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Cain, D. L.

Publications and source records attributed to Cain, D. L..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Viking relativity experiment - Verification of signal retardation by solar gravity

Analysis of 14 months of data obtained from radio ranging to the Viking spacecraft verified, to an estimated accuracy of 0.1%, the prediction of the general theory of relativity that the round-trip times of light signals traveling between the earth and Mars are increased by the direct effect of solar gravity. The corresponding value for the metric parameter gamma is 1.000 plus or minus 0.002, where the quoted uncertainty, twice the formal standard deviation, allows for possible systematic errors.

Reasenberg, R. D.↗
NASA NTRS1979

Nutation of Mars

The mathematical theory of the nutation of Mars is derived by classical rigid-body dynamics. The effect of nutation is to produce a 26-m maximum horizontal amplitude oscillation (at the surface of Mars) with a period of half a Martian year. This effect should be detectable in the Viking-Lander data.

Lyttleton, R. A.↗
NASA NTRS1978

Mars gravity - Additional resolution from Viking Orbiter I

Doppler radio tracking data taken from Viking Orbiter I at a 300 km periapsis altitude are now capable of resolving shorter wavelength features such as Olympus Mons and Alba Patera. The number of data is limited as is the area of high resolution which forms a narrow band near 35 deg N latitude. The masses of 71 disks, placed in a geometric pattern on the surface, were estimated. Location of each disk, the mass estimate, and the corresponding uncertainty are given for each disk mass included in the estimator. The new gravity results are compared with previous gravity reductions. The corresponding acceleration surface at 350 km altitude is displayed. It is concluded that systematic postfit residuals imply that further information can be extracted with more detailed modeling.

Sjogren, W. L.↗
NASA NTRS1977

The Viking Radio Science Investigations

The Viking radio science investigations utilize data from the radio tracking and communications systems of the orbiters and landers. The primary areas of research are: (1) dynamical, surface, and internal properties of Mars, (2) atmospheric and ionospheric properties of Mars, and (3) solar system properties. The instrumentation and facilities used are those required for trajectory and orbit determination, spacecraft control, and data transmission. The X-band downlink on the orbiters is also used for communications experiments and for the improvement of radio science capabilities.

Michael, W. H., Jr.↗
NASA NTRS1977

The Viking Relativity Experiment

Measurements of the round-trip time of flight of radio signals transmitted from the earth to the Viking spacecraft are being analyzed to test the predictions of Einstein's theory of general relativity. According to this theory the signals will be delayed by up to approximately 250 microsec owing to the direct effect of solar gravity on the propagation. A very preliminary qualitative analysis of the Viking data obtained near the 1976 superior conjunction of Mars indicates agreement with the predictions to within the estimated uncertainty of 0.5%.

Shapiro, I. I.↗
NASA NTRS1976

Mars dynamics, atmospheric and surface properties - Determination from Viking tracking data

Approximately three months of radio tracking data from the Viking landers have been analyzed to determine the lander locations, the orientation of the spin axis of Mars, and a first estimate from Viking data of the planet's spin rate. Preliminary results have also been obtained for atmospheric parameters and radii at occultation points and for properties of the surface in the vicinity of lander 1.

Michael, W. H., Jr.↗
NASA NTRS1976

Viking lander location and spin axis of Mars - Determination from radio tracking data

Radio tracking data from the Viking lander have been used to determine the lander position and the orientation of the spin axis of Mars. The areocentric coordinates of the lander are 22.27 deg N, 48.00 deg W, and 3389.5 kilometers from the center of mass; the spin axis orientation, referred to earth's mean equator and equinox of 1950.0, is 317.35 deg right ascension and 52.71 deg declination.

Michael, W. H., Jr.↗
NASA NTRS1975

Relativity experiment on Helios - A status report

The relativity experiment on Helios (Experiment 11) uses S-band and Doppler data, and spacecraft-solar-orbital data to measure the effects of general relativity in the solar system and the quadrupole moment in the solar gravitational field. Specifically, Experiment 11 is converned with measuring the following effects: (1) relativistic orbital corrections described by two parameters of the space-time metric which are both equal to unity in Einstein's theory; (2) orbital perturbations caused by a finite quadrupole moment of an oblate sun, described by zonal harmonics in the solar gravitational field.

Anderson, J. D.↗
NASA NTRS1974

Preliminary results on the atmospheres of Io and Jupiter from the Pioneer 10 S-band occultation experiment

The preliminary analysis of data from the Pioneer 10 S-band radio occultation experiment has revealed the presence of an ionosphere on the Jovian satellite Io having an electron density peak of about 60,000 electrons per cubic centimeter at an altitude of approximately 60 to 140 kilometers. This suggests the presence of an atmosphere having a surface number density of about 10 billion to one trillion per cubic centimeter, corresponding to an atmospheric surface pressure of between .1 and 10 nanobar, at or below the detection threshold of the Beta Scorpii stellar occultation. A measurement of the atmosphere of Jupiter was obtained down to the level of about 80 millibars, indicating a large temperature increase at about the 20 millibar level, which cannot be explained by the absorption of solar radiation by methane alone and can possibly be due to absorption by particulate matter.

Kliore, A.↗
NASA NTRS1973

S-band occultation experiment: A summary

The objectives and requirements of the experiment are described. The Martian atmosphere and ionosphere, and the radius and shape of Mars are discussed.

Kliore, A. J.↗
NASA NTRS1973

Surface properties working group

The objectives of the Mars surface properties working group are described. The objectives were: (1) determine a simple reference surface that would adequately represent the shape of the planet for cartographic purposes; (2) monitor the topographic results and to assess the relative calibration and accuracies of these techniques, thereby leading to a composite topographic map of the planet; and (3) facilitate the exchange of data in closely connected disciplines. The shape, topography, and isobaric surface are discussed along with the gravity field, and crustal density model. It was found that there is no simple reference figure for the planetary surface, although an offset, triaxial ellipsoid is adequate for most purposes.

Whitehead, A. B.↗
NASA NTRS1973

Approximations to the mean surface of Mars and Mars atmosphere using Mariner 9 occultations

When the Mariner 9 spacecraft passed behind Mars in its orbiting phase, the radio beam was cut off by some physical feature. These occultations occurred during the months of November and December 1971 and again in April and May 1972. The fairly good global spread of these data was used to estimate the shape of the Martian globe, as definable by mathematical shapes (ellipsoidal and spherical harmonic). The refraction profiles allowed the estimation of pressure near the occultation point; these, corrected back to an arbitrary fixed value of pressure, chosen to be 6.1 mb, were used as radii to an isobaric surface. Preliminary results showed a figure displacement from the mass center with a best fit southeast by 2.85 km. There was also an equatorial displacement in the direction of about 100 deg W. Atmospheric approximations for the mass center to 6.1-mb pressure distances were fit to an ellipsoid.

Cain, D. L.↗
NASA NTRS1972

The atmosphere of Mars from Mariner 9 radio occultation measurements.

Mariner-9 S-band radio occultation measurements conducted during November and December 1971 are described in terms of new information that was obtained about the shape and atmosphere of Mars. The arrival of the spacecraft coincided with a severely obscuring global dust storm, and the effect of the dust in the atmosphere was reflected in the reduced temperature gradients that were measured in the daytime near-equatorial atmosphere, indicating (1) heating of the atmosphere by solar radiation absorbed by dust and (2) simultaneous cooling of the surface. In general, surface atmospheric pressures measured in the equatorial regions are in very good agreement with previous radio-occultation and earth-based measurements. A global disparity in pressures strongly suggests that the physical shape of Mars is more oblate than the shape of its gravitational equipotential surface.

Kliore, A. J.↗
NASA NTRS1972

The shape of Mars from the Mariner 9 occultations.

The extinction time of the radio signal, as the Mariner 9 spacecraft was occultated by Mars, together with an accurate ephemeris of the spacecraft were used to determine radii from the mass center to the occulting feature. Similarly estimations were made of the radius to a point where the pressure reached a certain fixed value. Several simple models were proposed to fit both sets of radii data.

Cain, D. L.↗
NASA NTRS1972

Radio science experiments - The Viking Mars Orbiter and Lander.

The objective of the radio science investigations is to extract the maximum scientific information from the data provided by the radio and radar systems on the Viking Orbiters and Landers. Unique features of the Viking missions include tracking of the landers on the surface of Mars, dual-frequency S- and X-band tracking data from the orbiters, lander-to-orbiter communications system data, and lander radar data, all of which provide sources of information for a number of scientific investigations. Post-flight analyses will provide both new and improved scientific information on physical and surface properties of Mars, on atmospheric and ionospheric properties of Mars, and on solar system properties.

Michael, W. H., Jr.↗
NASA NTRS1972

Mariner 9 S-band Martian occultation experiment - Initial results on the atmosphere and topography of Mars.

A preliminary analysis of 15 radio occultation measurements taken on the day side of Mars between 40 deg S and 33 deg S has revealed that the temperature in the lower 15 to 20 km of the atmosphere of Mars is essentially isothermal and warmer than expected. This result, which is also confirmed by the increased altitude of the ionization peak of the ionosphere, can possibly be caused by the absorption of solar radiation by fine particles of dust suspended in the lower atmosphere. The floor of the classical bright area of Hellas was found to be about 6 km below its western rim and 4 km below the mean radius of Mars at that latitude.

Kliore, A. J.↗