Search Publications
Jupiter's X-Ray and UV Dark Polar Region
Jackman, C. M.; Johnson, R. E.; Branduardi-Raymont, G. +16 more
We present 14 simultaneous Chandra X-ray Observatory (CXO)-Hubble Space Telescope (HST) observations of Jupiter's Northern X-ray and ultraviolet (UV) aurorae from 2016 to 2019. Despite the variety of dynamic UV and X-ray auroral structures, one region is conspicuous by its persistent absence of emission: the dark polar region (DPR). Previous HST o…
Evidence of Alfvén Waves Generated by Mode Coupling in the Magnetotail Lobe
Zhang, Tielong; Sun, Jicheng; Wang, Guoqiang +2 more
Mode coupling is an important mechanism to excite Alfvén waves and has been extensively investigated based on numerical simulations. However, no direct observational evidence has been found regarding to this mechanism in the magnetotail lobe. Here, we report an in-situ observation that an Alfvén wave with a period of several minutes is clearly rel…
Tracking the Evolution of an Ocean Within Mimas Using the Herschel Impact Basin
Rhoden, A. R.; Denton, C. A.
Mimas' small size, lack of geologic activity, and high eccentricity suggest a frozen, inactive history. However, Cassini libration measurements are best explained by a present-day liquid ocean under an ice shell 24-31 km thick, a configuration that tidal heating can support. These unexpected findings have motivated further study of Mimas' surface …
BepiColombo Mio Observations of Low-Energy Ions During the First Mercury Flyby: Initial Results
Persson, Moa; Saito, Yoshifumi; Delcourt, Dominique +14 more
We present initial results of low-energy ion observations from BepiColombo's first Mercury flyby. Unprecedentedly high time resolution measurements of low energy ions at Mercury by BepiColombo Mio reveal rapid (a few seconds) and large (1-2 orders of magnitude) fluctuations of ion flux around the magnetopause and within the magnetosphere. Around t…
Paleolake Inlet Valley Formation: Factors Controlling Which Craters Breached on Early Mars
Fassett, C. I.; Bamber, Emily R.; Goudge, T. A. +2 more
The ancient surface of Mars is dominated by degraded impact craters with reduced or eliminated rim relief. Some degraded craters have an inlet valley, while many remain fluvially isolated. Despite controlling Martian fluvial connectivity, few constraints exist on why some—but not all—degraded craters possess inlets. We compared a suite of properti…
Saturn Anomalous Myriametric Radiation, a New Type of Saturn Radio Emission Revealed by Cassini
Jackman, C. M.; Kurth, W. S.; Cecconi, B. +10 more
A new radio component namely Saturn Anomalous Myriametric Radiation (SAM) is reported. A total of 193 SAM events have been identified by using all the Cassini Saturn orbital data. SAM emissions are L-O mode radio emission and occasionally accompanied by a first harmonic in R-X mode. SAM's intensities decrease with increasing distance from Saturn, …
In Situ Observation of a Magnetopause Indentation that Is Correspondent to Throat Aurora and Is Caused by Magnetopause Reconnection
Shi, Run; Li, Bin; Zhou, Su +6 more
Throat auroras have been suggested to correspond to magnetopause indentations, but how such indentations can be generated is an open question. Using coordinated magnetopause in situ and two-dimensional auroral imaging observations, we showed that a transient magnetopause crossing observed by Time History of Events and Macroscale Interactions durin…
Geologic Context of the Bright MARSIS Reflectors in Ultimi Scopuli, South Polar Layered Deposits, Mars
Landis, M. E.; Whitten, J. L.
Radar-bright basal reflectors have been detected below the South Polar Layered Deposits (SPLD), using Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) data and have an exciting but controversial interpretation: liquid water from subglacial lakes. We mapped the surface of the SPLD immediately above and surrounding the putative la…
MAVEN Proton Observations Near the Martian Moon Phobos: Does Phobos Backscatter Solar Wind Protons?
André, N.; Halekas, J. S.; Fowler, C. M. +7 more
ESA's Mars Express (MEX) may have observed twice solar wind protons backscattered by Phobos. However, these detections remain uncertain and call for an independent confirmation. Here, we analyze the proton measurements collected by the Suprathermal And Thermal Ion Composition experiment onboard NASA's Mars Atmosphere and Volatile EvolutioN mission…
Observations of Modulation of Ion Flux in the Coma of Comet 67P/Churyumov-Gerasimenko
Altwegg, K.; Nilsson, H.; Goldstein, R. +4 more
On 6-8 June 2015, the Ion and Electron Sensor on board Rosetta observed keV-range water-group pickup ions arriving from the solar direction. Based on magnetic field intensification and variations, the appearance of the ions was likely to have been caused by a coronal mass ejection. During the 3-day period when Rosetta was 200 km from the comet, pe…