Search

High-resolution observations of the third largest asteroid, (2) Pallas, from SPHERE unveil a heavily cratered surface, probably due to Pallas’s inclined and eccentric orbit, a density almost equal to carbonaceous chondrites and hint at surficial salt-enriched spots.

The origin of the numerous linear grooves and craters that litter the Martian moon Phobos' surface remains enigmatic. Here, by modelling low-velocity escaping ejecta from impacts to Phobos, the authors show that several of these chains can be explained by reimpacting sesquinary ejecta shortly after ejection.

By comparing boulders’ surface distribution and shapes on the binary asteroid system, Didymos, authors show that both bodies are rubble piles produced in their progenitor catastrophic disruption and that the secondary, Dimorphos, likely inherited its material from the primary through spin up and mass shedding.

Images collected during NASA’s DART mission of the asteroid Didymos and its moon, Dimorphos, are used to explore the origin and evolution of the binary system. Authors analysis indicate that both asteroids are weak rubble piles and that Didymos’ surface should be about 40 to 130 times older than Dimorphos.

The Earth co-orbital asteroid Kamo‘oalewa, which is a target of the Chinese Tianwen-2 mission, may have a lunar origin instead of an asteroidal one. Dynamical constraints from numerical simulations suggest that it could be an escaping fragment from the lunar Giordano Bruno crater.

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.

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.

The impact of the DART spacecraft on the asteroid Dimorphos is reported and reconstructed, demonstrating that kinetic impactor technology is a viable technique to potentially defend Earth from asteroids.

This study finds that the Moon accreted from an initially liquid-rich silicate disk and that rocky and icy exoplanets whose radii are smaller than 1.6 Earth radii are ideal candidates for hosting large exomoons.

Three-dimensional simulations of the global evolution of asteroid 4 Vesta under two overlapping planet-scale collisions closely reproduce its observed shape; but expected large areas of olivine-rich rocks and pure diogenites are not observed on the surface, possibly implying that the outer ∼100 km is composed mainly of a basaltic crust (eucrites) with ultramafic intrusions (diogenites).

Unlike the other terrestrial planets, Mercury has a relatively thin silicate mantle. Numerical and statistical models suggest that Mercury and other metallic planetary bodies could be survivors of accretion that had their mantles stripped in collisions with larger impactors.

Analysis of the size and depth of craters on boulders on the asteroid (101955) Bennu indicates that Bennu has been in near-Earth space for 1.75 ± 0.75 million years.

Data on Vesta’s surface material provided by the Dawn probe and impacts modelling reveals that Vesta’s crust–mantle boundary must be deeper than 80 kilometres below the surface.

The absence of fine regolith on the asteroid Bennu is due to the high porosity of its rocks, which compress rather than fragment after impacts and exhibit slow thermal cracking.

Dimorphos ejecta plume properties were revealed by the observations from the LICIACube cube satellite, which was deployed 15  days in advance of the impact of DART.

When the Philae lander bounced on the surface of comet 67P/Churyumov–Gerasimenko, it exposed primitive icy-dust material within cometary boulders; the intrinsic strength and porosity of this material is reported.

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.

The moon Phobos is spiralling inwards towards its disintegration to eventually form a ring around Mars from which new moons may form. Simulations suggest that this is just the latest of multiple ring–moon cycles over the history of Mars.

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.

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.

Sand flume studies show that the distinct morphology of martian stepped deltas could only have originated from a single basin-filling event on a timescale of tens of years and may have required an amount of water comparable to that discharged by large terrestrial rivers.

High resolution surface images of Hyperion, Saturn's largest known, irregularly shaped satellite are presented. These reveal a unique sponge-like appearance at scales of a few kilometres, with a high surface density of relatively well-preserved 2–10 km-sized craters.

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.