Observations of Jupiter's Low-Frequency Radio Emissions from the Juno Waves Instrument in Collaboration with the Earth-Based Radio Telescopes

The radio and plasma wave instrument (Waves) onboard the Juno spacecraft, which is now successfully orbiting Jupiter, utilizes one electric dipole antenna and one magnetic search coil sensor. The Juno Waves instrument is capable of recording the entire Jovian radio spectrum (from kilometer (KOM) to decameter (DAM) through hectometer wavelength (HOM) radio components) in a wide frequency coverage of 50 Hz to 40 MHz, and of estimating a one-dimensional determination of the direction of incoming waves below 5 MHz in the framework of the short dipole approximation. During Juno's interplanetary cruise prior to the Jupiter orbit insertion on July 5, 2016, the first observations were made for KOM in March, and for HOM and DAM in May, 2016. By analyzing the Waves data from Juno's approach and initial orbit of Jupiter, we show the characteristics of each radio component as viewed from Juno at higher and lower Jovigraphic latitudes. In addition, some preliminary results of the coordinated DAM observations with Juno and Earth-based radio telescopes (e.g., Nançay Decameter Array in France) are presented. Because of the unique polar trajectory, the Juno Waves instrument may perform the first in-situ measurements of Jovian auroral radio emission sources, and stereoscopic observations of Jovian DAM emissions with Juno and the ground-based radio telescopes may lead to a better understanding of the latitudinal beaming structures from Jupiter's polar regions.