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Research about Mars

Source-linked reports with geographic coverage including Mars.

At least 415 records · Page 23Linked to original sources
USGS1976

The surface of Mars: The view from the Viking 1 lander

The first photographs ever returned from the surface of Mars were obtained by two facsimile cameras aboard the Viking 1 lander, including black-and-white and color, 0.12° and 0.04° resolution, and monoscopic and stereoscopic images. The surface, on the western slopes of Chryse Planitia, is a boulder-strewn deeply reddish desert, with distant eminences—some of which may be the rims of impact craters—surmounted by a pink sky. Both impact and aeolian processes are evident. After dissipation of a small dust cloud stirred by the landing maneuvers, no subsequent signs of movement were detected on the landscape, and nothing has been observed that is indicative of macroscopic biology at this time and place.

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USGS1976

The Viking landing sites: Selection and certification

During the past several years the Viking project developed plans to use Viking orbiter instruments and Earth-based radar to certify the suitability of the landing sites selected as the safest and most scientifically rewarding using Mariner 9 data. During June and July 1976, the Earth-based radar and orbital spacecraft observations of some of the prime and backup sites were completed. The results of these combined observations indicated that the Viking 1 prime landing area in the Chryse region of Mars is geologically varied and possibly more hazardous than expected, and was not certifiable as a site for the Viking 1 landing. Consequently, the site certification effort had to be drastically modified and lengthened to search for a site that might be safe enough to attempt to land. The selected site considered at 47.5°W, 22.4°N represented a compromise between desirable characteristics observed with visual images and those inferred from Earth-based radar. It lies in the Chryse region about 900 kilometers northwest of the original site. Viking 1 landed successfully at this site on 20 July 1976.

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USGS1976

Radar characteristics of Viking 1 landing sites

Radar observations of Mars at centimeter wavelengths in May, June, and July 1976 provided estimates of surface roughness and reflectivity in three potential landing areas for Viking 1. Surface roughness is characterized by the distribution of surface landing slopes or tilts on lateral scales of the order of 1 to 10 meters; measurements of surface reflectivity are indicators of bulk surface density in the uppermost few centimeters. By these measures, the Viking 1 landing site at 47.5°W, 22.4°N is rougher than the martian average, although it may be near the martian average for elevations accessible to Viking, and is estimated to be near the Mars average in reflectivity. The AINW site at the center of Chryse Planitia, 43.5°W, 23.4°N, may be an area of anomalous radar characteristics, indicative of extreme, small-scale roughness, very low surface density, or a combination of these two characteristics, Low signal-to-noise ratio observations of the original Chryse site at 34°W, 19.5°N indicate that that area is at least twice as rough as the Mars average.

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USGS1976

Preliminary results from the Viking x-ray fluorescence experiment: The first sample from Chryse Planitia, Mars

Iron, calcium, aluminum, silicon, and sulfur are major elements in the first surface sample of Mars that has been analyzed by the Viking x-ray fluorescence spectrometer. Titanium is present in minor quantities. This is consistent with the sample being a mixture of fine silicate and oxide mineral grains, with a significant proportion of sulfates, possibly hydrated. Ferric oxide is regarded as the red pigmenting agent on the martian surface, but if it coats silicate grains, the coatings must be very thin (≤ 2 micrometers) or discontinuous. A high abundance of Fe, relatively low abundances of Al, Rb, Sr, and Zr, and a high Ca/K ratio are distinctive features of the spectra. Preliminary determinations indicate the following abundances (as percentages by weight): Fe, 14 ± 2; Ti < 1; S, 2 to 5; the Ca/K ratio by weight is greater than 5.

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USGS1976

Fine particles on Mars: Observations with the Viking 1 lander cameras

Drifts of fine-grained sediment are present in the vicinity of the Viking 1 lander. Many drifts occur in the lees of large boulders. Morphologic analysis indicates that the last dynamic event was one of general deflation for at least some drifts. Particle cohesion implies that there is a distinct small-particle upturn in the threshold velocity-particle size curve; the apparent absence of the most easily moved particles (150 micrometers in diameter) may be due to their preferential transport to other regions or their preferential collisional destruction. A twilight rescan with lander cameras indicates a substantial amount of red dust with mean radius on the order of 1 micrometer in the atmosphere.

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USGS1976

The "Soil" of Mars (Viking 1)

The location of the Viking 1 lander is most ideal for the study of soil properties because it has one footpad in soft material and one on hard material. As each soil sample was acquired, information on soil properties was obtained. Although analysis is still under way, early results on bulk density, particle size, angle of internal friction, cohesion, adhesion, and penetration resistance of the soil of Mars are presented.

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USGS1976

Viking orbital colorimetric images of Mars: Preliminary results

Color reconstruction and ratios of orbital images of Mars confirm Earth-based measurements showing red/violet ratios for bright areas to be roughly 1.5 times greater than dark areas. The new results show complex variation among dark materials; dark streaks emanating from craters in southern cratered terrains are much bluer than dark materials of the north equatorial plains on which Viking 1 landed.

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USGS1976

Geologic map of the Oxia Palus Quadrangle of Mars

The Oxia Palus quadrangle contains three distinct geologic provinces: (1) an elevated cratered plateau that occupies three-fourths of the quadrangle and is similar to much of the southern hemisphere of Mars; (2) the low, relatively featureless Chryse Planitia in the northwest corner; and (3) a complex province of chaotic terrain and immense channels or valleys that divides the plateau and terminates in Chryse Planitia. Generally, the oldest geologic units occur in the plateau province and the youngest in Chryse Planitia. Discovery by Mariner 9 of the channels, the four largest of which are given names meaning “Mars” in Akkadian, Sumerian, Angelo-Saxon, and Greek (west to east), renews the possibility of water and therefore life on Mars. This possibility may be tested in July 196 by a landing of the unmanned Viking spacecraft in Chryse Planitia at the mouths of the channels (lat 19 1/2˚ N., long 34˚).

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USGS1976

Geologic map of the Hellas Quadrangle of Mars

The area of MC-28 is centered on the east edge of the Hellas Planitia (Hellas basin and surrounding plains) within densely cratered terrain that covers more than half the surface of Mars ( Carr , 1973, fig. 1). The deepest pa rt of the basin lies 4-5 km below the surface of the cratered terrain ( Hanel and others , 1972). An irregular band of mountain and knobby material about the eastern margin and the basin and broad bands of mantled rough material on the floor of the basin represent ejecta from this very old impact. The vast, gently slo p ing, featureless eastern and southern part of the Hellas Planitia, shown on the Shaded Relief Map of Mars (U.S .G.S., Atlas of Mars, MM 25M IR, 1972), is probably the result of extensive volcanic flooding from shield volcanoes and from the possible fissures in the northeast part of the quadrangle. Long, flat-flo o red sinu ous channels originate in these volcanic terrains and course into the basin.

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USGS1973

Mars cartography: the 1:5,000,000 map series

This catalog illustrates the 1:5,000,000 series of Mars base maps being compiled as part of the Mariner 9 scientific data reduction effort. This effort is sponsored by four different Centers within the National Aeronautics and Space Administration: 1) The Jet Propulsion Laboratory, California Institute of Technology, 2) The Langley Research Center, 3) NASA Headquarters, and 4) The Planetology Programs Office at NASA Headquarters. The catalog will be updated periodically as new materials become available, and will eventually be expanded to include cartographic products at scales of 1:1, 000, 000 and 1:250,000. Detailed discussions of the many aspects of Mars cartography are given in papers listed in the bibliography. Only brief notes are given here to aid the reader's understanding of existing products. Data returned by Mariner 9 spacecraft permit detailed mapping of landforms with dimensions as small as 1 to 3 km over the entire surface of Mars. A few special areas can be mapped to show landforms with dimensions as small as 100 m. Prior to the use of spacecraft television, telescopic views of the planet resolved only light and dark markings having dimensions greater than 100 km. Topographic features as such have not been identified telescopically. It was not until the flights of Mariners 4, 6, and 7 that Martian surface topography was revealed. High resolution pictures taken by these spacecraft covered only 20% of theplanet. By chance, the areas photographed by these spacecraftconsisted mostly of cratered terrain and no data were obtained thatsuggested the presence of the spectacular volcanoes and canyonsrevealed by the first time by Mariner 9. Mariner 9 covered at least 70% of the surface of Mars with pictures resolving features 1 to 2 km in size and the remainder with pictures resolving features about 3 km in size. These pictures, therefore, are now the definitive sources of data for the cartography of Mars and, because of their completeness, are not likely to be surpassed in this decade or perhaps this century.

Open-File Report↗
USGS1973

Preliminary geologic map of the Memnonia quadrangle of Mars, Viking Mars 1975 landing site

This mosaic is made with computer-enhanced, unrectified Mariner 9 pictures provided by The Jet Propulsion Laboratory Mission and Test Video System (MTVS). The Vertical Automatic Gain Control (Vert. AGC) version is used. The pictures were scaled for a "best fit" by the U.S. Geological Survey using spacecraft tracking data. Discrepancies between image positions are as large as one degree in latitude and longitude.

Open-File Report↗