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Schwerer, F. C.

Publications and source records attributed to Schwerer, F. C..

6 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Ferromagnetic-superparamagnetic granulometry of lunar surface materials

A technique of magnetic granulometry is applied to previously reported data for the temperature dependence of isothermal remanent magnetization (IRM) in 13 lunar surface samples, including three soils. Observed increases in IRM with decreasing temperature are attributed to changes from superparamagnetic to single-domain types of behavior for fine metallic-iron particles. Based on this hypothesis, the temperature dependence of IRM in the examined samples is analyzed to obtain particle-size distributions over the range of mean diameters from 30 to 130 A. It is found that the distribution functions for the soils and a low-grade breccia vary as the inverse square of particle volume and that the distributions for recrystallized breccias and igneous rocks apparently peak about mean values.

Schwerer, F. C.↗
NASA NTRS1974

Coercivity maxima at low temperatures

Recent measurements have shown that the magnetic coercive forces of some Apollo lunar samples show an unexpected decrease with decreasing temperature at cryogenic temperatures. This behavior can be explained quantitatively in terms of a model which considers additive contributions from a soft, reversible magnetic phase and from a harder, hysteretic magnetic phase.

Schwerer, F. C.↗
NASA NTRS1974

Electrical conductivity of lunar surface rocks - Laboratory measurements and implications for lunar interior temperatures

Results are reported for laboratory measurements of the dc and low-frequency ac electrical conductivity of three lunar rocks with ferrous iron contents of 5 to 26 wt %. The measurements were made at temperatures ranging from 20 to 1000 C, and Mossbauer spectroscopy was used to determine the dependence of electrical conductivity on furnace atmosphere. It is found that the magnitude of electrical conductivity generally increases with increasing iron content. A comparison of the data on these samples with data on terrestrial olivines and pyroxenes shows that the electrical conductivity of anhydrous silicate minerals is influenced primarily by the concentration, oxidation state, and distribution of iron, while the silicate crystal structure is only of secondary importance. Lunar interior temperatures are deduced from experimental lunar conductivity profiles, and the resulting temperature-depth profiles are found to be consistent with those calculated for two different lunar evolutionary models as well as with various experimental constraints.

Schwerer, F. C.↗