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  • 1
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    Geophysical and astronomical models applied in the analysis of very long baseline interferometry (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Very long baseline interferometry presents an opportunity to measure at the centimeter level such geodetic parameters as baseline length and instantaneous pole position. In order to achieve such precision, the geophysical and astronomical models used in data analysis must be as accurate as possible. The Mark-3 interactive data analysis system includes a number of refinements beyond conventional practice in modeling precession, nutation, diurnal polar motion, UT1, solid Earth tides, relativistic light deflection, and reduction to solar system barycentric coordinates. The algorithms and their effects on the recovered geodetic, geophysical, and astrometric parameters are discussed.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Radio Interferometry; p 153-159
    Format: application/pdf
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  • 2
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    Polar motion and UT1: Comparison of VLBI, lunar laser, satellite laser, satellite Doppler, and conventional astrometric determinations (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Very long baseline interferometry observations made with a 3900 km baseline interferometer (Haystack Observatory in Massachusetts to Owens Valley Observation in California) were used to estimate changes in the X-component of the position of the Earth's pole and in UT1. These estimates are compared with corresponding ones from lunar laser ranging, satellite laser ranging, satellite Doppler, and stellar observations.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Radio Interferometry; p 33-44
    Format: application/pdf
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  • 3
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    The Mark 3 data base handler (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A data base handler which would act to tie Mark 3 system programs together is discussed. The data base handler is written in FORTRAN and is implemented on the Hewlett-Packard 21MX and the IBM 360/91. The system design objectives were to (1) provide for an easily specified method of data interchange among programs, (2) provide for a high level of data integrity, (3) accommodate changing requirments, (4) promote program accountability, (5) provide a single source of program constants, and (6) provide a central point for data archiving. The system consists of two distinct parts: a set of files existing on disk packs and tapes; and a set of utility subroutines which allow users to access the information in these files. Users never directly read or write the files and need not know the details of how the data are formatted in the files. To the users, the storage medium is format free. A user does need to know something about the sequencing of his data in the files but nothing about data in which he has no interest.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Radio Interferometry; p 337-346
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  • 4
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    Mark 3 interactive data analysis system (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The interactive data analysis system, a major subset of the total Mark 3 very long baseline interferometry (VLBI) software system is described. The system consists of two major and a number of small programs. These programs provide for the scientific analysis of the observed values of delay and delay rate generated by the VLBI data reduction programs and product the geophysical and astrometric parameters which are among the ultimate products of VLBI. The two major programs are CALC and SOLVE. CALC generates the theoretical values of VLBI delay rate as well as partial derivatives based on apriori values of the geophysical and astronometric parameters. SOLVE is a least squares parameters estimation program which yields the geophysical and astrometric parameters using the observed values by the data processing system and theoretical values and partial derivatives provided by CALC. SOLVE is a highly interactive program in which the user selects the exact form of the recovered parameters and the data to be accepted into the solution.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Radio Interferometry; p 347-353
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  • 5
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    Possible dust devils - Vortices on Mars (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: This paper presents the results of a study of local vortices, and dust devils, on Mars as observed by Viking Landers 1 and 2. It is found that these vortices are most common during Martian spring and summer, as occurs on earth. Seven of the vortices involve wind speeds that may raise dust from the Martian surface. There is no indication that these possible dust devils contribute to the planet-wide spread of major dust storms. However, it appears that they may help in maintaining the atmospheric dust content. The data indicate that there is no preference in rotation direction, at least to core diameters of 300 m (corresponding to a region of influence of about 3 km diameter).
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; 11005-11
    Format: text
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  • 6
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    Two major dust storms, one Mars year apart - Comparison from Viking data (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The Viking Mars Landers have been on the Mars surface for over two Mars years. During the first year two major, probably global, dust storms occurred. The first was unusually early compared to most previous earth-based observations. A major storm occurred during the second year, almost precisely one year after the first storm of the first year. Meteorological data show roughly similar atmospheric behavior for the two early storms. Of particular note is the increase in amplitude of pressure oscillations (probably of baroclinic origin) and concurrent increases in wind speed during the build-up phase of all three storms. The generation of these waves appears to be a natural consequence of seasonal effects not associated with the dust storms. It is suggested that baroclinic waves, should they exist in the Southern Hemisphere during the time of dust storm generation, could be an important factor in the growth and development of the dust storms.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 86; Apr. 20
    Format: text
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  • 7
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    H2O frost point detection on Mars (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The Viking Mars landers contain meteorological instrumentation to measure wind, temperature, and pressure but not atmospheric water content. The landings occurred during local summer, and it was observed that the nocturnal temperature decrease at sensor height (1.6 m) did not exhibit a uniform behavior at either site. It was expected that the rate of decrease would gradually slow, leveling off near sunrise. Instead, a leveling occurred several hours earlier. Temperature subsequently began a more rapid decrease which slowed by sunrise. This suggested that the temperature sensors may be detecting the frost point of water vapor. Analysis of alternative hypotheses demonstrates that none of these are viable candidates. The frost point interpretation is consistent with other lander and orbiter observations, with terrestrial experience, and with modeling of Mars' atmospheric behavior. It thus appears that the meteorology experiment can help provide a basis toward understanding the distribution and dynamics of Martian water vapor.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 86; Jan. 20
    Format: text
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  • 8
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    Local Mars dust storm generation mechanism (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: On an areocentric solar longitude of 340 deg, first Mars year of Viking on the surface, a local dust storm was observed at the Viking Lander No. 1 site by Viking Orbiter A. The storm lasted less than one Martian day (sol) with the dust raised affecting the site for about three sols. It is concluded that this storm was caused by baroclinic waves and that the threshold wind speed for saltation was 25-30 m/sec.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 8; Aug. 198
    Format: text
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  • 9
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    Mars atmosphere pressure periodicities from Viking observations (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The first Martian year of pressure data taken by the Viking landers on Mars is subjected to power spectrum analysis. The analysis suggests that strong periodicities are present in the Martian atmosphere, especially at the high-latitude (48 deg N) site of the second lander. Most of these periodicities are probably due to the passage of baroclinic waves. Inspection of individual segments of data shows that the periodicities of the dominant waves vary significantly with time of year. This may be related to the amount of dust in the atmosphere since the dominant frequencies of the waves during times of major dust storms are quite different than at other times.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of the Atmospheric Sciences; 37; Sept
    Format: text
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  • 10
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    Mars atmospheric circulation - Aspects from Viking Landers (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Winds measured by the two Viking Landers have been filtered and then compared with predictions from the general circulation model and to Orbiter observations of clouds and surface phenomena that indicate wind direction. This was done to determine the degree to which filtered winds may represent aspects of the general circulation. Excellent agreement was found between wind direction data from Lander 1 and the model predictions and Orbiter observations. For Lander 2, agreement was generally good, but there were periods of disagreement which indicate that the filtering did not remove other extraneous effects. It is concluded that Lander 1 gives a good representation of the general circulation at 22.5 deg N latitude but that Lander 2 is suspect. Most wind data from Lander 1 have yet to be analyzed. It appears that when analyzed these Lander 1 data (covering 3.5 Mars years) can provide information about interannual variations in the general circulation at the Lander latitude.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 6319-632
    Format: text
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