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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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Oceanic heat storage and heat storage rate are correlated to the sea surface height anomaly signals from the TOPEX/Poseidon altimeter data from 1992 to 1998.
Topex/Poseidon is a satellite mission that will use altimetry to make precise measurements of sea-level with unprecedented acuracy such that small-amplitude, basin wide sea-level with unprecedented accuracy such that small-amplitude, basin wide sea-level changes caused by large-scale ocean circulation can be detected.
The TOPEX/POSEIDON orbit maintenance strategy was changed following launch to include the effects of observed unmodeled, and hence anomalous, along-track accelerations.
TOPEX/POSEIDON batteries continue to operate and support science loads after six years of operations.
TOPEX/POSEIDON is a joint American/French ocean topography experiment currently in the last year of its nominal mission and soon to enter a three year extended mission. To meet science requirements, the satellite must point the altimeter antenna at the ocean local nadir with good accuracy. This paper discusses the pointing accuracy of the Operational Orbit Ephemeris and its Fourier power series representation in the On-Board Computer. The consequences for the extended mission due to this performance are also discussed.
The TOPEX/Poseidon mission, a joint project between the United States and France is described with particular emphasis on measurement capabilities and performance. This satellite provides measurements of global sea level, using 2 microwave radar altimeters, a microwave radiometer, and 3 precision tracking systems. The satellite and measurement systems will be discussed, and science results given.
The TOPEX/Poseidon Project Satellite Performance Analysis Team's roles and responsibilities have grown to include functions that are typically performed by other teams on JPL flight projects.
We present preliminary estimates for the mean bias of the TOPEX/Poseidon NASA altimeter (ALT) and the CNES altimeter (SSALT) using in situ data gathered at platform Harvest during the first 36 cycles of the mission. Data for 21 overflights of the ALT and 3 overflights of the SSALT have been analyzed.
During TOPEX/POSEIDON, mission design process, the need was identified for sofware capabl of generating a predicted set or orbitala events for use in view period scheduling planning.
The TOPEX/POSEIDON spacecraft was launched on August 10, 1992. This paper will present data on the measured performance of the ASTRA Star Trackers supplied by Hughes Danbury Optical Systems (HDOS) for this satellite.
Results of operational Orbit detemination, Performed as part of the TOPEX/Poseidon (T/P) Global Positionin Satellite (GPS) demonstration experiment, are presented in this paper. Elements of this experiment include the GPS satellite constellation, GPS Demonstration Receiver on-board T/P, six ground GPS receivers, the GPS Data Handling Facility and the GPS Data processing Facility (GDPF).
The TOPEX/POSEIDON satellite requires real-time on-board knowledge of the satellite and TDRS ephemerides for attitude determination and control and High Gain Antenna (HGA) pointing.
The reduced dynamic tracking technique has been applied for the first time as part of the GPS experiment on TOPEX/Poseidon.
The TOPEX/POSEIDON altimeter measurement system is evaluated over the Great Lakes. Using in situ lake level measurements, the temporal variations in lake level are removed from the altimeter measurements, thus permitting the performance of the altimeter system to be assessed.
Results of the in-flight calibration and performance evaluation campaign for the TOPEX/Poseidon Microwave Radiometer are presented.
This paper describes the TOPEX/POSEIDON mission, ...with particular emphasis on measurement capabilities and performance.
Global efforts are under way to model the earth as a complete planet so that weather patterns may be predicted on time scales of months and years. A major limitation in developing models of global weather is the inability to model the circulation of the oceans including the geostrophic surface currents. NASA will soon be initiating a satellite program to correct this deficiency by directly measuring these currents using the science of radar altimetry. Measurement of the ocean topography with broad, frequent coverage of all ocean basins for a long period of time will allow the derivation of the spatial and temporal behavior of surface ocean currents. The TOPEX/POSEIDON mission is a cooperative effort between NASA and the French Centre National d'Etudes Spatiales. This paper describes the goals of this research mission, the data type to be acquired, the satellite and sensors to be used to acquire the data, and the methods by which the data are to be processed and utilized.
The Ocean Topography Experiment (TOPEX/POSEIDON) mission orbit requirements are outlined, as well as its control and maneuver spacing requirements including longitude and time targeting. A ground-track prediction model dealing with geopotential, luni-solar gravity, and atmospheric-drag perturbations is considered. Targeting with all modeled perturbations is discussed, and such ground-track prediction errors as initial semimajor axis, orbit-determination, maneuver-execution, and atmospheric-density modeling errors are assessed. A longitude targeting strategy for two extreme situations is investigated employing all modeled perturbations and prediction errors. It is concluded that atmospheric-drag modeling errors are the prevailing ground-track prediction error source early in the mission during high solar flux, and that low solar-flux levels expected late in the experiment stipulate smaller maneuver magnitudes.