Mars once had a dense atmosphere enabling liquid water existing on its surface, however, much of that atmosphere has since escaped to space. We examine how incoming solar and solar wind energy fluxes drive escape of atomic and molecular oxygen ions (O+ and O2+) at Mars. We use MAVEN data to evaluate ion escape from February 1, 2016 through May 25, 2022. We find that Martian O+ and O2+ both have increased escape flux with increased solar wind kinetic energy flux and this relationship is generally logarithmic. Increased solar wind electromagnetic energy flux also corresponds to increased O+ and O2+ escape flux, however, increased solar wind electromagnetic energy flux seems to first dampen ion escape until a threshold level is reached, at which point ion escape increases with increasing electromagnetic energy flux. Increased solar irradiance (both total and ionizing) does not obviously increase escape of O+ and O2+. Our results suggest that the solar wind electromagnetic energy flux should be considered along with the kinetic energy flux as an important driver of ion escape, and that other parameters should be considered when evaluating solar irradiance’s impact on O+ and O2+ escape.

Mars once had a dense atmosphere enabling liquid water existing on its surface, however, much of that atmosphere has since escaped to space. We examine how incoming solar and solar wind energy fluxes drive escape of atomic and molecular oxygen ions (O+ and O2+) at Mars. We use MAVEN data to evaluate ion escape from February 1, 2016 through May 25, 2022. We find that Martian O+, and O2+ all have increased escape flux with increased solar wind kinetic energy flux. Increased solar wind electromagnetic energy flux also corresponds to increased O+ and O2+ escape flux. Increased solar irradiance (both total and ionizing) does not obviously increase escape of O+ and O2+. Together, these results suggest that the solar wind electromagnetic energy flux should be considered along with the kinetic energy flux, and that other parameters should be considered when evaluating solar irradiance’s impact on O+ and O2+ escape.

Primitive achondrites like the acapulcoites-lodranites (AL) clan are meteorites that formed on bodies in the process of forming a metallic core, providing a unique window into how early solar system processes transformed unmelted material into differentiated bodies. However, the size and structure of the parent body of ALs and other primitive achondrites are largely unknown. Paleomagnetism can establish the presence or absence of a metallic core by looking for evidence of a dynamo magnetic field. We conducted a magnetic study of the Acapulco acapulcoite to determine its ferromagnetic minerals and their recording properties. This is the first detailed rock magnetic and first paleomagnetic study of a primitive achondrite group. We determined that metal inclusions located inside silicate grains consist of two magnetic minerals, kamacite and tetrataenite, which have robust recording properties. However, the mechanisms and timing by which these minerals acquired any natural remanent magnetization are unknown. Despite this, Acapulco has not been substantially remagnetized since arriving on Earth and therefore should retain a record dating to 4.55 billion years ago. Future studies could characterize this record by using high resolution magnetometry measurements of individual grains and developing an understanding of how and when they became magnetized. Our discovery of tetrataenite in ALs provides the first mineralogical evidence for slow cooling (~5 x 103 °C Ma-1) of the AL parent body at low temperatures (~320°C). Its presence means that the AL parent body is unlikely to have been catastrophically disrupted at AL peak temperatures (~1200°C) without subsequent reaccretion.

A document by William K. Peterson. Click on the document to view its contents.

On January 15, 2022, at around 04:00 UTC, the submarine volcano Hunga Tonga-Hunga Ha‘apai explosively erupted. We examine data from ten Pacific Ocean geomagnetic observatories and process the data using both high pass filters and cross-wavelet analyses to enable evaluating the time-frequency characteristics of the magnetic signals across the Pacific region. At the Western Samoa observatory (API), magnetic signals of 3-8 minutes period, and ~1nT amplitudes, arrived at ~04:44 UTC. API’s signals are likely due to ionospheric sources. The observatories at Chichijima Island (CBI) and Easter Island (IPM) both had local magnetic signatures concurrent with the eruption’s water wave arrival and period ranges from, respectively, 13-93 minutes and 5-100+ minutes. At CBI and IPM, the magnetic signal may be due to both the eruption’s tsunami water wave and atmospheric/ionospheric sources. Our results suggest that the magnetic signatures from the eruption are identifiable and may be further separated in future studies.