Communications and telemetry - A compilation
Microwave antenna tracking system performance
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Geodetic studies by laser ranging to satellites
Using laser tracking systems to detect motion of pole of rotation for earth
Smith, D. E.↗
Geodetic satellite mission and GEOS-C spacecraft
GEOS-C geodetic satellite purpose and equipment, discussing earth gravitational field study, radar altimeter possibility and tracking systems usefulness
Vonbun, F. O.↗
Radio tracking with the Deep Space Network
Range and Doppler measurements for the Mariner 6 and 7 spacecraft are described. The Doppler tracking system and the two systems of spacecraft ranging apparatus being used in the Deep Space Network are illustrated. Charged particle calibration is considered. Equipment characteristics are presented for the ranging apparatus.
Martin, W. L.↗
S-band transponder experiment
The experiment which derives data from three lunar-orbiting objects, the command-service module (CSM), the lunar module (LM), and the subsatellite in the S-band is described. Each provides detailed information on the near-side lunar gravitational field. The primary emphasis is on the low-altitude (20 km) CSM data. The LM data cover a very short time span and are somewhat redundant with the CSM data. The resolution of the high-altitude (100 km) CSM data is not as great as that of the low altitude data. The low-altitude CSM and LM data coverage and the complementary coverage obtained during the Apollo 14 mission are presented. The experiment uses the same technique of gravity determination employed on the Lunar Orbiter, in the data of which the large anomalies called mascons were first observed. The data consist of variations in the spacecraft speed as measured by the Earth-based radio tracking system.
Sjogren, W. L.↗
Polar motion from laser tracking of artificial satellites
Laser ranges to the Beacon Explorer C spacecraft from a single Goddard Space Flight Center tracking system were used to determine the change in latitude of the station arising from polar motion. A precision of 0.03 arcsecs rms was obtained for the latitude during a five-month period in 1970.
Smith, D. E.↗
Surface refractivity measurements at NASA spacecraft tracking sites
High-accuracy spacecraft tracking requires tropospheric modeling which is generally scaled by either estimated or measured values of surface refractivity. This report summarizes the results of a worldwide surface-refractivity test conducted in 1968 in support of the Apollo program. The results are directly applicable to all NASA radio-tracking systems.
Schmid, P. E.↗
Tests and comparisons of gravity models.
Optical observations of the GEOS satellites were used to obtain orbital solutions with different sets of geopotential coefficients. The solutions were compared before and after modification to high order terms (necessary because of resonance) and were then analyzed by comparing subsequent observations with predicted trajectories. The most important source of error in orbit determination and prediction for the GEOS satellites is the effect of resonance found in most published sets of geopotential coefficients. Modifications to the sets yield greatly improved orbits in most cases. The results of these comparisons suggest that with the best optical tracking systems and gravity models, satellite position error due to gravity model uncertainty can reach 50-100 m during a heavily observed 5-6 day orbital arc. If resonant coefficients are estimated, the uncertainty is reduced considerably.
Marsh, J. G.↗
Single arc tracking errors associated with altimeter measurements
This study investigated the accuracies of orbit determinations in the radial coordinate utilizing currently available tracking systems. The results pinpoint certain areas which are critical for the efficient utilization of altimeter measurements.
Mcgoogan, J. T.↗
Smoothing of functions of range and range rate measurements from earth orbiting satellites
It is shown that for satellites in circular Earth orbits with altitudes of 500 kilometers to 1500 kilometers, and for satellites in elliptical orbits with an approximate 4000 kilometer height of perigee, a high degree least squares polynomial (e.g., a 9th or 10th degree in some cases) is required to smooth both range and range rate data for purposes of input to orbit determination programs. In order to circumvent this problem, functions of range and range rate are smoothed with lower degree least squares polynomials (e.g., 3rd and 4th degree) and it is shown that under the above geometric constraints the standard deviation of fit can be reduced to levels commensurate with typical S-band tracking system resolution which is 1 to 2 meters in range and 0.005 meters/second in range rate for a 1 per second data rate. Also shown are the effects of Gaussian random noise, biases, and periodic noise. This analysis includes numerous examples applied to the 44 point data smoothing interval currently used in much of the operational preprocessing at the Goddard Space Flight Center.
Grenchik, T. J.↗
A determination of the earth tidal amplitude and phase from the orbital perturbations of the Beacon Explorer C spacecraft
An analysis of the orbital inclination of the Beacon Explorer C spacecraft over a period of nearly five months in 1970 revealed a very clear and distinctive perturbation caused by the earth and ocean tides. The perturbation has a full amplitude of about 1.8 seconds of arc and a period of about 85 days. This amplitude is approximately 15% smaller than would be expected from the solid-earth tide alone and is shifted slightly in phase. The perturbation can be represented almost exactly by a Love number of k sub 2 = 0.245 with a phase lag of 3.2 degrees. The data used were laser range measurements obtained by a NASA Goddard Space Flight Center tracking system in Greenbelt, Maryland.
Smith, D. E.↗
Polar motion from laser tracking of artificial satellites.
Measurements of the range to the Beacon Explorer C spacecraft from a single laser tracking system at Goddard Space Flight Center have been used to determine the change in latitude of the station arising from polar motion. A precision of 0.03 arc second was obtained for the latitude during a 5-month period in 1970.
Smith, D. E.↗
Passive solar array orientation devices for terrestrial application.
A passive solar array orientation device, called a thermal heliotrope, is described, and several terrestrial applications are illustrated. The thermal heliotrope consists of a bimetallic helical coil that serves as the motor element, producing torque and angular displacement. A control mechanism in the form of one or more shades completes the basic device. In comparison with electromechanical tracking systems, the thermal heliotrope is electrically passive, has relatively few parts, and is low cost. After describing the principle of operation and several models built for space applications, the design considerations for several terrestrial thermal heliotrope units are presented. It is suggested that the use of the thermal heliotrope for solar array orientation could significantly reduce array cost, thereby increasing the competitive economic posture of solar arrays for terrestrial applications. The thermal heliotrope modified for terrestrial use is readily adaptable to orient solar energy concentrators, such as furnaces and stills.
Fairbanks, J. W.↗
The ATS-F/Nimbus-E tracking experiment.
The objective of the ATS-F/Nimbus-E tracking experiment, the first of its kind, is presented. Specifically, this experiment has a twofold purpose: first, to gain experience in the practical use of satellite-to-satellite range and range rate data for very accurate orbit determination (this was its original intent); and second, to evaluate the real usefulness of such a technique for geodetic studies despite the fact that the 1000-km Nimbus orbit is not ideally suited for such a purpose. The accuracies of the tracking systems of the satellite-to-satellite and satellite-to-ground link (ATS-F to the Rosman, N.C. ground station) will be about 0.035 cm/sec in range rate and about 1 m in range - utilizing a 10 sec integration time. With these values it is possible to obtain, based upon performed error analyses, orbit height errors of the order of 0.1 to 0.3 m for the near earth orbiting Nimbus spacecraft. This experiment will therefore hopefully prove to be a significant first step for future earth applications spacecraft carrying altimeters systems for measuring ocean height variations.
Von Bun, F. O.↗
Tracking the Apollo Lunar Rover with interferometry techniques.
Apollo 16 and 17 Lunar Rover position history while transporting astronauts over the lunar surface has been determined to a resolution of better than 1 m and uncertainties of less than 25 m utilizing a specialized very-long baseline interferometry (VLBI) tracking technique. This paper describes the technique, discusses the National Aeronautics and Space Administration worldwide tracking system used to obtain data, discusses the data, and presents results.
Salzberg, I. M.↗
Definition phase of Grand Tour missions/radio science investigations study for outer planets missions
Scientific instrumentation for satellite communication and radio tracking systems in the outer planet exploration mission is discussed. Mission planning considers observations of planetary and satellite-masses, -atmospheres, -magnetic fields, -surfaces, -gravitational fields, solar wind composition, planetary radio emissions, and tests of general relativity in time delay and ray bending experiments.
Tyler, G. L.↗
The statistics of laser returns from cube-corner arrays on satellite
A method first presented by Goodman is used to derive an equation for the statistical effects associated with laser returns from satellites having retroreflecting arrays of cube corners. The effect of the distribution on the returns of a satellite-tracking system is illustrated by a computation based on randomly generated numbers.
Lehr, C. G.↗
Miniature sonar fish tag
Self-powered sonar device may be implanted in body of fish. It transmits signal that can be detected with portable tracking gear or by automatic detection-and-tracking system. Operating life of over 4000 hours may be expected. Device itself may be used almost indefinitely.
Lovelady, R. W.↗