SEARCH · Search NASA
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
The JPL Micro-Precision Interferometer (MPI) is a testbed for studying the use of control-structure interaction and vibration isolation technology in the design of precision space-based interferometry.
The dependence of sea surface directional reflectance on surface wind speed from space-based lidar measurements of sea surface backscatter. In particular lidar measurements in the nidir angle range from 10-30 degrees appear to be most sensitive to surface wind speed variability in the regime below 10m/s.
Space-based interferometers dedicated to wide-angel astrometry would dramatically increase the accuracy of angular measurement fundamental to a wide range of astrophysical problems. The propsosed global Astrometric Interferometer for Astrophysics (GAIA) a continuously rotating instruments comprising two or three interferometers, will reach the 5-20 mue as level on more that 35 million objects.
The JPL/NASA Deep Space Network (DSN) plans to participate in the upcoming Space VLBI missions by using its 70m antenna time to co-observe with space-based radio telescopes. To enhance this support, the DSN is upgrading its radio astronomy equipment at L- and K-band, its VLBI recorders, and its computers and software for co-observing operations.
Space deployable antennas are needed for a variety of applications that include space based very-long-baseline interferometry, mobile communications, active microwave sensing, earth observation radiometry, synthetic aperture radar, spacecraft communications, and DOD space-based radar. Design and development concepts discussed are low cost, reliability, low weight, packaging, precision and stability.
This oral presentation describes the Astrometric Imaging Telescope as a space-based observatory designed to detect and study planetary systems and circumstellar material around hundreds of nearby stars.
Inflatable structural concepts have been proposed for numerous applications such as antennas for microwave remote sensing, space-based interferometry, solar concentrators, and for dual purposes (e.g. concentrator for power/antenna for communication). In comparison to other mechanically deployable systems, inflatable structures have significant advantages of a much lower cost, weight, and packaging volume, but higher deployment reliability and damping properties.
Low-power, high-speed, accurate computation of centroid from a pre-defined window in the image plane is important for a number of space-based and commercial applications.
The purpose of this paper is to re-examine the impact of upper tropospheric water vapor on greenhouse warming in midlatitudes by analyzing the recent observations of the upper tropospheric water vapor from the Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite (UARS), in conjuction with other space-based measurement and model simulation products.
Current global analyses contain significant errors in primary hydrological fields such as precipitation, evaporation, and related cloud and moisture in the tropics. The Data Assimilation Office at NASA's Goddard Space Flight Center has been exploring the use of space-based rainfall and total precipitable water (TPW) estimates to constrain these hydrological parameters in the Goddard Earth Observing System (GEOS) global data assimilation system. We present results showing that assimilating the 6-hour averaged rain rates and TPW estimates from the Tropical Rainfall Measuring Mission (TRMM) and Special Sensor Microwave/Imager (SSM/I) instruments improves not only the precipitation and moisture estimates but also reduce state-dependent systematic errors in key climate parameters directly linked to convection such as the outgoing longwave radiation, clouds, and the large-scale circulation. The improved analysis also improves short-range forecasts beyond 1 day, but the impact is relatively modest compared with improvements in the time-averaged analysis. The study shows that, in the presence of biases and other errors of the forecast model, improving the short-range forecast is not necessarily prerequisite for improving the assimilation as a climate data set. The full impact of a given type of observation on the assimilated data set should not be measured solely in terms of forecast skills.
Heterodyne interferometer laser gauges are used in space-based astronomical interferometers to very accurately measure and compensate for variations in starlight pathlength.
In this paper the requirements, specifications, design procedures, and analytical results for a dual frequency space-based telescope are discussed.
The Space Interferometry Mission (SIM) is designed as a space-based optical interferometer operating in the visible waveband. This mission will open up many areas of astrophysics, via astrometry with unprecedented accuracy during its 5-year mission.
The Terrestrial Planet Finder (TPF) is a space-based infrared interferometer that will combine high sensitivity and spatial resolution to detect and characterize planetary systems within 15 pc of our sun.
The Space Interferometry Mission (SIM) will be NASA's first dedicated space-based optical interferometer.
The Space Interferometry Mission (SIM) will be NASA's first space-based optical interferometer designed for precision astrometry.
This paper describes a type of cosmic ray detector suitable for the construction of a small, low power space-based instrument to detect the energy and isotope of energetic nuclei, such as those produced by solar flares. The detector is similar to previous types of silicon PIN detectors where the fully depleted body of the wafer comprises intrinsic region of the PIN structure. The novel aspect of this detector is that the one surface is divided into a two-dimensional array of pixels, and that the collected holes are divided between a row and a column collector in each pixel, yielding both dimensions of position information from this side of the detector.
Stratospheric ozone measurements made by the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment from onboard the Space Shuttle during the period 8-16 April 1992 are compared with other space-based remote sensing measurements.