Search

A Ryugu sample shows hydrothermal alteration (230–400 °C), linking returned material to Hayabusa2 spectral data and supporting Ryugu’s formation via a disruptive impact event, bridging spacecraft and sample observations.

Samples returned from asteroid Bennu by NASA’s OSIRIS-REx mission contain N-rich organics with prebiotic implications. This material probably formed in the earliest stages of the asteroid’s history possibly even before its water ice melted.

Samples returned from asteroid Bennu largely comprise hydrated sheet silicates with sulfides, magnetite and carbonate that indicate alteration by a fluid that evolved from neutral to alkaline, according to a micro- and nanoscale mineralogical study.

Bennu comprises components of intra- and extra-Solar System origins. The parent bodies of Bennu, Ryugu and CI chondrites likely formed from a shared but heterogeneous reservoir in the outer parts of the solar protoplanetary disk.

Experimental simulations of space weathering demonstrate the formation of enigmatic whiskers on sulfide grains, revealing how asteroidal surface materials record evidence of exposure to interplanetary space.

Samples from the asteroid (101955) Bennu, returned by the OSIRIS-REx mission, include sodium-bearing phosphates and sodium-rich carbonates, sulfates, chlorides and fluorides formed during evaporation of a late-stage brine.

Carbon-rich and oxygen-rich material coexist in a presolar grain originated by an outburst of a CO nova and found within the LaPaz Icefield 031117 meteorite. Condensation of both carbon and oxygen can thus happen in the same circumstellar environment, contrary to previous assumptions.

Iron nitride (Fe₄N) is detected on magnetite particles within the Ryugu sample returned by Hayabusa2. It is probably the product of impacts of nitrogen-rich dust from the outer Solar System on the surface of Ryugu, indicative of a flux of N-rich dust in the inner Solar System.

The presence of NaCl crystals within the sample gathered from S-type asteroid Itokawa and genetically linked to the surrounding plagioclase indicates the presence of an active hydrothermal system within Itokawa, contrary to the assumption that parent asteroids of ordinary chondrites were relatively water-depleted.

A close-up look at the action of space weathering on carbonaceous asteroids, provided by Ryugu’s returned samples, highlights its role on the dehydration of the first micrometre-thick layer of the surface, possibly hiding a water-rich interior. The depth of the 2.7 µm hydration band may be an indication of the level of space weathering withstood by a C-type asteroid.

Bennu’s surface presents evidence of a variety of particle sizes, from fine regolith to metre-sized boulders. Its moderate thermal inertia suggests that the boulders are very porous or blanketed by thin dust. Bennu’s boulders exhibit high albedo variations, indicating different origins and/or ages.

Signatures of phyllosilicate-like hydrated minerals are widespread on Bennu’s surface, indicating significant aqueous alteration. The lack of spatial variations in the spectra down to the scale of ~100 m indicates both a relatively uniform particle size distribution and a lack of compositional segregation, possibly due to surficial redistribution processes.

Vicinity of small bodies might be dangerous to the spacecrafts and to their instrumentation. Here the authors show the operational environment of asteroid Bennu, validate its photometric phase function and demonstrate the accelerating rotational rate due to YORP effect using the data acquired during the approach phase of OSIRIS-REx mission.

Bennu’s surface has experienced continuous changes, mostly induced by its accelerating spin rate, which could have resulted in a collapse of its interior in the past. This scenario is also supported by the heterogeneity of Bennu’s internal mass distribution.

Near-Earth rubble-pile asteroid Bennu has an unexpectedly old surface, with numerous candidate impact craters and morphologically diverse boulders, according to early observations by the OSIRIS-REx mission.

Near-Earth asteroid Bennu has a top-like shape with longitudinal ridges, macroporosity, prominent boulders and surface mass wasting, suggesting that it is a stiff rubble pile, according to early observations by the OSIRIS-REx mission.

Observations of asteroid (101955) Bennu with NASA’s OSIRIS-REx spacecraft reveal an unexpected surficial diversity that poses a challenge to the success of the sample-return mission.