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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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Mariner 5 space probe radio occultation analysis, Pioneer 8 space probe data, and bistatic radar data reduction from Lunar Orbiter and Mariner 5
Estimates of surface temperature and pressure of Venus from radio and radar measurements
Microwave techniques at X and L band were used to determine the dependence of ocean-wave radar modulation transfer functions (MTFs) on various environmental and radar parameters during the Marine Remote Sensing experiment of 1979 (MARSEN 79). These MIF are presented, as are coherence functions between the AM and FM parts of the backscattered microwave signal. It is shown that they both depend on several of these parameters. Besides confirming many of the properties of transfer functions reported by previous authors, indications are found that MTFs decrease with increasing angle between wave propagation and antenna-look directions but are essentially independent of small changes in air-sea temperature difference. However, coherence functions are much smaller when the antennas are pointed perpendicular to long waves. It is found that X band transfer functions measured with horizontally polarized microwave radiation have larger magnitudes than those obtained by using vertical polarization.
The pioneering satellite radar altimeter aboard Skylab has provided a wealth of information about ocean surface topography for both the oceanographic and geodetic communities. This report describes typical satellite altimetry concepts and discusses the parameters measured, geometry utilized, and techniques employed to generate ocean geoid estimates. The standard deviation of the noise on the altitude measurements is shown to range from one to three meters when the altimeter antenna is nadir aligned. The altimeter is shown to sense short wavelength ocean surface features which are not included in present conventional global geoids. An estimate of a local geoid in the Atlantic, using only altimeter data, is presented. Finally, results demonstrate that the Skylab radar altimeter system capability is less than 10 meters RMS.
Both quasi-stationary and dynamic departures from the marine geoid were successfully detected using altitude measurements from the GEOS-3 radar altimeter. The quasi-stationary departures are observed either as elevation changes in single pass profiles across the Gulf Stream or at the crowding of contour lines at the western and northern areas of topographic maps generated using altimeter data spanning one month or longer. Dynamic features such as current meandering and spawned eddies can be monitored by comparing monthly mean maps. Comparison of altimeter inferred eddies with IR detected thermal rings indicates agreement of the two techniques. Estimates of current velocity are made using derived slope estimates in conjunction with the geostrophic equation.
With increased reliance on Virtual Aid(s) to Navigation (VAtoN) - also known as electronic Aid(s) to Navigation (eAtoN), or virtual buoys - a cyber event is likely to cause disruption to international maritime shipping. VAtoN has no physical hardware for visual reference and displays only on a vessel’s Electronic Chart Display Information System (ECDIS) and Automatic Radar Plotting Aid (ARPA); therefore, mariners must rely on the accuracy of the information provided. As VAtoN uses the National Maritime Electronics Association (NMEA) 0183 protocol for both Global Navigation Satellite System (GNSS) and Automatic Identification System (AIS), an insecure protocol that has been proven susceptible to spoofing, denial, and manipulation, the likelihood of a cyber-related event increases substantially.
Venus atmosphere and radius measurements by Mariner 5, Venera 4 and radar, comparing values
In the present paper, the results are summarized of a study aimed at determining the small-scale surface properties of Mars (for the Viking project) from a thorough review of all available Martian radar data for the 1973 opposition. Analysis of the quasi-specular echo component showed changes in apparent reflectivity of at least 5 to 1. If attributed entirely to variations in surface material, these correspond to dielectric constants between 1.6 and 4.0. Values of rms surface slope on 1- to 100-m scales range from as low as 0.5 degrees in tablelands near Valles Marineris to more than 3.0 degrees in certain other areas. There is a weak correlation between the small-scale surface characteristics inferred from radar and those inferred from Mariner 9 images and other remote-sensing data sets.
Ranging measurements and equipment for Mariner Venus space probe
A model is presented of the atmosphere and surface of Venus which best fits in the least-squares sense the available radio-brightness, radar cross-section, radio interferometric, and Mariner 5 and 10 radio occultation observations. The determinations of the radius of the planet obtained by others from radar time-delay measurements are included in the data set. The values of the adjusted parameters are: molar fraction of CO2 = 95 plus or minus 3%; fraction of combined nitrogen and argon = 5 plus or minus 3%; total atmospheric opacity at a wavelength of 1 cm = 19.4 plus or minus 1.3; mean radius of the surface = 6050.7 plus or minus 0.8 km; mean dielectric constant of the surface = 4.1 plus or minus 0.2, and percentage of total opacity due to chemical species other than CO2 = 45 plus or minus 12. The model temperature and pressure at the mean surface are 755 K and 91.4 atm, respectively.
The 1971 and 1973 Goldstone radar data on the Memnonia Fossae region of Mars is used as a test case for the characterization of surface materials. In addition to the discovery of greater relief in the radar-derived topographic measurements of this area than had been inferred from Mariner 9 estimates, and although a tendency for the radar measurements to break down over very rugged terrain has been observed, good correlation is found between radar topography and surface features. Photogeological mapping has identified six surface units which have distinctive radar properties that correlate well with surface features observed in the Viking Orbiter's 10 m/pixel resolution images
The instrument package of the Seasat-A satellite, scheduled for launch in 1978, consists of a short-pulse radar altimeter, a wind field scatterometer, a scanning multichannel microwave radiometer, and an experimental L-band synthetic aperture radar. Objectives of the mission include precision altimetry for marine geoid and sea surface topography assessments, the determination of wave directional spectra through radar scatterometry, and sea surface temperature measurements through microwave emission analysis. The synthetic aperture radar, operated selectively, is intended to yield land and sea imagery with a resolution of 25 m for such requirements as coastal surveys.
The research on model functions for ADEOS and ERS-1 are summarized and an analysis of the differences between the three kinds of models is provided in this final report. The success of the AMI on ERS-1 obtained at GSFC and NMC is highlighted. The problem of wind stress description is reviewed within and the scatterometer model being developed for high winds monitoring for the AMI on ERS-1 and ERS-2 is described.
Venus surface temperature and pressure estimated from radio and radar measurements by Venera 4 and Mariner 5 space probes
Solar wind turbulence spectrum from Mariner 6 and 7 space probe radar measurements, using differenced range vs integrated Doppler technique
Current least squares fits to solar system data, including transit circle observations of the terrestrial and giant planets, radar observations of the terrestrial planets, Mariner 9 range fixes to Mars, and Pioneer 10/11 range fixes to Jupiter, have yielded some new results of interest to experimental relativity. Solutions have been obtained for the parameterized post-Newtonian (PPN) parameters beta and gamma, the solar gravitational quadrupole moment J2, a time variation in the gravitational constant G, and four Nordtvedt parameters.
Summer raincells in a marine temperate climate were monitored using radar, and the probability of raincell occurrence was described as a function of altitude, rain intensity and cell size. The study aimed at defining a cell model for communications engineers concerned with precipitation-induced interference or signal attenuation.
The vertical structure of three polar lows is described using profiling radar, lidar, and passive remote sensors deployed at a coastal site in northern Norway. The data were collected as part of the Cold-air Outbreaks in the Marine Boundary Layer Experiment (COMBLE). These data are examined in the context of satellite imagery, operational weather radar reflectivity imagery, and output from the AROME-Arctic model. A comparison to satellite images shows that AROME-Arctic captured the polar lows well. All three polar lows form in marine cold-air outbreaks and are surrounded by open-cellular convection typical of such outbreaks. Two of the lows form in a forward shear environment, and one under reverse shear. Initially, the three polar lows are comma-shaped; two of them transition to be more spirali-form at their mature stage and have mostly cloud-free warm cores. The warm cores are the result of a warm-seclusion process. All three lows have stratiform precipitation bands, marked by little cloud liquid water, and rather high surface precipitation rate. The vertical drafts and turbulence in these stratiform clouds are generally weak. In conclusion, all three lows also have convective clouds, which have stronger vertical drafts, stronger turbulence, and pockets of high liquid water content.