Juno Waves detection of dust impacts near Jupiter

The Juno spacecraft entered orbit at Jupiter on July 5, 2016. Since then, Juno has orbited Jupiter in high inclination orbits, crossing the ring plane near perijove. During 20 of the first 21 crossings, the Waves instrument detected signals associated with dust impacts. The impact rate profiles show peaks of order 6 s‐1 around the ring plane with half width at half maximum ~2000‐3000 km.

The polarity ratio of the impact signals didn't follow the areas of the antennas exposed to dust impacts that change due to the rotation of the spacecraft, suggesting Waves detects impacts on the Juno spacecraft and not just on the Waves antennas. The impact rate profile changed during Perijove 19, when the spacecraft rotation axis was tilted to the south, increasing the area of the solar panels exposed to impacts, indicating that the detected impacts were on the spacecraft body.

Grain sizes of order 1 μm are estimated, and the differential size distribution has a slope of ‐5.1 and with number densities of order 3 x 10‐6 m‐3.