Thermal properties of processed lunar regolith simulant

Abstract

Future exploration of the Moon is in the exploration roadmaps of major space agencies1, as is the need to make such exploration a sustainable endeavor. In this context, In‐Situ Resource Utilisation (ISRU) is attracting a considerable degree of attention as a means to realize such sustainable exploration ambition. Regarding lunar ISRU, the focus has predominantly been on utilizing the loose (bulk) regolith material abundantly found on the lunar surface, as a source of volatiles or potentially utilized in construction.2‒4 In the context of terrestrial testing with regolith or investigating ISRU applications, the available actual lunar soil for laboratory experiments is scarce as less than 400 kg was returned from the Apollo missions.5 This hinders the use of actual lunar regolith for in situ construction investigation, which would necessitate altering the regolith samples. Hence, simulant materials are used for such investigations. Materials on the Moon are divided in two categories of anorthositic (highlands) and basaltic (maria) rocks. As reported, lunar regolith contains several minerals such as pyroxene (augite, diopside, enstatite, hedenbergite), plagioclase (anorthite, albite), olivine (fayalite, forsterite), and oxides (ilmenite, magnetite, hematite) which are also known in terrestrial rocks.6 Based on the reported data6 of actual lunar samples, simulants created from mined volcanic ashes have been developed in order to enable the use of terrestrial materials for lunar application. Regarding the lunar simulant development, Johnson Space Center (JSC) from National Aeronautics and Space Administration (NASA) mimicked Apollo samples of 14 163, (using Arizona mined volcanic sediments) by categorizing a lunar regolith simulant called JSC‐1, which represented the mare regolith with low titanium content.7 Over time and as needs demanded, different space agencies introduced various simulants such as DNA (mare simulant), FJS (mare simulant in three different types with low and high titanium content), and NU‐LHT (highlands).8 Nonetheless, JSC‐1 is among the widely used and published test materials so far and its chemical and physical properties such as minerals and particles size distribution are well evaluated and compared to the actual lunar Apollo samples.7 Received: 5 December 2018 | Revised: 20 February 2019 | Accepted: 26 April 2019 DOI: 10.1111/ijac.13267