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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 649 records · Page 36
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Maximum likelihood failure detection techniques applied to the shuttle orbiter reaction control subsystem

A technique for on-board detection and identification of hard failures and leaks of the shuttle orbiter reaction control subsystem jets, during the orbital flight phase, is presented. The method uses gimbal angle and linear accelerometer measurements from the orbiter inertial measurement unit and requires no additional hardware. Extended Kalman filters with residual traps are employed for state estimation, and generalized likelihood ratio tests for jet failure identification. Rigid body simulation results indicate identification times of less than 2 seconds for hard jet failures and less than 70 seconds for jet leaks.

Deckert, J. C.↗
NASA NTRS1975

Leak rate measurements for satellite subsystems and residual gas analysis during space environment tests

The measuring and evaluation procedure for the determination of leak rates of satellite subsystems with a quadrupole mass spectrometer, and the results of the residual gas analysis are described. The method selected for leak rate determination was placing the system into a vacuum chamber and furnishing the chamber with a mass spectrometer and calibrated leaks. The residual gas of a thermal vacuum test facility, in which the thermal balance test radiation input was simulated by a heated canister, was analyzed with the mass spectrometer in the atomic mass unit range up to 300 amu. In addition to the measurements during the space environment tests, mass spectrometric studies were performed with samples of spacecraft materials. The studies were carried out during tests for the projects HELIOS, AEROS B and SYMPHONIE.

Nuss, H. E.↗
NASA NTRS1975

A shuttle radar microwave subsystem for earth resources applications

Microwave subsystem considerations are discussed as a design example for a radar for earth resources applications to be used in conjunction with the shuttle spacelab. This system with a multiplicity of frequencies and polarizations - L-band (25-cm wavelength), S-band (10-cm wavelength), and X-band (3.2-cm wavelength) at two orthogonal linear polarizations - was tentatively selected. The space shuttle vehicle constrains the antenna to approximately 8 m in length and 3 m in width. The frequencies and antenna size comprise the major constraints on the system described, and determine the sensor altitude, coverage, and major hardware parameters.

Source record↗
NASA NTRS1975

Reception-Conversion Subsystem (RXCV) for microwave power transmission system

As part of a program to demonstrate the feasibility of power transmission from space, an approximately 25 sq m Reception-Conversion Subsystem was designed and tested. The device collects high power microwave energy, converts it into dc, and dissipates it in an instrumented demonstration load.

Raytheon Company↗
NASA NTRS1975

Space shuttle rudder/speedbrake subsystem analysis

The Continuous System Modeling Program (CSMP) is described with its uses, its limitations, and its application to the rudder/speedbrake (R/SB) subsystem. The space shuttle R/SB is analyzed using the CSMP. Areas of analysis emphasized include: step response, ramp response, and the delay time or deadspace observed in system response. Results are presented and discussed.

Duke, H. G.↗
NASA NTRS1975

Experiment Pointing Subsystems (EPS) requirements for Spacelab missions

The goal of the experiment pointing subsystems (EPS) is to accommodate a broad spectrum of instrument types by providing a number of stability and control functions that greatly exceed the capability of the shuttle. These functions include target acquisition, target tracking through wide gimbal ranges, stabilization, simultaneous pointing to one or more targets, instrument rastering, and on-orbit calibration. The experiments will vary widely in size, weight, geometry, and instrument types, and many have not been completely defined. This great diversity of requirements reflects the long term plans of the user community and establishes challenging performance requirements for the EPS.

Nein, M. E.↗
NASA NTRS1975

Portable Oxygen Subsystem (POS)

Concept selection, design, fabrication, and testing of a Portable Subsystem (POS) for use in space shuttle operations are described. Tradeoff analyses were conducted to determine the POS concept for fabrication and testing. The fabricated POS was subjected to unmanned and manned tests to verify compliance with statement of work requirements. The POS used in the development program described herein met requirements for the three operational modes -- prebreathing, contaminated cabin, and personnel rescue system operations.

Source record↗
NASA NTRS1975

Use of STS subsystems and components for MMSE, volume 1

Multiuse mission support equipment (MMSE) is flight/ground equipment for the shuttle era which is used in conjunction with more than one mission payload. Initial verification of STS subsystem's applicability to MMSE is provided along with the cost savings potential and programmatic data needed for further program planning decisions. Some 70 MMSE requirements were found to be potentially satisfied by STS equipment, and and 6 items of particular interest were chosen for special emphasis. All were found to be feasible and beneficial. Program cost savings through their use are estimated to be substantial. Further study is recommended to identify additional MMSE requirements and hardware.

Source record↗
NASA NTRS1976

Preliminary input to the space shuttle reaction control subsystem failure detection and identification software requirements (uncontrolled)

The current baseline method and software implementation of the space shuttle reaction control subsystem failure detection and identification (RCS FDI) system is presented. This algorithm is recommended for conclusion in the redundancy management (RM) module of the space shuttle guidance, navigation, and control system. Supporting software is presented, and recommended for inclusion in the system management (SM) and display and control (D&C) systems. RCS FDI uses data from sensors in the jets, in the manifold isolation valves, and in the RCS fuel and oxidizer storage tanks. A list of jet failures and fuel imbalance warnings is generated for use by the jet selection algorithm of the on-orbit and entry flight control systems, and to inform the crew and ground controllers of RCS failure status. Manifold isolation valve close commands are generated in the event of failed on or leaking jets to prevent loss of large quantities of RCS fuel.

Bergmann, E.↗
NASA NTRS1975

Apu/hydraulic/actuator Subsystem Computer Simulation. Space Shuttle Engineering and Operation Support, Engineering Systems Analysis

Major developments are examined which have taken place to date in the analysis of the power and energy demands on the APU/Hydraulic/Actuator Subsystem for space shuttle during the entry-to-touchdown (not including rollout) flight regime. These developments are given in the form of two subroutines which were written for use with the Space Shuttle Functional Simulator. The first subroutine calculates the power and energy demand on each of the three hydraulic systems due to control surface (inboard/outboard elevons, rudder, speedbrake, and body flap) activity. The second subroutine incorporates the R. I. priority rate limiting logic which limits control surface deflection rates as a function of the number of failed hydraulic. Typical results of this analysis are included, and listings of the subroutines are presented in appendicies.

Source record↗
NASA NTRS1976

Lacie phase 1 Classification and Mensuration Subsystem (CAMS) rework experiment

An experiment was designed to test the ability of the Classification and Mensuration Subsystem rework operations to improve wheat proportion estimates for segments that had been processed previously. Sites selected for the experiment included three in Kansas and three in Texas, with the remaining five distributed in Montana and North and South Dakota. The acquisition dates were selected to be representative of imagery available in actual operations. No more than one acquisition per biophase were used, and biophases were determined by actual crop calendars. All sites were worked by each of four Analyst-Interpreter/Data Processing Analyst Teams who reviewed the initial processing of each segment and accepted or reworked it for an estimate of the proportion of small grains in the segment. Classification results, acquisitions and classification errors and performance results between CAMS regular and ITS rework are tabulated.

Chhikara, R. S.↗
NASA NTRS1975

Tracking subsystem test requirements survey

A survey of the test and checkout requirements of the tracking portion of the communications and tracking subsystem was performed to evaluate adequacy of planned tests and test requirement documents. Emphasis is placed on identifying test completeness, duplications, and omissions. Items that may save time, aid in testing, and present a more complete integrated test program are also noted. The results of this survey are summarized.

Orr, D. H.↗
NASA NTRS1975

A cost effective data management subsystem for the LST

The paper outlines the approach used in developing DMS (Data Management Subsystem) alternatives for the LST (Large Space Telescope) and in selecting the concept considered to be the most cost effective means of implementing the LST DMS requirements. Two candidate DMS concepts are discussed: a functionally integrated and a functionally separated one. For the single vehicle LST program, separation of the DMS functions best provides high reliability, operations flexibility, minimal interface complexity, and the least complex software development and verification task. The use of available hardware and NASA standard components is stressed.

Dougherty, J. A.↗
NASA NTRS1976

The Viking Orbiter Visual Imaging Subsystem

Two Viking spacecraft each consisting of an Orbiter and a Lander are on trajectories toward Mars with arrival dates in June and August 1976. A Visual Imaging Subsystem consisting of two slow-scan television cameras forms part of the scientific payload of each Orbiter. These cameras will be used to evaluate the potential landing sites on Mars and to conduct other scientific investigations of the planet. The camera system described in this paper was subjected to an extensive test and calibration program prior to launch. Based on this calibration and subsequent analyses, absolute photometric accuracies of 8.0% may be achieved. Surface resolution exceeding 100 meters will be achieved from the periapsis portion of the Viking orbits. The inherent geometric accuracies of the Orbiter cameras supersede those of previous planetary missions. The analyses of images acquired during the cruise phase of the mission confirms that the cameras have survived the rigors of launch and are performing in a manner consistent with the prelaunch calibrations.

Wellman, J. B.↗