Engineering topics
Publications and source records attributed to Cameron, W. S..
Planetary and heliocentric spacecraft, including planetary flybys and probes, are described. Imaging, particles and fields, ultraviolet, infrared, radio science and celestial mechanics, atmospheres, surface chemistry, biology, and polarization are discussed.
The anomalies in V magnitude in photometric data on lunar features obtained by Wildey and Pohn (1964) are analyzed in the three colors of their UBV observations. The data have been averaged with respect to phase and graphed, and deviations from the average have been tabulated for each color. Sigma equal to or exceeding 3 for V, B-V, and U-B measures are shown on table. These variations are found to be similar to the much larger body of observations of lunar transient phenomena (LTP). The data for 25 features with 25 observations each show that in terms of individual measures the frequency of anomalies is approximately 3%, similar to frequencies obtained in other analyses of LTP data.
This catalog lists 1468 descriptions of observed lunar transient phenomena reported in the literature.
More than 1400 observations of lunar transient phenomena (LTP), encompassing brightenings, darkenings, and gaseous, reddish, and bluish events, are analyzed in an attempt to determine the possible causes of LTP. Hypotheses considered include effects of earth tides on the moon, low-angle illumination, thermal luminescence, UV heating, solar-particle acceleration by the magnetopause of earth's magnetotail, terrestrial magnetotail bow-shock-front turbulence, cathode luminescence due to magnetotail effects, and solar-flare particle bombardment. Analysis are performed in terms of histograms of the number of observations vs. phase of anomalistic period and of number vs. moon's age, percentage of numbers of observed phenomena and percentage of expected numbers as well as their ratios, and albedo behavior over a lunation period of chosen permanent points in ten specific features. The results indicate that different phenomena may have different causes, strong tidal effects are dubious, correlations with sunrise are most frequent, and the distribution of all LTP sites is distinct from that of deep- and shallow-focus moonquake epicenters.
An observing program designed to monitor sites of lunar transient phenomena (LTP) is discussed in the context of the distribution of LTP sites and possible sources of the events. It is noted that the distribution of LTP sites shows a strong preference for the edges of maria and a paucity in the north and south highlands, suggesting a relationship with dark smooth material known to be volcanic and implying internal activity at the sites. The observing program, which is aimed at those LTP described as brightenings, has been conducted to determine the normal brightness of each observed feature for all phases of a lunation and to establish a quantified 'seeing' scale. The procedure for establishing the albedo scale of a given feature is outlined, and some observations of the crater Dawes are analyzed as an example.
The possibility is considered that tektites are lunar volcanic ejecta, and lunar regions are examined from which tektites could be ejected with the necessary velocities and trajectories to reach the earth. The examined regions include areas around the Lunar Transient Phenomena sites near Censorinus, Messier, Messier A, and Taruntius, the area of Mare Foecunditatis near Secchi X, areas near Cauchy and Capella, and the eastern part of Mare Tranquillitatis. Evidence of acidic volcanic activity in these regions is described in detail, including possible calderas, mudflows, and endogenous domes. It is suggested that the moon is still gently degassing and that more violent eruptions of material may still occur on rare occasions. Remotely-sensed evidence of recent lunar internal activity is noted.
The availability of Apollo 17 pictorial data is announced as an aid to the selection of the photographs for study. Brief descriptions are presented of the Apollo 17 flight, and the photographic equipment used during the flight. The following descriptions are also included: service module photography, command module photography, and lunar surface photography.
A search for lunar features that showed characteristics of terrestrial ring dikes was conducted, using the Lunar Orbiter series of photographs. Features exhibiting one or more of the following four criteria were included as lunar analogs to terrestrial ring dikes: (1) inner ridges approximately concentric with the crater wall, (2) inner rills approximately concentric with the crater wall, (3) outer ridges and/or rills approximately concentric with the crater wall, and (4) interior and exterior slopes of the crater wall approximately equal. Features exhibiting each of the four criteria were found, and some had combinations of two or more including rills merging into ridges - e.g., in Taruntius and Posidonius. Gambart is an example of equal inner and outer slopes, while Hesiodus A and Marth are two of the best examples of complete inner rings concentric with the outer rings. Ten per cent of the candidates were probable impact craters but had subsequent volcanic activity of a ring dike nature. The initial search showed a distribution of the possible lunar ring dikes that was nonrandom and strongly associated with the margins of the maria, further implying that they are volcanic features.
Observations of lunar transient phenomena for the Association of Lunar and Planetary Observers (ALPO) are reported. The procedures for making visual observations for estimating albedo are described, and the reported albedo analyzed for lunar topographic features. It is shown that a catalog or scale of albedos can be established for each feature.
The calculation of tektite ablation has been redone, taking into account transient effects, internal radiation, melting and nonequilibrium vaporization of the glass, and the drag effect of the flanges. It is found that the results confirm the earlier calculations of Chapman and his group and of Adams and his co-workers. The general trend of the results is not sensitive to reasonable changes of the physical parameters. The ablation is predominantly by melting rather than by vaporization at all velocities up to 11 km/sec; this is surprising in view of the lack of detectable melt flow in most tektites. Chemical effects have not been considered.
Brief descriptions are given of the Apollo 15 mission objectives, photographic equipment, and photographic coverage and quality. The lunar photographic tasks were: (1) ultraviolet photography of the earth and moon; (2) photography of the gegenschein from lunar orbit; (3) service module orbital photographic tasks; and (4) command module photographic tasks.
From the author's collection of more than 900 reports of lunar transient phenomena (LTP) covering the period 1540-1970, 771 positive plus 112 negative observations (several times more than any previously published analyses) with sufficient ancillary data were analyzed for five hypotheses of causes. Treated as two groups they were divided into four categories (gaseous, reddish, bluish, and brightenings) and were analyzed separately and combined with respect to the hypotheses. The five hypotheses involved effects of tides, sunrise, low-angle illumination, earth's magnetic tail, and solar particles.
Discussion of various kinds of lunar features generally agreed to be of entirely volcanic origin. Possible mechanisms of formation of lunar domes, crater chains (especially those that lie along a rill), craters surrounded by dark halos, sinuous rills, mare ?wrinkle' ridges, dark smooth level material, and ring dike-like structures through volcanic activity are suggested. The examples considered are believed to provide strong evidence and implications that considerable volcanism has occurred on the moon, has played a large part in modifying and shaping the visible surface features, and may still be mildly active at present.
Compilation and comparative analysis of observations of lunar transient phenomena
Lunar transients in Aristarchus region with respect to tidal, sunrise, illumination, magnetic tail, bow shock and solar activity hypotheses
Hadley, Prinz and Schroter lunar sinuous rills morphology from Orbiter photography, discussing rills origin
Rock distribution in vicinity of small lunar craters
Moon Blink project for detecting red or blue temporary color phenomena