JSC-1

JSC-1, a lunar soil simulant, was developed and characterized under the auspices of the NASA Johnson Space Center. This simulant was produced in large quantities to satisfy the requirements of a variety of scientific and engineering investigations. JSC-1 is derived from volcanic ash of basaltic composition, which has been ground, sized, and placed into storage. The simulant's chemical composition, mineralogy, particle size distribution, specific gravity, angle of internal friction, and cohesion have been characterized and fall within the ranges of lunar mare soil samples.

JSC-1 was produced specifically for large- and medium-scale engineering studies in support of future human activities on the Moon. Such studies include material handling, construction, excavation, and transportation. The simulant is also appropriate for research on dust control, spacesuit durability, and agriculture. JSC-1 is currently being used in studies of oxygen production and sintering. The simulant is available in large quantities to any qualified investigator.

This material complements, but does not replace, lunar simulant MLS-1, produced by the University of Minnesota (Weiblen et al, 1990). MLS-1 is derived from a high-titanium basalt hornfels which approximates the chemical composition of Apollo 11 soil The starting material is totally crystalline. As described below, JSC-1 approximates a low-titanium mare soil, and contains a high percentage of glass.

Source

JSC-1 was mined from a volcanic ash deposit located in the San Francisco volcano field near Flagstaff, AZ. This ash was erupted from vents related to Merriam Crater (35°20' N, 111°17' W). One basalt flow from a nearby vent has a K-Ar age of 0.15 ± 0.03 million years. The exposure is described as "airfall ash and lapilli, usually black, locally red, as much as several meters thick ... (which) forms broad, smooth-surfaced deposits over large areas" (Moore and Wolfe, 1987). The source quarry is within an area mapped by these authors as "slightly porphyritic basalt".

Preparation

The ash was mined from a commercial cinder quarry near the south flank of Merriam Crater. Following coarse sieving the ash was comminuted in an impact mill. This method broke down the material by means of multiple impacts with other ash particles, resulting in minimal metal contamination. The ash from several millings was allowed to partially dry in air and was then mixed. The average water content of the final mix was 2.70 ± 0.31 wt. %. The material, in 45 - 50 lb quantities, was loaded into plastic bags and the bags were heat sealed.

Characterization

Chemical Composition

The results of x-ray fluorescence (XRF) analysis are presented in Table 1. Samples were allowed to dry in air for approximately two months prior to analysis. The crushed rock was ground to pass an 80 mesh (177 μm) sieve. Oxide abundances, loss on ignition, and Fe₂O₃ / FeO partitioning were determined by the methods of Boyd and Mertzman (1987).

The loss on ignition (LOI) value was derived by heating samples in argon for one hour at 900°C. This value reflects the loss of volatiles, including water as well as sulfur and chlorine compounds. The analyses were performed on well-dried samples, and reflect lower water contents than those of samples from newly-opened bags.

Table 1: Major Element Compositions
	JSC-1 (mean of 3)		Lunar Soil 14163*
Oxide	Conc.	Std. Dev.	Conc.
	Wt %	Wt %	Wt %
SiO2	47.71	0.10	47.3
TiO2	1.59	0.01	1.6
Al2O3	15.02	0.04	17.8
Fe2O3	3.44	0.03	0.0
FeO	7.35	0.05	10.5
MgO	9.01	0.09	9.6
CaO	10.42	0.03	11.4
Na2O	2.70	0.03	0.7
K2O	0.82	0.02	0.6
MnO	0.18	0.00	0.1
Cr2O3	0.04	0.00	0.2
P2O5	0.66	0.01	...
LOI	0.71	0.05	...
Total	99.65		99.8
LOI = Loss on ignition * Papike et al (1982)

The results of x-ray fluorescence (XRF) analysis are presented in Table 1. Samples were allowed to dry in air for approximately two months prior to analysis. The crushed rock was ground to pass an 80 mesh (177 μm) sieve. Oxide abundances, loss on ignition, and Fe₂O₃ / FeO partitioning were determined by the methods of Boyd and Mertzman (1987).

Table 2. Trace Element Concentrations in JSC-1
Element	Conc. (ppm)	Std. Dev. (ppm)	Element	Conc. (ppm)	Std. Dev. (ppm)
Sc	29.2	0.5	Yb	1.99	0.04
Co	47.7	1.6	Zr	125	3
Ni	137	18	Hf	3.55	0.08
Rb	12.3	1.5	Ta	1.96	0.04
Cs	0.339	0.012	U	1.51	0.08
Sr	860	36	Th	5.65	0.07
Ba	822	13	As	18.7	8.9
La	48.2	0.9	Se	< 0.5	0.0
Ce	94.6	1.7	Sb	0.564	0.569
Nd	42	2	W	36.1	2.6
Sm	7.44	0.13	Au (ppb)	40.7	29.4
Eu	2.18	0.04	Br	0.85	0.07
Tb	0.825	0.012	Lu	0.293	0.007

The loss on ignition (LOI) value was derived by heating samples in argon for one hour at 900°C. This value reflects the loss of volatiles, including water as well as sulfur and chlorine compounds. The analyses were performed on well-dried samples, and reflect lower water contents than those of samples from newly-opened bags.

The trace element concentrations in JSC-1 are listed in Table 2. These data were averaged from instrumental neutron activation analyses (INAA) performed on three samples. The samples, loaded into pure silica tubes, were irradiated the University of Missouri Research Reactor Facility for 20 hours each at a flux of 7.6 x 1013 n/cm2-sec. Counting and data reduction were performed at the Johnson Space Center.

Mineralogy

The major mineral species in JSC-1 samples were identified by x-ray diffraction (XRD), optical microscopy, and scanning electron microscopy (SEM). Qualitative elemental abundances were determined for some SEM samples by energy-dispersive x-ray spectrometry (EDS). The major crystalline phases are plagioclase, pyroxene and olivine. Minor minerals include the oxides ilmenite and chromite, plus traces of clay. The glass and minerals in a typical grain are shown in Figure 1.

File:JSC-1-1.png

Figure 1. JSC-1 grains in polished section. Phases include glass (GL), plagioclase (PL) and olivine (OL). SEM back-scattered electron image. Frame width = 520 μm. Photo Credit: NASA

File:JSC-1-2.png

Figure 2. JSC-1 glass (GL) and olivine (OL) grains. SEM secondary electron image. Frame width = 1100 μm. Photo Credit: NASA

File:JSC-1-5.png

Figure 5. Lunar mare soil grain (78221,8) in polished section. Phases include glass (GL), plagioclase (PL), pyroxene (PX), and ilmenite (IM). SEM back-scattered electron image. Frame width = 660 μm. Photo Credit: NASA

External Links

• NASA JSC-1 Lunar Simulant - LPI