Andrew J Westphal

• MSAA, PhD
• Fellow at University of California, Berkeley

A literature compilation of 1136 low‐Ca pyroxene compositions from chondrules from 12 primitive type 2–3 carbonaceous, ordinary and enstatite chondrite groups define unique regions on an Al 2 O 3 and Cr 2 O 3 diagram when compared to low‐Ca pyroxenes from equilibrated type 4‐6 chondrites. Measured compositions of 100 low‐Ca pyroxenes from comet Wil...

We measured oxygen isotope ratios of 16 silicate fragments from seven aerogel tracks (turnip-like type B tracks 77, 149, 172, 191, and 220; carrot-like type A tracks 22 and 175) of the comet 81P/Wild 2 collector from NASA’s Stardust mission using secondary ion mass spectrometry. Thirteen were prepared by ultramicrotomy; three from track 220 were pr...

Leveraging advancements in micro-scale technology, we propose a fleet of autonomous, low-cost, small solar sails for interplanetary exploration. The Berkeley Low-cost Interplanetary Solar Sail (BLISS) project aims to utilize small-scale technologies to create a fleet of tiny interplanetary femto-spacecraft for rapid, low-cost exploration of the inn...

Control of oxygen fugacity during high-temperature phase equilibrium experiments is required to simulate the conditions that exist in natural systems. At high pressures, oxygen fugacity may be imposed using solid buffer equilibria via the classic “double capsule” technique. This design becomes untenable, however, at temperatures above the melting p...

Introduction: Basic characterization of the chemistry and mineralogy of the presolar cloud is a major unsolved problem in Planetary Science. Laboratory analyses of cometary materials collected in the stratosphere[1], in Antarctic ices[2], and returned by the Stardust spacecraft [3] have shown that comets are heterogeneous on a submi-cron scale, and...

The NASA Stardust Interstellar Dust collection provides our current best sample set for direct laboratory analysis of dust grains from the contemporary interstellar dust stream. While a handful of likely interstellar dust grains were identified within the silica aerogel collection media, interstellar dust also impacted Al foils covering the collect...

NASA's Stardust mission utilized a sample collector composed of aerogel and aluminum foil to return cometary and interstellar particles to Earth. Analysis of the aluminum foil begins with locating craters produced by hypervelocity impacts of cometary and interstellar dust. Interstellar dust craters are typically less than one micrometer in size and...

We assess whether chondrules, once-molten mm-sized spheres filling the oldest meteorites, could have formed from super-km/s collisions between planetesimals in the solar nebula. High-velocity collisions release hot and dense clouds of silicate vapor which entrain and heat chondrule precursors. Thermal histories of CB chondrules are reproduced for c...

We consider how chondrules, once-molten mm-sized spheres filling the oldest meteorites, may have formed as the thermally processed fallout from planetesimal collisions in the primordial solar nebula. We focus on the cloud of hot and dense silicate vapor released from a collision, and its expansion into cold and rarefied nebular hydrogen. Collisiona...

Comets likely formed in the outer regions of the protosolar nebula where they incorporated and preserved primitive presolar materials, volatiles resident in the outer disk, and more refractory materials from throughout the disk. The return of a sample of volatiles (i.e., ices and entrained gases), along with other components of a cometary nucleus,...

A Sintered and Sulfidized Equilibrated Aggregate from an Interplanetary Dust Particle - Zack Gainsforth, Andrew Westphal, Christine Jilly-Rehak

We advocate for the realization of volatile sample return from various destinations including: small bodies, the Moon, Mars, ocean worlds/satellites, and plumes. As part of recent mission studies (e.g., Comet Astrobiology Exploration SAmple Return (CAESAR) and Mars Sample Return), new concepts, technologies, and protocols have been considered for s...

Space Sciences Series of ISSI

We report the structure, chemical composition, O, Al-Mg, He, and Ne isotope systematics of an interplanetary dust particle, “Manchanito”. These analyses indicate that Manchanito solidified as refractory glass (with oxidized Fe but reduced Ti) in a chondrule-like formation environment more than 3.2 Myr after CAIs, after which it was exposed to Q-lik...

Interstellar dust from the Local Interstellar Cloud was detected unambiguously for the first time in 1992 (Grün et al. in Nature 362:428–430, 1993). Since then, great progress has been made in observing local interstellar dust in the Solar System using a variety of methods that, all together, provide complementary views of the dust particles from o...

STEM/EDS Tomography of Cometary Dust - Volume 25 Supplement - Zack Gainsforth, Peter Ercius, Karen Bustillo, Anna L. Butterworth, Christine E. Jilly-Rehak, Andrew J. Westphal

XAS Between the Stars - Volume 25 Supplement - Zack Gainsforth, Anna L. Butterworth, John A. Tomsick, Andrew J. Westphal

The recent detection of 60Fe in the cosmic rays provides conclusive evidence that there is a recently synthesized component (few MY) in the GCRs (Binns et al. 2016). In addition, these nuclei must have been synthesized and accelerated in supernovae near the solar system, probably in the Sco-Cen OB association subgroups, which are about 100 pc dista...

In a consortium analysis of a large particle captured from the coma of comet 81P/Wild 2 by the Stardust spacecraft, we report the discovery of a field of fine‐grained material (FGM) in contact with a large sulfide particle. The FGM was partially located in an embayment in the sulfide. As a consequence, some of the FGM appears to have been protected...

The relative fractions of Fe in metal, sulfide, or oxide - the Fe oxidation state - in the interstellar medium (ISM) can provide constraints on the processes that operated on material in the protosolar disk. We used synchrotron-based X-ray absorption spectra of three mineral standards and two kinds of primitive extraterrestrial materials to constra...

Helium and neon distributions are reported for a variety of Stardust comet 81P/Wild 2 samples, including particle tracks and terminal particles, cell surface and subsurface slices from the comet coma and interstellar particle collection trays, and numerous small aerogel blocks extracted from comet cells C2044 and C2086. Discussions and conclusions...

In a consortium analysis of a large particle captured from the coma of comet 81P/Wild 2 by the Stardust spacecraft, we report the discovery of a field of fine-grained material (FGM) in contact with a large sulfide particle. The FGM was partially located in an embayment in the sulfide, so appears to have been largely protected from damage during hyp...

The oxidation state of iron in the interstellar medium (ISM) can provide constraints on the processes that operated on material in the protosolar disk. We used synchrotron-based X-ray absorption spectra of several mineral standards and two kinds of primitive extraterrestrial materials to constrain the oxidation state and mineralogy of the host-phas...

Lauretta (2005) produced sulfide in the laboratory by exposing canonical nebular metal analogs to H2S gas under temperatures and pressures relevant to the formation of the Solar System. The resulting reactions produced a suite of sulfides and nanophase materials not visible at the microprobe scale, but which we have now analyzed by TEM for comparis...

Recent observations indicate that >99% of the small bodies in the Solar System reside in its outer reaches --- in the Kuiper Belt and Oort Cloud. Kuiper Belt bodies are probably the best preserved representatives of the icy planetesimals that dominated the bulk of the solid mass in the early Solar System. They likely contain preserved materials inh...

Recent observations indicate that >99% of the small bodies in the Solar System reside in its outer reaches --- in the Kuiper Belt and Oort Cloud. Kuiper Belt bodies are probably the best preserved representatives of the icy planetesimals that dominated the bulk of the solid mass in the early Solar System. They likely contain preserved materials inh...

The Super Trans-Iron Galactic Element Recorder (SuperTIGER) long-duration balloon instrument and the Cosmic Ray Isotope Spectrometer (CRIS) on the NASA Advanced Composition Explorer (ACE) satellite have measured the abundances of galactic cosmic-ray elements from _(10)Ne to _(40)Zr with high statistics and single-element resolution. SuperTIGER laun...

div class="title">MultiLaue: A Technique to Extract d-spacings from Laue XRD - Volume 22 Issue S3 - Zack Gainsforth, Matthew A. Marcus, Nobumichi Tamura, Andrew J. Westphal

When cosmic dust particles were first identified almost 140 years ago, few would have predicted that much would ever be known about these miniscule objects, given the existing state of the art in analytical techniques. Times have changed. Today, in a single extraterrestrial dust particle, we can detect all the elements present, measure isotopic rat...

In 2006, NASA's Stardust spacecraft delivered to Earth dust particles collected from the coma of comet 81P/Wild 2, with the goal of furthering the understanding of solar system formation. Stardust cometary samples were collected in a low-density, nanoporous silica aerogel making their study technically challenging. This article demonstrates the ide...

Using chemical and petrologic evidence and modeling, we deduce that two chondrule-like particles named Iris and Callie, from Stardust cometary track C2052,12,74, formed in an environment very similar to that seen for type II chondrules in meteorites. Iris was heated near liquidus, equilibrated, and cooled at ≤100 °C h-1 and within ≈2 log units of t...

Individual particles from comet 81P/Wild 2 collected by NASA’s Stardust mission vary in size from small sub-μm fragments found in the walls of the aerogel tracks, to large fragments up to tens of μm in size found towards the termini of tracks. The comet, in an orbit beyond Neptune since its formation, retains an intact a record of early-Solar-Syste...

We measured metal content of a giant cluster IDP, and show that collection biases do not explain the difference in metal content between CP-IDPs and Wild 2.

Advances in the spatial resolution of modern analytical techniques have tremendously augmented the scientific insight gained from the analysis of natural samples. Yet, while techniques for the elemental and structural characterization of samples have achieved sub-nanometre spatial resolution, infrared spectral mapping of geochemical samples at vibr...

The NASA Stardust mission used silica aerogel slabs to slowly decelerate and capture impinging cosmic dust particles for return to Earth. During this process, impact tracks are generated along the trajectory of the particle into the aerogel. It is believed that the morphology and dimensions of these tracks, together with the state of captured grain...

Hard X-ray, quantitative, fluorescence elemental imaging was performed on the ID22NI nanoprobe and ID22 microprobe beam lines of the European Synchrotron Research facility (ESRF) in Grenoble, France, on eight interstellar candidate impact features in the framework of the NASA Stardust Interstellar Preliminary Examination (ISPE). Three features were...

With the discovery of bona fide extraterrestrial materials in the Stardust Interstellar Dust Collector, NASA now has a fundamentally new returned sample collection, after the Apollo, Antarctic meteorite, Cosmic Dust, Genesis, Stardust Cometary, Hayabusa, and Exposed Space Hardware samples. Here, and in companion papers in this volume, we present th...

Here, we report the identification of 69 tracks in approximately 250 cm2 of aerogel collectors of the Stardust Interstellar Dust Collector. We identified these tracks through Stardust@home, a distributed internet-based virtual microscope and search engine, in which > 30,000 amateur scientists collectively performed >9 9 107 searches on approximatel...

We report the quantitative characterization by synchrotron soft X-ray spectroscopy of 31 potential impact features in the aerogel capture medium of the Stardust Interstellar Dust Collector. Samples were analyzed in aerogel by acquiring high spatial resolution maps and high energy-resolution spectra of major rock-forming elements Mg, Al, Si, Fe, and...

We discuss the inherent difficulties that arise during "ground truth" characterization of the Stardust interstellar dust collector. The challenge of identifying contemporary interstellar dust impact tracks in aerogel is described within the context of background spacecraft secondaries and possible interplanetary dust particles and beta-meteoroids....

Under the auspices of the Stardust Interstellar Preliminary Examination, picokeystones extracted from the Stardust Interstellar Dust Collector were examined with synchrotron Fourier transform infrared (FTIR) microscopy to establish whether they contained extraterrestrial organic material. The picokeystones were found to be contaminated with varying...

Here, we report analyses by synchrotron X-ray fluorescence microscopy of the elemental composition of eight candidate impact features extracted from the Stardust Interstellar Dust Collector (SIDC). Six of the features were unambiguous tracks, and two were crater-like features. Five of the tracks are so-called "midnight" tracks-that is, they had tra...

The NASA Stardust spacecraft exposed an aerogel collector to the interstellar dust passing through the solar system. We performed X-ray fluorescence element mapping and abundance measurements, for elements 19 <= Z <= 30, on six "interstellar candidates," potential interstellar impacts identified by Stardust@Home and extracted for analyses in picoke...

On the basis of an interstellar dust model compatible with Ulysses and Galileo observations, we calculate and predict the trajectories of interstellar dust (ISD) in the solar system and the distribution of the impact speeds, directions, and flux of ISD particles on the Stardust Interstellar Dust Collector during the two collection periods of the mi...

The Stardust Interstellar Preliminary Examination team analyzed thirteen Al foils from the NASA Stardust interstellar collector tray in order to locate candidate interstellar dust (ISD) grain impacts. Scanning electron microscope (SEM) images reveal that the foils possess abundant impact crater and crater-like features. Elemental analyses of the cr...

Seven particles captured by the Stardust Interstellar Dust Collector and returned to Earth for laboratory analysis have features consistent with an origin in the contemporary interstellar dust stream. More than 50 spacecraft debris particles were also identified. The interstellar dust candidates are readily distinguished from debris impacts on the...

Advances in the spatial resolution of modern analytical techniques have tremendously augmented the scientific insight gained from the analysis of natural samples. Yet, while techniques for the elemental and structural characterization of samples have achieved sub-nanometre spatial resolution, infrared spectral mapping of geochemical samples at vibr...

Characterizing Fe an interstellar dust particle by synchrotron X-ray absorption.

A microcalorimeter is being developed to measure trace elements in cometary and interstellar particles returned by Stardust.

Condensation via troilite to pyrrhotite and other mechanisms are considered for a Ni-zoned pyrrhotite from a Stardust grain to understand its origin.

We present a backside-profiling SIMS technique with imaging, which allows pixel-by-pixel depth correction, and present results for solar wind Mg in Genesis Si.

We report the presence of preserved primitive fine-grained material containing an enstatite whisker with the crystallographic characteristics of a primary condensate in a sample of the Jupiter-family comet Wild 2, returned to earth by NASAʼs Stardust mission. The preserved primitive material is composed of silica-rich amorphous material embedded wi...

The oxidation state of transition metal elements is an indicator of the environmental conditions during formation and history of extraterrestrial materials. We studied the iron valence state of fine-grained material from a bulbous track extracted from the Stardust cometary collector. It likely originated from primitive material of the comet Wild 2....

Using synchrotron-based X-ray diffraction measurements, we identified crystalline material in two particles of extraterrestrial origin extracted from the Stardust Interstellar Dust Collector. The first particle, I1047,1,34 (Hylabrook), consisted of a mosaiced olivine grain approximately 1 mu m in size with internal strain fields up to 0.3%. The uni...

We present a summary of mineralogical and isotopic analyses of coarse- and fine-grained particles in Stardust Track C2052,2,74.

Near-field infrared spectroscopy by elastic scattering of light from a probe tip resolves optical contrasts in materials at dramatically sub-wavelength scales across a broad energy range, with the potential for chemical identification at the nanoscale. However, current models of the probe-sample near-field interaction still cannot provide a suffici...

Helium and neon concentrations and isotopic compositions from Stardust cell C2044 track 41 and aerogel samples.

Helium- and neon-isotope ratios in a large amorphous particle extracted from a cluster IDP closely match compositions measured in the meteoritic Q-phase.

We present compendia for the Stardust cometary and interstellar dust collections. The compendia are readable globally and editable by Stardust investigators.

NanoFTIR is a new technique to probe infrared modes below the diffraction limit of FTIR. We apply it here to examine an amorphous Stardust silicate.

We present the application of scanning near-field microscopy and nanoscale broadband infrared spectroscopy to the study of chondrites and presolar grains.

We report a novel approach to measure the O isotopic composition of fine-grained material in the bulb of a Stardust cometary track by SIMS.

We report the discovery of Simeio, an ultra Ni-poor metal particle in the Stardust cometary collection. The composition of Simeio is inconsistent with most chondritic metals, and appears to be most similar to rare Ni-poor metal particles in CM.

We report the discovery of preserved primitive fine-grained material from Comet 81P/Wild 2. It is composed of silica-rich amorphous matrix embedded with iron sulfides and silicates. An enstatite whisker is identified inside the matrix.

We present the results of laboratory campaigns investigating the effects of particle density and composition on the dimensions of tracks created by hypervelocity dust grains hitting Stardust flight spare aerogel collectors.

We report combined oxygen and 26Al-26Mg analyses of an Al-rich amorphous IDP by ion probe.

The Stardust mission returned cometary, interplanetary and (probably) interstellar dust in 2006 to Earth that have been analysed in Earth laboratories worldwide. Results of this mission have changed our view and knowledge on the early solar nebula. The Rosetta mission is on its way to land on comet 67P/Churyumov-Gerasimenko and will investigate for...

Transmission electron microscopy examination of 87 large fragments from 16 carrot-shaped and bulbous Stardust (SD) tracks was performed to study the range and diversity of materials present in comet Wild 2. Olivines and low-Ca pyroxenes represent the largest proportions of fragments observed; however, a wide range of minerals and rocks were found i...

In this study, several Stardust samples have been analyzed by different experimental techniques to quantify the amount of light elements, such as carbon or nitrogen, to have access to information about the region where the comets formed. We used FTIR, TEM, EDAX, and nuclear reaction analysis (NRA) to measure in Stardust particles the areal concen...

Quantification of synchrotron XRF analyses is typically done through comparisons with measurements on the NIST SRM 1832/1833 thin film standards. Unfortunately, these standards are inhomogeneous on small scales at the tens of percent level. We are synthesizing new homogeneous multilayer standards using the Atomic Layer Deposition technique and char...

Helium and neon concentrations and compositions were measured in 49 samples of "blank" aerogel from Stardust cell C2044. Five samples show interesting compositions that if related to the Track 41 impactor indicate a complicated parent particle.

We characterize the Fe valence state distribution of the GEMS-like material and combine the results with TEM characterization to better understand the chemical modifications during capture versus the primary nature of the Wild 2 fine-grained material.

Here we describe a cometary coma dust collector based on silicon nitride "spiderwebs." The basic technology is already flight-proven on the Planck cosmic microwave background mission.

We report the discovery of preserved primitive fine-grained material from Comet 81P/Wild 2. It is composed of silica-rich amorphous matrix embedded with iron sulfides and silicates. An enstatite whisker is identified inside the matrix.

We report S-isotopic measurements (^32S, ^33S, ^34S, ^36S) of a pyrrhotite grain from Comet Wild 2 returned by NASA's Stardust mission.

In 2006, Stardust returned dust grains from Comet 81P/Wild2 as well as (candidate) interstellar dust grains. We simulated the flow of interstellar dust through the solar system and calculated impact velocities and directions on Stardust.

A microcalorimeter and an environmental scanning electron microscope modified to permit material-selective, gas-mediated, electron beam-induced etching are coupled to chemically analyze cometary particles and interstellar dust returned by Stardust.

TEM studies of large fragments from Stardust track 77 indicate that Comet Wild 2 is mineralogically heterogeneous on the micrometer scale. Isotopic measurements further suggest the fragments were derived from diverse source regions in the nebula.

The Stardust mission returned two types of unprecedented extraterrestrial samples: the first samples of material from a known solar system body beyond the moon, the comet 81P/Wild2, and the first samples of contemporary interstellar dust. Both sets of samples were captured in aerogel and aluminum foil collectors and returned to Earth in January 200...

The Stardust mission returned cometary, interplanetary and (probably) interstellar dust in 2006 to Earth that have been analysed in Earth laboratories worldwide. Results of this mission have changed our view and knowledge on the early solar nebula. The Rosetta mission is on its way to land on comet 67P/Churyumov-Gerasimenko and will investigate for...

We report the petrology, O isotopic composition, and Al-Mg isotope systematics of a chondrule fragment from the Jupiter-family comet Wild 2, returned to Earth by NASA's Stardust mission. This object shows characteristics of a type II chondrule that formed from an evolved oxygen isotopic reservoir. No evidence for extinct 26Al was found, with (26Al/...

Keystones removed from the Stardust Cometary Collector show varying degrees of visible luminescence when exposed to UV light, with the brightest luminescence associated with the space-exposed surface. The spatial characteristics of this phenomenon were investigated further by using fluorescence microscopy and synchrotron FTIR spectromicroscopy to a...

Introduction: In 2000 and 2002 the Stardust Mission exposed aerogel collector panels for a total of about 200 days to the stream of interstellar grains sweeping through the solar system [1]. The material was brought back to Earth in 2006. The goal of this work is the laboratory calibration of the collection process by shooting high speed [5 -30km/s...

Special Issue: 74th Annual Meeting of the Meteoritical Society, August 8-12, 2011, London, U.K.