Character and Spatial Distribution of OH/H
            <sub>2</sub>
            O on the Surface of the Moon Seen by M
            <sup>3</sup>
            on Chandrayaan-1

Pieters, C. M.; Goswami, J. N.; Clark, R. N.; Annadurai, M.; Boardman, J.; Buratti, B. J.; Combe, Jean-Philippe; Dyar, M. D.; Green, R.; Head, J. W.; Hibbitts, C. A.; Hicks, M.; Isaacson, P.; Klima, R. L.; Kramer, G.; Kumar, Shashi; Livo, Eric; Lundeen, S.; Malaret, E.; McCord, T. B.; Mustard, John F.; Nettles, J. W.; Petro, N. E.; Runyon, C.; Staid, M.; Sunshine, J. M.; Taylor, L. A.; Tompkins, S.; Varanasi, P.

doi:10.1126/science.1178658

Cited by 700 publications

(435 citation statements)

References 24 publications

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“…† For example, there is intense interest in water at the poles of the Moon (10,(25)(26)(27). A fundamental and as-yet unresolved question is the source of the water.…”

Section: Discussionmentioning

confidence: 99%

Detection of solar wind-produced water in irradiated rims on silicate minerals

Bradley

Ishii

Gillis-Davis

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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The solar wind (SW), composed of predominantly ∼1-keV H + ions, produces amorphous rims up to ∼150 nm thick on the surfaces of minerals exposed in space. Silicates with amorphous rims are observed on interplanetary dust particles and on lunar and asteroid soil regolith grains. Implanted H + may react with oxygen in the minerals to form trace amounts of hydroxyl (−OH) and/or water (H 2 O). Previous studies have detected hydroxyl in lunar soils, but its chemical state, physical location in the soils, and source(s) are debated. If −OH or H 2 O is generated in rims on silicate grains, there are important implications for the origins of water in the solar system and other astrophysical environments. By exploiting the high spatial resolution of transmission electron microscopy and valence electron energy-loss spectroscopy, we detect water sealed in vesicles within amorphous rims produced by SW irradiation of silicate mineral grains on the exterior surfaces of interplanetary dust particles. Our findings establish that water is a byproduct of SW space weathering. We conclude, on the basis of the pervasiveness of the SW and silicate materials, that the production of radiolytic SW water on airless bodies is a ubiquitous process throughout the solar system. solar wind radiolysis | prebiotic water | cosmic dust | astrobiology | aberration-corrected scanning transmission electron microscopy T here are two principal space weathering processes, solar wind (SW) ion irradiation and micrometeorite impacts, that produce rims on exposed mineral surfaces (1). Our focus here is on SW irradiation because of its possible connection to the production of water and hydroxyl radicals (2-5). Space-weathered rim thicknesses vary with the densities of implanted solar flare (SF) tracks, and track densities depend on the exposure ages of individual interplanetary dust particles (IDPs) in space. On lunar soil grains and grains on surfaces of IDPs, rims are typically 75-150 nm thick with SF track densities of 10 10 -10 11 cm −2 that are consistent with 10 4 -to 10 5 -y SW exposure ages (6, 7) ( Fig. 1 B-D). Rims on asteroid Itokawa regolith grains are 30-60 nm thick with SF track densities of 5 × 10 9 cm −2 that are consistent with ∼10 3 -y exposure ages (8) (Origins and Properties of Rims on IDPs, Asteroid Itokawa, and Lunar Soil Grains). This correlation between amorphous rim thicknesses and SF track densities indicates that SW irradiation is the primary mechanism for amorphous rim formation. We examine rims on surface grains in IDPs because they are solely due to SW irradiation, whereas rims on lunar soil grains are due to SW irradiation, impact vapor deposition, or a combination of both (9), and remote observations suggest that if water is indeed produced in rims on lunar soil grains, it is not efficiently retained (10). Typical 5-to 25-μm diameter chondritic porous (CP) IDPs are low-density aggregates of predominantly submicrometer-sized grains, and they are collected in the stratosphere (11) (Fig. 1 A-D and Origins of CP IDPs). Chemical ana...

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“…† For example, there is intense interest in water at the poles of the Moon (10,(25)(26)(27). A fundamental and as-yet unresolved question is the source of the water.…”

Section: Discussionmentioning

confidence: 99%

Detection of solar wind-produced water in irradiated rims on silicate minerals

Bradley

Ishii

Gillis-Davis

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…Hydroxyl-and/or water-bearing materials are widely spread across the lunar surface (Pieters et al 2009). …”

Section: Water In the Planetsmentioning

confidence: 99%

“…Searches for water and OH features in near-Earth objects (NEOs) were upended by the discovery of OH in the lunar regolith by three spacecraft Pieters et al 2009;Clark 2009). Detections of water and/or hydroxyl on large asteroids have been reported for (175706) 1996 FG3 (Rivkin et al 2015), (16) Psyche (Takir et al 2017), and (433) Eros and (1036) Ganymede .…”

Section: Evidence For Water In Asteroidsmentioning

confidence: 99%

The Main Belt Comets and ice in the Solar System

Snodgrass

Agarwal

Combi

et al. 2017

Astron Astrophys Rev

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We review the evidence for buried ice in the asteroid belt; specifically the questions around the so-called Main Belt Comets (MBCs). We summarise the evidence for water throughout the Solar System, and describe the various methods for detecting it, including remote sensing from ultraviolet to radio wavelengths. We review progress in the first decade of study of MBCs, including observations, modelling of ice survival, and discussion on their origins. We then look at which methods will likely be most effective for further progress, including the key challenge of direct detection of (escaping) water in these bodies.

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“…Evidence for hydroxyl/water on the lunar surface has been detected by using remote sensing data from the Moon Mineralogy Mapper (M 3 ) instrument on board the Chandrayaan-1 spacecraft (17)(18)(19). Moreover, evidence for water within the lunar interior has been reported through ongoing lunar sample analysis efforts.…”

mentioning

confidence: 99%

Nominally hydrous magmatism on the Moon

McCubbin

Steele

Hauri

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

275

185

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For the past 40 years, the Moon has been described as nearly devoid of indigenous water; however, evidence for water both on the lunar surface and within the lunar interior have recently emerged, calling into question this long-standing lunar dogma. In the present study, hydroxyl (as well as fluoride and chloride) was analyzed by secondary ion mass spectrometry in apatite [Ca 5 ðPO 4 Þ 3 ðF,Cl,OHÞ] from three different lunar samples in order to obtain quantitative constraints on the abundance of water in the lunar interior. This work confirms that hundreds to thousands of ppm water (of the structural form hydroxyl) is present in apatite from the Moon. Moreover, two of the studied samples likely had water preserved from magmatic processes, which would qualify the water as being indigenous to the Moon. The presence of hydroxyl in apatite from a number of different types of lunar rocks indicates that water may be ubiquitous within the lunar interior, potentially as early as the time of lunar formation. The water contents analyzed for the lunar apatite indicate minimum water contents of their lunar source region to range from 64 ppb to 5 ppm H 2 O. This lower limit range of water contents is at least two orders of magnitude greater than the previously reported value for the bulk Moon, and the actual source region water contents could be significantly higher. O ne of the scientific discoveries resulting from the Apollo missions was the pervasive waterless nature of the Moon and its rocks. The initial studies of the returned samples were pristine and showed no evidence of aqueous alteration, and water analyses were below detection limits. Moreover, hydrous phases were absent from the lunar rocks aside from a few unconfirmed reports of possible amphibole grains (1), which are now considered by many to represent either misidentifications or terrestrial contamination (as summarized by ref. 2). The subsequent forty years of lunar sample analysis have only supported and strengthened the idea that indigenous water was nearly absent from the Moon's interior. In fact, this conclusion has been incorporated into many petrologic and geophysical models constructed to aid in our understanding of lunar formation and lunar geology (3-11). The bulk water content of the Moon was recently estimated to be less than 1 ppb (11), which would make the Moon at least six orders of magnitude drier than the interiors of Earth (12, 13) and Mars (14). This extremely low water content is in keeping with the pervasive volatile-element depletion signature recorded in all lunar materials, because hydrogen is the most volatile of the elements. The exact cause for this volatile-element depletion is still under question; however, many have argued that it stems from the high temperatures associated with the Moon-forming giant-impact event at ∼4.5 Ga (i.e., refs. 3,8,15,and 16).Facilitated by advancements in analytical detection sensitivities for water, several recent discoveries have indicated that the story of water on the Moon is far from complete. Evi...

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Character and Spatial Distribution of OH/H ₂ O on the Surface of the Moon Seen by M ³ on Chandrayaan-1

Cited by 700 publications

References 24 publications

Detection of solar wind-produced water in irradiated rims on silicate minerals

Detection of solar wind-produced water in irradiated rims on silicate minerals

The Main Belt Comets and ice in the Solar System

Nominally hydrous magmatism on the Moon

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Character and Spatial Distribution of OH/H 2 O on the Surface of the Moon Seen by M 3 on Chandrayaan-1

Cited by 700 publications

References 24 publications

Detection of solar wind-produced water in irradiated rims on silicate minerals

Detection of solar wind-produced water in irradiated rims on silicate minerals

The Main Belt Comets and ice in the Solar System

Nominally hydrous magmatism on the Moon

Contact Info

Product

Resources

About

Character and Spatial Distribution of OH/H ₂ O on the Surface of the Moon Seen by M ³ on Chandrayaan-1