Detection of Negative Carbon and Oxygen Pickup Ions From Dust Orbiting Jupiter

We report on observations of negative carbon and oxygen pickup ions (PUIs) originating from dust orbiting Jupiter. The PUIs are observed at altitudes of a few thousand kilometers (∼4,800–10,200 km) above the 1-bar level of Jupiter's atmosphere and up to ∼11,000–15,000 km from the equatorial plane, thus providing constraints on the location of the dust population and its composition. The Jovian Auroral Distributions Experiment–Electron sensors on Juno detect these PUIs because of the combination of a fast-moving spacecraft and the large Keplerian orbital speed of the dust near Jupiter. We demonstrate that this scenario is consistent with the observations. We find a PUI C/O ratio of 10 ± 5 and a PUI energy release of ∼11 ± 9 eV. Electron stimulated desorption is a likely process for creating these PUIs. The dust is well inside the halo population and likely carbonaceous.