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NASA NTRS1973

Determination of the relativistic time delay from the Mariner 9 superior conjunction data

The purpose of the analyses performed is to investigate the Mariner 9 superior conjunction range and Doppler data in order to determine the values for the relativity and solar corona time-delay parameters. This approach is complementary to the long arc normal point approach. The two methods of analysis differ insofar as: (1) This analysis investigates a much shorter arc of data. (2) This procedure deals directly with the Mariner 9 Doppler and range data; therefore it avoids the intermediate step involved in constructing pseudo-data. It is complementary to the reduction of the normal point data because it relies upon the generation of an Earth-Mars ephemeris, which is determined from the analysis of normal points as well as past optical and radar data.

Esposito, P. B.↗

NASA NTRS1973

Time-delay test of general relativity and Earth-Mars ephemeris improvement from analysis of Mariner 9 tracking data

Because of the large systematic errors that accompany the conversion of spacecraft ranging data to equivalent Earth-Mars time delays, the corresponding determination of gamma does not now allow the predictions of general relativity to be distinguished from those of the Brans-Dicke scalar-tensor theory with the fraction s of scalar field admixture being 0.06. The uncertainty in the determination of (1 plus gamma)/2 at the present stage of the Mariner 9 data analysis is at about the 10% level. The ephemeris of Mars suffers from the same problem: Only with the elimination of a major fraction of the systematic errors affecting the Mariner 9 pseudo observables will a truly substantial improvement be possible in the determination of the orbit.

Shapiro, I. I.↗

NASA NTRS1973

Effect of Mariner 9 normal points on planetary ephemerides

A set of ephemerides due to Mariner 9 normal points was created and used in conjunction with radar range time delay measurements to improve the range residuals in planetary gravity field measurements. In addition to the ephemeris of Mars, the Mariner 9 spacecraft data have also affected the geocentric ephemeris of Venus, producing changes up to 5 km in range.

Keesey, M. S. W.↗

NASA NTRS1972

Mariner 9 Michelson interferometer.

The Michelson interferometer on Mariner 9 measures the thermal emission spectrum of Mars between 200 and 2000 per cm (between 5 and 50 microns) with a spectral resolution of 2.4 per cm in the apodized mode. A noise equivalent radiance of 0.5 x 10 to the minus 7th W/sq cm/ster/cm is deduced from data recorded in orbit around Mars. The Mariner interferometer deviates in design from the Nimbus 3 and 4 interferometers in several areas, notably, by a cesium iodide beam splitter and certain aspects of the digital information processing. Special attention has been given to the problem of external vibration. The instrument performance is demonstrated by calibration data and samples of Mars spectra.

Hanel, R.↗

NASA NTRS1972

Mariner 9 ultraviolet spectrometer experiment - Photometry and topography of Mars.

Reflectance properties of Mars were measured in a 100-A band (centered at 3050 A) by the UV spectrometer on board Mariner 9 during the period from Nov. 14, 1971 to Mar. 1, 1972. A topographic map of Mars based on the scattering of UV light from the Mars atmosphere (after clearing of the dust storm) is illustrated. The UV light which is Rayleigh-scattered by the Mars molecular atmosphere (with allowance for uniform turbidity) is proportional to surface pressure regardless of the atmospheric temperature structure. Comparison with Mariner 9 radio occultation measurements determines the fraction of total reflectance that is due to atmospheric scattering.

Hord, C. W.↗

NASA NTRS1973

Earth-moon mass ratio from Mariner 9 radio tracking data.

The phase-coherent range and Doppler tracking data obtained as a basis for the navigation of the Mariner 9 spacecraft from earth to Mars determine also the earth-moon mass ratio. As the earth revolves about the center of mass of the earth-moon system, a sinusoidal curve is impressed on the range and Doppler tracking data with a frequency equal to the sidereal mean motion of the moon. The mass ratio was determined from range and Doppler data obtained over a period of 15 weeks. The results from the Mariner Mars 1971 data are presented in a table together with previous results obtained in connection with other spacecraft.

Wong, S. K.↗

NASA NTRS1973

Mariner 9 star photography.

Mariner 9 achieved successful photography of the stars, the purpose of the experiment being to measure camera parameters associated with point source photometry, and to examine the feasibility of using stars as invariant calibration sources and a reference for optical navigation. The Mariner 9 camera-B photography demonstrated photometric response consistency over a limited sample of data to better than 15%. Camera performance verified the ability to model vidicon response characteristics as well as demonstrated an imaging capability sufficient to permit the use of stars for photometric calibration.

Thorpe, T. E.↗

NASA NTRS1972

Mariner Mars 1971 photogrammetric calibrations.

One of the major objectives of the Mariner Mars 1971 mission was the systematic mapping of Mars. This required a complex and thorough photogrammetric calibration of both the wide-angle and narrow-angle cameras mounted on the spacecraft scan platform. Because of the peculiarities of the TV imaging techniques (transmission quality, low resolution, electronic distortion, etc.), combined with the extremely small vidicon format, many unique difficulties were encountered and many unprecedented problems had to be solved. Their successful solution, based on experience gained during the Surveyor and Mariner Mars 1969 projects, is discussed, and the calibration procedure for the parameters of interior orientation, as well as for opto-mechanical orthogonality, is described in detail.

Benesh, M.↗

NASA NTRS1973

Remote sensing of chlorophyll and temperature in marine and fresh waters.

An airborne differential radiometer was demonstrated to be a sensitive, real-time detector of surface chlorophyll content in water bodies. The instrument continuously measures the difference in radiance between two wavelength bands, one centered near the maximum of the blue chlorophyll a absorption region and the other at a reference wavelength outside this region. Flights were made over fresh water lakes, marine waters, and an estuary, and the results were compared with 'ground truth' measurements of chlorophyll concentration. A correlation between output signal of the differential radiometer and the chlorophyll concentration was obtained. Examples of flight data are illustrated. Simultaneous airborne measurements of chlorophyll content and water temperature revealed that variations in chlorophyll are often associated with changes in temperature. Thus, simultaneous sensing of chlorophyll and temperature provides useful information for studies of marine food production, water pollution, and physical processes such as upwelling.

Arvesen, J. C.↗

NASA NTRS1973

Mariner 9 celestial mechanics experiment - A status report.

There are two basic efforts in the Mariner 9 celestial mechanics experiment: the determination of the gravity field of Mars and the performance of a very precise test of the theory of general relativity. In addition, there are a number of astrodynamic constants that are being determined. All the analyses are based on the Mariner 9 radio tracking data.

Lorell, J.↗

NASA NTRS1973

Verification of performance of the Mariner 9 television cameras.

The large volume of picture data produced by the Mariner 9 Television Experiment, in addition to providing a description of the planet Mars, emphasizes the need for in situ verification of camera performance. Such data provide the basis for initial quantitative image interpretation by confirmation of the relevance of preflight measurement. This information must be the result of planned calibration sequences rather than extraction from nominal mission photography. A lack of sufficient numbers of frames restricted Mariner camera verifications to only limited operational modes under optimal conditions and required significant extrapolation over the duration of the mission. The evidence does suggest that measurable photometric changes occurred, whereas agreement with preflight data is observed for other parameters.

Thorpe, T. E.↗

NASA NTRS1973

Mariner 9 control net Mars, June 1973

The latitude and longitude are reported for 1645 primary points in the control net of Mars. The points were derived from Mariner 9 photographs as of June 1973. The new Mariner 9 aerographic coordinates system used in performing the computations is discussed.

Davies, M. E.↗

NASA NTRS1972

Mariner Jupiter/Saturn infrared instrument study

The Mariner Jupiter/Saturn infrared instrumentation conceptual design study was conducted to determine the physical and operational characteristics of the instruments needed to satisfy the experiment science requirements. The design of the instruments is based on using as many proven concepts as possible. Many design features are taken from current developments such as the Mariner, Pioneer 10, Viking Orbiter radiometers, and Nimbus D spectrometer. Calibration techniques and error analysis for the instrument system are discussed.

Source record↗

NASA NTRS1973

Photogeologic mapping of Meridiani Sinus region from Mariner 6 and 7 imagery

Photogeologic mapping of Mariner photographs characterizes major stratigraphic units of the Martian equatorial region. The low resolution photomosaic ship across Meridiani Sinus Deucalionus Regio is divided into regional map units based on albedo and crater density. High resolution frames reveal map units defined by varying surface texture, crater densities, and degree of crater sharpness. Mariner photographs provide clear evidence of eolian action and channelization by fluid flow.

Dehon, R. A.↗

NASA NTRS1973

Mariner 9 navigation

A final, comprehensive description of the navigation of Mariner 9-the first U.S. spacecraft to orbit another planet is provided. The Mariner 9 navigation function included not only precision flight path control but also pointing of the spacecraft's scientific instruments mounted on a two degree of freedom scan platform. To the extent appropriate, each section describes the perflight analyses on which the operational strategies and performance predictions were based. Inflight results are then discussed and compared with the preflight predictions. Postflight analyses, which were primarily concerned with developing a thorough understanding of unexpected in-flight results, are also presented.

Neil, W. J.↗

NASA NTRS1973

Martian lineaments from Mariner 6 and 7 images

Mariner 6 and 7 images are used to investigate the nature and importance of linear surface trends on Mars. Cross correlations of frequency-azimuth distributions of linear trends from different Mariner frames indicate that lineations not recognized as topographic features have a component of artifacts, probably introduced during digital reconstruction of the images. Consequently, topographic and nontopographic lineations should be treated separately prior to interpretation of the data. Similar statistical tests may aid in the analysis of surface trends from future satellites and space probes.

Schultz, P. H.↗

NASA NTRS1974

Observations at Venus encounter by the plasma science experiment on Mariner 10

Preliminary results from the rearward-looking electrostatic analyzer of the plasma science experiment during the Mariner 10 encounter with Venus are described. They show that the solar-wind interaction with the planet probably involves a bow shock rather than an extended exosphere, but that this is not a thin boundary at the point where it was crossed by Mariner 10. An observed reduction in the flux of electrons with energies greater than 100 electron volts is interpreted as evidence for some direct interaction with the exosphere. Unusual intermittent features observed downstream of the planet indicate the presence of a comet-like tail hundreds of scale lengths in length.

Bridge, H. S.↗

NASA NTRS1974

Venus - Mass, gravity field, atmosphere, and ionosphere as measured by the Mariner 10 dual-frequency radio system

The unique properties of the Mariner 10 radio system, and the preliminary scientific results obtained from the analysis of the radio signals are described. In the normal two-way communication mode, a command- and range-modulated 2115-MHz signal is transmitted to the spacecraft for reception on its omnidirectional antenna. As implemented for Mariner 10, the dual-frequency system has proven fully capable of performing interplanetary columnar electron content measurements while achieving the prime goals of the celestial mechanics and radio science team. The determination of the mass and gravitational potential of Venus is one of the major objectives of the radio science experiments. Information on Venus's atmosphere was deduced from analysis of the radio signals during occultation. Open-loop receiver differential Doppler data were used to measure the nightside and dayside ionospheres of Venus.

Howard, H. T.↗