Planetary science

  • Article
    | Open Access

    Formation of peptide bonds in cold gas-phase environments might represent a prebiotic synthesis route of polypeptides. Here, the authors show the formation of up to tetra-peptide species in the collision of He2+ ions, with kinetic energies typical for solar wind ions, with cold β-alanine clusters.

    • Patrick Rousseau
    • , Dariusz G. Piekarski
    •  & Bernd A. Huber
  • Article
    | Open Access

    Helium is generally considered too inert to be present in giant ice planet mantles. The authors, by first-principles calculations and crystal structure searches, find stable ammonia–helium compounds at the conditions of Uranus and Neptune’s upper mantles, with possible implications in the planet composition models.

    • Jingming Shi
    • , Wenwen Cui
    •  & Yinwei Li
  • Article
    | Open Access

    Anomalously specular radar reflections (ASRR) from Titan’s tropical region were interpreted earlier as evidence for liquid surfaces, but the Cassini spacecraft did not observe lakes/seas at the anomalously specular locations. Here, the authors show that ASRR originate from one terrain unit, likely paleolakes/paleoseas.

    • Jason D. Hofgartner
    • , Alexander G. Hayes
    •  & Stephen D. Wall
  • Article
    | Open Access

    Salts in water at extreme conditions play a fundamental role in determining the properties of the Earthʼs mantle constituents. Here the authors shed light on ion-water and ion-ion interactions for NaCl dissolved in water at conditions relevant to the Earthʼs upper mantle by molecular dynamics simulations.

    • Cunzhi Zhang
    • , Federico Giberti
    •  & Giulia Galli
  • Article
    | Open Access

    In this study, the authors investigate in the influence of atmospheric dust on the habitability of exoplanets. They find that atmospheric dust may postpone planetary water loss; for tidally locked planets in particular, dust can significantly widen the habitable zone by cooling the day side and warming the night side.

    • Ian A. Boutle
    • , Manoj Joshi
    •  & Krisztian Kohary
  • Article
    | Open Access

    In this study, the authors present a global map of rockfalls on the lunar surface and determine impact events as short- and long-term driver for rockfall events.

    • Valentin Tertius Bickel
    • , Jordan Aaron
    •  & Urs Mall
  • Article
    | Open Access

    The authors here present a 3D model that simulates the formation of the Chicxulub impact crater. Based on asymmetries in the subsurface structure of the Chicxulub crater, the authors diagnose impact angle and direction and suggest a steeply inclined (60° to horizontal) impact from the northeast.

    • G. S. Collins
    • , N. Patel
    •  & T. J. Bralower
  • Article
    | Open Access

    Applying high-pressure and -temperature experiments, the authors here measure sound velocities in various liquid Fe-S alloys under conditions expected for the upper Martian core. The results together with future InSight mission data will help to understand whether the Martian core is molten Fe-S.

    • Keisuke Nishida
    • , Yuki Shibazaki
    •  & Kei Hirose
  • Article
    | Open Access

    The authors analyze a system of multi-layered hazes above Saturn’s hexagonal-wave cloud tops in the visual range. Analyses suggest the formation to be caused by condensation processes, and the vertical distribution of stacked layers by the upward propagation of internal gravity waves.

    • A. Sánchez-Lavega
    • , A. García-Muñoz
    •  & J. Peralta
  • Article
    | Open Access

    Earth rotation variation reflects the physics, dynamics and the magnetic field changes of Earth’s interior. The authors find a significant ~8.6 year periodic increasing oscillation in length of day and its good link to geomagnetic jerks related to Earth’s core oscillations, which may be used to predict the future jerk timings.

    • Pengshuo Duan
    •  & Chengli Huang
  • Article
    | Open Access

    Using high-resolution orbital imagery of the Martian surface, the authors Salese et al. here describe the first discovered stratigraphic product of multiple extensive fluvial-channel belts in an exposed vertical section at Izola Mensa in the northwestern rim of the Hellas Basin.

    • Francesco Salese
    • , William J. McMahon
    •  & Maarten G. Kleinhans
  • Article
    | Open Access

    The surface of active asteroid (3200) Phaethon, parent body of the Geminid meteor shower, reaches temperatures sufficient to destabilize hydrated materials. Here, the authors show that the northern hemisphere and the equatorial region of this asteroid reveal no evidence of hydration in the near-infrared spectra.

    • Driss Takir
    • , Theodore Kareta
    •  & Tomoko Arai
  • Article
    | Open Access

    Applying first-principles molecular dynamic simulations and thermodynamic modelling, the authors suggest a vertical oxygen fugacity gradient in magma oceans of Earth, Mars, and the Moon. Consequently, the study proposes larger planets like Earth to have stronger oxidized upper mantles than smaller bodies such as Mars or the Moon.

    • Jie Deng
    • , Zhixue Du
    •  & Kanani K. M. Lee
  • Article
    | Open Access

    Mars has long been thought to contain organic compounds, but the origins and plausibility are debated. Here the authors employ a new technique to assess organic nitrogen compounds in a Martian meteorite, concluding that these compounds are indeed likely to originate from the Red Planet.

    • Mizuho Koike
    • , Ryoichi Nakada
    •  & Atsuko Kobayashi
  • Article
    | Open Access

    Earth’s surface underwent a dramatic transition ~2.3 billion years ago when atmospheric oxygen first accumulated during the Great Oxidation Event. Here, the authors find that biogenic methane and volcanic emissions played a vital role in the reduced Late Archean atmosphere.

    • Aubrey L. Zerkle
    • , Runsheng Yin
    •  & Stephen E. Grasby
  • Article
    | Open Access

    The authors here analyse the petrology of the meteorite NWA 8321 (parent body Vesta). They find sulfidation processes of olivine suggesting metasomatism in the Vestan interior and a partial melting origin for the host noritic diogenite.

    • Ai-Cheng Zhang
    • , Noriyuki Kawasaki
    •  & Hisayoshi Yurimoto
  • Article
    | Open Access

    The authors here investigate troilite (FeS) grains recovered from the regolith of asteroid Itokawa. Finding wide-spread occurrence of metallic iron whiskers, the authors suggest them to be a decomposition product formed through irradiation of the sulfide by energetic ions of the solar wind.

    • Toru Matsumoto
    • , Dennis Harries
    •  & Takaaki Noguchi
  • Article
    | Open Access

    Cooling of the iron core in the early Earth may have been too slow to allow for the generation of a magnetic field. Based on quantum mechanical and geodynamical modelling approaches, the authors find that the electrical conductivity of silicate liquid at high pressure and temperature conditions could have been sufficient to generate a silicate dynamo and a magnetic field in the early Earth.

    • Lars Stixrude
    • , Roberto Scipioni
    •  & Michael P. Desjarlais
  • Article
    | Open Access

    The InSight spacecraft landed on Mars on November 2018. Here, the authors characterize the surficial geology of the landing site and compare with observations and models derived from remote sensing data prior to landing and from ongoing in situ geophysical investigations of the subsurface.

    • M. Golombek
    • , N. H. Warner
    •  & W. B. Banerdt
  • Article
    | Open Access

    The authors here present the diurnal tides of dust within the southern Martian atmosphere. The dust tides imply a fast meridional exchange of heat and materials on Mars and allow water content near the summer pole to be rapidly transported to the middle latitudes in the nighttime which is then lifted by daytime deep convection.

    • Zhaopeng Wu
    • , Tao Li
    •  & Jun Cui
  • Article
    | Open Access

    Following the impact of the protoplanet Theia, planet Earth likely transformed into a magma ocean. New high temperature and pressure experiments by Xie et al. suggest that a layer enriched in bridgmanite formed during the magma ocean phase of Earth–remnants of this ancient layer today may be responsible for the viscosity peak between 660 and 1500 km in present solid mantle.

    • Longjian Xie
    • , Akira Yoneda
    •  & Denis Andrault
  • Article
    | Open Access

    The ~70 km-diameter Yarrabubba impact structure in Western Australia has previously been regarded as among Earth’s oldest meteorite craters, but has hitherto lacked absolute age constraints. Here, the authors determine a precise impact age of 2229 ± 5 Ma, which extends the terrestrial cratering record back in time by > 200 million years and establishes Yarrabubba as the oldest recognised meteorite impact structure on Earth.

    • Timmons M. Erickson
    • , Christopher L. Kirkland
    •  & Thomas M. Davison
  • Article
    | Open Access

    Telecommunication, navigation and remote sensing services are highly dependent on how well satellites provide global coverage. Here the authors show a pair of four-satellite low-cost longer-life constellations that provide nearly continuous global coverage to support Earth observation.

    • Lake A. Singh
    • , William R. Whittecar
    •  & Patrick M. Reed
  • Article
    | Open Access

    Lithium use in electronics has increased dramatically, but the environmental impacts are poorly understood. Here the authors show lithium in river and tap water in South Korea is coincident with population density, and that waste water treatment is ineffective at scrubbing this potential toxin.

    • Hye-Bin Choi
    • , Jong-Sik Ryu
    •  & Nathalie Vigier
  • Article
    | Open Access

    A reference function for describing the orientation of clay platelets in clay-rich materials is still lacking, but is necessary for applications such as prediction of water and solute transfer and designs of innovative materials. Here, the authors determine a reference orientation function of clay platelets, and validate their function for both engineered and natural clay-rich media.

    • Thomas Dabat
    • , Fabien Hubert
    •  & Eric Ferrage
  • Article
    | Open Access

    The elevation and high heat flow of Southern South Africa has controversially been attributed to a mantle plume. Here, the authors link degassed CO2 to a non-degassed mantle source rather than the convecting upper mantle, confirming plume-related mantle melting.

    • S. M. V. Gilfillan
    • , D. Györe
    •  & F. M. Stuart
  • Article
    | Open Access

    The occurrence of longitudinal ridges on large landslide masses on planetary bodies is enabled by long runout distances, which have so far been attributed to the presence of ice. The authors here present a challenging model based on mechanical instabilities within the flow, suggesting that ice is not needed.

    • Giulia Magnarini
    • , Thomas M. Mitchell
    •  & Harrison H. Schmitt
  • Article
    | Open Access

    Fractured rocks of impact craters have been suggested to be suitable hosts for deep microbial communities on Earth, and potentially other terrestrial planets, yet direct evidence remains elusive. Here, the authors show that the Siljan impact structure is host to long-term deep methane-cycling microbial activity.

    • Henrik Drake
    • , Nick M. W. Roberts
    •  & Mats E. Åström
  • Article
    | Open Access

    The formation of nucleobases can take place in extraterrestrial environments. Here the authors show the simultaneous synthesis of three purine nucleobases and three pyrimidine from interstellar ice analogues that suggest the evolution from molecular clouds to stars and planets provide suitable environment for nucleobase synthesis in space.

    • Yasuhiro Oba
    • , Yoshinori Takano
    •  & Akira Kouchi
  • Article
    | Open Access

    Gigantic jets, lightning discharges originating from tropical thunderstorms that can reach the base of the ionosphere at 90 km altitude, have not been captured using high-speed video cameras before. Here, the first such images are reported, showing a step-wise evolution of gigantic jets during their rising phase.

    • Oscar A. van der Velde
    • , Joan Montanyà
    •  & Steven A. Cummer
  • Article
    | Open Access

    The Chang’E-4 mission in January 2019 had the major challenge to land on the lunar far side without traditional radiometric techniques due to the missing line-of-sight. The authors here describe landing trajectory reconstruction and positioning techniques based upon the Moon’s digital terrain model that allowed reproducing the entire process of a successful landing.

    • Jianjun Liu
    • , Xin Ren
    •  & Weibin Wen
  • Article
    | Open Access

    Due to active geological resurfacing, the record of large impact basins (e.g. in Chryse Planitia) on Mars seems to be widely absent. Based on high-quality global datasets, the authors here propose a buried impact basin, covered by up to 1 km of sediments or lava flows after its formation more than 4 billion years ago.

    • Lu Pan
    • , Cathy Quantin-Nataf
    •  & Chloé Michaut
  • Article
    | Open Access

    Thunderstorms are commonly represented through simplified parametrizations in weather and climate models. Here it is shown that an increase in model resolution over West Africa, enabling the explicit modeling of Sahelian convective systems, can improve 5–8 day tropical and mid-latitude weather forecasts.

    • Gregor Pante
    •  & Peter Knippertz
  • Article
    | Open Access

    Cyanide is thought to be crucial for the origin of life. Here, the authors showed that iron cyanocarbonyl complexes are present in meteorites and propose that these compounds were a source of free cyanide on early Earth and served as precursors to the active sites of ancient hydrogenases.

    • Karen E. Smith
    • , Christopher H. House
    •  & Michael P. Callahan
  • Article
    | Open Access

    Intense electromagnetic impulses induced by Jupiter’s lightning can produce both low-frequency dispersed whistler emissions and non-dispersed radio pulses. Here, the authors show Jupiter dispersed pulses associated with Jovian lightning that are evidence of low density holes in Jupiter’s ionosphere.

    • Masafumi Imai
    • , Ivana Kolmašová
    •  & Steven M. Levin
  • Article
    | Open Access

    Sublimation of ice is believed to have generated a variety of landforms on Mars and other planetary bodies. Here the authors show the first long-term in situ effective diffusion coefficient of terrestrial ice-free loess (Mars analog soil), scaled to Mars average pressure, temperature and CO2 atmosphere.

    • Thomas A. Douglas
    •  & Michael T. Mellon
  • Article
    | Open Access

    Recent studies have shown that lightning is initiated by a newly-recognized discharge process called fast positive breakdown. Here, the authors present observational evidence of fast breakdown but of negative polarity, seemingly contrary to current understanding of discharge physics.

    • Julia N. Tilles
    • , Ningyu Liu
    •  & Jennifer Wilson
  • Article
    | Open Access

    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.

    • C. W. Hergenrother
    • , C. K. Maleszewski
    •  & B. Marty