Space physics

  • Article
    | Open Access

    Superbolts are powerful, rare lightning events. Here, the authors show simultaneous satellite and ground measurements of a superbolt, and demonstrate different properties of superbolts and lightnings.

    • J.-F. Ripoll
    • , T. Farges
    •  & S. Pédeboy
  • Article
    | Open Access

    It was predicted that Alfvén waves can account for the acceleration of precipitating auroral electrons. Here, the authors show laboratory measurements of the resonant transfer of energy from Alfvén waves to electrons under conditions relevant to the auroral zone as a direct test.

    • J. W. R. Schroeder
    • , G. G. Howes
    •  & S. Dorfman
  • Article
    | Open Access

    During geomagnetic substorms, the energy accumulated from solar wind is abruptly transported to ionosphere. Here, the authors show application of community detection on the time-varying networks constructed from all magnetometers collaborating with the SuperMAG initiative.

    • L. Orr
    • , S. C. Chapman
    •  & W. Guo
  • Article
    | Open Access

    Hurricanes in the Earth’s low atmosphere are known, but not detected in the upper atmosphere earlier. Here, the authors show a long-lasting hurricane in the polar ionosphere and magnetosphere with large energy and momentum deposition despite otherwise extremely quiet conditions.

    • Qing-He Zhang
    • , Yong-Liang Zhang
    •  & Li-Dong Xia
  • Article
    | Open Access

    Seasonally averaged energy input into the ionosphere from geospace is generally considered to be symmetric. Here, the authors show preference for electromagnetic energy input at 450 km altitude into the northern hemisphere, on both the dayside and the nightside, when averaged over season.

    • I. P. Pakhotin
    • , I. R. Mann
    •  & D. J. Knudsen
  • Article
    | Open Access

    Very-Low-Frequency (VLF) communication transmitters, operate worldwide, radiate emissions at particular frequencies 10-30 kHz. Here, the authors show VLF transmitter emissions that leak from the Earth’s ground are primarily responsible for bifurcating the energetic electron belt over 20–100 keV.

    • Man Hua
    • , Wen Li
    •  & Geoffrey D. Reeves
  • Article
    | Open Access

    Electrons in the Van Allen radiation belts can have energies in excess of 7 MeV, however, the energization mechanism is debated. Here, the authors show phase space density peaks in magnetic coordinate space as a way of analyzing satellite observations which demonstrates that local acceleration is capable of heating electrons up to 7 MeV.

    • Hayley J. Allison
    •  & Yuri Y. Shprits
  • Article
    | Open Access

    Magnetic reconnection is a fundamental plasma process of magnetic energy conversion to kinetic energy. Here, the authors show direct evidence of secondary reconnection in the filamentary currents within the flux ropes indicating a significant contribution to energy conversion in the kinetic scale during turbulent reconnection.

    • Shimou Wang
    • , Rongsheng Wang
    •  & Shui Wang
  • Article
    | Open Access

    Space debris laser ranging is a technique to measure distances to defunct satellites or rocket bodies in orbits around Earth which was only possible within a few hours around twilight. Here, the authors show the first space debris laser ranging results during daylight while correcting inaccurate predictions using a real-time target detection software.

    • Michael A. Steindorfer
    • , Georg Kirchner
    •  & Tim Flohrer
  • Article
    | Open Access

    Energetic particle generation is an important component of a variety of astrophysical systems. Here, the authors show when magnetic pumping is extended to a spatially-varying magnetic flux tube, magnetic trapping of superthermal particles renders pumping an effective energization method for particles moving faster than the speed of the waves.

    • E. Lichko
    •  & J. Egedal
  • Article
    | Open Access

    Theoretical studies suggested that plasmapause surface waves related to the sharp inhomogeneity exist and act as a source of geomagnetic pulsations. Here, the authors show direct observations of a plasmapause surface wave and its impacts during a geomagnetic storm using multi-satellite and ground-based observations.

    • Fei He
    • , Rui-Long Guo
    •  & Wei-Xing Wan
  • Article
    | Open Access

    Various types of plasma waves are generated around electron diffusion regions (EDRs). Here the authors show electron Bernstein waves (EBWs), at the electron-scale boundary of the Hall current reversal near EDR, are sufficiently strong to diffuse electrons and modify electron pressure tensor.

    • W. Y. Li
    • , D. B. Graham
    •  & J. L. Burch
  • Article
    | Open Access

    Chorus waves are crucial on radiation belt dynamics in the space of magnetized planets. Here, the authors show that initially excited single-band chorus waves can quickly accelerate medium energy electrons, and divide the anisotropic electrons into low and high energy components, which subsequently excite two-band chorus waves.

    • Jinxing Li
    • , Jacob Bortnik
    •  & Daniel N. Baker
  • 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

    Heating of the upper solar atmospheric layers is an open question. Here, the authors show observational evidence that ubiquitous Alfven pulses are excited by prevalent photospheric swirls, which are found to propagate upwards and carry enough energy flux needed to balance the local upper chromospheric energy loss.

    • Jiajia Liu
    • , Chris J. Nelson
    •  & Robert Erdélyi
  • 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

    Magnetohydrodynamic (MHD) waves and plasma instabilities can be studied during solar flares. Here the authors show evidence for an MHD sausage mode oscillation periodically triggering electron acceleration at a magnetic null point in the solar corona, indicating MHD oscillations in plasma can indirectly lead to loss-cone instability modulation.

    • Eoin P. Carley
    • , Laura A. Hayes
    •  & Peter T. Gallagher
  • Article
    | Open Access

    Magnetic cavities are universal phenomena existing in cosmic plasma environments. Here Liu et al. show electron scale magnetic cavities in proton scale magnetic cavities observed by Magnetospheric Multiscale (MMS) spacecraft in the Earth’s magnetosheath, and depict the boundary of the electron scale magnetic cavity using particle sounding technique.

    • H. Liu
    • , Q.-G. Zong
    •  & R. Rankin
  • Article
    | Open Access

    Various physical mechanisms are proposed to explain the heating observed in turbulent astrophysical plasmas. Here, Chen et al. find a signature consistent with one of these mechanisms, electron Landau damping, by applying a field-particle correlation technique to in situ spacecraft data of turbulence in the Earth’s magnetosheath.

    • C. H. K. Chen
    • , K. G. Klein
    •  & G. G. Howes
  • Article
    | Open Access

    Surface waves on the boundary between a magnetosphere and the surrounding plasma might get trapped by the ionosphere forming an eigenmode. Here, Archer et al. show direct observations of this proposed mechanism at Earth’s magnetosphere by analyzing the response to an isolated fast plasma jet detected by the THEMIS satellites.

    • M. O. Archer
    • , H. Hietala
    •  & V. Angelopoulos
  • Article
    | Open Access

    Electron precipitation plays major role in magnetospheric physics and space weather. Here the authors show nonlinear behavior of the wave–particle interaction in the magnetosphere as the evolution of chorus electromagnetic waves detected by the Arase satellite and PWING observatory.

    • Mitsunori Ozaki
    • , Yoshizumi Miyoshi
    •  & Iku Shinohara
  • Article
    | Open Access

    There is significant interest in providing real-world applications for metamaterials. Here, the authors design an Advanced Short Backfire Antenna, augmented with anisotropic metamaterial surfaces to achieve high aperture efficiency across two frequency bands, making the antenna ideal for spaceborne applications.

    • J. Daniel Binion
    • , Erik Lier
    •  & Douglas H. Werner
  • Article
    | Open Access

    Magnetic reconnection is the process of releasing energy by magnetized and space plasma. Here the authors report experimental observation of magnetic reconnection in laser-produced plasma and the role of electron scaling on reconnection.

    • Y. Kuramitsu
    • , T. Moritaka
    •  & M. Hoshino
  • Article
    | Open Access

    Radial diffusion is the only mechanism considered to accelerate trapped electrons to relativistic energies in Saturn’s magnetic field, forming radiation belts. Here the authors show another mechanism, electron acceleration via Doppler shifted cyclotron resonant interaction with Z-mode waves, which can form radiation belts inside the orbit of Enceladus.

    • E. E. Woodfield
    • , R. B. Horne
    •  & W. S. Kurth
  • Article
    | Open Access

    Remote sensing of geomagnetic fields in mesosphere is both challenging and interesting to explore the magnetic field structures and atomic collision processes. Here the authors demonstrate an atomic magnetometer that utilizes the Larmor frequency in sodium atoms and operates in kilometers range.

    • Felipe Pedreros Bustos
    • , Domenico Bonaccini Calia
    •  & Simon Rochester
  • Article
    | Open Access

    Alumina is thought to be the main condensate to form in the gas outflow from oxygen-rich evolved stars. Here, the authors perform a condensation experiment with alumina in a low-gravity environment, and find spectroscopic evidence for a sharp feature at a wavelength of 13.55 μm.

    • Shinnosuke Ishizuka
    • , Yuki Kimura
    •  & Yuko Inatomi
  • Article
    | Open Access

    Tree rings retain information of sudden variations of ancient radiocarbon (14C) content, however the origin and exact timing of these events often remain uncertain. Here, the authors analyze a set of Arctic tree rings and link a rapid increase in 14C to a solar event that occurred during the spring of AD 774.

    • J. Uusitalo
    • , L. Arppe
    •  & M. Oinonen
  • Article
    | Open Access

    The ionosphere can give rise to irregularities that can interfere with radio communication, navigation and satellite systems. Here the authors present unique observations from the Arecibo Radio Observatory in Puerto Rico to reveal the existence of plasma irregularities occur in the mid-latitude F-region.

    • David Hysell
    • , Miguel Larsen
    •  & Michael Sulzer
  • Article
    | Open Access

    Observations of Jupiter’s magnetosphere provide opportunities to understand how magnetic fields interact with particles. Here, the authors report that the chorus wave power is increased in the vicinity of Europa and Ganymede. The generated waves are able to accelerate particles to very high energy.

    • Y. Y. Shprits
    • , J. D. Menietti
    •  & D. A. Gurnett
  • Article
    | Open Access

    Solar eruptions are large explosions occurring in the solar atmosphere. Here, the authors perform magnetohydrodynamic simulations to unveil the dynamics of a solar eruption, and find that these are dominated by nonlinear processes involving flux tube evolution and reconnection.

    • Satoshi Inoue
    • , Kanya Kusano
    •  & Jan Skála
  • Article
    | Open Access

    Ions produced by cosmic rays have been thought to influence aerosol and cloud processes by an unknown mechanism. Here the authors show that the mass flux of ions to aerosols enhances their growth significantly, with implications for the formation of cloud condensation nuclei.

    • H. Svensmark
    • , M. B. Enghoff
    •  & J. Svensmark
  • Article
    | Open Access

    White-light flares are rare solar events entailing emission in the optical continuum. Here, the authors report a nearly circular white-light flare observed on March 10th 2015 that contains simultaneously both impulsive and gradual white-light kernels.

    • Q. Hao
    • , K. Yang
    •  & Z. Li
  • Article
    | Open Access

    Radio observations of the solar atmosphere provide a unique view on the non-thermal processes in the outer atmosphere. Here the authors use LOFAR observations to demonstrate that the observed radio burst characteristics are dominated by propagation effects rather than underlying emission variations.

    • E. P. Kontar
    • , S. Yu
    •  & P. Subramanian
  • Article
    | Open Access

    14C can be absorbed by trees as a result of the interaction of cosmic rays produced by high-energy phenomena with the Earth’s atmosphere. Here, the authors observe a rapid increase of 14C in an ancient buried tree from BC 3372 to BC 3371, and suggest that it could originate from a large solar proton event.

    • F. Y. Wang
    • , H. Yu
    •  & K. S. Cheng
  • Article
    | Open Access

    Solar eruptions provide opportunities to study magnetic flux ropes, a structure of fundamental importance for both plasma physics and space weather. Here the authors reveal the dynamic formation of a flux rope through its footprint on the solar surface, revealing a highly twisted core structure.

    • Wensi Wang
    • , Rui Liu
    •  & Chunming Zhu