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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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The Jet Propulsion Laboratory (JPL) and other institutions under the umbrella of the Southern California Earthquake Center (SCEC) are implementing a continuously operating dense GPS array in greater Los Angeles to measure movement along fault lines.
The International GPS Service for Geodynamics (IGS) is an approved activity of the International.
Satellites of the Global Positioning System (GPS) can be used to provide precise position and velocity information for receivers on the surface of the Earth, in aircraft, or in low-Earth orbit.
Ionospheric total electron mapping content (TEC) data derived from dual-frequency Global Positioning System (GPS) signals from 30 globally distributed network sites are fit into a simple ionospheric shell model,...
This paper will discuss the objectives, approach, and anticipated results of a study of earthquakes in Costa Rica. GPS measurements will be taken and field surveys will be made. Assessments of seismic strain accumulation and post-seismic deformation will be made in an effort to understand the effect these processes have on regional tectonic models.
The results of a preliminary study to access the accuracy of global ionospheric maps are presented. Global ionospheric maps, produced using dual-frequency data from the global network of GPS receivers, are.
A globally distributed network of dual-frequency global positioning system (GPS) receivers is the primary source of data used to measure ionospheric total electron content (TEC) on global scales. Maps of TEC useful for calibrating propagation delays, or monitoring the solar-terrestrial environment, can be produced using this continuously operating network. The maps can also form the basis of a TEC calibration service for users around the world. Potential users may include single-frequency satellite altimetry missions, satellite tracking stations, and astronomical observatories.
This paper presents methods of analyzing the perturbation due to thermal radiation and determining its effects on the long term orbital behavior of GPS satellites.
This paper examines the dependence of the threat model upon the spatial distribution of GPS measurements.
This paper presents a method for characterizing in terms of a scalar metric the degree which a given spatial region is sampled densely and uniformly by a given set of GPS measurements.
This paper discusses the frequency transfer in space using GPS measurements.
The paper discusses orbit determination of VSOP-2 regarding GPS measurements.
The Global Positioning System (GPS) constellation of satellites is revolutionizing the science and technology of the Earth's ionosphere.
Data from terrestrial GPS receivers are being used in growing numbers of applications requiring precise tropospheric sensing. One emerging application is the calibration of water vapor measurements from spaceborne microwave radiometers.
During the 1998-1999 Antarctic field season, we installed three autonomous GPS stations in Marie Byrd Land, West Antarctica to measure glacio-isostatic rebound and rates of spreading across the West Antartic Rift System.
In this paper, we describe some recent advances in GPS-based precise orbit determination for low-Earth orbiting satellites.
Technology is currently available to support real-time on-board knowledge of the position of a low earth orbitor at the 5-15 meter level using the civilian broadcast GPS signal with sophisticated models and filtering techniques onboard the spacecraft.
Data from a worldwide Global Positioning System (GPS) tracking network spanning six days during the EPOCH '92 campaign are used to estimate variations of the Earth's pole position every 30 minutes. The resulting polar motion time series is compared with estimates derived from very long baseline interferometry (VLBI) observations.