Blocky craters: Implications about the lunar megaregolith

Radar, infrared, and photogeologic properties of lunar craters have been studied to determine whether there is a systematic difference in blocky craters between the maria and terrae and whether this difference may be due to a deep megaregolith of pulverized material forming the terra surface, as opposed to a layer of semi-coherent basalt flows forming the mare surface. Some 1310 craters from about 4 to 100 km diameter have been catalogued as radar and/or infrared anomalies. In addition, a study of Apollo Orbital Photography confirmed that the radar and infrared anomalies are correlated with blocky rubble around the crater.Analysis of the radar and infrared data indicated systematic terra—mare differences. Fresh terra craters smaller than 12 km were less likely to be infrared and radar anomalies than comparable mare craters: but terra and mare craters larger than 12 km had similar infrared and radar signatures. Also, there are many terra craters which are radar bright but not infrared anomalies.Our interpretation of these data is that while the maria are rock layers (basaltic flow units) where craters eject boulder fields, the terrae are covered by relatively pulverized megaregolith at least 2 km deep, where craters eject less rocky rubble. Blocky rubble, either in the form of actual rocks or partly consolidated blocks, contributes to the radar and infrared signatures of the crater. However, aging by impacts rapidly destroys these effects, possibly through burial by secondary debris or by disintegration of the blocks themselves, especially in terra regions.PSI Contribution No. 110.     

An investigation of some large directional discontinuities in the solar wind plasma using multisatellite observations

Eleven large directional discontinuities in the solar wind, simultaneously observed by Explorers 33, 35 and Heos 1 in the period Dec. 1968 to Jan. 1969, have been studied by the triangulation method. Testing the discontinuity normals deduced from the wind speed and timing parameters against those given by the magnetometer observations on different models suggests that 8 were tangential, 2 were rotational while 1 could not be identified. 3 small tangential discontinuities arriving within a period 35 min were also studied and as a result it is suggested that the solar wind remained stratified in separation planes over a distance 0.01 AU during that time. The implication of these results is briefly discussed.     

Testing the effects of ocean heat transport on climate

An atmospheric general circulation model is run with boundary conditions representing different amounts of equator-to-pole oceanic heat transport. Oceanic heat transport underneath sea ice is held fixed, minimizing positive feedbacks due to sea ice and thereby providing a lower bound on the effects of oceanic heat transport on climate. When oceanic heat transport is reduced, some compensating increases in atmospheric heat transport occur, but tropical surface temperatures increase and atmospheric circulation and precipitation patterns undergo significant changes. We conclude that the ability of the oceans to generate past and future climatic changes through transport of heat is substantial, even though it is limited by a tendency of the atmosphere to partly compensate for changes in oceanic heat transport.     

Collective effects in diffuse matter-antimatter plasma: II

It is shown that even very slightly ionized clouds of matter and anti-matter can interpenetrate only a little on collision. Initial interpenetration produces fast electrons and positrons from annihilation. These, in turn, produce strong magneto-hydrodynamic shocks which give the small ionized component enough energy to ionize the neutral fraction and produce a Leidenfrost layer in about ten years after which interpenetration stops.     

The Aristarchus-Harbinger region of the moon: Surface geology and history from recent remote-sensing observations

The region including the Aristarchus Plateau and Montes Harbinger is probably the most diverse, geologically, of any area of comparble size on the Moon. This part of the northwest quadrant of the lunar near side includes unique dark mantling material; both the densest concentration and the largest of the sinuous rilles; apparent volcanic vents, sinks, and domes; mare materials of various ages and colors; one of the freshest large craters (Aristarchus) with ejecta having unique colors and albedos; and three other large craters in different states of flooding and degradation (krieger, Herodotus, and Prinz). The three best-authenticated lunar transient phenomena were also observed here.This study is based principally on photographic and remote sensing observations made from Earth and Apollo orbiting space craft. Results include (1) delineation of geologic map units and their stratigraphic relationships; (2) discussion of the complex interrelationships between materials of volcanic and impact origin, including the effects of excavation, redistribution and mixing of previously deposited materials by younger impact craters; (3) deduction of physical and chemical properties of certain of the geologic units, based on both the remote-sensing information and on extrapolation of Apollo data to this area; and (4) development of a detailed geologic history of the region, outlining the probable sequence of events that resulted in its present appearance.A primary concern of the investigation has been anomalous red dark mantle on the Plateau. Based on an integration of Earth- and lunar orbit-based data, this layer seems to consist of fine-grained, block-free material containing a relatively large fraction of orange glass. It is probably of pyroclastic origin, laid down at some time during the Imbrian period of mare flooding.     

North Atlantic sea-level and circulation

Summary. Monthly sea-levels from an extensive array of North Atlantic tide gauges (26-50N) are examined. The spatial scale of the sea-level variations, and the reasons for them, are discussed; one application of such a study is clearly in the design of a tide gauge network for monitoring eustatic changes of sea-level.
The spatial scale of the sea-level changes is large. There is a coherent sea-level signal which can be traced along the eastern boundary of the North Atlantic from Newlyn (50N) to Tenerife (28N). There are also two distinct groupings of tide gauges along the western boundary, separated by Cape Hatteras.
The contribution of local air pressure and wind stress is quantified at each gauge through multiple regression techniques and the gains are then interpreted in terms of recent theoretical and numerical modelling studies. For example, the gains suggest that the wind-forced boundary current along the Nova Scotian shelf is trapped to within about 16 km of the coast.
The influence of local meteorology cannot account for the large-scale modes of variability. The coherent signal along the eastern boundary is correlated with changes in the Sverdrup transport of the North Atlantic and hence the large-scale wind field. The two modes on the western boundary appear to be related to baroclinic boundary current variations.
The Newlyn sea-level record is finally 'corrected' for some of the above effects to illustrate the utility of such a residual series in the identification of eustatic changes and vertical crustal movement.     

Observation and explanation of a 0.3% sunward radial streaming of 1 to 5 GV cosmic radiation

Solar Physics - Quiet-time anisotropy data have been obtained by the HEOS-1 spacecraft between December 1968 and April 1970 using an 8-sector analysis of a ?erenkov telescope which has a...