Network functions and facilities
The objectives, functions, and organization of the Deep Space Network are summarized; deep space station, ground communication, and network operations control capabilities are described.
Renzetti, N. A.↗
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Network functions and facilities
The objectives, functions, and organization of the Deep Space Network are summarized. Deep space station, ground communication, and network operations control capabilities are described.
Renzetti, N. A.↗
Network functions and facilities
The objectives, functions, and organization of the Deep Space Network are summarized; deep space station, ground communication, and network operations control capabilities are described.
Renzetti, N. A.↗
Millimeter wave satellite concepts. Volume 1: Executive summary
The objectives of the program were: (1) development of methodology based on the technical requirements of potential services that might be assigned to millimeter wave bands for identifying the viable and appropriate technologies for future NASA millimeter research and development programs, and (2) testing of this methodology with user applications and services. The scope of the program included the entire communications network, both ground and space subsystems. The reports include: (1) cost, weight, and performance models for the subsystems, (2) conceptual design for point-to-point and broadcast communications satellites, (3) analytic relationships between subsystem parameters and an overall link performance, (4) baseline conceptual systems, (5) sensitivity studies, (6) model adjustment analyses, (7) identification of critical technologies and their risks, (8) brief R&D program scenarios for the technologies judged to be moderate or extensive risks.
Hilsen, N. B.↗
Network functions and facilities
The objectives, and organization of the Deep Space Network are summarized. Deep space station, ground communication, and network operations control capabilities are described.
Renzetti, N. A.↗
Portable zero-delay assembly
Instrument is calibrated using back-to-back method. In comparison standard, S-X isolators are opposite from device being tested to permit signal flow in reverse direction. After calibration portable zero-delay assembly (PZDA) is used to set time delays of deep-space network ground-station ranging systems. Approach is also used to calibrate microwave links in other communications systems.
Franco, M. M.↗
Network functions and facilities
The objectives, functions, and organization of the Deep Space Network are summarized. Deep Space Station, ground communication, and network operations control capabilities are described.
Renzetti, N. A.↗
Network functions and facilities
The objectives, functions, and organization of the Deep Space Network are summarized. Deep space station, ground communication, and network operations control capabilities are described.
Renzetti, N. A.↗
Network functions and facilities
The objectives, functions, and organization of the Deep Space Network are summarized; deep space station, ground communication, and network operations control capabilities are described.
Renzetti, N. A.↗
Interferometry Measures Elliptical Satellite Orbits
Very-long-baseline interferometry offers advantages over conventional Doppler measurements. Conference paper shows feasibility of using data from very-long-baseline interferometry (VLBI) to locate and predict motion of satellites in highly elliptical orbits about Earth. VLBI data obtained from Deep Space Network. Data not only improves navigation accuracy but also acquired with less use of worldwide network of ground stations.
Frauenholz, R. B.↗
Active Optical Sounding of Ozone and Minor Constituents in the Middle Atmosphere: a Review of Ground-based Lidar Measurements
Due to the rapid development of powerful laser sources in the UV wavelength range which includes nd:yag pumped dye lasers and excimer lasers, ground-based lidar systems are now operational for ozone monitoring in the troposphere and the stratosphere. Such systems will play an important role in the determination of long term ozone trends in the photochemical region. The capacities of active lidar systems in terms of high temporal and spatial resolution and measurements continuity, allow the observation of the ozone variations at various time and space scales which are important in present day areas of interest. The already operational character of the lidar systems will constitute the basis for development of a ground-base network for middle atmospheric observations of ozone and other race gases.
Megie, G.↗
Overview of Solar Seismology: Oscillations as Probes of Internal Structure and Dynamics in the Sun
The physical nature of solar oscillations is reviewed. The nomenclature of the subject and the techniques used to interpret the oscillations are discussed. Many of the acoustic and gravity waves that can be observed in the atmosphere of the Sun are actually resonant or standing modes of the interior; precise measurements of the frequencies of such modes allow deductions of the internal structure and dynamics of this star. The scientific objectives of such studies of solar seismic disturbances, or of solar seismology, are outlined. The reasons why it would be very beneficial to carry out further observations of solar oscillations both from ground based networks and from space will be discussed.
Toomre, J.↗
The structure of a microburst - As observed by ground-based and airborne Doppler radar
Attention is given to the microburst observed near Denver, CO, on June 29, 1982, in the course of the Joint Airport Weather Study (JAWS). The JAWS ground radar network was specifically established to furnish high spatial and temporal resolution multiple Doppler data for microburst observations. The data, which were collected from directly above the microburst, permitted direct measurements of vertical velocities to be made. P-3 surveillance aircraft Doppler data was also available for this microburst, whose considerable complexity is noted.
Mueller, C. K.↗
The mission oriented terminal area simulation facility
The Mission Oriented Terminal Area Simulation (MOTAS) was developed to provide an ATC environment in which flight management and flight operations research studies can be conducted with a high degree of realism. This facility provides a flexible and comprehensive simulation of the airborne, ground-based and communication aspects of the airport terminal area environment. Major elements of the simulation are: an airport terminal area environment model, two air traffic controller stations, several aircraft models and simulator cockpits, four pseudo pilot stations, and a realistic air-ground communications network. MOTAS has been used for one study with the DC-9 simulator and a series of data link studies are planned in the near future.
Kaylor, J. T.↗
The VEGA Venus balloon experiment
In June 1985, two instrumented balloons were placed in the atmosphere of Venus as part of the VEGA mission. Each balloon traveled about 30 percent of the way around the planet at a float altitude near 54 kilometers. In situ sensors measured pressure, temperature, vertical wind velocity, cloud particle backscatter, ambient light level, and frequency of lightning. A ground-based network of 20 radio antennas tracked the balloons by very long baseline interferometry (VLBI) techniques to monitor the Venus winds. The history, organization, and principal characteristics of this international balloon experiment are described.
Sagdeev, R. Z.↗
Network functions and facilities
The objectives, functions, and organization of the Deep Space Network (DSN) are summarized: tracking complexes, ground communications, and network operations control capabilities are described.
Amorose, R. J.↗
Combining electric field and aurora observations from DE 1 and 2 with ground magnetometer records to estimate ionospheric electromagnetic quantities
Global distribution of electric fields and currents in the high-latitude ionosphere was estimated using data from the ground-based network of magnetometers and from nearly simultaneous observations with DE 1 and DE 2 satellites. The electric field and current distributions at high altitudes were calculated from instantaneous ionospheric conductivity (estimated from the DE 1 auroral data), using the Kamide et al. (1981) magnetogram inversion technique; an optimum conductivity was then chosen iteratively so that the resultant electric fields would become consistent with electric field deduced from ion drifts measured along the DE-2 orbit. It is demonstrated that, when analyzing the large-scale electrodynamics of individual substorms, statistical conductivity models are not fully adequate for use with the magnetogram inversion technique.
Kamide, Y.↗
Toward decimeter Topex orbit determination using GPS
Several practical aspects of precision GPS-based Topex orbit determination are investigated. Multipath signals contaminating Topex pseudorange data are greatly reduced by placing the GPS antenna on a conducting backplate consisting of concentric choke rings to attenuate signals coming in from the Topex horizon and below, and by elevating it on a boom to keep it well above all reflecting surfaces. A proper GPS antenna cutoff view angle is chosen so that a sufficient number of GPS satellites with good geometry are in view while reception of reflected signals is minimized. The geometrical strength of the tracking data is optimized by properly selecting GPS satellites to be observed so as to provide data with moderate continuity, low PDOP, and common visibility with ground tracking sites. The tracking performance is greatly enhanced when three complementary sites are added to the minimum ground tracking network consisting of the three NASA DSN sites.
Wu, Sien-Chong↗