Mars global simulant MGS-1: A Rocknest-based open standard for basaltic martian regolith simulants

In the paper

“Crystalline carbonates were not detected in Rocknest, but evolved gas analysis suggests that one or more carbonate-bearing phases is present (Sutter et al., 2017), such that a mixture could be present, or the carbonates could be poorly crystalline.”

What the sources say

• Supported

  Section 4.6 (CO₂; page not provided) says the carbonate amounts inferred for Rocknest (RN), if present, are below CheMin detection limits. Section 5.2 (Rocknest/Gobabeb Eolian Sediments; page not provided) reports that about 30% of Rocknest’s evolved CO₂ is consistent with carbonate. Together, these support the distinction between no detected crystalline carbonate and evidence suggesting carbonate-bearing material. (LLM, conf=0.91)

  cites Sutter et al., 2017 source

In the paper

“This suggests that a mixture of such salts is likely present, or they are present as amorphous/adsorbed species.”

What the sources say

• Partly supported

  Section 3.3 (page unavailable) says evolved O₂ is consistent with decomposition of an oxychlorine salt such as perchlorate; it does not report detection of evolved ClO₄. Sections 3.1 and 3.2 favor Ca-perchlorate while leaving Mg-perchlorate possible, but do not conclude that a mixture is likely or that the salts occur as amorphous or adsorbed species. (LLM, conf=0.84)

  cites Archer et al., 2014 sourceExperimental — accuracy not yet measured

In the paper

“No crystalline (per)chlorate salts were detected in Rocknest above the ~1 wt.% detection limit, but evolved ClO4 was detected (Archer et al., 2014).”

What the sources say

• Partly supported

  Section 3.1 (page unavailable) says CheMin did not detect a perchlorate salt in Rocknest and that estimated abundances were below its detection limits. Section 3.3 (page unavailable) reports evolved O₂ and chlorinated hydrocarbons consistent with perchlorate decomposition, not detection of evolved ClO₄. The cited passages also do not establish a ~1 wt.% detection limit for (per)chlorate salts. (LLM, conf=0.87)

  cites Archer et al., 2014 sourceExperimental — accuracy not yet measured

In the paper

“The soil itself has a basaltic composition (Yen et al., 2005; Ming and Morris, 2017), derived from a globally basaltic crust (McSween et al., 2009).”

What the sources say

• ?Not checked — no full text of the sourcecites Yen et al., 2005 source
• Supported

  The Summary states that Martian soil and dust have basaltic compositions, directly supporting the clause attributed to Ming and Morris. The separate claim about a globally basaltic crust is cited to McSween et al., not to this source. The supplied copy does not give page numbers. (LLM, conf=0.94)

  cites Ming and Morris, 2017
• ?Not checked — no full text of the sourcecites McSween et al., 2009 source

In the paper

“Oxychlorine species are also present in martian soil and could include (per)chlorate salts (Hecht et al., 2009; Sutter et al., 2017) and/or peroxide species (Clancy et al., 2004; Crandall et al., 2017). Nitrates are also present (Stern et al., 2015).”

What the sources say

• ?Not checked — no full text of the sourcecites Hecht et al., 2009 source
• Supported

  Sutter et al.’s §4.8 (O₂; page not available in our copy) reports oxygen evolved from all examined Gale Crater samples, suggesting oxychlorine phases such as chlorate or perchlorate. That supports the (per)chlorate portion attached to this citation; the sentence cites other works for peroxide species and nitrates. (LLM, conf=0.93)

  cites Sutter et al., 2017 source
• Supported

  The citation to Stern et al. (2015) supports the sentence's nitrate claim, not the preceding oxychlorine claim. The Significance of Results section reports nitrate in a sample representing martian dust/local soil and in two samples from a potential relict lakebed. (LLM, conf=0.92)

  cites Stern et al., 2015 source

In the paper

“Unit cell parameters for Rocknest minerals indicate ~An57 plagioclase (Bish et al., 2013), a mixture of augite and pigeonite (Bish et al., 2013), and ~Fo40 olivine (Morris et al., 2015).”

What the sources say

• Supported

  In Crystalline Components, the paper derives a plagioclase composition of Ca₀.₅₇Na₀.₄₃ from refined unit-cell parameters and reports pigeonite together with augite. Table 1 labels the plagioclase ~An57. The ~Fo40 olivine clause cites Morris et al. (2015), not this source, so it is outside this verdict. (LLM, conf=0.94)

  cites Bish et al., 2013 source
• ?Not checked — no full text of the sourcecites Morris et al., 2015

In the paper

“The surface of Mars is covered by an unconsolidated regolith produced by the combined action of impact comminution, physical erosion by wind, water, and lava, and chemical weathering by fluids and oxidants (mostly early in the history of Mars) (McCauley, 1973; Malin and Edgett, 2000; Golombek and Bridges, 2000; Goetz et al., 2005; Yen et al., 2005; Murchie et al., 2009).”

What the sources say

• ?Not checked — no full text of the sourcecites McCauley, 1973 source
• ?Not checked — no full text of the sourcecites Malin and Edgett, 2000 source
• Partly supported

  The Martian Surface Layer discussion describes sand and dust on Mars and identifies impact, volcanic, and mechanical weathering as sources of sand; it also discusses wind erosion and evidence for a wetter past. It does not establish that Mars is covered by an unconsolidated regolith produced by all the listed processes, particularly erosion by lava and chemical weathering by fluids and oxidants. Page numbers are unavailable in our copy. (LLM, conf=0.86)

  cites Golombek and Bridges, 2000 sourceExperimental — accuracy not yet measured

In the paper

“Most of the older simulant varieties contain almost no sulfur, whereas martian regolith contains up to 6 wt.% SO3 (assuming all S is in the form of sulfate; Yen et al., 2005; Ming and Morris, 2017).”

What the sources say

• ?Not checked — no full text of the sourcecites Yen et al., 2005 source
• Partly supported

  The Chemical Properties section (Table 1; page unavailable) reports 4.90 wt.% SO3 for average Martian soil, supporting the presence of sulfur at roughly the claimed level. But it also reports 7.42 wt.% for dust and a soil maximum of 35.06 wt.%, so 6 wt.% is not an upper limit. The cited paper does not address sulfur in older simulants or state the assumption that all sulfur is sulfate. (LLM, conf=0.88)

  cites Ming and Morris, 2017Experimental — accuracy not yet measured

In the paper

“Martian dust is somewhat chemically distinct from the underlying soil, with a larger component of npOx responsible for its ochre hue (Morris et al., 2001; Berger et al., 2016).”

What the sources say

• ?Not checked — no full text of the sourcecites Morris et al., 2001 source
• Partly supported

  The Results and Discussion report that Martian dust is compositionally similar to soil but enriched in Fe, S, and Cl; the Discussion also concludes that global dust is enriched in nanophase iron oxide (npOx). The cited paper does not say that npOx is responsible for the dust’s ochre hue. Page numbers are unavailable in our copy. (LLM, conf=0.85)

  cites Berger et al., 2016 sourceExperimental — accuracy not yet measured

In the paper

“Soil major element chemistry and mineralogy are quite similar at the Spirit, Opportunity, and Curiosity landing sites (Yen et al., 2013; Ming and Morris, 2017), supporting the presence of a global basaltic soil that may be locally to regionally enriched in rarer evolved volcanic compositions (e.g., Christensen et al., 2005) or alteration phases (e.g., Squyres et al., 2008).”

What the sources say

• ?Not checked — no full text of the sourcecites Yen et al., 2013
• Partly supported

  The Chemical Properties section (page not supplied) says basaltic soil at the Spirit, Opportunity, and Curiosity landing sites has similar composition, supporting the claim about chemistry and a widespread basaltic soil. It also notes differences in local basaltic mineralogies; the Mineralogical Properties section describes minerals observed by the rovers but does not establish that mineralogy is quite similar across all three sites. (LLM, conf=0.83)

  cites Ming and Morris, 2017Experimental — accuracy not yet measured

In the paper

“the SAM instrument detected a broad H2O release in Rocknest starting at low temperatures, finding 2.0 ± 1.3 wt.% total evolved water averaged over four runs (Archer et al., 2014).”

What the sources say

• Supported

  Section 3.1 (page unavailable) reports an average of 2.0 ± 1.3% water released from Rocknest material across four runs; its table identifies H₂O abundances in weight percent. The same section describes a broad H₂O release below 450°C, peaking at 250°C, which supports the low-temperature description. (LLM, conf=0.94)

  cites Archer et al., 2014 source

In the paper

“Mastcam data (filled circles) were reproduced from Fig. 5 in Wellington et al. (2017)”

What the sources say

• Supported

  The Figure 5 caption describes Mastcam reflectance images and a plot of spectra derived from the marked regions. This confirms that Wellington et al. (2017) Figure 5 is a source of Mastcam spectral data; the source paper alone cannot independently verify the citing paper’s reproduction of them. (LLM, conf=0.90)

  cites Wellington et al. (2017) source

In the paper

“Pike et al. (2011) reported that ~1 vol. % of the Phoenix surface materials were <4 µm”

What the sources say

• Partly supported

  The Approach and Results section describes a cumulative-volume particle-size distribution for Phoenix soil, and the Discussion reports less than 0.05% by volume below 2 µm. The passages do not give a volume fraction below 4 µm, so they do not establish the claimed ~1 vol.%. (LLM, conf=0.78)

  cites Pike et al. (2011) sourceExperimental — accuracy not yet measured

In the paper

“Ming and Morris (2017) estimate that due to chemical alteration, 15-25 wt.% of typical soils should consist of clay-sized grains.”

What the sources say

• Supported

  The discussion of clay-sized particles estimates that about 21% of typical Mars soil has undergone chemical alteration and concludes that its clay fraction is reasonably estimated at 15–25 wt.%. The Summary repeats the 15–25 wt.% estimate for martian soil. No page number is provided in our copy. (LLM, conf=0.94)

  cites Ming and Morris (2017)

In the paper

“weighted by the proportions in Table 1, with the actual crystal chemistries of martian silicates from Bish et al. (2013) and Morris et al. (2015).”

What the sources say

• Supported

  The Crystalline Components section gives estimated compositions for Rocknest olivine, plagioclase, pigeonite, and augite, derived from refined unit-cell parameters. These provide the martian silicate chemistries attributed to Bish et al.; the cited paper does not need to describe the citing authors’ MGS-1 weighting procedure. (LLM, conf=0.90)

  cites Bish et al. (2013) source
• ?Not checked — no full text of the sourcecites Morris et al. (2015)

In the paper

“Upon heating and drying, the sodium metasilicate forms a polymer network that acts as a binder, such that the resulting cobbles are solid and quite hard (Fig. 2c).”

In the paper

“These species can be synthesized in amorphous form by evaporating appropriate solutions in vacuum, but they are prone to recrystallize in normal laboratory conditions.”

In the paper

“JSC Mars-1 is not recommended for these applications because it has virtually none of the same minerals as actual Mars soil, and its volatile content (>20 wt.% H2O) is highly unrealistic.”

In the paper

“However, the negative spectral slope at wavelengths >1000 nm in the remote data is not as strong in the simulant, and the simulant is brighter.”

In the paper

“JSC Mars-1 has a significantly higher albedo than the remote measurements, with strong H2O- and OHrelated absorptions at 1400 and 1900 nm.”

In the paper

“The particle size distribution of simulants is highly adjustable through crushing and sieving.”

In the paper

“Other elements such as SiO2, Al2O3, and SO3 are much closer to the measured values from Rocknest, and compare favorably to older martian simulants.”

In the paper

“The MMS-1 and MMS-2 simulants from The Martian Garden company have even higher albedos than JSC-Mars 1, and at shorter wavelengths are dominated by the signature of hematite.”

In the paper

“In the prototype simulants we added crystalline siderite.”

In the paper

“In the prototype simulants we added crystalline iron (III) sulfate pentahydrate.”

In the paper

“Again, due to apparent changes between MMS and MMS-1/2, we do not recommend these simulants.”

In the paper

“The utility of these simulants (JSC Mars-1, MMS, and their updated versions) comes mostly from the fact that they are fine-grained, roughly basaltic composition materials: this may be appropriate for certain uses that do not require high fidelity simulants, but inappropriate for others.”

In the paper

“JSC Mars-1 is extremely hygroscopic, contains >20 wt.% H2O at ambient conditions, and is known to contain significant amounts of organic matter as well.”

In the paper

“Magnetite, anhydrite and hematite were also near the detection limit, but magnetite is important for magnetic properties, anhydrite for sulfur contents, and hematite for pigmenting properties.”

In the paper

“As noted above, the MMS-2 simulant is spiked with sulfates and other phases to resolve discrepancies in bulk chemistry, but the composition on the package confusingly lists both mineral percentages and wt.% oxides in the same table, summing them to 100%.”

In the paper

“By starting with the correct mineral constituents, the derived properties (geotechnical, spectral, chemical, etc.) should fall out of the final product, with adjustments made where necessary based on analyzing initial prototypes.”

In the paper

“However, The Martian Garden company had no contact with the creators of MMS, and their simulants do not resemble the original version (compare Fig. 1d with Fig. 2 in Peters et al. (2008)). The company is instead mining the highly altered red cinder material described by Beegle et al. (2007) instead of the original Saddleback Basalt.”

What the sources say

• ?Not checked — no full text of the sourcecites Peters et al. (2008) source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Beegle et al. (2007)

In the paper

“As well, silicate minerals are likely shocked to various degrees on Mars, whereas the basic MGS-1 standard does not account for this.”

In the paper

“Other Mars simulants have also been developed based on terrestrial basalts, natural weathering profiles, and commercial sand products.”

In the paper

“Here, we describe the Mars Global Simulant (MGS-1), a new open standard designed as a high fidelity mineralogical analog to global basaltic regolith on Mars, as represented by the Rocknest windblown deposit at Gale crater.”

In the paper

“Quantitative mineralogical analysis is not available for either JSC Mars-1, MMS, MMS-1, or MMS-2, although this is not really feasible for JSC Mars-1 due to its mostly amorphous character.”

In the paper

“The most prominent Mars simulant is Johnson Space Center JSC Mars-1 (Allen et al., 1998), which was later reproduced as JSC Mars-1A by Orbitec when the original supply ran out.”

What the sources say

• ?Not checked — no full text of the sourcecites Allen et al., 1998

In the paper

“Dehouck et al. (2014) and Morris et al. (2015) isolated the elemental chemistry of the amorphous component using a mass balance approach (Table 2), showing that it is deficient in SiO2, Al2O3, and CaO, and enriched in SO3 and H2O compared to the bulk soil.”

What the sources say

• ?Not checked — no full text of the sourcecites Dehouck et al. (2014) source
• ?Not checked — no full text of the sourcecites Morris et al. (2015)

In the paper

“The other notable Mars simulant is Mojave Mars (MMS) (Peters et al., 2008), that is not currently available outside of NASA.”

What the sources say

• ?Not checked — no full text of the sourcecites Peters et al., 2008 source

In the paper

“We included crystalline nitrate and perchlorate salts in some of our initial prototypes designed for agricultural studies, but do not include them in the root MGS-1 standard.”

In the paper

“Martian soils have been examined in-situ at seven locations by landers and rovers, with supplemental information from orbital remote sensing.”

In the paper

“Previous simulants often sacrificed accuracy for convenience, had poor documentation, and the resulting products have been assumed to be appropriate for all types of research.”

What the sources say

• ?Not checked — no full text of the sourcecites Taylor et al., 2016 source

In the paper

“Mars Global is not meant to be a perfect standard for simulants (if such a thing exists), and there are almost certainly trace mineral species present in martian soil that aren't represented in MGS-1: these could include phosphates, sulfides, chromates, oxalates, and other rare species.”

In the paper

“These simulants have not yet been widely distributed or adopted.”

In the paper

“Simulants designed to match bulk chemistry might provide a close match to more readily available measurements (from Alpha Particle X-ray Spectrometer instruments, for example), but a simulant could be designed from infinite combinations of random compounds to reproduce the bulk chemistry of a reference material without having any of the right minerals inside of it.”

In the paper

“While we have chosen to add the plagioclase, pyroxene and olivine separately in our prototypes, they could also be added in the form of basalt or ultramafic rocks provided the mineral proportions are accurate.”

In the paper

“Additional phases may be present in an amorphous or poorly-crystalline state, as discussed above.”

In the paper

“soils at the Pathfinder landing site had an estimated bulk density of 1.07-1.64/cm 3 (Moore et al., 1999)”

What the sources say

• ?Not checked — no full text of the sourcecites Moore et al., 1999 source

In the paper

“As well, in the prototypes we did not control for detailed aspects like particle shape that can be important in influencing geotechnical properties, and our initial physical properties measurements in this study are limited.”

In the paper

“The other phases in the MGS-1 standard are available in relatively pure forms from either natural sources or as synthetic chemical supplies.”

In the paper

“TGA data are not available for MMS-1 or MMS-2, but judging from their spectral properties (Fig. 4) these simulants have significant water contents, possibly on par with JSC Mars-1.”

In the paper

“These observed differences may be caused by a combination of differences in crystal chemistry, the specific amorphous compounds present on Mars, shock darkening, as well as the fact that the simulant spectra were measured at ambient laboratory conditions.”

In the paper

“For example, clay-rich Noachian regolith, or perchlorate and nitrate-bearing agricultural soils can be created by adding the desired additional components to the root simulant.”

In the paper

“In the past, simulant production has followed a now predictable lifecycle: the need for a specific simulant arose, a NASA center or private company produced an initial large batch of the simulant, then eventually the batch ran out, or national interest in a given planetary body faded and the simulant was discarded.”

In the paper

“However, the geotechnical properties of actual martian regolith are poorly constrained compared to returned lunar regolith that has been studied extensively on Earth.”

In the paper

“NASA developed the concept of 'root' and 'branch' simulants for the Moon, where the root is a basic, well-characterized version of the simulant.”

In the paper

“Using more accurate Fe- and Ca-rich silicate compositions would result in higher densities.”

In the paper

“drift material at the Viking 1 landing site had an estimated bulk density of 1.15±0.15 g/cm 3 (Moore and Jakosky, 1989)”

What the sources say

• ?Not checked — no full text of the sourcecites Moore and Jakosky, 1989 source

In the paper

“Natural, high-purity sources of fayalitic olivine, pigeonite, and unweathered calcic plagioclase are rare on Earth, but efforts to source them in the future will greatly improve the bulk chemistry of the simulants.”

In the paper

“In this way, there is no batch of MGS-1 to run out, but a general standard to follow.”

In the paper

“Indeed, a group at the Johnson Space Center is also developing a Rocknest-based version of the MMS simulant to be used for ISRU development (Archer et al., 2018).”

What the sources say

• ?Not checked — no full text of the sourcecites Archer et al., 2018

In the paper

“None of the spectra have been offset or scaled.”

In the paper

“MMS has recently been augmented further to achieve even more realistic volatile release patterns (Archer et al., 2018).”

What the sources say

• ?Not checked — no full text of the sourcecites Archer et al., 2018

In the paper

“The significant and unrealistic water contents of JSC Mars-1 were cited as a motivating factor in developing the original MMS simulant (Peters et al., 2008)”

What the sources say

• ?Not checked — no full text of the sourcecites Peters et al., 2008 source

In the paper

“Average of 5 measurements.”

In the paper

“Allen et al. (1998) reported that JSC Mars-1 lost 21.1 wt.% (mostly water) when heated to 600 °C”

What the sources say

• ?Not checked — no full text of the sourcecites Allen et al. (1998)

In the paper

“However, sourcing this kind of material presents its own set of challenges, and usually requires a large capital investment if the right material is not already being mined.”

In the paper

“These minerals have been crushed into powders and analyzed by XRD, VNIR spectroscopy, and X-ray Fluorescence (XRF) to verify their identity and detect any contaminants present.”

In the paper

“The TEGA instrument did not a detect low temperature water release in soil samples at the Phoenix landing site (Smith et al., 2009), but did detect a minor H2O release starting at 295 °C and a major release starting at 735 °C.”

What the sources say

• ?Not checked — no full text of the sourcecites Smith et al., 2009 source

In the paper

“The prototype simulants were analyzed using a variety of imaging techniques and bulk analyses. Results from these analyses were compared to relevant datasets from various orbital and in-situ spacecraft measurements as appropriate.”

In the paper

“The differences between the MGS-1 based simulant and Rocknest could be due to hygroscopicity in a humid terrestrial atmosphere, and the exact nature of the amorphous component in Rocknest is probably key to understanding the unique water release patterns measured by SAM (Archer et al., 2018).”

What the sources say

• ?Not checked — no full text of the sourcecites Archer et al., 2018

In the paper

“Mojave Mars Simulant was developed specifically for geotechnical applications (Peters et al. 2008)”

What the sources say

• ?Not checked — no full text of the sourcecites Peters et al. 2008 source

In the paper

“MGS-1 will benefit from the same scheme, where the recipe in Table 1 forms the basic root, and various branches can be created either by us or others.”

In the paper

“Peters et al. (2008) report that MMS lost 1.7 wt.% by 100 °C and 7.2 wt.% by 500 °C.”

What the sources say

• ?Not checked — no full text of the sourcecites Peters et al. (2008) source

In the paper

“Unlike previous simulants sourced from landscaping material, Mars Global is meant to be assembled ab initio from pure components to provide an accurate match to the mineralogy of martian regolith.”