Evidence of both molecular cloud and fluid chemistry in Ryugu regolith.

The sulfur chemistry of (162173) Ryugu particles can be a powerful tracer of molecular cloud chemistry and small body processes, but it has not been well explored. We report identification of organosulfurs and a sulfate grain in two Ryugu particles, A0070 and A0093. The sulfate grain shows oxygen isotope ratios (δO = -11.

Moon-forming impactor as a source of Earth's basal mantle anomalies.

Seismic images of Earth's interior have revealed two continent-sized anomalies with low seismic velocities, known as the large low-velocity provinces (LLVPs), in the lowermost mantle. The LLVPs are often interpreted as intrinsically dense heterogeneities that are compositionally distinct from the surrounding mantle. Here we show that LLVPs may represent buried relics of Theia mantle material (TMM) that was preserved in proto-Earth's mantle after the Moon-forming giant impact.

Some Pertinent Issues for Interstellar Panspermia Raised after the Discovery of 1I/'Oumuamua.

The interstellar objects 1I/'Oumuamua and 2I/Borisov confirm the long-held expectation that bodies from one stellar system will be carried to another, allowing, interstellar panspermia. Life might be transferred between stellar systems, depending on the nature of the bodies and how they escaped their systems. 2I/Borisov appears to be a comet, with no more likelihood of carrying life than Solar System comets.

Best Practices for Determination of Initial Be/Be in Early Solar System Materials by Secondary Ion Mass Spectrometry.

Beryllium-10 ( = 1.4 Ma) is a short-lived radionuclide present in the early Solar System. It is produced solely by irradiation reactions and can provide constraints on the astrophysical environment of the Sun's formation.

The background temperature of the protoplanetary disk within the first four million years of the Solar System.

The background temperature of the protoplanetary disk is a fundamental but poorly constrained parameter that strongly influences a wide range of conditions and processes in the early Solar System, including the widespread process(es) by which chondrules originate. Chondrules, mm-scale objects composed primarily of silicate minerals, were formed in the protoplanetary disk almost entirely during the first four million years of Solar System history but their formation mechanism(s) are poorly understood. Here we present new constraints on the sub-silicate solidus cooling rates of chondrules at <873 K (600°C) using the compositions of sulfide minerals.

Impact of the Arizona NExSS Winter School on Astrobiology Knowledge and Attitudes.

Astrobiology is an inherently interdisciplinary area of study, demanding communication across multiple fields: astronomy, geochemistry, planetary science, and so on. Successful communication requires that researchers be aware of the basic findings, open questions, and tools and techniques of allied fields and possess an appreciation and respect for what these fields consider good science. To facilitate this communication between early-career researchers, the Arizona NExSS Winter School was hosted in February 2016, bringing together graduate students and postdoctoral researchers from backgrounds spanning the field of astrobiology.

Paleomagnetism. Solar nebula magnetic fields recorded in the Semarkona meteorite.

Magnetic fields are proposed to have played a critical role in some of the most enigmatic processes of planetary formation by mediating the rapid accretion of disk material onto the central star and the formation of the first solids. However, there have been no experimental constraints on the intensity of these fields. Here we show that dusty olivine-bearing chondrules from the Semarkona meteorite were magnetized in a nebular field of 54 ± 21 microteslas.

Astrobiological stoichiometry.

Chemical composition affects virtually all aspects of astrobiology, from stellar astrophysics to molecular biology. We present a synopsis of the research results presented at the "Stellar Stoichiometry" Workshop Without Walls hosted at Arizona State University April 11-12, 2013, under the auspices of the NASA Astrobiology Institute. The results focus on the measurement of chemical abundances and the effects of composition on processes from stellar to planetary scales.

Report on a NASA astrobiology institute-funded workshop without walls: stellar stoichiometry.

We report on the NASA Astrobiology Institute-funded Workshop Without Walls entitled "Stellar Stoichiometry," hosted by the "Follow the Elements" team at Arizona State University in April 2013. We describe several innovative practices we adopted that made effective use of the Workshop Without Walls videoconferencing format, including use of information technologies, assignment of scientific tasks before the workshop, and placement of graduate students in positions of authority. A companion article will describe the scientific results arising from the workshop.

Phyllosilicate emission from protoplanetary disks: is the indirect detection of extrasolar water possible?

Phyllosilicates are hydrous minerals formed by interaction between rock and liquid water, and are commonly found in meteorites that originate in the asteroid belt. Collisions between asteroids contribute to zodiacal dust, which therefore reasonably could include phyllosilicates. Collisions between planetesimals in protoplanetary disks may also produce dust that contains phyllosilicates.