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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 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

OMEGA navigation system status and future plans

OMEGA is described as a very low frequency (VLF) radio navigational system operating in the internationally allocated navigation band in the electromagentic spectrum between 10 and 14 kilohertz. Full system implementation with worldwide coverage from eight transmitting stations is planned for the latter 1970's. Experimental stations have operated since 1966 in support of system evaluation and test. These stations provided coverage over most of the North Atlantic, North American Continent, and eastern portions of the North Pacific. This coverage provided the fundamental basis for further development of the system and has been essential to the demonstrated feasibility of the one to two nautical mile root-mean-square system accuracy. OMEGA is available to users in all nations, both on ships and in aircraft.

Nolan, T. P.↗
NASA NTRS1975

Boost navigation and guidance

The verification that the boost mode portion of the flight program correctly provides navigation and guidance functions for the vehicle during periods when significant, measurable accelerations exist was described. Many test cases and performance cases are made, testing the ability of the navigation and guidance routines to properly compensate for several perturbations. Various plots of special interest parameters are made on all performance cases, facilitating a check on each calculation (each boost major loop) of these parameters.

Source record↗
NASA NTRS1975

Terminal guidance and navigation for comet and asteroid rendezvous

A terminal guidance and navigation scheme developed in earlier work was modified and evaluated for a solar electric propulsion rendezvous mission to comet Encke. The scheme is intended for autonomous, on-board use. The guidance algorithm is based on optimal control theory and minimizes the time integrated square of thrust acceleration. The navigation algorithm employs a modified Kalman filter set in measurement variables. Random sequences were generated to simulate measurement errors, and the evaluation was conducted with detailed numerical computations which include actual motions of spacecraft and comet. The evaluations showed that the scheme attains rendezvous and maintains station after rendezvous within less than 10 km for estimated best measurements and within less than 100 km for estimated worst measurements. The measurements required are angles, range, and range rate. Angles and range appear to be absolutely necessary; range rate is not as strong a measurement type, and further modifications of the filter will allow a scheme that does not require the rate measurements.

Bennett, A. G.↗
NASA NTRS1975

Navigation results of the Mariner Venus/Mercury 1973 mission

The navigation aspects of the Mariner Venus/Mercury 1973 mission are presented. Principal emphasis is on the maneuver strategy employed, propellant costs and the results of the navigation performance relating to the accomplishment of the mission objectives including an extended mission for a second Mercury encounter. Key error sources and mission constraints are discussed. Of particular interest is the impact of in-flight adaptation of the pre-launch maneuver strategy (due to spacecraft anomalies) on propellant cost and the delivery achieved at the first Mercury encounter. The maneuver strategy and propellant cost for the extended mission are shown to be heavily influenced by the delivery achieved at the first Mercury encounter and the science objectives at the second Mercury encounter.

Bantell, M. H., Jr.↗
NASA NTRS1974

Autonomous target relative navigation

The present work outlines eight candidate navigation systems for autonomous target relative navigation near a comet, asteroid, or planet. An analytic model is developed for each system, showing how the solution of the relative state vector is obtained from measurement data.

Brock, H. I.↗
NASA NTRS1975

Position accuracy of aircraft area navigation systems and the effect of system parameters

The steady-state solution to the stochastic differential equation describing the error covariance matrix for a simplified area navigation system has been obtained. The solution shows that nominal error deviations of less than 1.0 nmi are feasible for a DME system. The manner in which estimates are affected by range, air data system accuracy, measurement time interval, and gust deviations, and their impacts on the area navigation system are discussed.

Foudriat, E. C.↗
NASA NTRS1975

Development of the NASA VALT digital navigation system

The research to develop and fabricate a terminal area navigation system for use in the NASA VTOL Approach and Landing Technology (VALT) program. The results of that effort are reported. The navigation system developed and fabricated was based on a general purpose airborne digital computer. A set of flight hardware units was fabricated to create the necessary analog, digital and human interface with the computer. A comprehensive package of software was created to implement the control and guidance laws required for automatic and flight director approaches that are curved in two planes. A technique was developed that enables the generation of randomly shaped lateral paths from simple input data. The lateral path concept combines straight line and elliptical-curved segments to fit a continuous curved path to the data points. A simple, fixed base simulation was put together to assist in developing and evaluating the system. The simulation was used to obtain system performance data during simulated curved-path approaches.

Mcconnell, W. J., Jr.↗
NASA NTRS1975

The mini-O, a digital superhet, or a truly low-cost Omega navigation receiver

A quartz tuning fork filter circuit and some unique CMOS clock logic methods provide a very simple OMEGA-VLF receiver with true hyperbolic station pair phase difference outputs. An experimental system was implemented on a single battery-operated circuit board requiring only an external antenna preamplifier, and LOP output recorder. A bench evaluation and preliminary navigation tests indicate the technique is viable and can provide very low-cost OMEGA measurement systems. The method is promising for marine use with small boats in the present form, but might be implemented in conjunction with digital microprocessors for airborne navigation aids.

Burhans, R. W.↗
NASA NTRS1976

Results of Skylab experiment T00-2, manual navigation sightings

An analysis of navigation data collected using a hand-held space sextant on the second and third manned Skylab missions was presented. From performance data and astronaut comments it was determined that: (1) the space sextant, the sighting station, and the sighting techniques require modification; (2) the sighting window must be of good optical quality; (3) astronaut performance was stable over long mission time; and (4) sightings made with a hand-held sextant were accurate and precise enough for reliable interplanetary manual navigation.

Randle, R. J.↗
NASA NTRS1976

Possible methods for USSR-VLF navigation receivers

The U.S.S.R. has a VLF navigation system similar to OMEGA. Beukers has reported some information on the signal format, frequencies used, and the probable radiated power levels. From this data it appears possible to derive receiver operation modes and some implied reasons for the unique choice of the time-multiplexed frequency time base used. Of interest are receiver methods requiring processor gate complexity similar to a digital wristwatch including the use of mass-produced low frequency quartz crystal reference oscillators. The stability required of the local reference oscillator is probably much less critical than for other VLF receivers because of the signal format. One conclusion is that U.S.S.R.-VLF receivers might be fabricated at quite low cost making it possible for all persons in remote areas each to have his own private positioning aid. Further study of the actual transmitted signal format is warranted. While the nature of this memorandum is speculative because of the lack of confirming data, the receiver method proposed has evolved from related principles which have been applied to the operating OMEGA-VLF navigation system.

Burhans, R. W.↗
NASA NTRS1976

Analysis of test data on the simplex strapdown navigation system

The results of a study of test data taken on the simplex strapdown navigation system were presented. That system consisted of the following components: strapdown platform, altimeter, digital computer, tape recorder, typewriter, and power source. The objective of these tests was to isolate error sources which may cause degradation of the system's accuracy and to recommend appropriate changes to the system test procedures or computer software. The following recommendations were made: (1) addition of a gyro compassing alignment program into the navigation program, (2) addition of line drivers at the signal processor end of the transmission line, (3) need for extensive laboratory testing to determine sensor misalignments, biases, and scale factors, (4) need to stabilize the power source to prevent transients during power transfer, (5) need to isolate and eliminate the source of the large noise inputs.

Source record↗
NASA NTRS1976

Simulation analysis of a microcomputer-based, low-cost Omega navigation system

The current status of research on a proposed micro-computer-based, low-cost Omega Navigation System (ONS) is described. The design approach emphasizes minimum hardware, maximum software, and the use of a low-cost, commercially-available microcomputer. Currently under investigation is the implementation of a low-cost navigation processor and its interface with an omega sensor to complete the hardware-based ONS. Sensor processor functions are simulated to determine how many of the sensor processor functions can be handled by innovative software. An input data base of live Omega ground and flight test data was created. The Omega sensor and microcomputer interface modules used to collect the data are functionally described. Automatic synchronization to the Omega transmission pattern is described as an example of the algorithms developed using this data base.

Lilley, R. W.↗
NASA NTRS1976

Apollo experience report guidance and control systems: Primary guidance, navigation, and control system development

The primary guidance, navigation, and control systems for both the lunar module and the command module are described. Development of the Apollo primary guidance systems is traced from adaptation of the Polaris Mark II system through evolution from Block I to Block II configurations; the discussion includes design concepts used, test and qualification programs performed, and major problems encountered. The major subsystems (inertial, computer, and optical) are covered. Separate sections on the inertial components (gyroscopes and accelerometers) are presented because these components represent a major contribution to the success of the primary guidance, navigation, and control system.

Holley, M. D.↗
NASA NTRS1976

Navigation between the planets

Recent advances in spacecraft tracking, chronometry, ephemerides, and orbit and trajectory determinations are reviewed. Improvements in timekeeping are reviewed, as well as precision distance and range measurements; orbit determinations, trajectory-correction maneuvers, flight path optimization, and information provided by rotation of the tracking station with the earth's surface. Doppler and tropospheric wave propagation effects are dealt with. Nongravitational perturbations (solar radiation pressure, release of gases from the spacecraft, stochastic unmodeled accelerations and sequential estimation to cope with them), the effect of the target planet's gravitational field upon close approach, and navigation problems in the outer reaches of the solar system (TV data telemetered back for inertial navigation) are covered. By-products of the research include: refined data on the mass of planets, on planetary mass distributions, planet configurations, on physical properties of the atmospheres and ionospheres of planets, and opportunities for refined tests of gravitation and relativity theories and models.

Melbourne, W. G.↗
NASA NTRS1977

A flight investigation of a 4D area navigation system concept for STOL aircraft in the terminal area

A digital avionics system referred to as STOLAND was test flown in the NASA CV-340 aircraft to obtain performance data for time controlled guidance in the manual flight director mode. The advanced system components installed in the cockpit included an electronic attitude director indicator and an electronic multifunction display. Navigation guidance and control computations were performed on a digital computer. A detailed 4D area navigation systems description is given. The pilot/system interface and systems operation and performance are also described. Approach flightpaths were flown which included a 180 deg turn and a 1-min, 5 deg straight-in approach to 30 m altitude, at which point go-around was initiated. Results are presented for 19 approaches.

Neuman, F.↗
NASA NTRS1976

Computer program for design and performance analysis of navigation-aid power systems

The paper examines the requirements, design rationale, operation, and verification of a computer program designated as design synthesis/performance analysis (DSPA) computer program, which is capable of performing all the calculations necessary to understand the overall characteristics of solar array/battery power systems for navigation-aid applications. Despite the uncertainties in the erratic solar array degradation data and the potential impact on actual battery behavior, verification of the DSPA is considered successful. The program is shown to have the capability of simulating the performance of solar array/battery navigation-aid power systems. It can also be used to synthesize power system designs and provide essential design and cost data.

Weiner, H.↗
NASA NTRS1977

User manual and programmer reference manual for the ATS-6 navigation model AOIPS and McIDAS versions, part 2

Development of a navigation system for a given satellite is reported. An algorithm for converting a satellite picture element location to earth location and vice versa was defined as well as a procedure for measuring the set of constants needed by the algorithm. A user manual briefly describing the current version of the navigation model and how to use the computer programs developed for it is presented.

Chatters, G. C.↗