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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Science aspects of a remotely controlled Mars surface roving vehicle.

Particular attention is given to aspects pertinent to teleoperation, remote control, onboard control, and man-machine relationships in carrying out scientific operations with such a vehicle. It is assumed that landed operations would comprise one Martian year and that the traverse would extend across an area approximately 500 km wide. The mission is assumed to be planned for the early 1980s. Its objective is to obtain data which will aid in answering a number of questions regarding the history of the solar system, the formation of Mars, and the evolution of life on Mars. A series of candidate rover payloads is proposed to meet the requirements. The smallest payload includes a TV camera, a general-purpose manipulator arm, a crusher and siever, an X-ray diffractometer-spectrometer, a gravimeter, a magnetometer, meteorological instruments, and a radio transponder.

Choate, R.↗
NASA NTRS1975

Experimental results of a continuous wave laser radar system

A 1.06 micron CW laser radar system was used to establish the feasibility of remotely measuring sea surface wind magnitude and direction. Simultaneous correlation of collected laser data with the environment was established by using meteorological instruments. The experimental system and methods of analysis are summarized. Results of the experiments, including wind magnitude and direction correlation, are reported. Results are compared with theoretical predictions.

Petri, K. J.↗
NASA NTRS1975

Saltation on Mars and expected lifetime of Viking 75 wind sensors

With the use of the wind-tunnel measurements of Bagnold and Zingg, a model is developed for estimating the parameters that describe the flux of sand on Mars. Application of this model to the sensor-breakage problem indicates that the expected lifetime on Mars of the wind sensors of the Viking 75 Meteorology Instrument System is about 40 earth years. This expected lifetime is adequate for both the primary Viking 75 mission and for a proposed extended mission.

Henry, R. M.↗
NASA NTRS1976

Preliminary meteorological results on Mars from the Viking 1 lander

The results from the meteorology instruments on the Viking 1 lander are presented for the first 4 sols of operation. The instruments are working satisfactorily. Temperatures fluctuated from a low of 188 K to an estimated maximum of 244 K. The mean pressure is 7.65 millibars with a diurnal variation of amplitude 0.1 millibar. Wind speeds averaged over several minutes have ranged from essentially calm to 9 meters per second. Wind directions have exhibited a remarkable regularity which may be associated with nocturnal downslope winds and gravitational oscillations, or to tidal effects of the diurnal pressure wave, or to both.

Hess, S. L.↗
NASA NTRS1976

Mars - Wind friction speeds for particle movement

Wind friction threshold speeds for particle movement were determined in a low pressure boundary layer wind tunnel at an atmospheric pressure of 5.3 mb. The results imply that for comparable pressures on Mars, the minimum wind friction threshold speed is about 2.5 m/sec, which would require free-stream winds of 50 to 135 m/sec, depending on the character of the surface and the atmospheric conditions. The corresponding wind speeds at the height of the Viking lander meteorology instrument would be about a factor of two less than the free-stream wind speed. The particle size most easily moved by winds on Mars is about 160 microns; particles both larger and smaller than this (at least down to about 5 microns) require stronger winds to initiate movement.

Greeley, R.↗
NASA NTRS1976

The surface of Mars - The view from the Viking 1 lander

Imagery of the surface of Mars obtained by Viking 1 is analyzed. The lander is situated on the western slopes of the 5-km deep Chryse Planitia depression, about 2 km higher than the floor. The topography is gently rolling. Angular rocks and small sand dunes are visible. There are very few craters; initial evaluations indicate that crater area densities are several orders of magnitude below saturation for crater sizes less than about 50 m. The presence of scour marks and of fine-grained deposits in some boulders indicates that some aeolian activity has occurred. Almost all the sky brightness can be attributed to scattering by particles present in the atmosphere. No signs of movement have been detected, consistent with the low seasonal winds recorded by meteorological instruments.

Mutch, T. A.↗
NASA NTRS1976

Mars climatology from Viking 1 after 20 sols

Results from the meteorology instruments on the Viking 1 lander are presented for the first 20 sols of operation. The daily patterns of temperature, wind, and pressure have been highly consistent during the period. Hence, these have been assembled into 20-sol composistes and analyzed harmonically. Maximum temperature was 241.8 K and minimum was 187.2 K. The composite wind vector has a mean diurnal magnitude of 2.4 meters per second with prevailing wind from the south and counterclockwise diurnal rotation. Pressure exhibits diurnal and semidiurnal oscillations. The diurnal is ascribed to a combination of effects, and the semidiurnal appears to be the solar semidiurnal tide. Similarities to earth are discussed. A major finding is a continual secular decrease in diurnal mean pressure. This is ascribed to carbon dioxide deposition at the south polar cap.

Hess, S. L.↗
NASA NTRS1976

Early meteorological results from the Viking 2 lander

Early results from the meteorological instruments on the Viking 2 lander are presented. As on lander 1, the daily patterns of temperature, wind, and pressure have been highly repetitive during the early summer period. The average daily maximum temperature was 241 K and the diurnal minimum was 191 K. The wind has a vector mean of 0.7 meter per second from the southeast with a diurnal amplitude of 3 meters per second. Pressure exhibits both diurnal and semidiurnal oscillations, although of substantially smaller amplitude than those of lander 1. Departures from the repetitive diurnal patterns begin to appear on sol 37.

Hess, S. L.↗
NASA NTRS1977

NASA aviation safety reporting system

A decline in reports concerning small aircraft was noted; more reports involved transport aircraft, professional pilots, instrument meteorological conditions, and weather problems. A study of 136 reports of operational problems in terminal radar service areas was made. Pilot, controller, and system factors were found to be associated with these occurrences. Information transfer difficulties were prominent. Misunderstandings by pilots, and in some cases by controllers, of the policies and limitations of terminal radar programs were observed.

Source record↗
NASA NTRS1979

Survey of helicopter control/display investigations for instrument decelerating approach

Control-display requirements for helicopters conducting decelerating approaches in the terminal area under instrument meteorological conditions were surveyed. The programs are organized on the basis of the control augmentation concepts that were considered, and the results are summarized and compared. Nine control-display combinations are hypothesized as possible candidates for future ground and in-flight investigation. Specific guidelines for the guidance relationship, control characteristics, and display presentation concepts are given.

Lebacqz, J. V.↗
NASA NTRS1979

Data reduction and analysis of graphite fiber release experiments

The burn and burn/explode effects on aircraft structures were examined in a series of fifteen outdoor tests conducted to verify the results obtained in previous burn and explode tests of carbon/graphite composite samples conducted in a closed chamber, and to simulate aircraft accident scenarios in which carbon/graphite fibers would be released. The primary effects that were to be investigaged in these tests were the amount and size distribution of the conductive fibers released from the composite structures, and how these various sizes of fibers transported downwind. The structures included plates, barrels, aircraft spoilers and a cockpit. The heat sources included a propane gas burner and 20 ft by 20 ft and 40 ft by 60 ft JP-5 pool fires. The larger pool fire was selected to simulate an aircraft accident incident. The passive instrumentation included sticky paper and sticky bridal veil over an area 6000 ft downwind and 3000 ft crosswind. The active instrumentation included instrumented meteorological towers, movies, infrared imaging cameras, LADAR, high voltage ball gages, light emitting diode gages, microwave gages and flame velocimeter.

Lieberman, P.↗
NASA NTRS1980

Analysis of general aviation single-pilot IFR incident data obtained from the NASA aviation safety reporting system

Data obtained from the NASA Aviation Safety Reporting System (ASRS) data base were used to determine problems in general aviation single pilot IFR operations. The data examined consisted of incident reports involving flight safety in the National Aviation System. Only those incidents involving general aviation fixed wing aircraft flying under IFR in instrument meteorological conditions were analyzed. The data were cataloged into one of five major problem areas: (1) controller judgement and response problems; (2) pilot judgement and response problems; (3) air traffic control intrafacility and interfacility conflicts; (4) ATC and pilot communications problems; and (5) IFR-VFR conflicts. The significance of the related problems, and the various underlying elements associated with each are discussed. Previous ASRS reports covering several areas of analysis are reviewed.

Bergeron, H. P.↗
NASA NTRS1980

An airborne system for detection of volcanic surface deformations

A technique is proposed for measuring volcanic deformation on the order of centimeters per day to centimeters per year. An airborne multifrequency pulsed radar, tracking passive ground reflectors spaced at 1 kilometer intervals over a 50 square kilometer area is employed. Identification of targets is accomplished by Doppler and range resolution techniques, with final relative position measurements accomplished by phase comparison of multifrequency signals. Atmospheric path length errors are corrected by an airborne refractometer, meteorological instruments, or other refractive index measuring devices. Anticipated system accuracy is 1-2 cm, with measuring times on the order of minutes. Potential problems exist in the high intrinsic data assimilation rate required of the system to overcome ground backscatter noise.

Lunine, J.↗
NASA NTRS1981

A review of in-flight emergencies in the ASRS data base

A series of 154 in-flight emergencies as reported to the Aviation Safety Reporting System are described. The various types of emergencies are examined and an attempt is made to determine the human errors and other factors associated with each incident, as well as the measures taken to resolve the emergency. It is concluded that nearly one half of those emergencies reported were related to failure or malfunction of aircraft subsystems. Of all the emergencies, nearly one quarter were associated with power plant failure. Other frequently encountered emergency types are associated with operation in instrument meteorological conditions without appropriate clearance or qualification, and with low fuel state situations. Human error is prominently featured in many of the incidents, appearing in the actions of pilots and air traffic controllers.

Porter, R. F.↗
NASA NTRS1982

Helical automatic approaches of helicopters with microwave landing systems

A program is under way to develop a data base for establishing navigation and guidance concepts for all-weather operation of rotorcraft. One of the objectives is to examine the feasibility of conducting simultaneous rotorcraft and conventional fixed-wing, noninterfering, landing operations in instrument meteorological conditions at airports equipped with microwave landing systems (MLSs) for fixed-wing traffic. An initial test program to investigate the feasibility of conducting automatic helical approaches was completed, using the MLS at Crows Landing near Ames. These tests were flown on board a UH-1H helicopter equipped with a digital automatic landing system. A total of 48 automatic approaches and landings were flown along a two-turn helical descent, tangent to the centerline of the MLS-equipped runway to determine helical light performance and to provide a data base for comparison with future flights for which the helical approach path will be located near the edge of the MLS coverage. In addition, 13 straight-in approaches were conducted. The performance with varying levels of state-estimation system sophistication was evaluated as part of the flight tests. The results indicate that helical approaches to MLS-equipped runways are feasible for rotorcraft and that the best position accuracy was obtained using the Kalman-filter state-estimation with inertial navigation systems sensors.

Foster, J. D.↗
NASA NTRS1984

Red and near-infrared sensor response to off-nadir viewing

It has first been intended to employ the Advanced Very High Resolution Radiometer (AVHRR) as a meteorological instrument to aid in detecting clouds and atmospheric temperature stratifications over large areas. However, more recently the satellite data have been used for monitoring large areas of vegetation with emphasis on the visible (VIS) and near-infrared (NIR) bands. The present investigation is concerned with the objective to model ranges in AVHRR VIS and NIR radiances and normalized differences expected under typical AVHRR viewing and illumination conditions. Atmospheric data sets reported by Dave (1978) and Dave and Braslau (1975) were used. It is shown that sensor response to atmospheric path length can be substantial for the AVHRR VIS and NIR channels and normalized difference (ND) values. However, errors can be minimized by high sun and clear atmosphere viewing.

Holben, B.↗
NASA NTRS1984

Sensitivity analysis of helicopter IMC decelerating steep approach and landing performance to navigation system parameters

The present investigation is concerned with a sensitivity analysis of the Decelerated Steep Approach and Landing (DSAL) maneuver to on-board and ground-based navigation system parameters. The Instrument Meteorological Conditions (IMC) DSAL maneuver involves decelerating to zero range rate while tracking the localizer and glideslope. The considered study investigated the performance of the navigation systems using Constant Deceleration Profile (CDP) guidance and a six degrees glideslope trajectory. A closed-loop computer simulation of the UH1H helicopter DSAL system was developed for the sensitivity analysis. Conclusions on system performance parameter sensitivity are discussed.

Karmali, M. S.↗
NASA NTRS1984

Early Air Force Flight Test Center (AFFTC) experience with Peripheral Vision Horizon Displays (PVHD)

Three separate Air Force Flight Test Center (AFFTC) tests were conducted in 1980 and 1981 on two models of the peripheral vision horizon displays (PVHD) (Malcolm Horizon). A fixed base simulator test was conducted with twenty test pilot subjects using the Flight Simulator Demonstration Model which incorporated a Helium Neon laser as the light bar medium. Two separate flight tests were conducted by the Test Pilot School classes 80A and 80B in a Twin Otter commuter aircraft using the Stage A Model PVHD. The Xenon lighted A Model was tested in its original configuration by class 80A. Class 80B used a modified configuration which incorporated an AFFTC designed and manufactured hood. With the hood, the PVHD projected a thinner, distinct light bar. Only a few general remarks concerning the tests and unrestricted, overall conclusions reached by the author are presented. The conclusions of all three AFFTC evaluations of the PVHD concept were that it has not yet been adequately evaluated. There seems to be a significant learning curve associated with the PVHD and the project pilots for Test Pilot School Class 80B only got a good start on the learning curve. A lengthy learning curve for the PVHD should be anticipated in view of the training period required for the attitude display indicator (ADI). This does seem to point out that the PVHD, in its present form, is simply not as compelling as the natural horizon. It can also be concluded that any attempt at a valid evaluation of the PVHD concept can be done only under instrument meteorological conditions (IMC) or validly simulated IMC conditions. The knee in the learning curve, however, may be reached without full IMC, although it may take much longer to reach.

Schofield, B. L.↗