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Davies, M. E.

Publications and source records attributed to Davies, M. E..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

The control network of Rhea

A control network of the Saturnian satellite Rhea has been established photogrammetrically from pictures taken by the two Voyager spacecraft. Coordinates of 288 control points on Rhea have been computed and listed; some of these are identified on the preliminary U.S. Geological Survey map of Rhea and many of the control point features have been named. Pixel measurements of these points were made on 81 Voyager 1 and 3 Voyager 2 pictures. The longitude system on Rhea is defined by the crater Tore; the 340 deg meridian passes through the center of this crater. The mean radius of Rhea has been determined at 764 + or - 4 km.

Davies, M. E.↗
NASA NTRS1983

The control networks of Tethys and Dione

Control networks of the Saturnian satellites Tethys and Dione have been established photogrammetrically from pictures taken by the two Voyager spacecraft during their flybys. Coordinates of 110 points on Tethys and 126 points on Dione are listed; selected points are identified on U.S. Geological Survey maps of the satellites, and many are identified by name. Measurements of these points were made on six pictures from Voyager 1 and 21 from Voyager 2 for Tethys, and on 27 pictures from Voyager 1 and one from Voyager 2 for Dione. The longitude systems on the satellites have been defined by craters on their surfaces. The mean radii have been determined as 524 + or - 5 km for Tethys and 559 + or - 5 km for Dione.

Davies, M. E.↗
NASA NTRS1983

The 1982 control network of Mars

Attention is given to a planet-wide control network of Mars that was computed in September 1982 using a large single-block analytical triangulation with 47,524 measurements of 6853 control points on 1054 Mariner 9 and 757 Viking pictures. In all, 19,139 normal equations were solved, with a resulting standard error of measurement of 18.06 microns. The control points identified by name and letter designation are given, as are the aerographic coordinates of the control points. In addition, the coordinates of the Viking I lander site are given: latitude, 22.480 deg; longitude, 47.962 deg (radius, 3389.32 km). This study expands and updates the previously published network (1978). It is noted that the computation differs in many respects from standard aerial mapping photogrammetric practice. In comparison with aerial mapping photography, the television formats are small and the focal lengths are long; stereo coverage is rare, the scale of the pictures varies greatly, and the residual camera distortions are large.

Davies, M. E.↗
NASA NTRS1983

The control networks of Mimas and Enceladus

A bundle-type analytical triangulation program is employed to compute control networks for Mimas, whose network encircles the satellite with 110 points measured on 32 Voyager 1 pictures, and Enceladus, whose network does not completely encircle the satellite and contains 71 points measured on 22 Voyager 2 pictures. Many of the control points are identified on illustrations and by name, and their coordinates are presented in tabular form. The analytical triangulation program was used to solve for the mean radii and three principal axes of best-fit ellipsoids. The mean radius of Mimas is 197 + or - 3 km, while that of Enceladus is 251 + or - 5 km.

Davies, M. E.↗
NASA NTRS1981

Coordinates of features on the Galilean satellites

Control nets of the four Galilean satellites have been established photogrammetrically from pictures taken by the two Voyager spacecraft during their flybys of Jupiter in 1979. Coordinates of 504 points on Io, 112 points on Europa, 1547 points on Ganymede, and 439 points on Callisto are listed. Selected points are identified on U.S. Geological Survey maps of the satellites. Measurements of these points were made on 234 pictures of Io, 115 pictures of Europa, 282 pictures of Ganymede, and 200 pictures of Callisto. The systems of longitude were defined by craters on Europa, Ganymede, and Callisto. Preliminary solutions have been found for the directions of the axes of rotation of the Galilean satellites. New mean radii have been determined as 1815 + or - 5 km for Io, 1569 + or - 10 km for Europa, 2631 + or - 10 km for Ganymede, and 2400 + or - 10 km for Callisto.

Davies, M. E.↗
NASA NTRS1980

Coordinates of features on the Galilean satellites

The coordinate systems of each of the Galilean satellites are defined and coordinates of features seen in the Voyager pictures of these satellites are presented. The control nets of the satellites were computed by means of single block analytical triangulations. The normal equations were solved by the conjugate iterative method which is convenient and which converges rapidly as the initial estimates of the parameters are very good.

Davies, M. E.↗
NASA NTRS1980

Improved coordinates of features in the vicinity of the Viking lander site on Mars

The measurement of longitude of the Viking 1 landing site and the accuracy of the coordinates of features in the area around the landing site are discussed. The longitude must be measured photogrammatically from the small crater, Airy 0, which defines the 0 deg meridian on Mars. The computer program, GIANT, which was used to perform the analytical triangulations, and the photogrammetric computation of the longitude of the Viking 1 lander site are described. Improved coordinates of features in the vicinity of the Viking 1 lander site are presented.

Davies, M. E.↗
NASA NTRS1979

Control networks for the Galilean satellites, November 1979

Pictures of the four Galilean satellites taken as the two Voyager spacecraft approached Jupiter during March and July 1979 are presented. Control nets of the Galilean satellites, computed photogrammetrically, and measurements of the mean radii are presented. The pictures in the control nets are identified, the coordinates of the control points are given, and identifications of some of the control points are shown on figures. The use of star field pictures to compute the focal lengths of the camera is discussed and the geometric relationship between the narrow and wide and angle cameras is reported. A description of the coordinate systems of the Galilean satellites is presented and the status of the control net computations is reported.

Davies, M. E.↗
NASA NTRS1979

The Jupiter system through the eyes of Voyager 1

The cameras aboard Voyager 1 have provided a closeup view of the Jupiter system, revealing heretofore unknown characteristics and phenomena associated with the planet's atmosphere and the surfaces of its five major satellites. On Jupiter itself, atmospheric motions - the interaction of cloud systems - display complex vorticity. On its dark side, lightening and auroras are observed. A ring was discovered surrounding Jupiter. The satellite surfaces display dramatic differences including extensive active volcanism on Io, complex tectonism on Ganymede and possibly Europa, and flattened remnants of enormous impact features on Callisto.

Smith, B. A.↗
NASA NTRS1978

The control net of Mars - May 1977

The development of planet-wide control nets of Mars is reviewed, and the May 1977 update is described. This updated control net was computed by means of a large single-block analytical triangulation incorporating the new direction of the spin axis and the new rotation rate of Mars, as determined from radio tracking data provided by the Viking lander spacecraft. The analytical triangulation adjusts for planimetric control only (areocentric latitude and longitude) and for the camera orientation angles. Most of the areocentric radii at the control points were interpolated from radio occultation measurements, but a few were determined photogrammetically, and a substantial number were derived from elevation contours on the 1976 USGS topographic series of Mars maps. A value of V, measured from Mars' vernal equinox along the equator to the prime meridian (Airy-0) is presented.

Davies, M. E.↗
NASA NTRS1978

IAU nomenclature for albedo features on the planet Mercury

The International Astronomical Union has endorsed a nomenclature for the albedo features on Mercury. Designations are based upon the mythological names related to the god Hermes; they are expressed in Latin form. The dark-hued albedo features are associated with the generic term Solitudo. The light-hued areas are designated by a single name without generic term. The 32 names adopted are allocated on the Mercury map.

Dollfus, A.↗
NASA NTRS1977

Voyager imaging experiment

The Voyager imaging experiment, which involves two independently operated television systems (a narrow- and a wide-angle camera), is designed to conduct investigations of the atmospheres and surface properties of Jupiter, Saturn, their satellites and Saturn's rings. Objects of the investigations include the horizontal and vertical structure of visible clouds, the vertical structure of high, optically thin scattering layers on Jupiter and Saturn, the Great Red Spot, the South Equatorial Belt, chromophores on Io and Titan, the geology of several satellites, the masses, spin axes and periods of rotation of several satellites, the radial distribution of material in Saturn's rings, and the optical scattering properties of the primaries, rings, and satellites at a variety of wavelengths and phase angles.

Smith, B. A.↗
NASA NTRS1977

The prime meridian of Mars and the longitudes of the Viking landers

A planetwide control net of Mars has been computed by a single large-block analytical triangulation derived from 17,224 measurements of 3,037 control points on 928 Mariner 9 pictures. The computation incorporated the Viking-determined direction of the spin axis and rotation rate of Mars. The angle measured from the vernal equinox to the prime meridian (areocentric right ascension) of Mars was determined to be 148.368 deg + 350.891986 deg (JD - 2433282.5), where JD refers to the Julian date. The prime meridian of Mars passes through the center of the small crater Airy-O. The longitudes of the Viking landers are 47.82 + or - 0.1 deg for Lander 1 and 225.59 + or - 0.1 deg for Lander 2.

Davies, M. E.↗
NASA NTRS1977

Geodetic control net

Computer program, originally developed for Mariner flyby missions, computes planetary control net from measurements of topographical features identified on television pictures. Program solves for areocentric coordinates of 115 surface points and orthogonal camera matrices of 57 far and near encounter pictures.

Davies, M. E.↗
NASA NTRS1977

Television observations of Mercury by Mariner 10

The morphology and optical properties of the surface of Mercury resemble those of the Moon in remarkable detail, recording a very similar sequence of events; chemical and mineralogical similarity of the outer layers is implied. Mercury is probably a differentiated planet with an iron-rich core. Differentiation is inferred to have occurred very early. No evidence of atmospheric modification of any landform is found. Large-scale scarps and ridges unlike lunar or Martian features may reflect a unique period of planetary compression near the end of heavy bombardment, perhaps related to contraction of the core.

Murray, B. C.↗
NASA NTRS1975

Preliminary imaging results from the second Mercury encounter

The second Mercury encounter has resulted in the acquisition of about 360 pictures of the south polar regions which provide a reliable cartographic and geologic tie between the two sides of the planet photographed on the first encounter. Stereoscopic coverage of large areas of the southern hemisphere was obtained by combining Mercury 1 and 2 pictures taken at different viewing angles. The south polar regions consist of heavily cratered terrain and intercrater plains interspersed with patches of smooth plains. No large areas of smooth plains similar to those surrounding Caloris occur in the south polar regions. No new types of terrain have been recognized, but lobate scarps are common. The second largest basin seen by Mariner 10 has been confirmed on the new photography. At high solar elevations the surface displays an abundance of rays and rayed craters.

Strom, R. G.↗
NASA NTRS1975

Surface coordinates and cartography of Mercury

A control net of Mercury has been established photogrammetrically by using the Mariner 10 pictures; coordinates of 1328 points are given. The Mariner 10 coordinate system uses a system of longitudes in which the twentieth meridian passes through the center of the small crater Hun Kal and the spin axis is assumed normal to the orbital plane. A reference mosaic of Mercury has been published, and a series of 1:5,000,000 maps is now being produced.

Davies, M. E.↗