Attitude measurement: Principles and sensors

Tools used in the measurement of satellite attitude are described. Attention is given to the elements that characterize an attitude sensor, the references employed (stars, moon, Sun, Earth, magnetic fields, etc.), and the detectors (optical, magnetic, and inertial). Several examples of attitude sensors are described, including sun sensors, star sensors, earth sensors, triaxial magnetometers, and gyrometers. Finally, sensor combinations that make it possible to determine a complete attitude are considered; the SPOT attitude measurement system and a combined CCD star sensor-gyrometer system are discussed

Application of advanced technology to space automation

Automated operations in space provide the key to optimized mission design and data acquisition at minimum cost for the future. The results of this study strongly accentuate this statement and should provide further incentive for immediate development of specific automtion technology as defined herein. Essential automation technology requirements were identified for future programs. The study was undertaken to address the future role of automation in the space program, the potential benefits to be derived, and the technology efforts that should be directed toward obtaining these benefits

THE EFFECT OF MAGNETIC DECLINATION CORRECTION ON SMARTPHONES COMPASS SENSORS IN DETERMINING QIBLA DIRECTION

Qibla direction application on android phones generally utilizes a compass sensor (magnetic orientation) as a reference to determine the direction and detect qibla direction. The accuracy of the compass sensor in determining the direction of qibla is still doubtful, because the compass sensor is easily affected by the surrounding magnetic field, and the north direction shown by the compass sensor is not the geographical North direction but the north direction of the Earth's magnetic field. It certainly has a very influential effect on the accuracy of compass sensors in determining the direction of Qibla. The north direction produced by the compass sensor can be converted into the geographical north by adding a magnetic declination correction value. This study aims to analyze the effect of magnetic declination correction on the accuracy of compass sensors on android phones in determining qibla direction. The type of research used is a type of field research with a quantitative approach. In this study, observation was done by comparing the qibla direction of the android compass sensor with the qibla direction of a theodolite. The study showed that qibla direction measurement using android compass sensor with magnetic declination correction of angle difference (deviation) of 03° 55' 0.055" or 437.6815289 km, against qibla direction of the theodolite

THE EFFECT OF MAGNETIC DECLINATION CORRECTION ON SMARTPHONES COMPASS SENSORS IN DETERMINING QIBLA DIRECTION

Qibla direction application on android phones generally utilizes a compass sensor (magnetic orientation) as a reference to determine the direction and detect qibla direction. The accuracy of the compass sensor in determining the direction of qibla is still doubtful, because the compass sensor is easily affected by the surrounding magnetic field, and the north direction shown by the compass sensor is not the geographical North direction but the north direction of the Earth's magnetic field. It certainly has a very influential effect on the accuracy of compass sensors in determining the direction of Qibla. The north direction produced by the compass sensor can be converted into the geographical north by adding a magnetic declination correction value. This study aims to analyze the effect of magnetic declination correction on the accuracy of compass sensors on android phones in determining qibla direction. The type of research used is a type of field research with a quantitative approach. In this study, observation was done by comparing the qibla direction of the android compass sensor with the qibla direction of a theodolite. The study showed that qibla direction measurement using android compass sensor with magnetic declination correction of angle difference (deviation) of 03° 55' 0.055" or 437.6815289 km, against qibla direction of the theodolite

Differential correction and preliminary orbit determination for lunar satellite orbits

Differential correction and preliminary orbit calculation for lunar satellite orbit

An Active Pre-Alignment System and Metrology Network for CLIC

The pre-alignment tolerance on the transverse positions of the components of the CLIC linacs is typically ten microns over distances of 200 m. Such tight tolerances cannot be obtained by a static one-time alignment because normal seismic ground movement and cultural noise associated with human and industrial activity quickly creates significant errors. It is therefore foreseen to maintain the components in place using an active-alignment system which will be linked to a permanent metrology and geodetic network. This report describes the overall philosophy and implementation of such a system and proposes one possible solution for active-alignment which uses stepping-motors to move components and stretched-wires as reference lines. Special sensors have been developed to measure the position of the components with respect to the reference lines, and to measure local tilt and relative vertical position. An in-depth analysis has been made of the repercussions on the alignment system of perturbing effects due to the attraction of the moon and the sun, and of the presence of nearby geological masses. The active-alignment system was used to maintain the components of the 30 GHz Two-Beam Test Accelerator in position in the CLIC Test Facility CTF2 as a practical demonstration of successful operation in an accelerator environment. The hardware and control system that was built for this application are described together with the results obtained

SeaWiFS Technical Report Series

This document provides five brief reports that address several quality control procedures under the auspices of the Calibration and Validation Element (CVE) within the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Project. Chapter 1 describes analyses of the 32 sensor engineering telemetry streams. Anomalies in any of the values may impact sensor performance in direct or indirect ways. The analyses are primarily examinations of parameter time series combined with statistical methods such as auto- and cross-correlation functions. Chapter 2 describes how the various onboard (solar and lunar) and vicarious (in situ) calibration data will be analyzed to quantify sensor degradation, if present. The analyses also include methods for detecting the influence of charged particles on sensor performance such as might be expected in the South Atlantic Anomaly (SAA). Chapter 3 discusses the quality control of the ancillary environmental data that are routinely received from other agencies or projects which are used in the atmospheric correction algorithm (total ozone, surface wind velocity, and surface pressure; surface relative humidity is also obtained, but is not used in the initial operational algorithm). Chapter 4 explains the procedures for screening level-, level-2, and level-3 products. These quality control operations incorporate both automated and interactive procedures which check for file format errors (all levels), navigation offsets (level-1), mask and flag performance (level-2), and product anomalies (all levels). Finally, Chapter 5 discusses the match-up data set development for comparing SeaWiFS level-2 derived products with in situ observations, as well as the subsequent outlier analyses that will be used for evaluating error sources

Mars Geoscience Orbiter and Lunar Geoscience Orbiter

The feasibility of using the AE/DE Earth orbiting spacecraft design for the LGO and/or MGO missions was determined. Configurations were developed and subsystems analysis was carried out to optimize the suitability of the spacecraft to the missions. The primary conclusion is that the basic AE/DE spacecraft can readily be applied to the LGO mission with relatively minor, low risk modifications. The MGO mission poses a somewhat more complex problem, primarily due to the overall maneuvering hydrazine budget and power requirements of the sensors and their desired duty cycle. These considerations dictate a modification (scaling up) of the structure to support mission requirements

Lunar navigation study, sections 1 through 7 Final report, Jun. 1964 - May 1965

Lunar navigation analysis using passive nongyro, inertial navigation, and radio frequency technolog

Infrared horizon sensor modeling for attitude determination and control: Analysis and mission experience

The work performed by the Attitude Determination and Control Section at the National Aeronautics and Space Administration/Goddard Space Flight Center in analyzing and evaluating the performance of infrared horizon sensors is presented. The results of studies performed during the 1960s are reviewed; several models for generating the Earth's infrared radiance profiles are presented; and the Horizon Radiance Modeling Utility, the software used to model the horizon sensor optics and electronics processing to computer radiance-dependent attitude errors, is briefly discussed. Also provided is mission experience from 12 spaceflight missions spanning the period from 1973 to 1984 and using a variety of horizon sensing hardware. Recommendations are presented for future directions for the infrared horizon sensing technology