Apollo 16 Geochemical X-ray Fluorescence Experiment: Preliminary Report
The lunar surface was mapped with respect to magnesium, aluminum, and silicon as aluminum/ silicon and magnesium/ silicon intensity ratios along the projected ground tracks swept out by the orbiting Apollo 16 spacecraft. The results confirm the observations made during the Apollo 15 flight and provide new data for a number of features not covered before. The data are consistent with the idea that the moon has a widespread differentiated crust (the highlands). The aluminum/ silicon and magnesium/ silicon concentration ratios correspond to those for anorthositic gabbros through gabbroic anorthosites or feldspathic basalts. The x-ray results suggest the occurrence of this premare crust or material similar to it at the Descartes landing site.
Instrument Calibrations and Data Analysis Procedures for the NEAR X-Ray Spectrometer
Abstract The X-Ray spectrometer onboard the Near Earth Asteroid Rendezvous spacecraft will measure X-rays from the surface of 433 Eros in the energy region 0.7–10 keV. Detection of characteristic Kα line emissions from Mg, Al, Si, Ca, Ti, and Fe will allow the determination of surface abundances of these geologically important elements. Spatial resolution as fine as 3 km will be possible for those elements where counting statistics are not a limiting factor. These measurements will make it possible to relate Eros to known classes of meteorites and reveal geological processes that occurred on Eros. The calibration measurements and analysis procedures presented here are necessary for the reduction and analysis of the X-ray data to be collected during one year of orbital operations at Eros.
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.