.↗

The Controlled Re-Entry of the Compton Gamma Ray Observatory

On June 3, 2000, the Compton Gamma Ray Observatory (CGRO) successfully entered the Earth's atmosphere over the targeted Pacific Ocean. This is the first time NASA has conducted a controlled reentry of an unmanned spacecraft from Low Earth Orbit (LEO). The criticality of this operation was enhanced due to the large mass of the spacecraft, 14000 kg ( 15.5 tons) post final burn, and the loss of the primary propulsion system. This paper will present a brief mission history from launch, through in-orbit failures, from a spacecraft level systems perspective. A general hardware description is also included for clarity. The critical decision of re-entering the CGRO is covered, as well as key events through the mission design. Attitude Control System performance simulations used in the mission design and ground team training are compared to flight data results.

Mangus, David J.↗

Unattended deep space station tracking station development: Monitor and control technology

The major developments leading to successful demonstration of fully unattended operation of a Deep Space Network (DSN) station (DSS 13) are reviewed. Unattended operation was demonstrated by reliably tracking, commanding, and delivering telemetry from the Pioneer 8 spacecraft. Transfer of automated monitor and control technology to DSN implementation is summarized, along with related accomplishments.

Foster, C.↗

Testing Protocol Proposal to Identify and Evaluate Candidate Materials to Substitute for Silverized Teflon in Thermal Control Applications

Electrostatic discharge (ESD) has been shown to be the primary cause of several glitches in spacecraft operations. It appears that charged particles encountered in the natural environment in certain orbits can collect on the outer surfaces of a spacecraft, building up a charge of several thousand volts. If the potential exceeds the breakdown voltage of the charged material, then an ESD will occur. ESD events involving relatively low voltages, on the order of 100 V, have been shown to damage electronic components. When ESD occurs, electronic and electrical components can be damaged, computer instructions can be garbled, and ablation of material from the spacecraft may occur; degrading both the performance of the thermal control blankets, and the cleanliness of any surfaces on which the detritus becomes deposited. There appear to be six ways to prevent or mitigate the effects of ESD: (1) Choose an orbit where charging is not a problem; (2) Carry extra electromagnetic shielding; (3) Provide redundancy in components and programming; (4) Provide for active dissipation of the charge, by generating a plasma with which to bathe susceptible surfaces; (5) Provide for passive dissipation from a plasma contactors on the susceptible surfaces; and (6) Provide thermal control blankets that do not hold a charge, i.e., that are conductive enough to bleed a charge off harmlessly. These six options are discussed in detail in Losure (1996). Of these six options, number 1 is not always practical, given other requirements of the mission; 2, 3, 4 and 5 will require that extra mass in the form of shielding, etc., be carried by the spacecraft. The most attractive option from a mass and energy point of view seems to be that of finding a material which matches the other performance characteristics of the current thermal control blankets without their tendency to build up an electrostatic charge. The goal of this paper is to describe and justify a testing program which will lead to the approval of materials of this kind.

Losure, Nancy S.↗

Economic and technical aspects of repair, servicing, and retrieval of low earth orbit free flying spacecraft

The economic and technical aspects of the Solar Maximum Observatory Repair Mission at NASA are presented, in an effort to demonstrate the Space Shuttle capability to rendezvous with and repair on-orbit the Solar Maximum Observatory (SMM). A failure in the Attitude Control Subsystem (ACS) after 10 months of operation caused a loss in precision pointing capability. The Multimission Modular Spacecraft (MMS) used for the mission, was designed with on-orbit repairability, and to correct various instrument anomalies, repiar kits such as an electronics box, a thermal aperture closure, and a high energy particle reflection baffle will be used. In addition, a flight support system will be used to berth, electrically safe, and support all the repair activities. A two year effort is foreseen, and the economic return on SMM will be $176 M, in addition to two to three years of solar observation. The mission will eventually conduct studies on flare as a function of solar cycle.

Cepollina, F. J.↗