David W. Mittlefehldt

• Ph.D.
• Researcher at NASA/Johnson Space Center

Eucrites exhibit a range of igneous and metamorphic textures and geochemistries that can be used to study the evolution of early planetary differentiation and crust formation in the solar system. We integrated petrologic/textural observations, in-situ geochemical analyses, and thermodynamic modeling to explore the petrogenesis of Elephant Moraine (...

We report petrologic studies and oxygen isotope analyses of normal and anomalous eucrites, termed eucrite-type achondrites. Petrologically anomalous eucrite-type achondrites can have normal oxygen isotope compositions, and vice versa. Two basaltic eucrites with normal oxygen isotope compositions contain pyroxenes with anomalous Fe/Mn engendered by...

We have used Mars Exploration Rover Opportunity data to investigate the origin and alteration of lithic types along the western rim of Noachian‐aged Endeavour crater on Meridiani Planum. Two geologic units are identified along the rim: the Shoemaker and Matijevic formations. The Shoemaker formation consists of two types of polymict impact breccia:...

Petrogenetic relationships among members of the brachinite family were established by analyzing major and trace element concentrations of minerals for 9 representative specimens: Al Huwaysah 010, Eagles Nest, Northwest Africa (NWA) 4882, NWA 5363, NWA 7297, NWA 7299, NWA 11756, Ramlat as Sahmah (RaS) 309, and Reid 013. The brachinite family, which...

A geologic traverse along the rim of the 22-km-diameter Endeavour Crater by the Opportunity Mars rover has provided the first field geologic observations of outcrop-scale structure and stratigraphy at a complex impact crater, characteristics that were previously undocumented due to erosion of similar-size craters on Earth. Two findings of note are...

Quantifying the amounts of various igneous lithologies in Vesta’s crust allows the estimation of petrologic ratios that describe the asteroid’s global differentiation and subsequent magmatic history. The eucrite:diogenite (Euc:Diog) ratio measures the relative proportions of mafic and ultramafic components. The intrusive:extrusive (I:E) ratio asses...

Ureilite meteorites contain iron silicide minerals including suessite (Fe,Ni)3Si, hapkeite (Fe2Si) and xifengite (Fe5Si3). Despite occurring mostly in brecciated varieties presumed to be derived from the regolith of the ureilite parent asteroid, suessite has also been confirmed in one lithology of a dimict ureilite (NWA 1241). In contrast, Si-beari...

The howardite-eucrite-diogenite (HED) clan of meteorites represents a suite of mafic to ultramafic igneous rocks and breccias of them. They are linked together by O-isotope compositions [e.g., 1] and likely originate from the differentiated asteroid, 4 Vesta [2]. Radiogenic chronometers point to magmatic differentiation on the HED parent occurring...

Combined analyses of the surface elemental composition and mineralogy of Vesta and Ceres provide insights into their interior evolution, crustal formation, and regolith processes. Compositional data acquired by Dawn's Visible to Infrared Mapping Spectrometer (VIR) and Gamma Ray and Neutron Detector (GRaND) are sensitive to different depths and spat...

We report the results of geological studies by the Opportunity Mars rover on the Endeavour Crater rim. Four major units occur in the region (oldest to youngest): the Matijevic, Shoemaker, Grasberg and Burns formations. The Matijevic formation, consisting of fine-grained clastic sediments, is the only pre-Endeavour-impact unit and might be part of t...

Bunburra Rockhole is the first recovered meteorite of the Desert Fireball Network. We expanded a bulk chemical study of the Bunburra Rockhole meteorite to include major, minor and trace element analyses, as well as oxygen and chromium isotopes, in several different pieces of the meteorite. This was to determine the extent of chemical heterogeneity...

The Emmaville eucrite is a relatively poorly studied basaltic achondrite with an anomalous oxygen isotope signature. In this study, we report comprehensive mineralogical, petrographic, and geochemical data from Emmaville in order to understand its petrogenesis and relationship with the basaltic eucrites. Emmaville is an unusually fine-grained, horn...

We investigate the depth, variability, and history of regolith on asteroid Vesta using data from the Dawn spacecraft. High-resolution (15-20 m pixel⁻¹) Framing Camera images are used to assess the presence of morphologic indicators of a shallow regolith, including the presence of blocks in crater ejecta, spur-and-gully-type features in crater walls...

Mars Reconnaissance Orbiter HiRISE images and Opportunity rover observations of the ~22 km wide Noachian age Endeavour Crater on Mars show that the rim and surrounding terrains were densely fractured during the impact crater-forming event. Fractures have also propagated upward into the overlying Burns formation sandstones. Opportunity’s observation...

Endeavour crater (2.28°S, 354.77°E) is a Noachian-aged 22 km-diameter impact structure of complex morphology in southern Meridiani Planum. The degradation state of the crater has been studied using orbital data from the Mars Reconnaissance Orbiter and in situ data from the Opportunity rover. Multiple exposed crater rim segments range in elevation f...

The globally-averaged concentrations of radioelements K and Th within Vesta’s regolith are determined from gamma ray spectra acquired by Dawn’s Gamma Ray and Neutron Detector (GRaND). Spectra measured by GRaND’s bismuth germanate (BGO) scintillator, while in close proximity to Vesta, are analyzed. Improvements in data reduction and analysis methods...

Melting experiments of a synthesized, alkali-bearing, H-chondrite composition were conducted at ambient pressure with three distinct oxygen fugacity conditions (IW-1, IW, and IW+2). Oxygen fugacity conditions significantly influence the compositions of partial melts. Partial melts at IW-1 are distinctly enriched in SiO2 relative to those of IW and...

More than 200 years after its discovery, asteroid (4) Vesta is thought to be the parent body for the howardite, eucrite and diogenite (HED) meteorites. The Dawn spacecraft spent ∼14 months in orbit around this largest, intact differentiated asteroid to study its internal structure, geology, mineralogy and chemistry. Carrying a suite of instruments...

PADME is a proposed NASA Discovery mission to investigate the origin of two remarkable and enigmatic small bodies, Phobos and Deimos, the two moons of Mars.

In situ mapping identifies outcrops with enhanced aqueous and low-grade thermal alteration at structural boundaries between Endeavour crater rim segments.

Samples analyzed at Meridiani Planum, Gusev Crater, and Gale Crater show similar signatures of open-system chemical weathering.

Diogenite NWA 5480, potentially a sample of the interior of asteroid Vesta, is unique with mantle deformation features and preservation of a magnetic field.

We report new mineral chemistry and trace element abundances of a composite of ferroan anorthosite clasts contained in the lunar breccia 64435.

Opportunity is traversing rim segments of the 22-km-diameter Endeavour crater in Meridiani Planum and indicates variable but substantial degradation occurred.

Using the Mars Exploration Rover Opportunity, we have compiled one of the first field geologic maps on Mars while traversing the Noachian terrain along the rim of the 22-km diameter Endeavour crater (Lat -2° 16’ 33”, Long -5° 10’ 51”). In situ mapping of the petrographic, elemental, structural, and stratigraphic characteristics of outcrops and rock...

We used Dawn spacecraft data to identify and delineate geological units and landforms in the Marcia quadrangle of Vesta as a means to assess the role of the large, relatively young impact craters Marcia (~63. km diam.) and Calpurnia (~53. km diam.) and their surrounding ejecta field on the local geology. We also investigated a local topographic hig...

The howardite, eucrite and diogenite (HED) clan of meteorites are ultramafic and mafic igneous rocks and impact-engendered fragmental debris derived from a thoroughly differentiated asteroid. Earth-based telescopic observation and data returned from vestan orbit by the Dawn spacecraft make a compelling case that the asteroid (4) Vesta is the parent...

The collection of meteorites from Antarctica has greatly expanded the numbers and diversities of achondrite and iron meteorites available for study. This has allowed for the development of more robust models for magmatic processes on strongly heated asteroids. This chapter focuses on meteorite types that sample a range of regions in their parent as...

We report noble gas data of helium (He), neon (Ne), argon (Ar), krypton (Kr) and xenon (Xe), cosmic ray exposure (CRE) ages and nominal gas retention (K–Ar, U–Th–He) ages for seven howardites (CRE 01400, EET 87513, EET 87518, EET 99400, GRO 95535, GRO 95602, SAN 03472), in continuing research to identify regolithic samples, and better understand th...

Vesta spectra have prominent near-infrared absorption bands characteristic of pyroxenes, indicating a direct link to the howardite, eucrite and diogenite meteorites. Many localized dark and bright materials are present on Vesta’s surface. Here we focus on the bright material (BM) units to determine their spectral properties, their origin, the prese...

Remote sensing data acquired during Dawn’s orbital mission at Vesta showed several local concentrations of high-albedo (bright) and low-albedo (dark) material units, in addition to spectrally distinct meteorite impact ejecta. The thermal behavior of such areas seen at local scale (1–10 km) is related to physical properties that can provide informat...

We produced two 1:250,000 scale geologic maps of the adjacent quadrangles Av-6 Gegania and Av-7 Lucaria, located in the equatorial region of (4) Vesta (0º E – 144º E, 22º S – 22º N). The mapping is based on clear and color filter images of the Framing Camera (FC) onboard the Dawn spacecraft, which has captured the entire illuminated surface of Vest...

Like the Earth and other terrestrial planets, the asteroid Vesta has a basaltic crust and a large iron core [Russell, et al. (2012); De Sanctis, (2012)]; its surface is dominated by impact craters of all sizes and has tectonic features. The presence of basaltic compositions, olivine, howardite–eucrite–diogenite (HED) meteorites, and models of Vesta...

We present new O- and Cr-isotope and bulk chemistry for Bunburra Rockhole. It comes from a different parent than basaltic eucrites.

We will report min-pet, in situ trace element studies, Nd/Sr-isotope studies, and Ar-Ar chronology of the 64435 anorthosite and troctolitic anorthosites.

MIL 07001 is an unusual unbrecciated, olivine-bearing diogenite. Our petrological and compositional studies aim to put it in vestan differentiation context.

Vesta, the HED parent body, experienced complex igneous processes, and olivine and diogenite distribution is a key to understand its evolution.

Abundances of radioelements K and Th measured by Dawn’s gamma-ray spectrometer are consistent with Vesta's identification as the HED parent body.

We are examining geological structures in the walls of vestan craters using Dawn Framing Camera imagery. All appear to represent structures in the megaregolith. We have yet to find unequivocal evidence for primary crustal structures on Vesta.

Mass-balance and thermodynamics are used to constrain core size/density and mantle mineralogy of chondritic bodies with eucrite crust. Comparison with HED’s and data from Dawn is most consistent with a Na-poor H-chondrite bulk composition for Vesta.

In this work we will give a global view of the bright material on Vesta. We studied the mineralogy of the bright material units through the spectral parameters analysis.

Elemental mapping by Dawn’s gamma ray and neutron detector reveals the colorful chemistry of Vesta’s howarditic regolith.

HED meteorite siderophiles require separation of metal and silicates prior to eucrite solidification. Core formation most likely occurred as a metallic rain in a magma ocean. Dynamo models are sensitive to the distribution of heat producing elements.

Opportunity has investigated in detail rocks on the rim of the Noachian age Endeavour crater, where orbital spectral reflectance signatures indicate the presence of Fe+3-rich smectites. The signatures are associated with fine-grained, layered rocks containing spherules of diagenetic or impact origin. The layered rocks are overlain by breccias, and...

Olivine is a major component of the mantle of differentiated bodies, including Earth. Howardite, eucrite and diogenite (HED) meteorites represent regolith, basaltic-crust, lower-crust and possibly ultramafic-mantle samples of asteroid Vesta, which is the lone surviving, large, differentiated, basaltic rocky protoplanet in the Solar System. Only a f...

Simple mass-balance and thermodynamic constraints are used to illustrate the potential geochemical and geophysical diversity of a fully differentiated Vesta-sized parent body with a eucrite crust (e.g., core size and density, crustal thickness). The results of this analysis are then combined with data from the howardite–eucrite–diogenite (HED) mete...

Global maps of the macroscopic thermal neutron absorption cross section of Vesta's regolith by the Gamma Ray and Neutron Detector (GRaND) on board the NASA Dawn spacecraft provide constraints on the abundance and distribution of Fe, Ca, Al, Mg, and other rock-forming elements. From a circular, polar low-altitude mapping orbit, GRaND sampled the reg...

We have completed a mapping study of 7.6 MeV gamma rays produced by neutron capture by Fe at the surface of the main belt asteroid 4 Vesta as measured by the bismuth germanate scintillator of the Gamma Ray and Neutron Detector (GRaND) on the Dawn spacecraft. The procedures used to determine Fe counting rates are presented, along with a global map,...

Surface composition information from Vesta is reported using fast neutron data collected by the gamma ray and neutron detector on the Dawn spacecraft. After correcting for variations due to hydrogen, fast neutrons show a compositional dynamic range and spatial variability that is consistent with variations in average atomic mass from howardite, euc...

We present correlated studies of spectroscopy, petrology and chemistry of howadites, and discuss them in relation to Dawn mission results.

Mapping of the composition of Vesta's regolith by the NASA Dawn mission strengthens the connection between Vesta and Howardite, Eucrite, and Diogenite (HED) meteorites. The geologic context for HED rock types on Vesta's variegated surface provides constraints on thermal evolution and impact history. On Vesta, compositions outside the HED clan, such...

We present the results of petrologic and geochemical studies on diogenites, and will discuss them in the context of vestan geologic evolution.

NASA's Dawn mission observed a great variety of colored terrains on asteroid (4) Vesta during its survey with the Framing Camera (FC). Here we present a detailed study of the orange material on Vesta, which was first observed in color ratio images obtained by the FC and presents a red spectral slope. The orange material deposits can be classified i...

The Dawn spacecraft mission has provided extensive new and detailed data on Vesta that confirm and strengthen the Vesta-howardite-eucrite-diogenite (HED) meteorite link and the concept that Vesta is differentiated, as derived from earlier telescopic observations. Here, we present results derived by newly calibrated spectra of Vesta. The comparison...

The Dawn spacecraft mission has provided extensive new and detailed data on Vesta that confirm and strengthen the Vesta?howardite?eucrite?diogenite (HED) meteorite link and the concept that Vesta is differentiated, as derived from earlier telescopic observations. Here, we present results derived by newly calibrated spectra of Vesta. The comparison...

The Dawn mission was designed to test our hypothesis about the origin and evolution of the early solar system by visiting the largest differentiated basaltic asteroid, 4 Vesta, believed to be a survivor from the earliest times of rocky body formation. Observations from orbit show that Vesta is the parent body of the Howardite, Eucrite, Diogenite me...

We report noble gas data (helium (He), neon (Ne), argon (Ar), krypton (Kr) and xenon (Xe)), nominal gas retention ages (K–Ar, U–Th–He) and cosmic ray exposure (CRE) ages for the ten howardites EET 83376, EET 99408, LEW 85313, MET 00423, MET 96500, PCA 02066, PRA 04401, QUE 94200, QUE 97002, and SCO 06040, in research to better understand the regoli...

In situ measurements of minor/trace elements in diogenite orthopyroxenes show that some record fine-scale igneous zoning, some subsolidus equilibration effects.

Basaltic outcrops / Newberries, breccias, and veins / Clays still elusive.

We develop and test spectral indexes to detect mesosiderite materials on Vesta by means of the Dawn VIR hyperspectral data.

Study of the mineralogical composition of the different types of bright deposits on Vesta surface through band center and band depth analysis.

A preliminary map of Fe on Vesta derived from Dawn's Gamma Ray and Neutron Detector indicates a variation in the distribution of elemental Fe.

Measurements of neutron absorption by Dawn's Gamma Ray and Neutron Detector reveal global variations in the eucrite-diogenite ratio of Vesta's regolith.

The estimated excavation depth of the huge Rheasilvia impact basin is nearly twice the likely thickness of the Vestan basaltic crust, so the mantle should be exposed. Spectral mapping by the Dawn spacecraft reveals orthopyroxene-rich materials, similar to diogenite meteorites, in the deepest parts of the basin and within its walls. Significant amou...

The Dawn mission revealed distinct units on Vesta with red spectral slope. Oppia ejecta is identified as “Leslie unit" postulated by Gaffey (1997). Orange material composition is unlikely to be metal or olivine. Its nature is most likely impact melt.

The surface of the asteroid Vesta has prominent near-infrared absorption bands characteristic of a range of pyroxenes, confirming a direct link to the basaltic howardite-eucrite-diogenite class of meteorites. Processes active in the space environment produce 'space weathering' products that substantially weaken or mask such diagnostic absorption on...

Localized dark and bright materials, often with extremely different albedos, were recently found on Vesta's surface. The range of albedos is among the largest observed on Solar System rocky bodies. These dark materials, often associated with craters, appear in ejecta and crater walls, and their pyroxene absorption strengths are correlated with mate...

Vesta to the Core Vesta is one of the largest bodies in the main asteroid belt. Unlike most other asteroids, which are fragments of once larger bodies, Vesta is thought to have survived as a protoplanet since its formation at the beginning of the solar system (see the Perspective by Binzel , published online 20 September). Based on data obtained wi...

Water plays a key role in the evolution of the terrestrial planets, and notably the occurrence of Earth’s oceans. However, the mechanism by which water has been incorporated into these bodies -including the Earth- is still extensively debated. Here we report the detection of widespread 2.8-µm OH absorption bands on the surface of asteroid Vesta by...

Vesta’s surface mineralogy and composition have been studied for decades via telescopic spectroscopy and laboratory analyses of the howardite, eucrite, and diogenite (HED) meteorites, which are thought to originate from Vesta. Visible and infrared reflectance measurements by Dawn have broadly confirmed the paradigm established by Earth-based work,...

On Vesta, the thermal behavior of areas of unusual albedo seen at the local scale can be related to physical properties that can provide information about the origin of those materials. We used Dawn’s Visible and Infrared Mapping Spectrometer (VIR) hyperspectral cubes to retrieve surface temperatures and emissivities, with high accuracy as long as...