Juno at PJ12
JunoCam at Perijove-12 (2018 April 1): What the images show
John Rogers (2018 April 27)
PJ-12 was likely to be the last perijove this year at which the spacecraft would be turned so that the MWR, as well as JunoCam, could view the track below, also getting widespread coverage of the planet inbound and outbound. And JunoCam got the jackpot.
Highlights of the images include:
–The approach images, at high phase angle, revealed the complete pattern of northern hemisphere haze bands in swirling, eddying detail for the first time.
–An anticyclonic white oval (AWO) in the NNTZ, called NN-WS-4, was viewed close up and revealed spiral ridges of clouds and rapid rotation.
–In the NEB, a miniature ‘barge’ was viewed close up.
–High-quality images of the Equatorial Zone revealed ‘mesoscale waves’ to be very widespread.
–The spacecraft flew 10º p. the p. end of the GRS, and right over the region where the STropD was spilling turbulence into the STropZ. Thus JunoCam obtained unique closeups of this phenomenon, as well as complete views of the GRS as the spacecraft moved south, which will enable an animation of the complex dynamics.
–The view of the south polar pentagon of cyclones was perhaps the best yet, due to the displacement of the pentagon maximally into sunlight, and top-quality image return. These views confirm the cyclic behaviour of the pentagon, and give several new clues to its dynamics. It is still accompanied by a long haze band, which was brilliantly lit at the terminator.
Since our paper was published (Adriani et al., ‘Nature’, March 8), we are now able to post more details of the on the circumpolar cyclones (CPCs) and polar hazes – topics on which the JunoCam team is preparing further publications. Hence, this report is in two parts: (I) The polar regions; (II) Middle and lower latitudes. Each part is posted as a PDF with mini-figures, plus a ZIP file containing the full-size figures.
Part I, PDF: Report-on-Juno-PJ12_PartI.pdf
Part II, PDF: Report-on-Juno-PJ12_PartII.pdf
Part I, Figures: Report-on-PJ12_PartI_Figures.zip
Part II, Figures: Report-on-PJ12_Part2_Figures.zip
PS: FigC9_PJ12_GRS-STrD_cyl-map_Gerald.jpg should also be credited to Seán Doran.