NASA GreenSpar Lunar Simulant Abstract: “GREENLAND ‘WHITE MOUNTAIN’ ANORTHOSITE: A NEW LUNAR POLAR REGOLITH SIMULANT COMPONENT.”

GREENLAND ‘WHITE MOUNTAIN’ ANORTHOSITE: A NEW LUNAR POLAR REGOLITH SIMULANT COMPONENT. J. E. Gruener 1 , S. R. Deitrick 2 , V. M. Tu 2 , J. V. Clark 3 , D. W. Ming 1 , and J. Cambon 4 , 1 NASA Johnson Space Center, Houston, Texas ([email protected]), 2 Jacobs NASA Johnson Space Center, Houston, Texas, 3 Geocontrols Systems – Jacobs JETS Contract, NASA Johnson Space Center, Houston, Texas, 4 Hudson Resources, Inc., Vancouver, BC, Canada.

Introduction: The National Aeronautics and Space Administration (NASA) has been tasked by the National Space Council to land humans near the south pole of the Moon by 2024. This landing would mark the return of humans to the Moon, the first since the end of NASA’s Apollo Program in 1972. The 2024 mission is part of a much larger NASA program, called Artemis, that also includes a cis-lunar Gateway orbiting spaceship and human missions to Mars.

While the immediate focus on the 2024 mission, Space Policy Directive 1 calls for “the return of humans to the Moon for long-term exploration and utilization”. Equipment and systems will thus need to operate for long periods of time in the harsh lunar environment, and most surface systems will have some kind of interaction with the lunar regolith.

In order to thoroughly test these systems on Earth, NASA’s Space Technology Mission Directorate (STMD) is funding the development of ‘high-fidelity’ lunar simulants.

Lunar Polar Regolith: The lunar polar regions are included in a terrain type known as Feldspathic Highlands Terrane [2]. The Apollo 16 mission was the only human mission to a highlands landing site. While the Apollo 16 regolith also has mare and KREEP (potassium, rare-earth elements, phosphorus) components, Korotev [3] suggests that feldspathic lunar meteorites may best approximate the composition of the surface of the feldspathic highlands at large, including the far side and polar regions. Mineralogically, the highlands are dominated by plagioclase feldspar [4].

Existing Lunar Polar Regolith Simulants: During NASA’s Constellation Program (2005-2010), NASA and the United States Geological Survey (USGS) developed a lunar highlands type simulant (NU-LHT) to prepare for possible missions to the lunar poles [5]. This simulant was based on the Apollo 16 regolith, and used anorthosite from the Stillwater mine in Nye, Montana. Also in this timeframe, two similar lunar highland simulants, OB-1 and CHENOBI, were produced in Canada, using the Shawmere anorthosite [6]. More recently, the University of Central Florida (LHS-1) and Off Planet Research (OPRH series) are actively making lunar highlands simulants [7].

Greenland Anorthosite: Hudson Resources, Inc. is mining surface exposed anorthosite with their White Mountain Anorthosite Project, located approximately 85 km southwest of Kangerlussuaq, Greenland. Knudsen et al. [8] refer to this material as the Qaqortorsuaq anorthosite, found in Archean basement rocks, and report a CIPW plagioclase content of 94 wt.%, with an AN number of 83. Table 1 lists the major oxides in the anorthositic material, known as GreenSpar, at the White Mountain Project. The GreenSpar product is available in two size ranges, GreenSpar 250 and GreenSpar 90.

NASA Johnson Space Center’s Astromaterials Research and Exploration Science (ARES) division has conducted a preliminary analysis on the GreenSpar 250 material, for possible use as a lunar highlands and polar regolith simulant component.

Table 1. List of major oxides (average wt.%) for White Mountain feldspar. XRF data provided by Hudson Resources.

A CIPW Norm calculation based on the chemistry XRF data provided by Hudson Resources resulted in a plagioclase content of 94 wt. %, similar to Knudsen et al. X-ray diffraction analyses and whole pattern fitting and Rietveld refinement suggest a plagioclase content of approximately 82 wt. %. Other mineral components identified include pyroxene (~5 wt.%), quartz (~7 wt. %), and ~6 wt.% of an assemblage of minor minerals (muscovite, calcite, chamosite, and orthoclase). Laser particle size distribution analysis of the GreenSpar 250 material indicated a particle size range of 250-3 m, with a graphical mean particle size of 76 m. Thermal and evolved gas analysis resulted in only a very small amount of gases produced (~0.8 wt.% loss through heating up to 1000 °C), with CO2 being the most significant gas release (likely form the calcite present in the material). Further analyses will be conducted, to better determine the specific usefulness of this potential lunar polar regolith component.

Discussion: Initial analyses suggests that the White Mountain anorthosite (aka GreenSpar) would be useful as a mechanical simulant for testing of systems and components bound for the Moon. While quartz is quite rare on the Moon, the abrasiveness of the quartz in GreenSpar may be useful in simulating the abrasiveness of the lunar regolith. For large-scale testing facilities, such as the NASA Kennedy Space Center Granular Mechanics and Regolith Operations Laboratory (i.e., Swamp Works) [9], bulk GreenSpar may be useful asis. A higher-fidelity simulant would likely have glass, other rocks/minerals, agglutinates, and possibly ice added to the GreenSpar for smaller-scale testing in laboratory environments. While the White Mountain anorthosite is mined in Greenland, large amounts (10s to 100s of tons) of crushed GreenSpar material are stored in warehouses in Charleston, South Carolina for use in the United States. Also, since the mine site is located near a deep-water port in a fjord, this anorthosite could be useful for other international space agencies around the world via ocean shipping.

References:

[1] https://www.whitehouse.gov/presidentialactions/presidential-memorandum-reinvigoratingamericas-human-space-exploration-program/.

[2] Jolliff B. L. et al. (2000) JGR, 105, 4197–4216.

[3] Korotev R. L. et al. (2003) Geochim Cosmochim Acta, 67, 4895-4923. [4] Heiken G. et al. (1991) Lunar Sourcebook, Cambridge Univ. Press. [5] Stoeser D. B. et al. (2010) NASA TM-2010-216438. [6] Battler M. M. et al. (2009) Planetary and Space Science, 57, 2128-2131. [7] . [8] Knudsen C. et al. (2012) Geol. Surv. Denm. & Greenl. Bul. 26, 53-56. [9] https://sciences.ucf.edu/class/planetarysimulant-database/ https://kscpartnerships.ksc.nasa.gov/PartneringOpportunities/Capabilities-and-Testing/Testing-andLabs/Granular%20Mechanics%20and%20Regolith%2 0Operations%20Lab