Jupiter’s interior and deep atmosphere: The initial pole-to-pole passes with the Juno spacecraft

Abstract

Juno swoops around giant Jupiter Jupiter is the largest and most massive planet in our solar system. NASA's Juno spacecraft arrived at Jupiter on 4 July 2016 and made its first close pass on 27 August 2016. Bolton et al. present results from Juno's flight just above the cloud tops, including images of weather in the polar regions and measurements of the magnetic and gravitational fields. Juno also used microwaves to peer below the visible surface, spotting gas welling up from the deep interior. Connerney et al. measured Jupiter's aurorae and plasma environment, both as Juno approached the planet and during its first close orbit. Science , this issue p. 821 , p. 826

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

“…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.…”

“…The first is to understand the origin and evolution of Jupiter, informing the formation of our solar system and planetary systems around other stars. 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].…”

First look at Jupiter's synchrotron emission from Juno's perspective

“…The main difference between the MWR data and our simulations is a discrepancy in the brightness profiles (up to a factor of 3). The discrepancies between the data and simulations, combined with Juno's field and particle measurements [see, e.g., Bolton et al, 2017, Becker et al, 2017b, confirm that physical conditions close to the planet affecting synchrotron emission (electron energy spectra, pitch angle distributions, and the magnetic environment) are different than we anticipated. Model improvements and results on polarization will be the topic of a follow-up paper.…”

“…Another challenge is related to the fact that the radiation depends on the electron energy spectrum and scales in proportion to B × N (equations (1)- (4)). Large errors in our simulations can then be easily introduced from small uncertainties on B and N. Juno's first perijoves have confirmed strong discrepancies between magnetic and particle measurements and models, with differences of ∼2-3 Gauss for the magnetic field and by up to an order of magnitude for the particle observations [Bolton et al, 2017;Becker et al 2017b]. Knowing the current inaccuracy of magnetic field and electron distributions at Jupiter inside 1.5 R J and the fact that the synchrotron radiation is highly beamed, our simulations of polarized radiation are indeed difficult to both carry out and validate (which are the focus of ongoing modeling work).…”

A Vorticity-preserving Hydrodynamical Scheme for Modeling Accretion Disk Flows

“…Turbulence (invariably accompanied by long-lived vortices) is observed in a variety of planetary atmospheres (Salby 1984;Marcus 1988;Bolton et al 2017), and indeed, unsteady flow is nearly ubiquitous in fluid contexts where both strong shear and large Reynolds numbers are present (Abramowicz et al 1992). From a purely hydrodynamical standpoint, a compelling analogy supporting the alpha parameterization for effective viscosity in accretion disks is provided by the 1 Department of Astronomy, Yale University, darryl.seligman@yale.edu meteorological concept of eddy viscosity.…”