Search

The Juno spacecraft completed 35 successful orbits around Jupiter from orbit insertion in 2016 through the end of its prime mission phase in 2021. The Advanced Stellar Compass (ASC) and associated Camera Head Units (CHUs) comprise a dedicated attitude sensing system of the Magnetic Field Investigation (MAG), one of Juno's scientific payloads. The CHU is a CCD-based camera and is inherently susceptible to ionizing radiation. An energetic charged particle penetrating the camera head electronics shielding will deposit its energy and liberate charges in the charge wells. These events will register as isolated bright pixels in the integrated star tracker source images, and are distinguishable from optical sources that illuminate a number of collocated pixels spanning the imager's point spread function. By simply counting the number of such isolated bright pixels, an estimate of the number of charged particles penetrating the CCD can be established, eventually constraining the local external omnidirectional radiation flux (omniflux). The ASC performs the bright pixel count onboard and includes this count rate with the attitude telemetry, providing an energetic particle omniflux measurement at high time resolution. We describe here this additional functional capability of the ASC, including the filtering required to isolate the unbiased attitude cycles, the calibration required to circumvent count statistics effects, and the calibration of the sensor sensitivity, as well as the attenuation efficacy of the sensor shielding mass. Finally, we discuss the potential of the omniflux product for radiation field mapping as well as a proxy for investigating physical phenomena otherwise unattainable. [ABSTRACT FROM AUTHOR]

We investigate the variability of the power emission of Io's hotspots by using recent Juno/JIRAM infrared observations. The Jovian Infrared Auroral Mapper (JIRAM) is an imaging spectrometer which began observing Jupiter in August 2016. Although observing Jupiter's moons is not its primary objective, JIRAM can use the frequent opportunities to observe Io (up to once per orbit) to gather infrared images and spectra of its surface. The present study uses the data acquired by JIRAM during the last 2 years, including the location and morphology of Io's hotspots, and the temporal variability of the total output. A new photometric model for the hotspots and the dayside surface has been developed, which permits us to disentangle the temporal variability from the changes in the observation geometry. While the latitudinal dependence of the power output is not well constrained, low-latitude hotspots show a significantly more intense temporal variability and greater temperature. [ABSTRACT FROM AUTHOR]

Interchange instability is known to drive fast radial transport of electrons and ions in Jupiter's inner and middle magnetosphere. In this study, we conduct a statistical survey to evaluate the properties of energetic particles and plasma waves during interchange events using Juno data from 2016 to 2023. We present representative examples of interchange events followed by a statistical analysis of the spatial distribution, duration and spatial extent. Our survey indicates that interchange instability is predominant at M‐shells from 6 to 26, peaking near 17 with an average duration of minutes and a corresponding M‐shell width of <∼0.05. During interchange events, the associated plasma waves, such as whistler‐mode, Z‐mode, and electron cyclotron harmonic waves exhibit a distinct preferential location. These findings provide valuable insights into particle transport and the source region of plasma waves in the Jovian magnetosphere, as well as in other magnetized planets within and beyond our solar system. Plain Language Summary: The radial transport of plasma around a magnetized planet is crucial for understanding the underlying magnetospheric dynamics. Jupiter's magnetospheric dynamics are primarily dominated by the rapid rotation and plasma source from Io. This rapid rotation drives the interchange instability, where hot, low‐density plasma is moved toward the inner magnetosphere. During this process, the inward moving flux tube builds up magnetic pressure, potentially leading to the trapping of particles alongside plasma waves. In this study, we present several typical examples of interchange events, and conduct a statistical analysis to explore their spatial distribution, duration and spatial extent, as well as the typical features of the associated plasma waves. This survey provides insights into mass transport, the source of these plasma waves in Jupiter's magnetosphere, with potential implications for other magnetized planets within and beyond our solar system. Key Points: Our statistical survey indicates that interchange events occur over L (or M)‐shells ∼6–26 at Jupiter with a peak occurrence rate at M ∼ 17During interchange events, various types of plasma waves are intensified, each exhibiting a distinct preferential locationThe duration and the corresponding spatial extent of interchange events are analyzed for multiple events [ABSTRACT FROM AUTHOR]

Based on plasma observations from Juno's Joviana Auroral Distributions Experiment instrument and forward modeling, we investigate the dawn‐dusk asymmetries within Jupiter's magnetosphere between 10 and 40 RJ ${\mathrm{R}}_{J}$. On the dawnside, the flux tubes are depleted characterized by low density and near rigid‐corotation velocity, with a low temperature and thin plasma sheet. On the duskside, the flux tubes are assimilated characterized by high density and sub‐corotation velocity, with a hotter and thicker plasma sheet. Super‐corotating hot inflows originating from reconnection events are identified in the pre‐dawn sector. These observations are consistent with the Vasyliūnas cycle, suggesting it operates in a region closer to Jupiter than previous studies suggested. Outflows are locally coupled with swept‐back magnetic fields and are frequently observed near midnight. Inflows are locally coupled with swept‐forward fields with higher temperatures. The discernible temperature difference between inflows and outflows reveals their distinct origins. Plasma beta increases with radial distance, suggesting increased instabilities at larger distances. Plain Language Summary: Jupiter's magnetosphere is internally driven by plasma originating from its moons, particularly Io. As the plasma corotates around Jupiter and is transported outward, the force balance breaks with stretched magnetic field and pinched off plasma blobs, resulting in local time asymmetry. For the first time, this asymmetry is validated within 40 Jupiter radii using plasma observations from the Juno mission. Compared to the duskside, the dawnside plasma exhibits lower density, higher temperature, and larger corotational velocity (even exceeds rigid corotation sometimes). These results indicate distinct origins for inflows and outflows. This study brings us a step forward in our understanding of the dynamics of Jupiter's magnetosphere and provides a data set for comparison with simulations. Key Points: The dawn‐dusk asymmetry between 10 and 40 RJ is modulated by the Vasyliūnas cycle, featuring super‐corotating flows in the pre‐dawn sectorThe flux tubes are depleted and accelerated on the dawnside, while they are dense and sub‐corotational on the dusksideThe temperature difference between inflows and outflows suggests physically distinct origins [ABSTRACT FROM AUTHOR]

We present an application of the latest UCL‐AGA magnetodisc model (MDISC) to the study of the magnetic and plasma conditions in the near‐Ganymede space. By doing this, we provide a comparison with measurements from Juno's most recent flyby of the Jovian moon, perijove 34 (PJ34). We find good agreement between the model results and the magnetometer data, pointing toward a hot plasma index value Kh= ${K}_{h}=$ (2.719± $\pm $0.024)× ${\times} $107 Pa m T−1 and an effective magnetodisc radius rmax= ${r}_{\text{max}}=$ (79.5± $\pm $1.1) Jupiter radii for the Jovian magnetosphere, for the duration of the trajectory, suggesting a configuration with middling levels of expansion. We also predict the plasma conditions observed by Juno during the same flight‐path, as well as the typical conditions over the orbit of Ganymede, with the magnetic and hot plasma pressures assuming dominant roles. Finally, these results are compared with functional fits of a compilation of Galileo flyby data obtained in the vicinity of Ganymede's orbit, suggesting Juno experienced somewhat similar conditions, despite a systematic overestimation in magnetic field intensity in the near‐Ganymede space. Plain Language Summary: Being the largest moon in the Solar system and the only one with its own magnetic field, Ganymede presents a unique target for magnetospheric interaction studies. Although much weaker than the Jovian magnetic field surrounding it, Ganymede's field is strong enough to carve a small region in space, called a magnetosphere, which is itself contained within Jupiter's own magnetosphere. The interplay between these two structures gives rise to numerous phenomena that can affect the near‐Ganymede environment. There is also evidence for an additional inductive contribution resulting from the interaction of Jupiter's time varying magnetic field and a possible subsurface ocean. By understanding how the different field contributions affect the overarching environment around Ganymede, we can extract valuable information about the moon's atmosphere, internal composition and its relation with the Jovian environment. In this study we compare our model's predictions with data gathered by Juno during one of its orbits around Jupiter, which also included a Ganymede flyby, showing good agreement between the two. We then predict the plasma conditions the spacecraft encountered during the same trajectory, as well as over Ganymede's orbit, highlighting the main pressure contributions and how these vary according to the rotational phase of Jupiter's magnetic pole. Key Points: Strict constraints on magnetospheric field and plasma configuration can be inferred from magnetic field observations aloneJupiter's rotation and the position of Ganymede relative to the plasma sheet drive the magnetic and plasma environments surrounding the moonMagnetic and hot plasma pressures assume the dominant roles in dictating the plasma environment near Ganymede [ABSTRACT FROM AUTHOR]

Plasmoids and magnetic field dipolarizations are reconnection‐related phenomena often resulting in reconfiguration of the magnetic field and energetic particle acceleration in planetary magnetotail. Building on the work of Blöcker et al. (2023) (10.1029/2023JA031312), we selected seven specific events from their magnetic field dipolarization analysis, each exhibiting distinct ion dynamics during the time interval of the magnetic field dipolarizations. To gain further insights into the understanding why certain events were associated with ion intensity variations while others were not, we analyzed plasma moments, specifically ion flow velocity and density, for these selected events. Our findings revealed that certain magnetic field dipolarizations within our database exhibit sub‐Alfvénic flows and lack the properties typically associated with reconnection‐related magnetic field dipolarizations. These magnetic field dipolarizations also do not accelerate ions. Furthermore, we present a survey of Jovian plasmoids and magnetic field dipolarizations during the first 47 orbits of Juno. Applying Juno magnetic field data, we identified 119 magnetic field dipolarizations and 94 plasmoids within a local time range of 18:00–06:00. The majority of plasmoids were detected in the predawn sector, whereas magnetic field dipolarizations were observed closer to Jupiter and were not limited to a specific local time. Combining the statistics of plasmoids and dipolarizations is useful for contextualizing them within the framework of reconnection. Key Points: Certain magnetic field dipolarizations exhibit sub‐Alfvénic flows and deviate from typical reconnection‐related propertiesNonadiabatic ion acceleration is only observed in magnetic field dipolarizations with super‐Alfvénic ion flowsPlasmoids are concentrated in the predawn sector, while dipolarizations are distributed from 20:00 to 5:00 local time closer to Jupiter [ABSTRACT FROM AUTHOR]

In mammalian reproduction, testis-specific protein IZUMO1 and its receptor JUNO on the oocyte surface are essential for sperm-oocyte recognition, binding, and membrane fusion. However, these factors alone are insufficient to accomplish cytoplasmic membrane fusion. It is believed that other gametic proteins interact with them to facilitate sperm-oocyte interaction on the head and mid-tail of rat spermatozoa as well as on the surface of oocytes. In this study, Copper Transport Protein 2 (CTR2) has been identified on the head and mid-tail of rat spermatozoa as well as on the surface of oocytes. CTR2 directly interacts with both IZUMO1 and JUNO, colocalizing with IZUMO1 on the sperm head and with JUNO on the oocyte membrane. Treatment of the capacitated sperm and zona pellucida-free oocytes with anti -CTR2 antibody resulted in a significant decrease in fertilization rates in IVF experiments. These findings suggest that CTR2 plays an important role in mammalian fertilization by interacting with IZUMO1 and JUNO, providing new insights into the molecular mechanisms of mammalian sperm-oocyte adhesion and fusion. [ABSTRACT FROM AUTHOR]

Juno has allowed clear, high‐resolution imaging of Io's polar volcanoes using the Jovian Infrared Auroral Mapper (JIRAM) instrument. We have used data from JIRAM's M‐band (4.78 μm) imager from 11 Juno orbits to construct a global map of volcanic flux. This map provides short‐term insight into the spatial distribution of volcanoes and the ways in which high‐ and low‐latitude volcanoes differ. Using spherical harmonic analysis, we quantitatively compare our volcanic flux map to the surface heat flow distribution expected from models of Io's tidal heat deposition (summarized in de Kleer, Park, et al. (2019, https://doi.org/10.26206/d4wc‐6v82). Our observations confirm previously detected systems of bright volcanoes at high latitudes. Our study finds that both poles are comparably active and that the observed flux distribution is inconsistent with an asthenospheric heating model, although the south pole is viewed too infrequently to establish reliable trends. Plain Language Summary: Our study uses data from an infrared camera on Juno called the Jovian Infrared Auroral Mapper (JIRAM) to image Io, the innermost Galilean moon of Jupiter. Io is the most volcanically active body in the Solar System. Io's volcanoes are powered by both the extreme tides from Jupiter and the gravitational interactions between it and Jupiter's other moons. These tides generate friction inside Io. Simulations of Io's interior suggest that, depending on how deep that friction is being generated, the surface heat flow will be higher in certain areas (de Kleer, Park, et al., 2019, https://doi.org/10.26206/d4wc‐6v82). Using JIRAM, we have mapped where volcanoes are producing the most power and compared that to where we expect higher heat flow from the interior models. Our map doesn't agree with any of these models very well. JIRAM observed more volcanic activity at the poles than we expected to see based on previous observations. However, since the south pole was only observed twice, it's possible that these observations don't represent the average volcanic activity of the south pole. Very bright volcanoes that may have been continuously active for decades were also imaged during these Juno fly‐bys, some of which are nearer the poles than the equator. Key Points: We have produced a global volcanic flux map of Io using data from 11 Juno fly‐bysOur flux map doesn't agree well with tidal heat flow models reported in de Kleer, Park, et al. (2019, https://doi.org/10.26206/d4wc‐6v82)The M‐band flux is anti‐correlated with the asthenospheric heating model and has only very weak agreement with the global magma ocean model [ABSTRACT FROM AUTHOR]

In recent years, it has been found that magnetic dip caused by diamagnetic motion of injected plasma can provide an appropriate environment for excitation of electromagnetic ion cyclotron (EMIC) waves. These findings have been widely reported in the Earth's magnetic environment. However, it has rarely been reported in Jupiter's magnetic environment. This paper reports the characteristics of EMIC waves observed by Juno in the magnetic dip of Jupiter. Multiple‐band EMIC waves are observed in frequency range from 10−3 Hz to several Hz. The theoretical analysis shows that in this event both He+ band and O+ band EMIC waves can be constrained in the magnetic dip, which is consistent with the wave emissions observed inside the magnetic dip. Our result provides the first evidence that EMIC wave can be ducted inside a magnetic dip in Jupiter's magnetosphere. Plain Language Summary: The relationship between magnetic structures and electromagnetic waves in the Earth's magnetosphere has been widely reported. Recent studies have theoretically displayed the effects of the magnetic dip on the EMIC wave propagation in Earth's magnetic field. In this paper, we use the event observed by Juno in the magnetic environment of Jupiter to analyze the effect of the magnetic dip on the propagation of EMIC waves. As a result, the observed EMIC waves can be ducted inside the magnetic dip of Jupiter's magnetosphere. Since these ducted waves would influence the dynamics of energetic protons through longtime scattering effects, the magnetic dip is expected to play an important role in the dynamics of Jupiter's magnetosphere. Key Points: Electromagnetic ion cyclotron (EMIC) waves are observed during the magnetic dip by JunoTheoretical analysis about the effects of magnetic dips on the EMIC wave propagation in Jupiter's magnetosphere is performedBoth He+ and O+ band EMIC waves can be ducted inside the magnetic dip in Jupiter's magnetosphere [ABSTRACT FROM AUTHOR]

Jupiter's moon Europa contains a subsurface ocean whose presence is inferred from magnetic field measurements, the interpretation of which depends on knowledge of Europa's local plasma environment. A recent Juno spacecraft flyby returned new observations of plasma electrons with unprecedented resolution. Specifically, powerful magnetic field‐aligned electron beams were discovered near Europa. These beams, with energies from ∼30 to ∼300 eV, locally enhance electron‐impact‐excited emissions and ionization in Europa's atmosphere by more than a factor three over the local space environment, and are associated with large jumps of the magnetic fields. The beams therefore play an essential role in shaping Europa's plasma and magnetic field environment and thus need to be accounted for electromagnetic sounding of Europa's ocean and plume detection by future missions such as JUICE and Europa Clipper. Plain Language Summary: A recent Juno spacecraft close flyby of Jupiter's moon Europa revealed the presence of powerful electrons beams. Based on previous observations and modeling of electron beams at the moon Io, such beams were not expected to be observed so close to Europa. Overall, the proximity of the beams to Europa indicates that the acceleration of these electrons takes place much closer to Europa than anticipated and that these beams, therefore, stem from a new and previously unknown acceleration mechanism. The beams are predicted to have an outsized influence on the ionization of the constituents of Europa's tenuous atmosphere and are accompanied with large magnetic field perturbations. Hence, these electron beams are an important ionization source that modify the moon's ionosphere, the electric current systems, and the magnetic field environment. In particular, the presence of electron beams will affect plasma conditions that are used to infer the extent of a subsurface ocean via the magnetic induction signal. These beams significantly impact the space plasma environment around Europa which needs to be accounted for by future missions such as ESA's (European Space Agency) JUICE (Jupiter Icy Moons Explorer) and NASA's (National Aeronautics and Space Administration) Europa Clipper mission. Key Points: Powerful electron beams that significantly shape Europa's space environment are discovered during a Juno flybyThe beams enhance electron‐impact‐excited emissions in Europa's atmosphere and are associated with large jumps of the magnetic fieldsThe beams' proximity to Europa and their pitch angle distribution constrain the source acceleration to be near or within the plasma disk [ABSTRACT FROM AUTHOR]

Abstract Interchange instability is known to drive fast radial transport of electrons and ions in Jupiter's inner and middle magnetosphere. In this study, we conduct a statistical survey to evaluate the properties of energetic particles and plasma waves during interchange events using Juno data from 2016 to 2023. We present representative examples of interchange events followed by a statistical analysis of the spatial distribution, duration and spatial extent. Our survey indicates that interchange instability is predominant at M‐shells from 6 to 26, peaking near 17 with an average duration of minutes and a corresponding M‐shell width of

Abstract Based on plasma observations from Juno's Jovian Auroral Distributions Experiment instrument and forward modeling, we investigate the dawn‐dusk asymmetries within Jupiter's magnetosphere between 10 and 40 RJ. On the dawnside, the flux tubes are depleted characterized by low density and near rigid‐corotation velocity, with a low temperature and thin plasma sheet. On the duskside, the flux tubes are assimilated characterized by high density and sub‐corotation velocity, with a hotter and thicker plasma sheet. Super‐corotating hot inflows originating from reconnection events are identified in the pre‐dawn sector. These observations are consistent with the Vasyliūnas cycle, suggesting it operates in a region closer to Jupiter than previous studies suggested. Outflows are locally coupled with swept‐back magnetic fields and are frequently observed near midnight. Inflows are locally coupled with swept‐forward fields with higher temperatures. The discernible temperature difference between inflows and outflows reveals their distinct origins. Plasma beta increases with radial distance, suggesting increased instabilities at larger distances.

Because of the time-consuming nature of surgical neutering and the rapid rate of reproduction among domestic cats, it is crucial to investigate alternative, nonsurgical methods of contraception for this species. Sperm protein IZUMO1 and its oocyte receptor JUNO have been proposed as potential targets for nonsurgical contraceptives. This study aimed to demonstrate (1) the protein coding sequence of feline IZUMO1 and JUNO , (2) gene expression in specific organs by measuring mRNA levels in different visceral tissues, and (3) the expression of IZUMO1 and JUNO during sperm maturation and folliculogenesis, respectively. Amplification for sequencing of feline IZUMO1 and JUNO was performed using the RT-PCR method. Levels of gene expression in different tissues were evaluated using real-time PCR. In situ hybridization was performed to localize JUNO mRNA in ovarian tissues. The complete coding sequences of IZUMO1 and JUNO were obtained and analyzed. A comparison between protein orthologs demonstrated the conservation of IZUMO1 and JUNO in Felidae. The real-time PCR results from various visceral organs indicated that IZUMO1 was significantly higher in the testis than in other organs, whereas JUNO was significantly higher in the ovary than in other organs. Expression of IZUMO1 was found to be higher in the testes than in the caput, corpus, and cauda of epididymides. In situ hybridization revealed that JUNO mRNA was in the ooplasm and nucleus of the primordial, primary, secondary, and antral follicles. Importantly, this was the first study to demonstrate the IZUMO1 and JUNO genes in the testis and ovary of cats. The results are useful for future research related to these genes and for developing contraceptives against these targets. • IZUMO1 and JUNO protein coding sequences were demonstrated in the cat testis and ovaries, respectively. • IZUMO1 and JUNO mRNA was expressed dominantly in the cat testes and ovaries, respectively. • In the ovaries , JUNO mRNA was located in the nuclei and ooplasm of all stages of follicles. • Comparing with testes , IZUMO1 mRNA expression was lesser in all regions of the epididymides. [ABSTRACT FROM AUTHOR]

The thermal and energetic electrons along Ganymede's orbit not only weather the surface of the icy moon, but also represent a major threat to spacecraft. In this article, we rely on Juno plasma measurements to characterize the temporal and spatial variability of the electron environment upstream of Ganymede. In particular, we find that electron spectra observed by Juno have fluxes larger by a factor of 2–9 at energies above 10 keV than what was measured two decades earlier by Galileo. This result will advance our understanding of the surface weathering and may be a concern for the radiation safety of the JUICE mission. Furthermore, the June 2021 close fly‐by of Ganymede through the moon's wake reveals that the open field line regions of its magnetosphere attenuate electron fluxes at all energies by a factor of 1.6–5, thereby offering a natural shelter to visiting spacecraft crossing this region. Plain Language Summary: Ganymede, the only magnetized moon in our Solar System, orbits deep inside the giant magnetosphere of Jupiter where it interacts with the temporally and spatially variable magnetized disk of plasma in corotation around the planet, its magnetodisk. The intensities of ions and electrons precipitating to the surface of Ganymede in particular depend on the location of the moon with respect to the Jovian magnetodisk. In this work, we provide a full quantification of electron properties along the orbit of Ganymede as observed by Juno. This is done by combining observations from two instruments in order to build composite electron energy spectra and derive their omnidirectional fluxes, densities, and pressures. We report that the average electron omnidirectional fluxes are significantly attenuated when measured above or below the magnetodisk, as well as strongly inside the magnetosphere of the moon where its intrinsic magnetic field provides additional shielding. We confirm that the electron total density is dominated by the thermal population, whereas the total pressure is dominated by the suprathermal one. When comparing our results with Galileo‐based observations and models, we find that the latter the latter two underestimate fluxes in particular at high energies, and we put these observations in context for the future exploration of Ganymede by JUICE. Key Points: We present composite electron energy spectra combining all Juno particle data from 07/2017 to 08/2022 at Ganymede's orbitWe study the variability of electron fluxes inside and outside the Jovian magnetodisk as well as within Ganymede's magnetosphereGalileo‐based models underestimate the electron fluxes observed by Juno in particular at high energies [ABSTRACT FROM AUTHOR]

Juno flew over the northern mid‐latitudes of Ganymede during orbit 34 of the Juno mission, reaching an altitude of 1,053 km (16:56:07.972 UTC) at a sub spacecraft latitude/longitude of 33.66N, 57.5W degrees on 7 June 2021. Between 16:43 and 17:02 UT, Juno pierced Ganymede's magnetosphere at a velocity relative to Ganymede of 18.57 km s−1. Juno's instrumentation provided a unique opportunity to sample the local environment of Ganymede and its magnetosphere. We present measurements of the composition of the polar ionospheric outflow and the energetic electrons that penetrate Ganymede's atmosphere and produce its aurora. When these new observations are combined with modeling, conclusions can be drawn that affect our understanding of the atmosphere of Ganymede. The measured JADE precipitating plasma electrons provide an energy flux beyond that needed to create the observed oxygen emissions measured by UVS, but the electron energy spectrum is optically thin to the sparse atmosphere and does not provide the observed oxygen ultraviolet emission unless the O2 column density is increased by over an order of magnitude compared to previous atmospheric models. More than 99% of the electron energy flux passes through the atmosphere into the ice, thereby increasing the H2 and O2 content of the atmosphere. The increased H2 and O2 production is largely responsible for increasing the oxygen column density to a level that produces within known uncertainties the OI135.6 and OI130.4 nm emissions when bombarded by the electron energy flux observed by JADE. This suggests that past modeling efforts have underestimated the density of the atmosphere by over an order of magnitude. Plain Language Summary: Juno flew by the Jovian satellite Ganymede on orbit 34 of the mission coming within 1,053 km of the surface at high northern latitudes. Juno provides a unique data set from the particle, field, and ultraviolet imaging experiments that can be utilized to study the interaction between the magnetosphere of Ganymede and the magnetosphere of Jupiter. Compositionally diverse ion outflow was observed in the northern polar cap that can be linked to the exchange of plasma and energetic particles between Jupiter and Ganymede. Furthermore, an electron spectrum produced by magnetic reconnection processes was observed that can be linked to the aurora at Ganymede. These observations provide new information about Ganymede's atmosphere. They strongly suggest an increase in the column density of O2 in Ganymede's atmosphere of an order of magnitude relative to all previous models. The latter has implications for all water ice satellites in the outer solar system. Key Points: Multiple data sets from Juno's flyby of Ganymede indicate energetic particle impact of the surface and atmosphere resulting in ion outflowReconnection processes on the Jupiter‐facing flank of the magnetospheric interaction provide constraints on the auroral excitationInitial modeling strongly suggests an order of magnitude increase in atmospheric O2 column density relative to previous models [ABSTRACT FROM AUTHOR]

Abstract Juno has allowed clear, high‐resolution imaging of Io's polar volcanoes using the Jovian Infrared Auroral Mapper (JIRAM) instrument. We have used data from JIRAM's M‐band (4.78 μm) imager from 11 Juno orbits to construct a global map of volcanic flux. This map provides short‐term insight into the spatial distribution of volcanoes and the ways in which high‐ and low‐latitude volcanoes differ. Using spherical harmonic analysis, we quantitatively compare our volcanic flux map to the surface heat flow distribution expected from models of Io's tidal heat deposition (summarized in de Kleer, Park, et al. (2019, https://doi.org/10.26206/d4wc‐6v82). Our observations confirm previously detected systems of bright volcanoes at high latitudes. Our study finds that both poles are comparably active and that the observed flux distribution is inconsistent with an asthenospheric heating model, although the south pole is viewed too infrequently to establish reliable trends.

Abstract In recent years, it has been found that magnetic dip caused by diamagnetic motion of injected plasma can provide an appropriate environment for excitation of electromagnetic ion cyclotron (EMIC) waves. These findings have been widely reported in the Earth's magnetic environment. However, it has rarely been reported in Jupiter's magnetic environment. This paper reports the characteristics of EMIC waves observed by Juno in the magnetic dip of Jupiter. Multiple‐band EMIC waves are observed in frequency range from 10−3 Hz to several Hz. The theoretical analysis shows that in this event both He+ band and O+ band EMIC waves can be constrained in the magnetic dip, which is consistent with the wave emissions observed inside the magnetic dip. Our result provides the first evidence that EMIC wave can be ducted inside a magnetic dip in Jupiter's magnetosphere.

Abstract Jupiter's moon Europa contains a subsurface ocean whose presence is inferred from magnetic field measurements, the interpretation of which depends on knowledge of Europa's local plasma environment. A recent Juno spacecraft flyby returned new observations of plasma electrons with unprecedented resolution. Specifically, powerful magnetic field‐aligned electron beams were discovered near Europa. These beams, with energies from ∼30 to ∼300 eV, locally enhance electron‐impact‐excited emissions and ionization in Europa's atmosphere by more than a factor three over the local space environment, and are associated with large jumps of the magnetic fields. The beams therefore play an essential role in shaping Europa's plasma and magnetic field environment and thus need to be accounted for electromagnetic sounding of Europa's ocean and plume detection by future missions such as JUICE and Europa Clipper.

The electromagnetic coupling between the Galilean satellites at Jupiter and the planetary ionosphere generates an auroral footprint, which is detected with high spatial resolution in the infrared L band by the Jovian InfraRed Auroral Mapper (JIRAM) onboard the Juno spacecraft. We report the JIRAM data acquired since 27 August 2016 until 23 May 2022, which are used to compute the average position of the footprint tracks of Io, Europa and Ganymede. The result of the present analysis help to test the reliability of magnetic field models, to calibrate ground‐based observations and to highlight the variability in the footprint positions, which can be used to probe the plasma environment at the orbit of the satellites. The determination of the plasma properties around the moons is particularly relevant to complement the Juno flybys of the moons during its extended mission, and to support the future Juice and Europa Clipper missions. Lastly, we report no clear evidence of the auroral footprint of Callisto, which is likely due to a combination of its low expected brightness and its position very close to the main Jovian aurora. Plain Language Summary: The Jovian InfraRed Auroral Mapper onboard the Juno spacecraft around Jupiter has now been gathering 6 years of observations. Here, we report the position of the auroral infrared emission associated with the orbital motion of Io, Europa and Ganymede. The position of this emission ‐ called footprint ‐ carries information on the magnetic field geometry and the distribution of charged particles along the magnetic field. Therefore, the footprint tracks provided here can be used to test and constrain magnetic field models, and to improve the calibration of ground based observations of Jupiter: this can help better understand the source region of the main Jovian aurora and its variations. Lastly, by surveying the data acquired over 40 Juno orbits, we point out variations in the footprint position, which reflect the variability in the plasma conditions near the moons: this monitoring may help determine the mass loading of the magnetosphere, which affects the intensity of the main aurora. The possibility of investigating the plasma environment at the orbit of the satellites is important to complement the satellite flybys performed during the extended mission of Juno and to support the future Juice and Europa Clipper missions, which are dedicated to the Galilean moons. Key Points: The position of the Io, Europa and Ganymede footprints based on Juno‐JIRAM observations are reported with unprecedented spatial resolutionThe positions of the footprints support the Juno‐based magnetic field models and the calibration of ground‐based observationThe transversal shift of the Ganymede footprint suggests variations of the plasmadisk; the shift appears to be correlated with local time [ABSTRACT FROM AUTHOR]

A map of vertical cutoff rigidities has been calculated for galactic cosmic ray (GCR) entry into the atmosphere of Jupiter at the 1 bar pressure radius (1 RJ = 71,492 km) using the JRM33 comprehensive model of Jupiter's magnetic field (based on 32 close flybys of Jupiter by the Juno satellite) along with a particle trajectory code (Geomagnetic Cutoff Rigidity Computer Program). The map was combined with measurements of the GCR proton flux at Earth, from the BESS‐Polar ii campaign, to calculate a corresponding proton flux map at Jupiter. Additional cutoff rigidity maps were calculated for 1,000 km above the 1 bar level, and for 1.41 RJ. Furthermore, detections of heavy particles from Juno's Stellar Reference Unit were analyzed for their cutoff rigidities in multiple directions. Cutoff rigidities of 3.5–7.5 GV were found for five of the detections furthest out making them possible GCR candidates. The majority of points, located below 1.6 RJ are not likely to be GCR. Assuming instead that they are trapped particles we have calculated upper and lower limits on their equatorial pitch angles, resulting in a range from 10.1° to 27.1°, which can help constraining Jupiter's energetic radiation. Plain Language Summary: Using data of Jupiter's magnetic field, collected by the Juno satellite, we have calculated how galactic cosmic rays (energetic particles originating from supernovae) can enter into the atmosphere of Jupiter at different altitudes. This can aid our understanding of atmospheric phenomena on Jupiter and help in planning future missions to the planet. One of Juno's instruments, the Stellar Reference Unit, has detected some peculiar signatures. Some of them probably are galactic cosmic rays that have hit the instrument. Most of them are probably not, but instead they could be particles trapped by the strong magnetic field of Jupiter. If so, they can help us understand the radiation belts of the planet. Using knowledge of the location of the detections as well as the magnetic field we calculate the so‐called pitch angle of the detected particles. This angle is defined by the ratio between the motion of the particle perpendicular to the magnet field line and the motion parallel to the field line. The pitch angle is fundamental in constraining energetic radiation emanating from Jupiter's atmosphere. Key Points: A galactic cosmic ray cutoff rigidity map for Jupiter was made using the JRM33 model and the Geomagnetic Cutoff Rigidity Computer ProgramThe flux of galactic cosmic ray protons into Jupiter's atmosphere was calculated based on BESS‐Polar ii dataDetections of heavy ions by Juno's SRU were investigated and used to estimate their equatorial pitch angles [ABSTRACT FROM AUTHOR]

Fertilization is a complex process that depends on the fusion of the cell membrane of sperm with that of oocyte, and it involves sperm-oocyte recognition, binding, and fusion, which are mediated by multiple proteins. Among those proteins, IZUMO1 and its receptor JUNO have been identified as essential factors for sperm-oocyte recognition and fusion. However, the interaction between IZUMO1 and JUNO alone does not lead to cell membrane fusion, suggesting the involvement of additional proteins in sperm-oocyte membrane fusion. In this study, we have discovered that a protein called WDR54, which consists of WD-repeat modules, is located on the cell membrane of sperm, as well as on the cell membrane and in the cytoplasm of the oocyte. We have found that WDR54 is involved in sperm-oocyte fertilization. When sperm and oocyte were treated with anti-WDR54 ascites, the in vitro fertilization (IVF) rate significantly decreased. Furthermore, our research has shown that WDR54 interacts with both IZUMO1 and JUNO, and it colocalizes with IZUMO1 on the surface of the sperm head and with JUNO on the oocyte surface. Through structural analysis of the putative complexes of WDR54-IZUMO1 and WDR54-JUNO, we infer that these three proteins could form a complex of JUNO-WDR54-IZUMO1-JUNO (referred to as the "JWIJ complex") on the oocyte surface. Our findings suggest that WDR54 is an important factor involved in sperm-oocyte adhesion and fusion. This discovery provides new insight into the mechanisms of mammalian sperm-oocyte adhesion and fusion. • WDR54 is located on the surface of sperm and oocyte, and colocalizes with IZUMO1 and JUNO, on sperm head and oocyte surface, respectively. • The IVF rate was significantly inhibited when rat sperm and oocytes were treated with mouse anti-rat WDR54 ascites. • WDR54 is a candidate for mediating the interactions between sperm and egg plasma membranes. [ABSTRACT FROM AUTHOR]

We investigate the variability of the power emission of Io’s hotspots by using recent Juno/JIRAM infrared observations. The Jovian Infrared Auroral Mapper (JIRAM) is an imaging spectrometer which began observing Jupiter in August 2016. Although observing Jupiter’s moons is not its primary objective, JIRAM can use the frequent opportunities to observe Io (up to once per orbit) to gather infrared images and spectra of its surface. The present study uses the data acquired by JIRAM during the last 2 years, including the location and morphology of Io’s hotspots, and the temporal variability of the total output. A new photometric model for the hotspots and the dayside surface has been developed, which permits us to disentangle the temporal variability from the changes in the observation geometry. While the latitudinal dependence of the power output is not well constrained, low-latitude hotspots show a significantly more intense temporal variability and greater temperature.

The individual phases of the moon show us this nocturnal satellite subjected to the laws of a cycle of dying and rising. In ancient times different peoples honoured the moon and the stars and felt connected to them in some way. These two symbols are present in various ways on ancient coins such as Greek, Roman or even Celtic ones. The representation of these symbols on ancient coins is sometimes different and has different meanings. The symbol of the crescent moon with the star was revived again in the Middle Ages and was depicted in different ways on many European coins, especially in the 13th century AD. The depiction of the crescent moon with the star on these coins has a new meaning that relates to Christian symbolism. This article presents the history of this symbol, its meaning in antiquity and in the Middle Ages and its possible connection with astronomical events. In particular we analyzed a Trieste’s medieval coin minted in the second half of the 13th century by the bishop of the city of Trieste Arlongus, on which the symbol of the crescent moon with a six-pointed star is clearly visible.

The fusion of mammalian gametes requires the interaction between IZUMO1 on the sperm and JUNO on the oocyte. We have recently shown that ectopic expression of mouse IZUMO1 induces cell-cell fusion and that sperm can fuse to fibroblasts expressing JUNO. Here, we found that the incubation of mouse sperm with hamster fibroblasts or human epithelial cells in culture induces the fusion between these somatic cells and the formation of syncytia, a pattern previously observed with some animal viruses. This sperm-induced cell-cell fusion requires a species-matching JUNO on both fusing cells, can be blocked by an antibody against IZUMO1, and does not rely on the synthesis of new proteins. The fusion is dependent on the sperm’s fusogenic capacity, making this a reliable, fast, and simple method for predicting sperm function during the diagnosis of male infertility.

Interchange instability is known to drive fast radial transport of particles in Jupiter's inner magnetosphere. Magnetic flux tubes associated with the interchange instability often coincide with changes in particle distributions and plasma waves, but further investigations are required to understand their detailed characteristics. We analyze representative interchange events observed by Juno, which exhibit intriguing features of particle distributions and plasma waves, including Z‐mode and whistler‐mode waves. These events occurred at an equatorial radial distance of ∼9 Jovian radii on the nightside, with Z‐mode waves observed at mid‐latitude and whistler‐mode waves near the equator. We calculate the linear growth rate of whistler‐mode and Z‐mode waves based on the observed plasma parameters and electron distributions and find that both waves can be locally generated within the interchanged flux tube. Our findings are important for understanding particle transport and generation of plasma waves in the magnetospheres of Jupiter and other planetary systems. Plain Language Summary: The centrifugal interchange instability, which has been observed in rapidly rotating planets, like Saturn and Jupiter, moves cold plasmas inside of the magnetosphere further away, and transports hotter, less dense plasmas toward the inner magnetosphere. These moving flux tubes have been observed at Jupiter together with plasma waves, but their detailed characteristics are not fully understood. In the present study, we use observations from the Juno spacecraft to report multiple representative interchange events and evaluate the properties of energetic particles and plasma waves. Furthermore, we use linear theory to calculate the growth rates of Z‐mode and whistler‐mode waves during these events. Our findings reveal the typical features of plasma waves and particles during interchange events, which provide important insights into particle transport and generation of plasma waves at Jupiter and possibly other magnetized planets in our solar system and beyond. Key Points: Several plasma transport events associated with interchange instability are identified alongside plasma waves using Juno observationsLinear growth rate analyses indicate that waves can be locally generated during interchange events due to anisotropic electron distributionsOur findings provide insights into electron transport and plasma wave dynamics during interchange events in planetary magnetospheres [ABSTRACT FROM AUTHOR]

At Jupiter, part of the auroral radio emissions are induced by the Galilean moons Io, Europa and Ganymede. Until now, except for Ganymede, they have been only remotely detected, using ground–based radio–telescopes or electric antennas aboard spacecraft. The polar trajectory of the Juno orbiter allows the spacecraft to cross the range of magnetic flux tubes which sustain the various Jupiter–satellite interactions, and in turn to sample in situ the associated radio emission regions. In this study, we focus on the detection and the characterization of radio sources associated with Io, Europa and Ganymede. Using electric wave measurements or radio observations (Juno/Waves), in situ electron measurements (Juno/JADE–E), and magnetic field measurements (Juno/MAG) we demonstrate that the Cyclotron Maser Instability (CMI) driven by a loss–cone electron distribution function is responsible for the encountered radio sources. We confirmed that radio emissions are associated with Main (MAW) or Reflected Alfvén Wing (RAW), but also show that for Europa and Ganymede, induced radio emissions are associated with Transhemispheric Electron Beam (TEB). For each traversed radio source, we determine the latitudinal extension, the CMI–resonant electron energy, and the bandwidth of the emission. We show that the presence of Alfvén perturbations and downward field–aligned currents are necessary for the radio emissions to be amplified. Plain Language Summary: At Jupiter, the auroras are much more intense and long‐lasting than on Earth, and some are influenced by Jupiter's three largest moons: Io, Europa, and Ganymede. We're particularly interested in the radio signals from these auroras. Until recently, these signals were mainly studied from a distance, using Earth‐based telescopes or spacecraft passing by Jupiter. However, since 2016, the Juno spacecraft has been orbiting Jupiter, flying through the auroral zone. Our study investigates the creation of these radio auroras using Juno's instruments to measure radio waves, particles, and magnetic fields. Our research strongly suggests that a phenomenon called the Cyclotron Maser Instability is the cause of these radio signals. This instability happens because some electrons are not coming back from Jupiter after causing Ultraviolet aurora on top of Jupiter's atmosphere. These radio signals are connected to the moons' ultraviolet auroras. Additionally, our research highlights the importance of specific perturbations in Jupiter's magnetic field, known as Alfvén perturbations, and currents that link Jupiter to these moons. This study deepens our understanding of Jupiter‐moon interactions and sheds light on Jupiter's fascinating auroras. Key Points: All Jupiter‐moon radio emissions are shown to be similarly triggered by the CMIThe crossed radio sources are colocated with either MAW, RAW or TEB footprintsThe crossed radio sources coincide with downward field‐aligned currents and Alfvén perturbations [ABSTRACT FROM AUTHOR]

On 15 September 2021, Chandra carried out a 40‐hr (∼4 jovian rotations) observation as part of its longest planetary campaign to study the drivers of jovian X‐ray aurora that may be linked to ultra‐low frequency (ULF) wave activity. During this time, Juno's orbit had taken the spacecraft into Jupiter's dusk magnetosphere. Here is believed to be the most probable location of ULF waves propagating along jovian magnetic field lines that drive the X‐ray auroral emissions. This is the first time that this region has been observed by an orbiter since Galileo >20 years ago, and never before has there been contemporaneous in situ and X‐ray observations. A 1D solar wind propagation model identifies a compression event near the midpoint of the 40‐hr observation window. The influence of a compression is confirmed when comparing the measured magnetic field in the dusk lobes of the magnetotail from Juno MAG data against a baseline lobe field model. Data from the Juno Waves instrument also show activation of broadband kilometric (bKOM) emissions during the arrival of the shock, a feature that has previously been observed during compression events. Therefore this is the first time we can fully analyze the morphological variability during the evolution of a shock. Wavelet transforms and Rayleigh testing are used to search for statistically significant quasi‐periodic pulsations (QPPs) of the X‐ray emissions in the data set, and find significant QPPs with periods of 25–26 min for the northern auroral X‐rays. Key Points: We compare a 40‐hr Chandra observation of Jupiter's X‐ray aurora with in situ Juno measurements and a 1‐D solar wind propagation modelWe find statistically significant quasi‐periodic pulsation with a ∼25 min period likely linked to the arrival of a solar wind compressionUsing Juno MAG data form the dusk tail lobes, we infer the state of compression/loading of the magnetosphere [ABSTRACT FROM AUTHOR]

On 29 September 2022 Juno's low‐light sensitive Stellar Reference Unit (SRU) captured a high‐resolution (256–340 m/pixel) broadband (450–1,100 nm) visible image of Europa's icy surface during the first close flyby of the Jovian moon since Galileo's last encounter in 2000. Collected at a sub‐spacecraft altitude of 412 km while the surface was illuminated only by Jupiter‐shine (incidence angle: 48–51°), the SRU image reveals a 3 × 104 km2 region between ∼0°–6°N and 43.5°–51°W in remarkable detail at the highest resolution to date. Prior coverage by Galileo under high‐sun conditions at 1 km resolution led to the characterization of the terrain as ridged plains with undifferentiated linea. The SRU image reveals a much richer and more complex picture. Intricate networks of cross‐cutting ridges and lineated bands surround an intriguing 37 km (east‐west) by 67 km (north‐south) chaos feature with a concentric fracture system, depressed matrix margins, and low‐albedo materials potentially associated with brine infiltration. The morphology and local relief of the chaos feature are consistent with formation in the collapse of ice overlying a salt‐rich lens of subsurface water. Low‐albedo deposits, similar to features previously associated with hypothesized cryovolcanic plume activity, flank nearby ridges. The SRU's high‐resolution view of many types of features in a single image allows us to explore their regional context and greatly improve the geologic mapping of this part of Europa's surface. The image reveals several relatively youthful features in a potentially dynamic region, providing baselines for candidate locations that future missions can investigate for present day surface activity. Plain Language Summary: On 29 September 2022, the Juno spacecraft performed the first close flyby of Jupiter's icy moon Europa in generation. The low‐light sensitive Juno SRU navigation camera was used to photograph a part of the surface that was lit only by sunlight scattered off Jupiter, from a spacecraft‐to‐surface distance of 412 km. This innovative use of a high‐resolution star camera designed to detect dim stars produced Juno's highest resolution image of Europa, and provides the highest resolution coverage of the targeted region to date. The imaged area is revealed to be incredibly complex and rich with many different types of terrains and features. Dark stains that may be associated with plumes, and an area of ice shell disruption nicknamed "the Platypus," are compelling targets for future missions to investigate possible present day surface activity. Key Points: Juno's Stellar Reference Unit imaged Europa's surface at high resolution while it was illuminated by Jupiter‐shineThe image reveals a feature‐rich region between 0°–6°N and 43.5°–51°W with hints of relatively recent activityA young 37 km by 67 km chaos feature and some low‐albedo deposits adjacent to double ridges may be associated with subsurface liquid water [ABSTRACT FROM AUTHOR]

On 29 September 2022 the Juno spacecraft flew within 354 km of Europa's surface while several instruments probed the moon's surroundings. During the close flyby, radio occultations were performed by collecting single‐frequency Doppler measurements. These investigations are essential to the study of Europa's ionosphere and represent the first repeat sampling of any set of conditions since the Galileo era. Ingress measurements resulted in a marginal detection with a peak ionospheric density of 4,000 ± 3,700 cm−3 (3σ) at 22 km altitude. A more significant detection emerged on egress, with a peak density of 6,000 ± 3,000 cm−3 (3σ) at 320 km altitude. Comparison with Galileo measurements reveals a consistent picture of Europa's ionosphere, and confirms its dependence on illumination conditions and position within Jupiter's magnetosphere. However, the overall lower densities measured by Juno suggest a dependence on time of observation, with implications for the structure of the neutral atmosphere. Plain Language Summary: On 29 September 2022, NASA's Juno spacecraft flew very close to Jupiter's moon Europa. During the encounter, a radio occultation experiment was performed, where radio signals are exchanged between the spacecraft and ground stations as the former sets behind or rises from the moon as seen from the Earth. The scope of this experiment was studying the ionosphere of Europa, a layer of electrons and ions surrounding the moon. The Juno measurements confirmed the presence of the layer, with a structure similar to the one observed by the Galileo mission in the late 1990s. Key Points: Europa's ionosphere was detected from Juno's X‐band Doppler data via NASA's Deep Space Network during a close encounter in 2022Peak densities were 4,000 ± 3,700 cm−3 (3σ) at 22 km altitude during ingress and 6,000 ± 3,000 cm−3 (3σ) at 320 km during egressThe Juno ionospheric profiles are consistent with Galileo measurements, and show a dependence on solar zenith and magnetospheric ram angles [ABSTRACT FROM AUTHOR]

The first orbits around Jupiter of the Juno spacecraft in 2016 revealed a symmetric structure of multiple cyclones that remained stable over the next 5 years. Trajectories of individual cyclones indicated a consistent westward circumpolar motion around both poles. In this paper, we propose an explanation for this tendency using the concept of beta‐drift and a "center‐of‐mass" approach. We suggest that the motion of these cyclones as a group can be represented by an equivalent sole cyclone, which is continuously pushed by beta‐drift poleward and westward, embodying the westward motion of the individual cyclones. We support our hypothesis with 2D model simulations and observational evidence, demonstrating this mechanism for the westward drift. This study joins consistently with previous studies that revealed how aspects of these cyclones result from vorticity‐gradient forces, shedding light on the physical nature of Jupiter's polar cyclones. Plain Language Summary: The Juno spacecraft arrived at Jupiter in 2016, revealing a unique atmospheric phenomenon. Each of the poles of Jupiter is inhabited by a symmetrically structured group of cyclones, where a ring of cyclones surrounds one cyclone close to the pole. The collective observations of these cyclones over 5 years show that although they are relatively stable, they generally drift in the westward direction a few degrees per year. Here, we investigate the mechanism driving this drift by examining the cyclones as a group. This "center‐of‐mass" approach masks the interactions between the cyclones and only considers trends that happen simultaneously on all cyclones. Using model simulations, we show that the motion of a group's "center of mass" can be captured by a sole equivalent cyclone, pushed poleward and westward by the "beta‐drift" effect, which is known to contribute to the motion of tropical cyclones on Earth. This westward force on the group as a whole is thus suggested as the driver of the observed westward drift. We conclude by presenting observational evidence supporting this hypothesis. Key Points: The mean westward circumpolar motion of Jupiter's northern and southern polar cyclones is analyzed and explained by the β‐drift effectSimulations show that the "center of mass" of a group of cyclones behaves like one equivalent cyclone, moving poleward‐westward under β‐driftThis center‐of‐mass approach is applied to the Juno data, implying that the cyclones' collective β‐drift drives their observed westward drift [ABSTRACT FROM AUTHOR]

The document is a corrigendum for an article on Io's hotspots, correcting references to various studies and authors. The corrections ensure accurate citations and do not impact the scientific conclusions of the original article. The authors are from various institutions in Italy, the United States, and other countries, emphasizing international collaboration in space research. [Extracted from the article]

The Jiangmen Underground Neutrino Observatory (JUNO) features a 20 kt multi-purpose underground liquid scintillator sphere as its main detector. Some of JUNO's features make it an excellent location for 8B solar neutrino measurements, such as its low-energy threshold, high energy resolution compared with water Cherenkov detectors, and much larger target mass compared with previous liquid scintillator detectors. In this paper, we present a comprehensive assessment of JUNO's potential for detecting 8B solar neutrinos via the neutrino-electron elastic scattering process. A reduced 2 MeV threshold for the recoil electron energy is found to be achievable, assuming that the intrinsic radioactive background 238U and 232Th in the liquid scintillator can be controlled to 10-17g/g. With ten years of data acquisition, approximately 60,000 signal and 30,000 background events are expected. This large sample will enable an examination of the distortion of the recoil electron spectrum that is dominated by the neutrino flavor transformation in the dense solar matter, which will shed new light on the inconsistency between the measured electron spectra and the predictions of the standard three-flavor neutrino oscillation framework. If Δm221= 4.8 × 10-5(7.5 × 10-5) eV, JUNO can provide evidence of neutrino oscillation in the Earth at approximately the 3σ (2σ) level by measuring the non-zero signal rate variation with respect to the solar zenith angle. Moreover, JUNO can simultaneously measure Δm221using 8B solar neutrinos to a precision of 20% or better, depending on the central value, and to sub-percent precision using reactor antineutrinos. A comparison of these two measurements from the same detector will help understand the current mild inconsistency between the value of Δm221reported by solar neutrino experiments and the KamLAND experiment.

Abstract Interchange instability is known to drive fast radial transport of particles in Jupiter's inner magnetosphere. Magnetic flux tubes associated with the interchange instability often coincide with changes in particle distributions and plasma waves, but further investigations are required to understand their detailed characteristics. We analyze representative interchange events observed by Juno, which exhibit intriguing features of particle distributions and plasma waves, including Z‐mode and whistler‐mode waves. These events occurred at an equatorial radial distance of ∼9 Jovian radii on the nightside, with Z‐mode waves observed at mid‐latitude and whistler‐mode waves near the equator. We calculate the linear growth rate of whistler‐mode and Z‐mode waves based on the observed plasma parameters and electron distributions and find that both waves can be locally generated within the interchanged flux tube. Our findings are important for understanding particle transport and generation of plasma waves in the magnetospheres of Jupiter and other planetary systems.

Abstract On 29 September 2022 the Juno spacecraft flew within 354 km of Europa's surface while several instruments probed the moon's surroundings. During the close flyby, radio occultations were performed by collecting single‐frequency Doppler measurements. These investigations are essential to the study of Europa's ionosphere and represent the first repeat sampling of any set of conditions since the Galileo era. Ingress measurements resulted in a marginal detection with a peak ionospheric density of 4,000 ± 3,700 cm−3 (3σ) at 22 km altitude. A more significant detection emerged on egress, with a peak density of 6,000 ± 3,000 cm−3 (3σ) at 320 km altitude. Comparison with Galileo measurements reveals a consistent picture of Europa's ionosphere, and confirms its dependence on illumination conditions and position within Jupiter's magnetosphere. However, the overall lower densities measured by Juno suggest a dependence on time of observation, with implications for the structure of the neutral atmosphere.

Abstract The first orbits around Jupiter of the Juno spacecraft in 2016 revealed a symmetric structure of multiple cyclones that remained stable over the next 5 years. Trajectories of individual cyclones indicated a consistent westward circumpolar motion around both poles. In this paper, we propose an explanation for this tendency using the concept of beta‐drift and a “center‐of‐mass” approach. We suggest that the motion of these cyclones as a group can be represented by an equivalent sole cyclone, which is continuously pushed by beta‐drift poleward and westward, embodying the westward motion of the individual cyclones. We support our hypothesis with 2D model simulations and observational evidence, demonstrating this mechanism for the westward drift. This study joins consistently with previous studies that revealed how aspects of these cyclones result from vorticity‐gradient forces, shedding light on the physical nature of Jupiter's polar cyclones.

We calculate the time‐varying spatial distribution of energetic magnetospheric electron influx onto Europa's surface by combining a hybrid model of the moon's draped electromagnetic environment with a relativistic particle tracer. We generate maps of the energetic electron influx patterns at four distinct locations of Europa relative to the center of the Jovian magnetospheric current sheet. For a full synodic rotation of Jupiter, these results are applied to constrain the averaged number and energy influx patterns as well as the O2 sputtering rates associated with energetic electron precipitation. We also determine the relative contributions of magnetospheric ions and electrons to surface erosion and exospheric genesis at Europa. Our major results are: (a) Except for a small region near Europa's downstream apex, the moon's entire surface is exposed to heavy irradiation by magnetospheric electrons. (b) The spatial distribution of energetic electron influx onto Europa's surface is only slightly modified by field line draping and the induced magnetic field from the moon's subsurface ocean. (c) The contributions of magnetospheric electron and ion impacts to energy deposition onto Europa's surface are of the same order of magnitude. (d) Within uncertainties, impinging magnetospheric electrons and ions make similar contributions to O2 sputtering from Europa's surface. (e) The spatial distribution of electron energy influx and the observed concentrations of sulfuric acid (H2SO4) are only weakly correlated, suggesting that energy deposition by magnetospheric electron impacts is not a necessary agent for H2SO4 production within Europa's surface. Key Points: Europa's plasma interaction and induced magnetic field cause only subtle changes to energetic electron influx patterns on the moon's surfaceIntegrated across Europa's entire surface, impinging magnetospheric electrons deposit a similar amount of energy as magnetospheric ionsMagnetospheric electron and ion impacts release comparable numbers of oxygen molecules from Europa's surface into the moon's exosphere [ABSTRACT FROM AUTHOR]

One of the auroral features of Jupiter is the emission associated with the orbital motion of its moon Io. The relative velocity between Io and the surrounding plasma trigger perturbations that travels as Alfvén waves along the magnetic field lines toward the Jovian ionosphere. These waves can accelerate electrons into the atmosphere and ultimately produce an auroral emission, called the Io footprint. The speed of the Alfvén waves—and hence the position of the footprint—depends on the magnetic field and on the plasma distribution along the field line passing through Io, whose SO2‐rich atmosphere is the source of a dense plasma torus around Jupiter. Since 2016, the Jovian InfraRed Auroral Mapper (JIRAM) onboard Juno has been observing the Io footprint with a spatial resolution of ∼few tens of km/pixel. JIRAM detected evidences of variability in the Io footprint position that are not dependent on the System III longitude of Io. The position of the Io footprint in the JIRAM images is compared with the position predicted by a model of the Io Plasma Torus and of the magnetic field. This is the first attempt to retrieve quantitative information on the variability of the torus by looking at the Io footprint. The results are consistent with previous observations of the density and temperature of the Io Plasma Torus. However, we found that the plasma density and temperature exhibit considerable non‐System III variability that can be due either to local time asymmetry of the torus or to its temporal variability. Key Points: Juno‐JIRAM detected evidence of variability in the Io footprint that are not related to the System III longitude of IoQuantitative information on the state of the Io Plasma Torus and its variability are inferred from the Io footprint positionThe Io Plasma Torus electron density varies between <2,000 and ∼2,750 cm−3, while the thermal ion temperature varies between 40–100 eV [ABSTRACT FROM AUTHOR]

We use data from the plasma and energetic particle instruments on the Juno spacecraft, JADE and JEDI, to study the equatorial pitch angle distributions of energetic protons within Jupiter's inner magnetosphere during Juno's prime mission from 2016 to 2021. Averaging over all observations made by Juno within M‐shell bins between M = 6 and M = 30, we find protons at energies between 10 and 50 keV are predominantly field‐aligned at all M‐shells. In contrast, those at energies above 200 keV transition from being predominantly field‐aligned at M = 20 to having pancake‐like distributions at M < 10. We find the observed distributions are consistent either with charge exchange of protons with neutral toroidal clouds, or with adiabatic acceleration of protons originating from Jupiter that are transported inward from the middle magnetosphere. Plain Language Summary: Protons are seen throughout Jupiter's magnetosphere. Where these protons come from and how they evolve is not well understood. Previous observations by the Galileo spacecraft showed that protons in the vicinity of Europa have properties consistent with charge exchange with a neutral species, which effectively removes the charged particles from the magnetosphere. Using data from the Juno spacecraft, we survey proton distributions at different energies. Although charge exchange remains a plausible explanation for the observations, another possibility is that the distribution is a result of adiabatically transporting the protons through Jupiter's magnetic field. Key Points: 10–50 keV protons at Jupiter are predominantly field‐aligned at M‐shells between M = 7 and M = 20Normalized pitch angle distributions of >200 keV protons show evidence of adiabatic acceleration during inward radial transportObserved proton distributions could result from charge‐exchange with neutrals or conservation of adiabatic invariants during transport [ABSTRACT FROM AUTHOR]

Juno and CD9 protein, expressed in oolemma, are known to be essential for sperm-oocyte binding and fusion. Although evidence exists that these two proteins cooperate, their interaction has not yet been demonstrated. Here in, we present Juno and CD9 mutual localization over the surface of mouse metaphase II oocytes captured using the 3D STED super-resolution technique. The precise localization of examined proteins was identified in different compartments of oolemma such as the microvillar membrane, planar membrane between individual microvilli, and the membrane of microvilli-free region. Observed variance in localization of Juno and CD9 was confirmed by analysis of transmission and scanning electron microscopy images, which showed a significant difference in the presence of proteins between selected membrane compartments. Colocalization analysis of super-resolution images based on Pearson’s correlation coefficient supported evidence of Juno and CD9 mutual position in the oolemma, which was identified by proximity ligation assay. Importantly, the interaction between Juno and CD9 was detected by co-immunoprecipitation and mass spectrometry in HEK293T/17 transfected cell line. For better understanding of experimental data, mouse Juno and CD9 3D structure were prepared by comparative homology modelling and several protein-protein flexible sidechain dockings were performed using the ClusPro server. The dynamic state of the proteins was studied in real-time at atomic level by molecular dynamics (MD) simulation. Docking and MD simulation predicted Juno-CD9 interactions and stability also suggesting an interactive mechanism. Using the multiscale approach, we detected close proximity of Juno and CD9 within microvillar oolemma however, not in the planar membrane or microvilli-free region. Our findings show yet unidentified Juno and CD9 interaction within the mouse oolemma protein network prior to sperm attachment. These results suggest that a Juno and CD9 interactive network could assist in primary Juno binding to sperm Izumo1 as a prerequisite to subsequent gamete membrane fusion.

Abstract We use data from the plasma and energetic particle instruments on the Juno spacecraft, JADE and JEDI, to study the equatorial pitch angle distributions of energetic protons within Jupiter's inner magnetosphere during Juno's prime mission from 2016 to 2021. Averaging over all observations made by Juno within M‐shell bins between M = 6 and M = 30, we find protons at energies between 10 and 50 keV are predominantly field‐aligned at all M‐shells. In contrast, those at energies above 200 keV transition from being predominantly field‐aligned at M = 20 to having pancake‐like distributions at M

The driver of energetic electron precipitation into Ganymede's atmosphere has been an outstanding open problem. During the Juno flyby of Ganymede on 7 June 2021, Juno observed significant downward‐going electron fluxes inside the bounce loss cone of Ganymede's polar magnetosphere. Concurrently, Juno detected intense whistler‐mode waves, both in the quasi‐parallel and highly oblique directions with respect to the magnetic field line. We use quasi‐linear model to quantify energetic electron precipitation driven by quasi‐parallel and very oblique whistler‐mode waves, respectively, in the vicinity of Ganymede. The data‐model comparison indicates that in Ganymede's lower‐latitude (higher‐latitude) polar region, quasi‐parallel whistler‐mode waves play a dominant role in precipitating higher‐energy electrons above ∼100s eV (∼1 keV), whereas highly oblique waves are important for precipitating lower‐energy electrons below 100s eV (∼1 keV). Our result provides new evidence of whistler‐mode waves as a potential primary driver of precipitating energetic electrons into Ganymede's atmosphere. Plain Language Summary: During the Juno flyby of Ganymede on 7 June 2021, the Juno spacecraft detected energetic electrons precipitating into Ganymede's atmosphere. Simultaneously, Juno detected intense electromagnetic whistler‐mode waves in the vicinity of Ganymede. We use a physics‐based model to quantify the role of the observed whistler‐mode waves in energetic electron precipitation. The comparison between the Juno observation and modeling results reveals that whistler‐mode waves potentially play a dominant role in precipitating energetic electrons into Ganymede's atmosphere over a broad energy range from tens of eV to several hundred keV. Our findings are potentially important for understanding the loss process of energetic electrons in Ganymede's magnetosphere, as well as the generation of Ganymede's diffuse aurora. Key Points: We provide new evidence of whistler‐mode waves as a potential primary driver of precipitating energetic electrons into Ganymede's atmosphereThis finding is potentially important for the generation of aurora and the loss of energetic electrons in the vicinity of GanymedeJuno observations and quasi‐linear modeling are used to quantify energetic electron precipitation driven by whistler‐mode waves [ABSTRACT FROM AUTHOR]

Vitrification of oocytes is crucial for embryo biotechnologies, germplasm cryopreservation of endangered and excellent female animals, and the fertility of humans. However, vitrification significantly impairs the fertilization ability of oocytes, which significantly limits its widely used application. JUNO protein, a receptor for Izumo1, is involved in sperm-oocyte fusion and is an indispensable protein for mammalian fertilization, and its abundance is susceptible to vitrification. However, it is still unclear how vitrification reduces the fertilization capacity of bovine oocytes by affecting JUNO protein. This study was designed to investigate the effect of vitrification on the abundance and post-translational modifications of JUNO protein in bovine oocytes. Our results showed that vitrification did not alter the amino acid sequence of JUNO protein in bovine oocytes. Furthermore, the liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis results showed that vitrification significantly reduced the number and changed the location of disulfide bonds, and increased the number of both phosphorylation and glycosylation sites of JUNO protein in bovine oocytes. Finally, the fertilization capacity and development ability of vitrified oocytes treated with 200 pg JUNO mRNA microinjection and cholesterol-loaded methyl-β-cyclodextrin (CLC/MβCD) were similar to those of fresh oocytes. In conclusion, our results showed that vitrification of bovine oocytes did not alter the protein sequence of JUNO, but induced post-translational modifications and changed protein abundance. Moreover, the fertilization and development ability of vitrified bovine oocytes were improved by the combination treatment of JUNO mRNA microinjection and CLC/MβCD. [ABSTRACT FROM AUTHOR]

Fertilization proteins JUNO and CD9 play vital roles in sperm‐egg fusion, but little is known about their expression patterns during in vitro maturation (IVM) and their function during in vitro fertilization (IVF) of bovine oocytes. In this study, qRT‐PCR and immunofluorescence staining were used to detect the mRNA and protein expression levels of JUNO and CD9 genes in bovine oocytes and cumulus cells. Then, fertilization rate of MII oocytes treated with (i) JUNO antibody (1, 5 and 25 μg/ml) or (ii) CD9 antibody (1, 5 and 25 μg/ml) or (iii) CD9 antibody (5 μg/ml) + JUNO antibody (5 μg/ml) were recorded. Our results showed that the mRNA and protein expression levels of JUNO and CD9 genes significantly increased from bovine GV oocytes to MII oocytes, and similar mRNA expression patterns of JUNO and CD9 were also detected in cumulus cells. All groups of oocytes treated with CD9 antibody or JUNO antibody showed significantly decreased fertilization rates (p <.05). Particularly, the fertilization ability of oocytes treated with CD9 antibody (5 μg/ml) + JUNO antibody (5 μg/ml) sharply decreased to 3.48 ± 0.11%. In conclusion, our study revealed the expression levels of JUNO and CD9 genes in oocytes and cumulus cells increased during IVM of bovine oocytes, with JUNO protein playing a major role in the fertilization of bovine oocytes. [ABSTRACT FROM AUTHOR]

(1) Background: Streptococcus agalactiae or Group B Streptococcus (GBS) causes severe neonatal infections with a high burden of disease, especially in Africa. Maternal vaginal colonization and perinatal transmissions represent the common mode of acquiring the infection. Development of an effective maternal vaccine against GBS relies on molecular surveillance of the maternal GBS population to better understand the global distribution of GBS clones and serotypes. (2) Methods: Here, we present genomic data from a collection of colonizing GBS strains from Ismailia, Egypt that were sequenced and characterized within the global JUNO project. (3) Results: A large proportion of serotype VI, ST14 strains was discovered, a serotype which is rarely found in strain collections from the US and Europe and typically not included in the current vaccine formulations. (4) Conclusions: The molecular epidemiology of these strains clearly points to the African origin with the detection of several sequence types (STs) that have only been observed in Africa. Our data underline the importance of continuous molecular surveillance of the GBS population for future vaccine implementations. [ABSTRACT FROM AUTHOR]

The optical and radiochemical purification of the scintillating liquid which will fill the detector of the JUNO experiment plays a crucial role in achieving its scientific goals. Given its gigantic mass and dimensions, and an unprecedented target value of about 3 % at 1 MeV in energy resolution, JUNO has set severe requirements on the parameters of its scintillator, such as attenuation length (L at > 20 m at 430 nm), light yield, and content of radioactive contaminants (238U, 232Th < 10-15 g/g). To accomplish these needs, the scintillator will be processed using several purification methods, including distillation under vacuum and gas stripping, carried out in two large-scale plants installed at the JUNO site. In this paper, the layout, operating principles, and technical aspects which have driven the design and construction of the distillation and gas stripping plants are reviewed. The distillation is effective in enhancing the optical properties and removing high-boiling radioactive impurities (238U, 232Th, 40K), while the stripping process exploits pure water steam and high-purity nitrogen to extract gaseous contaminants (222Rn, 39Ar, 85Kr, O 2) from the scintillator. The plant operating parameters have been tuned during the recent commissioning phase at the JUNO site and several quality control measurements and tests have been performed to evaluate the performances of the plants. Preliminary results on the efficiency of these purification processes will be shown. [ABSTRACT FROM AUTHOR]

Abstract The driver of energetic electron precipitation into Ganymede's atmosphere has been an outstanding open problem. During the Juno flyby of Ganymede on 7 June 2021, Juno observed significant downward‐going electron fluxes inside the bounce loss cone of Ganymede's polar magnetosphere. Concurrently, Juno detected intense whistler‐mode waves, both in the quasi‐parallel and highly oblique directions with respect to the magnetic field line. We use quasi‐linear model to quantify energetic electron precipitation driven by quasi‐parallel and very oblique whistler‐mode waves, respectively, in the vicinity of Ganymede. The data‐model comparison indicates that in Ganymede's lower‐latitude (higher‐latitude) polar region, quasi‐parallel whistler‐mode waves play a dominant role in precipitating higher‐energy electrons above ∼100s eV (∼1 keV), whereas highly oblique waves are important for precipitating lower‐energy electrons below 100s eV (∼1 keV). Our result provides new evidence of whistler‐mode waves as a potential primary driver of precipitating energetic electrons into Ganymede's atmosphere.