Lunar rivers

Mature meanders in lunar sinuous rills strongly suggests that the rills are features of surface erosion by water. Such erosion could occur under a pressurizing ice cover in the absence of a lunar atmosphere. Water, outgassed from the lunar interior and trapped beneath a layer of permafrost, could be released by a meteoritic impact and overflow the crater to form an ice-covered river. A sinuous rill could be eroded in about 100 years.     

Lunar cinder cones

Data on terrestrial eruptions of pyroclastic material and ballistic considerations suggest that in the lunar environment (vacuum and reduced gravity) low-rimmed pyroclastic rings are formed rather than the high-rimmed cinder cones so abundant on the earth. Dark blanketing deposits in the Taurus-Littrow region (Apollo 17 landing area) are interpreted as being at least partly composed of lunar counterparts of terrestrial cinder cones.     

Lunar igneous intrusions

Photographs taken from Apollo 10 and 11 reveal a number of probable igneous intrusions, including three probable dikes that crosscut the wall and floor of an unnamed 75-kilometer crater on the lunar farside. These intrusions are distinguished by their setting, textures, structures, and brightness relative to the surrounding materials. Recognition of these probable igneous intrusions in the lunar highlands slupports the indications of the heterogeneity of lunar materials and the plausibility of intrusive igneous activity, in addition to extrusive volcanism, on the moon.     

Density of the Lunar Atmosphere

The minimum possible density of the lunar atmosphere at the surface is shown to be essentially the value for the interplanetary medium. This value, when combined with the observed maximum, places the particle density between 10(3) and 10(6) per cubic centimeter, while the electron density must be about 10(3) to 10(4) per cubic centimeter. These results are markedly different from those recently obtained by Firsoff.     

Micropaleontological Studies of Lunar Samples

Optical and electron microscopic studies of rock chips and dust from the bulk sample box returned by Apollo 11 and of petrographic thin sections and acid-resistant residues of lunar material have yielded no evidence of indigenous biological activity. vestigations.     

Lunar Ephemeris: Delaunay's Theory Revisited

Delaunay's reduced Hamiltonian of the main problem in lunar theory is checked against a new analytical theory based on Lie transforms. It is found to be correct up to order 9 with the exception of one error in addition at order 7.     

Lunar ring dikes from orbiter I

Orbiter photographs of the wall of a large circular formation on the moon show that the wall is a convex body resembling a flow of viscous lava. The slopes are less than the angle of repose of dry rock; hence an explanation in terms of mass wastage is hard to support. The viscosity is approximately 10(13) centimeter-gram- second units, indicating an acid lava.