SEARCH · Search NASA

Results for “subsystem”

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.

SourceResearch connectionFrom yearThrough year

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

At least 325 records · Page 18

All sources NASA NTRS DOE OSTI

NASA NTRS1988

Effect of earth albedo variation on the performance of a spatial acquisition subsystem aboard a planetary spacecraft

The effect of Earth albedo variation on the pointing and tracking subsystem of a planetary optical communication package is analyzed. By studying the Cramer-Rao bound of the tracking error variance, it is shown that, when the Earth albedo is precisely known, the variance in spatial tracking error is inversely proportional to the total signal count. In contrast, a small uncertainty in the Earth albedo can result in an irreducible error in the tracking subsystem.

Chen, C.-C.↗

NASA NTRS1988

Automated workstation for the operation of spacecraft engineering subsystems

This paper addresses the development of a workstation that exploits automated tools to enable an operator to monitor concurrently several engineering subsystems and/or several space missions. The use of artificial intelligence and advanced graphics capabilities to achieve fast prototypes is discussed. The monitoring of engineering telemetry data from the Power and Pyro Subsystem of the Galileo spacecraft is emphasized.

Bahrami, K. A.↗

NASA NTRS1988

Development of a two-stage membrane-based wash-water reclamation subsystem

A two-stage membrane-based subsystem was designed and constructed to enable the recycle of wash waters generated in space. The first stage is a fouling-resistant tube-side-feed hollow-fiber ultrafiltration module, and the second stage is a spiral-wound reverse-osmosis module. Throughout long-term tests, the subsystem consistently produced high-quality permeate, processing actual wash water to 95 percent recovery.

Mccray, S. B.↗

NASA NTRS1986

Independent Orbiter Assessment (IOA): Analysis of the instrumentation subsystem

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Instrumentation Subsystem are documented. The Instrumentation Subsystem (SS) consists of transducers, signal conditioning equipment, pulse code modulation (PCM) encoding equipment, tape recorders, frequency division multiplexers, and timing equipment. For this analysis, the SS is broken into two major groupings: Operational Instrumentation (OI) equipment and Modular Auxiliary Data System (MADS) equipment. The OI equipment is required to acquire, condition, scale, digitize, interleave/multiplex, format, and distribute operational Orbiter and payload data and voice for display, recording, telemetry, and checkout. It also must provide accurate timing for time critical functions for crew and payload specialist use. The MADS provides additional instrumentation to measure and record selected pressure, temperature, strain, vibration, and event data for post-flight playback and analysis. MADS data is used to assess vehicle responses to the flight environment and to permit correlation of such data from flight to flight. The IOA analysis utilized available SS hardware drawings and schematics for identifying hardware assemblies and components and their interfaces. Criticality for each item was assigned on the basis of the worst-case effect of the failure modes identified.

Howard, B. S.↗

NASA NTRS1987

Independent Orbiter Assessment (IOA): Analysis of the electrical power distribution and control/remote manipulator system subsystem

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the Electrical Power Distribution and Control (EPD and C)/Remote Manipulator System (RMS) hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained in the NASA FMEA/CIL documentation. This report documents the results of the independent analysis of the EPD and C/RMS (both port and starboard) hardware. The EPD and C/RMS subsystem hardware provides the electrical power and power control circuitry required to safely deploy, operate, control, and stow or guillotine and jettison two (one port and one starboard) RMSs. The EPD and C/RMS subsystem is subdivided into the four following functional divisions: Remote Manipulator Arm; Manipulator Deploy Control; Manipulator Latch Control; Manipulator Arm Shoulder Jettison; and Retention Arm Jettison. The IOA analysis process utilized available EPD and C/RMS hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based on the severity of the effect for each failure mode.

Robinson, W. W.↗

NASA NTRS1987

Independent Orbiter Assessment (IOA): Analysis of the electrical power distribution and control subsystem, volume 1

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Orbiter Electrical Power Distribution and Control (EPD and C) hardware. The EPD and C hardware performs the functions of distributing, sensing, and controlling 28 volt DC power and of inverting, distributing, sensing, and controlling 117 volt 400 Hz AC power to all Orbiter subsystems from the three fuel cells in the Electrical Power Generation (EPG) subsystem. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Of the 1671 failure modes analyzed, 9 single failures were determined to result in loss of crew or vehicle. Three single failures unique to intact abort were determined to result in possible loss of the crew or vehicle. A possible loss of mission could result if any of 136 single failures occurred. Six of the criticality 1/1 failures are in two rotary and two pushbutton switches that control External Tank and Solid Rocket Booster separation. The other 6 criticality 1/1 failures are fuses, one each per Aft Power Control Assembly (APCA) 4, 5, and 6 and one each per Forward Power Control Assembly (FPCA) 1, 2, and 3, that supply power to certain Main Propulsion System (MPS) valves and Forward Reaction Control System (RCS) circuits.

Schmeckpeper, K. R.↗

NASA NTRS1987

Independent Orbiter Assessment (IOA): Analysis of the Electrical Power Distribution and Control Subsystem, Volume 2

Schmeckpeper, K. R.↗

NASA NTRS1987

Independent Orbiter Assessment (IOA): Analysis of the active thermal control subsystem

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical (PCIs) items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results corresponding to the Orbiter Active Thermal Control Subsystem (ATCS) are documented. The major purpose of the ATCS is to remove the heat, generated during normal Shuttle operations from the Orbiter systems and subsystems. The four major components of the ATCS contributing to the heat removal are: Freon Coolant Loops; Radiator and Flow Control Assembly; Flash Evaporator System; and Ammonia Boiler System. In order to perform the analysis, the IOA process utilized available ATCS hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Of the 310 failure modes analyzed, 101 were determined to be PCIs.

Sinclair, S. K.↗

NASA NTRS1989

Automated monitor and control for deep space network subsystems

The problem of automating monitor and control loops for Deep Space Network (DSN) subsystems is considered and an overview of currently available automation techniques is given. The use of standard numerical models, knowledge-based systems, and neural networks is considered. It is argued that none of these techniques alone possess sufficient generality to deal with the demands imposed by the DSN environment. However, it is shown that schemes that integrate the better aspects of each approach and are referenced to a formal system model show considerable promise, although such an integrated technology is not yet available for implementation. Frequent reference is made to the receiver subsystem since this work was largely motivated by experience in developing an automated monitor and control loop for the advanced receiver.

Smyth, P.↗

NASA NTRS1990

Space Station Freedom Environmental Control and Life Support System (ECLSS) phase 3 simplified integrated test trace contaminant control subsystem performance

Space Station Freedom environmental control and life support system testing has been conducted at Marshall Space Flight Center since 1986. The phase 3 simplified integrated test (SIT) conducted from July 30, 1989, through August 11, 1989, tested an integrated air revitalization system. During this test, the trace contaminant control subsystem (TCCS) was directly integrated with the bleed stream from the carbon dioxide reduction subsystem. The TCCS performed as expected with minor anomalies. The test set the basis for further characterizing the TCCS performance as part of advance air revitalization system configurations.

Perry, J. L.↗

NASA NTRS1990

Technology for subsystems of space-based plant growth facilities

Technologies for different subsystems of space-based plant growth facilities are being developed at the Wisconsin Center for Space Automation and Robotics, a NASA Center for the Commercial Development of Space. The technologies include concepts for water and nutrient delivery, for nutrient composition control, and for irradiation. Effort is being concentrated on these subsystems because available technologies cannot be effectively utilized for space applications.

Bula, R. J.↗

NASA NTRS1990

Early mission characterization of the Galileo attitude control subsystem

Given the task of characterizing most of the spacecraft's subsystems in a very short time frame, the Galileo flight team followed a detailed attitude control subsystem characterization plan developed prior to launch. Gradual checkcouts and calibrations of the minimum set of sensors, actuators, and software algorithms required to execute the initial trajectory correction 22 days after launch were provided for in this plan. It is pointed out that the characterization was generally successful and no significant concerns about maneuver performance were identified.

Brown, G. Mark↗

NASA NTRS1990

Development of an automated electrical power subsystem testbed for large spacecraft

The NASA Marshall Space Flight Center (MSFC) has developed two autonomous electrical power system breadboards. The first breadboard, the autonomously managed power system (AMPS), is a two power channel system featuring energy generation and storage and 24-kW of switchable loads, all under computer control. The second breadboard, the space station module/power management and distribution (SSM/PMAD) testbed, is a two-bus 120-Vdc model of the Space Station power subsystem featuring smart switchgear and multiple knowledge-based control systems. NASA/MSFC is combining these two breadboards to form a complete autonomous source-to-load power system called the large autonomous spacecraft electrical power system (LASEPS). LASEPS is a high-power, intelligent, physical electrical power system testbed which can be used to derive and test new power system control techniques, new power switching components, and new energy storage elements in a more accurate and realistic fashion. LASEPS has the potential to be interfaced with other spacecraft subsystem breadboards in order to simulate an entire space vehicle. The two individual systems, the combined systems (hardware and software), and the current and future uses of LASEPS are described.

Hall, David K.↗

NASA NTRS1991

The CRAF/Cassini spacecraft propulsion subsystem - A preliminary design

The prelimary design of the propulsion subsystem for the CRAF and Cassini missions is described. It is noted that the propulsion module subsystem must provide impulse for a number of functions required by these missions. These functions include the acquisition of celestial references and trajectory correction maneuvers. A schedule for the CRAF/Cassini Project is provided.

Garrison, Philip W.↗

NASA NTRS1992

Final-Approach-Spacing Subsystem For Air Traffic

Automation subsystem of computers, computer workstations, communication equipment, and radar helps air-traffic controllers in terminal radar approach-control (TRACON) facility manage sequence and spacing of arriving aircraft for both efficiency and safety. Called FAST (Final Approach Spacing Tool), subsystem enables controllers to choose among various levels of automation.

Davis, Thomas J.↗

NASA NTRS1991

Laboratory measurements of on-board subsystems

Good progress was achieved on the test bed for on-board subsystems for future satellites. The test bed is for subsystems developed previously. Four test setups were configured in the INTELSAT technical labs: (1) TDMA on-board modem; (2) multicarrier demultiplexer demodulator; (3) IBS/IDR baseband processor; and (4) baseband switch matrix. The first three series of tests are completed and the tests on the BSM are in progress. Descriptions of test setups and major test results are included; the format of the presentation is outlined.

Nuspl, P. P.↗

NASA NTRS1991

Fault-tolerant multichannel demultiplexer subsystems

Fault tolerance in future processing and switching communication satellites is addressed by showing new methods for detecting hardware failures in the first major subsystem, the multichannel demultiplexer. An efficient method for demultiplexing frequency slotted channels uses multirate filter banks which contain fast Fourier transform processing. All numerical processing is performed at a lower rate commensurate with the small bandwidth of each bandbase channel. The integrity of the demultiplexing operations is protected by using real number convolutional codes to compute comparable parity values which detect errors at the data sample level. High rate, systematic convolutional codes produce parity values at a much reduced rate, and protection is achieved by generating parity values in two ways and comparing them. Parity values corresponding to each output channel are generated in parallel by a subsystem, operating even slower and in parallel with the demultiplexer that is virtually identical to the original structure. These parity calculations may be time shared with the same processing resources because they are so similar.

Redinbo, Robert↗

NASA NTRS1991

Development of an expert system for analysis of Shuttle atmospheric revitalization and pressure control subsystem anomalies

The paper describes the Shuttle Leak Management Expert System (SLMES), a preprototype expert system developed to enable the ECLSS subsystem manager to analyze subsystem anomalies and to formulate flight procedures based on flight data. The SLMES combines the rule-based expert system technology with the traditional FORTRAN-based software into an integrated system. SLMES analyzes the data using rules, and, when it detects a problem that requires simulation, it sets up the input for the FORTRAN-based simulation program ARPCS2AT2, which predicts the cabin total pressure and composition as a function of time. The program simulates the pressure control system, the crew oxygen masks, the airlock repress/depress valves, and the leakage. When the simulation has completed, other SLMES rules are triggered to examine the results of simulation contrary to flight data and to suggest methods for correcting the problem. Results are then presented in form of graphs and tables.

Lafuse, Sharon A.↗