Magnetospheric Science Objectives of the Juno Mission

Bagenal, F.; Adriani, A.; Allegrini, F.; Bolton, S. J.; Bonfond, Bertrand; Bunce, E. J.; Connerney, J. E. P.; Cowley, S. W. H.; Ebert, R. W.; Gladstone, G. R.; Hansen, C. J.; Kurth, W. S.; Levin, S. M.; Mauk, B. H.; McComas, D. J.; Paranicas, C.; Santos-Costa, Daniel; Thorne, R. M.; Valek, P. W.; Waite, J. H.; Zarka, Philippe

doi:10.1007/s11214-014-0036-8

Cited by 190 publications

(240 citation statements)

References 220 publications

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“…Servicing this objective, Juno's measurements of gravity, magnetic fields, and atmospheric composition and circulation probe deep inside Jupiter to constrain its interior structure and composition [1]. The second objective takes advantage of Juno's close-in polar orbits to explore Jupiter's polar magnetosphere and intense aurorae [2]. From a vantage point above the poles, Juno's fields and particles instrumentation gather direct in-situ observations of the particle populations exciting the aurora, which are imaged simultaneously by Juno's ultraviolet (UV) and infrared (IR) imaging spectrographs.…”

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“…These features are thought to be whistler-mode hiss, often called auroral hiss [14] and correspond to features in the energetic electron distributions described below. These waves exist at frequencies below the lower of f ce and f pe , the electron plasma frequency [related to electron density n e by n e = (f pe /8980) 2 with n e expressed in cm -3 and f pe in Hz]. The lack of features in the wave spectrum identifying the electron plasma frequency makes it difficult to determine the electron density.…”

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Jupiter’s magnetosphere and aurorae observed by the Juno spacecraft during its first polar orbits

Connerney

Adriani

Allegrini

et al. 2017

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Published in: ScienceLink to article, DOI: 10.1126/science.aam5928 Publication date: 2017 Document VersionPeer reviewed version Link back to DTU Orbit Citation (APA): Connerney, J. E. P., Adriani, A., Allegrini, F., Bagenal, F., Bolton, S. J., Bonfond, B., ... Waite, J. (2017). Jupiter's magnetosphere and aurorae observed by the Juno spacecraft during its first polar orbits. Science, 356(6340) Abstract:The Juno spacecraft acquired direct observations of the Jovian magnetosphere and auroral emissions from a vantage point above the poles. Juno's capture orbit spanned the Jovian magnetosphere from bow shock to the planet, providing magnetic field, charged particle, and wave phenomena context for Juno's passage over the poles and traverse of Jupiter's hazardous inner radiation belts. Juno's energetic particle and plasma detectors measured electrons precipitating in the polar regions, exciting intense aurorae, observed simultaneously by the ultraviolet and infrared imaging spectrographs. Juno transited beneath the most intense parts of the radiation belts, passed ~4,000 kilometers above the cloudtops at closest approach, well inside the Jovian rings, and recorded the electrical signatures of high velocity impacts with small particles as it traversed the equator.One Sentence Summary: Juno's instruments provide complete polar maps of Jovian UV aurorae, spatially resolved images of the IR southern aurorae, and in-situ direct measurements of precipitating charged particle populations exciting the aurora. only one bow shock upon approach suggests that the magnetosphere was expanding in size, a conclusion bolstered by the multiple BS encounters experienced outbound during the 53.5 day capture orbit at radial distances of 92-112 Rj before apojove on DOY 213 (~113 Rj), and at distances of 102-108 Rj thereafter . Apojove during the 53.5day orbits occurred at a radial distance of ~113 Rj, so Juno resides at distances of >92 Rj for little more than half of its orbital period (~29 days). Thus on the first two orbits, Juno encountered the MP boundary a great many times at radial distances of ~81-113 Rj.Juno's traverse through the well-ordered portion of the Jovian magnetosphere is illustrated in The magnetic field observed in the previously unexplored region close to the planet (radius<1.3Rj) was dramatically different from that predicted by existing spherical harmonic models, revealing a planetary magnetic field rich in spatial variation, possibly due to a relatively large dynamo radius [1]. Perhaps the most perplexing observation was one that was missing: the expected magnetic signature of intense field aligned currents (Birkeland currents) associated with the main aurora. We did not identify large magnetic perturbations associated with Juno's traverse of field lines rooted in the main auroral oval (supplementary material).Juno's Waves instrument made observations of radio and plasma wave phenomena throughout the first perijove ( Figure 2). These observations were obtained at low altitudes whilst crossing magnetic field lines...

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confidence: 99%

mentioning

confidence: 99%

Jupiter’s magnetosphere and aurorae observed by the Juno spacecraft during its first polar orbits

Connerney

Adriani

Allegrini

et al. 2017

Science

Self Cite

123

151

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“…Auroral hiss should provide an intense broadband signature extending up (Bagenal et al 2014;adapted from Carlson et al 1998) to the lower of f ce or f pe , where f pe is the electron plasma frequency f pe = 8980 √ n e in Hz and n e is in cm −3 . At Earth, these waves are associated with downgoing electrons in the upward current region.…”

Section: Auroral Plasma Wavesmentioning

confidence: 98%

“…Juno's unique polar orbit is critical to answering the fundamental questions of how Jupiter's auroras are generated (Bagenal et al 2014). Previous missions were confined to low latitudes although Ulysses did provide brief coverage at moderate latitudes.…”

Section: Exploring Jupiter's Polar Magnetosphere and Auroramentioning

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The Juno Waves Investigation

et al. 2017

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Jupiter is the source of the strongest planetary radio emissions in the solar system. Variations in these emissions are symptomatic of the dynamics of Jupiter's magnetosphere and some have been directly associated with Jupiter's auroras. The strongest radio emissions are associated with Io's interaction with Jupiter's magnetic field. In addition, plasma waves are thought to play important roles in the acceleration of energetic particles in the magnetosphere, some of which impact Jupiter's upper atmosphere generating the auroras. Since the exploration of Jupiter's polar magnetosphere is a major objective of the Juno mission, it is appropriate that a radio and plasma wave investigation is included in Juno's payload. This paper describes the Waves instrument and the science it is to pursue as part of the Juno mission.

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Magnetosphere‐ionosphere mapping at Jupiter: Quantifying the effects of using different internal field models

et al. 2015

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The lack of global field models accurate beyond the inner magnetosphere (<30 R J ) makes it difficult to relate Jupiter's polar auroral features to magnetospheric source regions. We recently developed a model that maps Jupiter's equatorial magnetosphere to the ionosphere using a flux equivalence calculation that requires equal flux at the equatorial and ionospheric ends of flux tubes. This approach is more accurate than tracing field lines in a global field model but only if it is based on an accurate model of Jupiter's internal field. At present there are three widely used internal field models-Voyager Io Pioneer 4 (VIP4), the Grodent Anomaly Model (GAM), and VIP Anomaly Longitude (VIPAL). The purpose of this study is to quantify how the choice of an internal field model affects the mapping of various auroral features using the flux equivalence calculation. We find that different internal field models can shift the ionospheric mapping of points in the equatorial plane by several degrees and shift the magnetospheric mapping to the equator by~30 R J radially and by less than 1 h in local time. These shifts are consistent with differences in how well each model maps the Ganymede footprint, underscoring the need for more accurate Jovian internal field models. We discuss differences in the mapping of specific auroral features and the size and location of the open/closed field line boundary. Understanding these differences is important for the continued analysis of Hubble Space Telescope images and in planning for Juno's arrival at Jupiter in 2016.

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Magnetospheric Science Objectives of the Juno Mission

Cited by 190 publications

References 220 publications

Jupiter’s magnetosphere and aurorae observed by the Juno spacecraft during its first polar orbits

Jupiter’s magnetosphere and aurorae observed by the Juno spacecraft during its first polar orbits

The Juno Waves Investigation

Magnetosphere‐ionosphere mapping at Jupiter: Quantifying the effects of using different internal field models

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