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Geology topics

N.J. Trask

Publications and source records attributed to N.J. Trask.

33 records · Page 2Linked to original sources
USGS1971

Imaging of Mercury and Venus from a flyby

This paper describes the results of study of an imaging experiment planned for the 1973 Mariner Venus/Mercury flyby mission. Scientific objectives, mission constraints, analysis of alternative systems, and the rationale for final choice are presented. Severe financial constraints ruled out the best technical alternative for flyby imaging, a film/readout system, or even significant re-design of previous Mariner vidicon camera/tape recorder systems. The final selection was a vidicon camera quite similar to that used for Mariner Mars 1971, but with the capability of real time transmission during the Venus and Mercury flybys. Real time data return became possible through dramatic increase in the communications bandwidth at only modest sacrifice in the quality of the returned pictures. Two identical long focal length cameras (1500 mm) were selected and it will be possible to return several thousand pictures from both planets at resolutions ranging from equivalent to Earthbased to tenths of a kilometer at encounter. Systematic high resolution ultraviolet photography of Venus is planned after encounter in an attempt to understand the nature of the mysterious ultraviolet markings and their apparent 4- to 5-day rotation period. Full disk coverage in mosaics will produce pictures of both planets similar in quality to Earthbased telescopic pictures of the Moon. The increase of resolution, more than three orders of magnitude, will yield an exciting first look at two planets whose closeup appearance is unknown.

Icarus↗
USGS1971

Geologic setting of the Apollo 14 samples

The Apollo 14 lunar module landed in a region of the lunar highlands that is part of a widespread blanket of ejecta surrounding the Mare Imbrium basin. Samples were collected from the regolith developed on a nearly level plain, a ridge 100 meters high, and a blocky ejecta deposit around a young crater. Large boulders in the vicinity of the landing site are coherent fragmental rocks as are some of the returned samples.

Science↗
USGS1969

Geologic maps of early Apollo landing sites of set C

Comparison of the five potential early Apollo landing sites of set C reveals significant geologic similarities and differences. No two sites are identical; the geology of each should be considered in the interpretation of returned lunar samples and observations. Geologic maps of each site have been prepared at scales of 1:5,000, 1:25,000, and 1:100,000. Features emphasized on the 1:5,000-scale maps are common to all the sites and include mainly the widespread lunar regolith and small craters of varied age and origin. Because they cover the lunar surface and because mobility will be limited on early missions, these ubiquitous features will be the main objects of scientific inquiry during the first manned landings. Regional geologic differences among the sites are more apparent on the 1:25,000- and 1:100,000-scale maps. Mare materials in sites 2 and 3 belong mainly to the Imbrian System; the materials in site 3 appear to be younger than those in site 2. Mare materials in sites 4 and 5 belong entirely to the Eratosthenian System. Most materials in site 1 have been assigned to the Copernican System. They consist of a young mantle of relatively low-cohesion material that covers an older cratered terrain, probably part of the terrae. Typical mare material occurs only in the eastern extremity of site 1. Ray materials and secondary impact craters related to large rayed primary impact craters are present in several of the sites.

Open-File Report↗
USGS1967

Distribution of Lunar craters according to morphology from Ranger VIII and IX photographs

A classification of the craters photographed by the Ranger VIII and IX missions into four categories according to relative sharpness shows that at diameters of 100 meters, the predominant craters have broad rims and low depth-diameter ratios and are partly covered with smaller craters which generally have sharper rims and higher depth-diameter ratios but include all classes. If competing processes of crater formation and destruction are responsible for the mix of crater types observed, an abrupt increase in the proportion of sharp craters suggests an intense episode of crater destruction to produce a smoothed surface that was subsequently recratered. Data comparable to those presented can readily be obtained from Lunar Orbiter photographs to determine if an increase in the proportion of sharp craters is present over more extensive areas and to test various cratering histories that may account for it.

Icarus↗