GSC-1: A LUNAR SIMULANT FROM A JURASSIC SILL IN LEESBURG, VIRGINIA

To support a NASA study in 2006 of possible lunar drilling techniques, a lunar simulant was needed. Existing simulants were not available, so a local source was sought. Samples were obtained from a quarry in a Jurassic diabase sill in Leesburg, Virginia, one of the many Mesozoic intrusions on the east coast. Similar rocks can be found in New York, New Jersey, Pennsylvania, and other areas. Petrographic study of Leesburg diabase samples, intentionally chosen away from hydrothermally altered parts of the sill, showed it to consist of plagioclase (An50), clinopyroxene (augite), magnetite, and minor quartz and biotite. The clinopyroxene showed pervasive diallage, presumably formed by subsolidus exsolution during slow cooling of the sill. The Leesburg simulant, GSC-1, was used successfully in drilling technique tests although texturally different from the lunar regolith. However, the gross mineralogy of GSC-1 turned out to be surprisingly similar to lunar mare basalts. In addition, UV reflectance of GSC-1 was almost identical to that of returned mare basalt samples. Petrographic study of this diabase showed it to be surprisingly similar in mineralogy, texture, and spectral reflectance to lunar mare basalts, although the samples studied were intentionally chosen to exclude hydrothermally altered parts of the sill. We are conducting engineering and fabrication test of GSC-1 to fabricate shielding material for a lunar outpost. We suggest that study of the widespread Mesozoic diabases and comparison with published description of lunar mare basalts could provide a suitable lunar simulant for engineering applications for future robotic or manned missions. Recently we have obtained sample from northeastern China which are being used as a lunar simulant by Chinese scientists and we are comparing this to our GSC-1 and JSC-1A.