The Parker Solar Probe (PSP) spacecraft completed its second Venus gravity assist maneuver (VGA2) on 26 December 2019. For a 20 minute interval surrounding closest approach, the PSP/FIELDS Radio Frequency Spectrometer (RFS) was set to ‘burst mode’, recording radio spectra from 1.3–19.2 MHz at sub-second cadence. We analyze this burst mode data, searching for signatures of radio frequency ‘sferic’ emission from lightning discharges. During the burst mode interval, only 4 spectra were observed with strong impulsive signals, and all 4 could be attributed to saturation of the RFS high gain stage by \emph{in situ} electrostatic plasma waves. These RFS measurements during VGA2 are consistent with previous non-detection of radio frequency lightning signals from Venus reported by Gurnett et al. (2001).

A high proportion of non-crystalline (X-ray-amorphous) components has been found in all samples analyzed by CheMin on the Curiosity rover at Gale crater on Mars, and such X-ray-amorphous components probably occur at all sites that have been investigated thus far by landers and rovers. The amorphous material at Gale crater is rich in volatiles (S, Cl, and H2O), as indicated by other science payload elements (APXS, SAM). We demonstrate here that amorphization of S and Cl salts can be induced by energetic electrons and free radicals generated in a medium-strength electrostatic discharge (ESD) process during martian dust activities such as dust storms, dust devils, and grain saltation. Furthermore, we found that the amorphization is commonly accompanied by dehydration of the salts and oxidation of Cl, S, and Fe species. On the basis of experimentally observed rates of the above phase transformations and the mission-observed dust activities and wind speeds on Mars, we anticipate that similar phase transformations could occur on Mars within a time frame of years to hundreds of years. Considering the high frequency, long duration, and large areal coverage of Martian dust activities, our study suggests that the ESD induced by Martian dust activities may have contributed to some the S- and Cl-rich portion of X-ray amorphous materials observed in surface soils at Gale crater. Furthermore, dust activities in the Amazonian period may have generated and deposited a significant quantity

The hypothesis that significant deposits of water ice exist in cold traps near lunar poles includes a supposition that acquired water is concentrated in the traps by exospheric lateral transport. That supposition, and by inference the trapped water hypothesis, are proven to be false by the present analysis of data obtained in 2013-2014 by the neutral mass spectrometer on the Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft. These data show no evidence of exospheric water. The upper limit for exospheric water at the lunar surface, $\sim3$ molecules cm$^{-3}$, is deficient by several orders of magnitude in accounting for the deposition of the chondritic influx of water in cold traps. The present hypothesis is that the precursor of clay formation, cation exchange involving water molecules and anorthite, is analogous to reversible chemi-sorption, and that adsorbed water on the lunar surface is rapidly removed from the moon by solar wind sputtering.

We describe the quasi-periodic (QP) whistler-mode emissions found in the plasmasphere as detected by electric and magnetic instrumentation onboard the Demonstration and Science Experiments (DSX) spacecraft in medium Earth orbit. Over the course of the nearly 2-year mission, at least 45 episodes of whistler mode QP emissions were detected by the Broad Band Receiver (BBR) onboard DSX. Episodes of QP emissions were identified by discrete events having a clear unambiguous periodic nature as detected by both the electric antennae and search coil magnetic sensor in the BBR survey data at 30 second temporal resolution. Most of the QP episodes occurred in a frequency range between 1- 4 kHz, in a band previously identified by Van Allen Probes and Cluster investigators. However, episodes were also detected by DSX at higher frequencies - events in these episodes extending all the way to 15 kHz. We present our findings on these unusual high frequency events in the presentation herein. Specifically, these high frequency QP episodes tended to be observed near dawn/dusk when the spacecraft was at relatively high magnetic latitudes and on magnetic L-shells between 3-5. Another unusual feature of these episodes is that individual up-drifting events making up the episode were found to sometimes occur concurrently in time: The high frequency portion of one up-drifting ‘polliwog-shaped’ event overlapped in time with the low frequency portion of the subsequent event. This behavior of the QP emissions has not been previously emphasized and we consider how this temporal concurrence relates to the source processes.