Geology topics
Eugene Merle Shoemaker
Publications and source records attributed to Eugene Merle Shoemaker.
Populations of the planet-crossing asteroids
The population of Apollo, Amor and Mars crossing asteroids is studied. With the 18-inch Schmidt camera of the Hale Observatories at Mt. Palomar, four new planet crossing asteroids were discovered. A formal theory relating the probability of discovery of asteroid of a given orbital class to condition of search has been developed. From the estimated populations the flux of the Apollo objects to magnitude 18 near the Earth is of the order of (0.4 ± 0.2) 10 -14 km -2 yr -1 . During 3.3 b.y. this flux produces an estimated 60 ± 20 craters of 10 km in diameter and larger per 10 6 km 2 on the Moon. This number seems to be consistent with the observed crater densities on 3. 3 b.y. old mare surfaces in the eastern Oceanus Procellarum and Mare lmbrium.
Application of ERTS images and image processing to regional geologic problems and geologic mapping in northern Arizona
The purpose of this study was to apply the techniques of computer image processing to ERTS images as an aid to the solution of some regional geologic problems of significant interest. ERTS-1 images were applied to studies in the Shivwits Plateau, Coconino Plateau, and north-central Arizona regions. Unprocessed ERTS images revealed a wealth of new structural information and enabled a broad regional study to be made of the tectonic history of the southwestern Colorado Plateau. Spectral information from ERTS-1 was shown to be compatible with ground spectral reflectance measurements made with a portable field instrument developed during this investigation, provided that allowance was made for atmospheric effects. Computer image processing yielded lithologic boundary information within the Coconino Plateau region not obtainable from unprocessed images. Various enhancement techniques were compared in the three areas of study, and some simple rules were developed to guide the processing of images in unknown areas. A new hypothesis was developed for the history of the Colorado River. An ancestral and relatively old Upper Colorado Drainage followed approximately its present course as far as the western side of the Kaibab Uplift, where it diverged from the present course by following a strike valley trending north-northwest. This drainage was captured relatively recently by a much younger Lower Colorado Drainage, which developed by headward erosion after the opening of the Gulf of California. A byproduct of the regional studies in each of the three areas was the identification of areas favorable for the localization of shallow and deep ground waters. On the Shivwits Plateau water trapped in the axis of the old strike valley underlying the Shivwits lavas is a potential source. On the Coconino Plateau sandstone lenses, underlain by clays, within the otherwise permeable Kaibab Limestone are potential perched aquifers. These can be identified on computer-enhanced images. Lineaments detected first on ERTS-1 frames and later verified on aerial photographs were used south of Flagstaff, Arizona, to identify maximum fracturing along the Oak Creek fault in the Woody Mountain well field; a site for a new deep well has been selected and is being drilled by the city of Flagstaff.
Television observations from Surveyor
Five successful Surveyor spacecraft landed on the Moon between June 1966 and January 1968 and returned over 87,000 pictures from the lunar surface. Surveyors I, III, V, and VI landed on mare surfaces; Surveyor VII landed in the southern highlands on the flank of the crater Tycho, the youngest, large bright-ray crater on the Moon.
Chapter 9: Theory and processes relating to the lunar maria from the surveyor experiments
Prior to the Surveyor missions, there were three principal theories about the chemical constitution of the lunar maria: that the maria were (1) chondritic, (2) basaltic, or (3) silicic. Three types of materials recovered on Earth were suspected of coming from the maria: (1) chondritic meteorites, (2) basaltic achondrites, and (3) tektites. The Surveyor chemists have now spoken: Turkevich, Franzgrote, and Patterson find that, in Mare Tranquillitatis (ref. 9-1) and Sinus Medii (see ch. 7 of this report), the composition is basaltic. It is unmistakably too poor in magnesium to be like either kind of chondritic meteorite. It is too rich in the heavier elements, iron and calcium, to resemble terrestrial silicic rocks (the granitic kindred) or tektites.
Chapter 3: Television observations from Surveyor VI
Surveyor VI landed on the lunar surface at 01:01:05 GMT on day 314 (November 10, 1967) in the southwestern part of Sinus Medii near the center of the visible face of the Moon. Over 30,000 pictures were transmitted from the spacecraft during the first lunar day of operation. The number of pictures taken by Surveyor VI almost equals the total number of pictures returned from the previous Surveyor missions combined. The pictures were received at the Goldstone, California, Canberra, Australia, and Madrid, Spain, tracking stations of the Deep Space Network.
Chapter 3: Television observations from Surveyor VII
Surveyor VII, the last spacecraft of the Surveyor series, successfully landed at 01:05:36 GMT, January 10, 1968, on the outer rim flank of the large crater Tycho, in the southern part of the Moon. The spacecraft landed about 30 hours after local lunar sunrise and transmitted about 21,000 pictures during the remainder of the first lunar day of operation. On January 22, after local sunset, almost 700 pictures were taken of the Earth, the Sun's corona and parts of the lunar surface illuminated by earthlight. On February 12, Surveyor VII was revived for operation on the second lunar day approximately 120 hours after local lunar sunrise. The camera was then operated in the 200-line (low-resolution) mode because of loss in horizontal sweep in the 600-line (high-resolution) mode. About 45 pictures were taken in the 200-line mode during the second lunar day before loss of power caused suspension of camera operation.
Chapter IX: Lunar theory and processes
Whereas the previous Surveyor missions were undertaken to examine mare surfaces as potential landing areas for the Apollo Program, the primary objective of the Surveyor VII mission, based on purely scientific motivations, was to explore a contrasting highland region and, specifically, to determine the chemistry of the highland material for comparison with the Surveyor V and VI chemical analyses at the mare sites. Site selection was limited to some extent by Surveyor operational constraints, but primarily by the requirements of 10-m-resolution photographs from the Lunar Orbiter Program for landing site certification. None of the nine sites studied in detail appeared capable of providing an unambiguous answer to the highland chemistry. The final selection of a site to the north of Tycho was based on the belief that the youthful character of the structure implied a minimum of contamination to the surface layers by foreign material via meteoritic processes. Moreover, the selection of a site near the rim of a major lunar crater promised insight into the “microscale” properties of a structure that represents the dominant morphologic feature on the moon.
Chapter III: Television observations from Surveyor V
Surveyor V landed on the lunar surface at 00:46:44 GMT on Day 254 (September 11), 35 hr after local sunrise on the moon. Between the time of landing and lunar sunset, 13 days later, it transmitted more than 18,000 high-quality television pictures of the lunar surface and parts of the spacecraft. The Surveyor V camera was operated extensively from the Goldstone, California, and Canberra, Australia, Tracking Stations of the Deep Space Network; some pictures were also received at the Madrid, Spain, Tracking Station.
Chapter III: Television observations from Surveyor III
Surveyor III landed on the lunar surface at 00:04 GMT, on Day 110 (April 20), 1967, approximately 23 h after local sunrise on the moon. The television camera was turned on about 1 h after touchdown, and 6315 pictures were taken during the remainder of the lunar day. The camera was operated extensively for the first period of lunar visibility from the Goldstone Tracking Station of the Deep Space Network (DSN) and, except on Day 115 (April 25), on each successive Goldstone pass of the moon. During this period, the sun rose from an elevation angle of 11 deg in the east to within 3 deg of the zenith and then sank almost due west of the spacecraft. Many pictures were obtained of the illuminated eastern horizon in the period immediately preceding sunset. In addition to those received at the Goldstone station, some were obtained at the Canberra, Australia, station of the DSN.
Chapter 8: Lunar theory and processes
Significant new information has been provided by Surveyor III's successful landing and operation on the lunar surface; some of the most significant and interesting events are presented here. Pending completion of data reduction and more detailed analysis of the information available from the Surveyor mission, only limited interpretive discussion is included.
Chapter VIII: Lunar theory and processes
Much valuable new information has been provided by Surveyor III ; some of the most significant and interesting events are presented here. Only a limited interpretive discussion is included at this time, pending completion of data reduction and more detailed analysis of information available from the Surveyor mission.
Hypervelocity impact of steel into Coconino Sandstone
Impact of a 0.4019-g steel sphere at 4.27 km/sec into Coconino Sandstone [Permian] from Meteor Crater, Arizona, produced a crater 11-12 cm across and 2.45 cm deep. The ejecta consist of sandstone fragments, disaggregated sand, splinters of sand grains, strongly shocked aggregates of crushed sandstone grains, and chips, splinters, small amounts of silica glass, and minute spheres of steel. Part of the shocked steel was melted, and some of the melted and unmelted steel occurs as impregnations in the strongly shocked sandstone. Small amounts of glass, which were produced by shock from the sandstone, were found. The fusion of the steel cannot be due to compressive heating alone but can be partly accounted for by conduction of heat from the shocked sandstone and by production of heat by viscous drag and friction along the sandstone-projectile interface and along shear planes in the projectile.
Diatremes and uranium deposits in the Hopi Buttes, Arizona
The Hopi Buttes diatremes erupted in a shallow lake that was filled in as volcanic activity progressed in Pliocene time. At the end of the period of volcanism the landscape included low lava domes capping some of the diatremes, a few flows, and numerous craters of the maar type, surrounded by rims of volcanic debris with gentle exterior slopes that merged with the surrounding plain. Erosion, probably chiefly during early and middle Pleistocene, has exposed the diatremes in varying stages of denudation.