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The author has identified the following significant results. Significant results are the continued detection of short-lived events. The following have been detected and analyzed: forest fires, oil spills, vegetation damage, volcanoes, storm ridges, and earthquakes. It is hoped that the Mississippi River flood scenes will arrive shortly and then floods be added to the list of identified short-lived events.
A generalized geologic map of Mars has been constructed largely on the basis of differences in the topography of the surface. A number of topographic features on Mars whose form is highly diagnostic of their origin are shown. Of particular note are the shield volcanoes and lava plains. In some areas, the original features have been considerably modified by subsequent erosional and tectonic processes. These have not, however, resulted in homogenization of the planet's surface, but rather have emphasized its variegated character by leaving a characteristic imprint in specific areas. The topography of the planet, therefore, lends itself well to remote geologic interpretation.
Some field observations of the occurrence of deep-seated rock fragments in three terrestrial volcanic features that may have counterparts on the moon or Mars are reviewed, and results of numerical hydrodynamic calculations of the eruption of these types of volcanoes are presented. In particular, the transport of entrained fragmental debris is investigated for the surface (muzzle) velocity of fragments that it yields as a function of fragment size and various values of surface gravity. The implications of these observations and inferences for possible future space missions are examined.
A geologic map of Mars has been constructed largely on the basis of photographic evidence. Four classes of units are recognized: (1) primitive cratered terrain, (2) sparsely cratered volcanic eolian plains, (3) circular radially symmetric volcanic constructs such as shield volcanoes, domes, and craters, and (4) tectonic erosional units such as chaotic and channel deposits. Grabens are the main structural features; compressional and strike slip features are almost completely absent. Most grabens are part of a set radial to the main volcanic area, Tharsis.
The author has identified the following significant results. Forest fires, oil spills, vegetation damage, volcanoes, storm ridges, earthquakes, and floods have been detected and analyzed.
The author has identified the following significant results. Detection of short-lived events has continued. Forest fires, oil spills, vegetation damage, volcanoes, storm ridges, earthquakes, and floods have been detected and analyzed.
The author has identified the following significant results. Most of the research emphasis was directed at the analysis of Icelandic icecaps on ERTS imagery. A number of new findings were made, including: (1) on low sun angle imagery of Hofsjokull, the outline of a probable central volcano can be seen delineated on the northwest part of the icecap; (2) on low sun angle imagery of Langjokull, two parallel hyaloclastite ridges can be seen to continue for more than 10 km in from the margin of the icecap; (3) measurements of contorted medial moraines on images of Skeioararjokull, acquired about 11 months apart show an approximate 600 m of annual glacier movement; (4) measurements on images of the surging glacier, Eyjabakkajokull, taken about 11 months apart show an approximate 1.8 km of movement during that time; and (5) successive ERTS images of the glacier-dammed lake, Graenalon, show an increase in area of the lake until the ice dam was partially breached, causing a jokulhlaup across the Skeioararsandur. Because of the shape of the lake basin the elevation of the post-jokulhlaup lake can be determined from ERTS imagery to + or - 2 m.
Historical, geographical, and regional geological settings for the conference are presented that include volcanic stratigraphy, a photographic essay describing various landforms observed during eruptive activity at Kilauea Volcano, and a general discussion of the geology of the island of Hawaii. Also included are guides for field trips to interesting geographic features.
The flight sequence in this guide is nominal and based on optimum weather conditions; it may be altered, depending upon weather and visibility. Also included at the end of the flight sequence for the island of Hawaii are sections for parts of Maui (Haleakala Volcano) and Molokai, which will be flown if Hawaii is completely obscured at flight time.
Discussion of the equipment and orbital specifications of the Mariner Mars 9 spacecraft - a Martian orbiter which was placed in orbit on Nov. 14, 1971, for an expected 50-year stay and has made possible a practically 100% photographic coverage of the planet's surface. The orbit has a nominal 12-hr period, a nominal periapsis of 1300 km, and a nominal apoapsis of 18,000 km. Many of the outstanding topographic features of the planet have been covered by the convergent stereopairs carried by the orbiter. Theoretical considerations are set forth concerning the necessary instrument orientation and rotation requirements to achieve such performance levels in this extraterrestrial application of photogrammetry. The photogrammetric method used in this mission is assessed as useful in the evaluation of outstanding Martian features such as the mammoth volcano of the Nix Olympica region.
A remarkable set of albedo changes has been uncovered by Mariner 9 photography of the upper slopes of the shield volcano Pavonis Mons, near its summit caldera. The most likely explanation of the event is aeolian transport of fine-grained particles. Since the atmospheric pressure in this locality is about 1.5 mb, minimum wind velocities above the surface boundary layer of about 110 m per sec are necessary, corresponding to 0.51 of the speed of sound. Slope winds in this velocity range are expected near the upper flanks of major Martian volcanic constructs.
Testing extraterrestrial craters and candidate terrestrial analogs for morphologic similitude is treated as a problem in numerical taxonomy. According to a principal-components solution and a cluster analysis, 402 representative craters on the Earth, the Moon, and Mars divide into two major classes of contrasting shapes and modes of origin. Craters of net accumulation of material (cratered lunar domes, Martian calderas, and all terrestrial volcanoes except maars and tuff rings) group apart from craters of excavation (terrestrial meteorite impact and experimental explosion craters, typical Martian craters, and all other lunar craters). Maars and tuff rings belong to neither group but are transitional. The classification criteria are four independent attributes of topographic geometry derived from seven descriptive variables by the principal-components transformation. Morphometric differences between crater bowl and raised rim constitute the strongest of the four components.
The structure, physical properties of ejecta, ballistics, and growth of Northeast crater, a young pyroclastic cone that originated in 1911 near the summit of Mount Etna, Sicily, were studied in order to form a model of volcano cinder cone growth. Four stages of growth were discerned: (1) a simple cone; (2) a cone with an outward-dipping talus slope; (3) destruction of rounded rim by the inward migration of the upper edge of the talus pile; and (4) extension of limits of talus pile beyond the ballistic limit of ejecta trajectories. The model is used to predict the features of lunar and Martian cones, assuming that they erupted under conditions qualitatively similar to Etna's Northeast crater.
A study was made of the shape of regolith particles in the 0.5 to 1.0 mm fraction; two parameters were calculated for this fraction: (1) Sphericity -- the ratio of the projection area of a particle to the area of the minimum circumscribed circle; and (2) the ratio of the perimeter of the projection of the particle to the perimeter of a circle having the same width. For comparison, this technique was used in studying geometrical figures and terrestrial formations: sands, slags of present day volcanoes, and crushed basalt. It was established that regolith particles are shaped from the following groups: spherules; breccias and fragments; slags and sinters. Regolith differs sharply from ordinary homogeneous terrestrial formations in the diversity of particle shapes, associated with their polygenicity. Fragments of crushed basalt are less regular than fragments of basalt from regolith.
Geographically, applications were made over nearly the entire area where direct readout could be accomplished using the data acquisition stations in the ERTS-1 system. The extreme areas included Iceland, the Canadian Arctic, Alaska, Hawaii and Central America. In the discipline sense the majority of applications were in the water resources area with other applications being formally and informally reported in meteorology, oceanography, volcano surveillance and forestry. Installation and maintenance of the data collection platforms, as is true with nearly all new systems, was not accomplished without difficulty. On the whole, however, it has gone well enough so that it is agreed that it is a system which is amenable to installation in a variety of physical situations and the installation is accomplished with an ease commensurate with eventual use in an operational system.
Reports, articles, and other documents announced between April and June 1974 in Scientific and Technical Aerospace Reports (STAR), and International Aerospace Abstracts (IAA) are cited. Documents related to the identification and evaluation by means of sensors in spacecraft and aircraft of vegetation, minerals, and other natural resources, and the techniques and potentialities of surveying and keeping up-to-date inventories of such riches are included along with studies of such natural phenomena as earthquakes, volcanoes, ocean currents, and magnetic fields; and such cultural phenomena as cities, transportation networks, and irrigation systems. The components and use of remote sensing and geophysical instrumentation, their subsystems, observational procedures, signature and analyses and interpretive techniques for gathering data are, described. All reports generated under NASA's Earth Resources Survey Program for the time period covered are included.
Two night eruptions of the volcano Stromboli were studied through 70-mm photography. Single-camera techniques were used. Particle sphericity, constant velocity in the frame, and radial symmetry were assumed. Properties of the particulate phase found through analysis include: particle size, velocity, total number of particles ejected, angular dispersion and distribution in the jet, time variation of particle size and apparent velocity distribution, averaged volume flux, and kinetic energy carried by the condensed phase. The frequency distributions of particle size and apparent velocities are found to be approximately log normal. The properties of the gas phase were inferred from the fact that it was the transporting medium for the condensed phase. Gas velocity and time variation, volume flux of gas, dynamic pressure, mass erupted, and density were estimated. A CO2-H2O mixture is possible for the observed eruptions. The flow was subsonic. Velocity variations may be explained by an organ pipe resonance. Particle collimation may be produced by a Magnus effect.
The present work summarizes the principal results of the radio occultation experiments carried out to date for Mars. The early measurements, made at the time of the Martian dust storm of 1971, showed greatly reduced temperature gradients in the daytime troposphere, indicating the heating effect of the dust. The temperature gradients that were measured later when the atmosphere was apparently free of dust, were still much lower than expected under conditions of radiative-convective balance, indicating that dynamics may play a large part in determining the temperature structure of the Martian troposphere. The surface atmospheric pressure was observed to vary widely with topography ranging from about 1 mb at the summit of the Middle Spot volcano (Pavonis Mons) to over 10 mb in the North circumpolar region. The radius of the planet was measured with accuracies ranging from about 0.25 to about 2.1 km over latitudes ranging from 86 to -80 deg. These measurements have shown that Mars has pronounced equatorial and north-south asymmetries, which make it difficult to represent its shape by a simple triaxial figure. The daytime ionosphere measurements indicated that the main ionization peak was similar in behavior to a terrestrial F1 layer and is probably produced by photoionization of carbon dioxide by solar extreme ultraviolet.