Nightside ionosphere of Mars: Modeling the effects of crustal magnetic fields and electron pitch angle distributions on electron impact ionization

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95654/1/jgre2678.pd

Initial results from the InSight mission on Mars

NASA’s InSight (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) mission landed in Elysium Planitia on Mars on 26 November 2018. It aims to determine the interior structure, composition and thermal state of Mars, as well as constrain present-day seismicity and impact cratering rates. Such information is key to understanding the differentiation and subsequent thermal evolution of Mars, and thus the forces that shape the planet’s surface geology and volatile processes. Here we report an overview of the first ten months of geophysical observations by InSight. As of 30 September 2019, 174 seismic events have been recorded by the lander’s seismometer, including over 20 events of moment magnitude Mw = 3–4. The detections thus far are consistent with tectonic origins, with no impact-induced seismicity yet observed, and indi- cate a seismically active planet. An assessment of these detections suggests that the frequency of global seismic events below approximately Mw = 3 is similar to that of terrestrial intraplate seismic activity, but there are fewer larger quakes; no quakes exceeding Mw = 4 have been observed. The lander’s other instruments—two cameras, atmospheric pressure, temperature and wind sensors, a magnetometer and a radiometer—have yielded much more than the intended supporting data for seismometer noise characterization: magnetic field measurements indicate a local magnetic field that is ten-times stronger than orbital estimates and meteorological measurements reveal a more dynamic atmosphere than expected, hosting baroclinic and gravity waves and convective vortices. With the mission due to last for an entire Martian year or longer, these results will be built on by further measurements by the InSight lander

Kinetic processes in the plasma sheet observed during auroral activity

Thesis (Ph. D.)--University of Washington, 2002In this dissertation we analyze plasma sheet magnetic field and plasma data observed during varying levels of auroral activity from very small, isolated events known as pseudobreakups to large, global events known as substorms. The plasma and magnetic field data are taken from instruments onboard the WIND spacecraft while it traverses the near-Earth plasma sheet. Simultaneous global auroral images from POLAR/UVI allow us to determine the auroral activity level. The goal of this dissertation is to provide the most complete set of plasma sheet observations during auroral activity currently available. The kinetic aspects of the plasma dynamics which have largely been ingnored in other works are emphasized here. We have the capability to resolve changes in the three dimensional ion distribution functions with a time resolution comparable to or faster than the local ion gyroperiod. In addition, we consider the typically neglected electron dynamics when relating plasma sheet processes to the aurora. We find that the plasma sheet signatures of both pseudobreakups and substorms appear very similar. During both types of events, increases in auroral precipitation into the ionosphere are associated with large amplitude, high frequency magnetic field fluctuations, large Earthward ion 〈 v〉, increases in the fluxes of high energy ions and electrons, and hardening of the electron spectrum. Both ion and electron distributions appear to be composed of multiple components. Electromagnetic waves with power at frequencies up to and above the local proton gyrofrequency area also observed. Additionally, the ion distributions can change significantly in one gyroperiod. Together, these results imply that the microphysical processes occurring in the plasma sheet during pseudobreakups and substorms are the same and that kinetic effects are important. Therefore, magnetohydrodynamics (MHD) cannot adequately describe the physics occurring during large ion 〈 v〉 events

Observations of Ionospheric Oxygen in the Vicinity of the Moon

Using data from the ARTEMIS spacecraft, we report on observations consistent with the detection of ionospheric oxygen ions in the terrestrial magnetosphere at lunar altitudes. Since there is no mass spectrometer onboard the spacecraft, oxygen can only be detected when the outflow velocities are sufficient to separate oxygen from hydrogen in energy (for the same velocity, oxygen will appear to have a higher energy). We catalog the occurrence of such signatures and relate the detection, number density, and energy of ionospheric oxygen ions to geomagnetic activity parameters. These observations shed light on the amount of ionospheric plasma that reaches the Moon in the magnetotail and how this plasma may participate in and contribute to magnetospheric activity and lunar exosphere production

Full STEAM Ahead with the NASA Opportunities in Visualization, Art, and Science (NOVAS) Program

There has been increasing interest in the use of art as a new tool in the teaching of Science, Technology, Engineering, and Mathematics (STEM). The concept has received major consideration by our federal government, design colleges, art institutes, and leading universities. Many have, in fact, fully embraced this concept, and it’s not unusual today to see “Art” added to STEM to get STEAM. On August 5, 2014, the NASA-funded NASA Opportunities in Visualization, Art, and Science (NOVAS) program team provided a professional development workshop at the Astronomical Society of the Pacific’s 2014 Annual Meeting. In this two-hour workshop, participants learned about the rise of STEAM and were shown valuable skills and techniques used by the NOVAS program for the application of STEAM in a variety of out-of-school time (OST) settings. The workshop highlighted how OST and other informal educators can use art and digital media to help teach about current, cutting-edge STEM investigations, and why scientists need artists to help visualize and communicate their research. Although NASA science and project outcomes from the NOVAS program were emphasized, participants also discussed how NOVAS’ methodologies could be applied to other STEM subjects and OST formats

Magnetic Mystery Planets

The magnetic fields of the large terrestrial planets, Venus, Earth, and Mars, are all vastly different from each other. These differences can tell us a lot about the interior structure, interior history, and they can even give us clues to the atmospheric history of these planets. This paper highlights a classroom presentation and accompanying activity that focuses on the differences between the magnetic fields of Venus, Earth, and Mars, what these differences mean, and how we measure these differences. During the activity, students make magnetic field measurements and draw magnetic field lines of “mystery planets” using orbiting “spacecraft” (small compasses). Based on their observations, the students then determine whether they are orbiting Venus-like, Earth-like, or Mars-like planets. This activity is targeted to middle and high school audiences. However, we have also used a scaled-down version with elementary school audiences

Space Weather Observations With InSight

Solar activity, in the form of coronal mass ejections and corotating interaction regions, results in changes in the solar wind that propagate out through the solar system and interact with the magnetic field environments of planets. Such phenomena have been observed to affect the magnetic field and plasma around Mars as seen from orbit. However, no surface observations have previously been possible because of the absence of ground-based instrumentation. Here, for the first time, we observe the effects of increased solar activity with the magnetometer on the InSight mission in December 2020. We find several days of increased activity including magnetic field fluctuations at periods of minutes to hours. Although only the flanks of this relatively weak coronal mass ejection hit Mars, the observed effects provide insight into how solar activity alters magnetic fields at the surface.ISSN:0094-8276ISSN:1944-800

Modeling Wind‐Driven Ionospheric Dynamo Currents at Mars: Expectations for InSight Magnetic Field Measurements

International audienceWe model expected dynamo currents above, and resulting magnetic field profiles at, InSight's landing site on Mars, including for the first time the effect of electron‐ion collisions. We calculate their diurnal and seasonal variability using inputs from global models of the Martian thermosphere, ionosphere, and magnetosphere. Modeled currents primarily depend on plasma densities and the strength of the neutral wind component perpendicular to the combined crustal and draped magnetic fields that thread the ionosphere. Negligible at night, currents are the strongest in the late morning and near solstices due to stronger winds and near perihelion due to both stronger winds and higher plasma densities from solar EUV photoionization. Resulting surface magnetic fields of tens of nanotesla and occasionally >100 nT may be expected at the InSight landing site. We expect currents and surface fields to vary significantly with changes in the draped magnetic field caused by Mars' dynamic solar wind environment

Deep nightside photoelectron observations by MAVEN SWEA: Implications for Martian northern hemispheric magnetic topology and nightside ionosphere source

The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission samples the Mars ionosphere down to altitudes of ∼150 km over a wide range of local times and solar zenith angles. On 5 January 2015 (Orbit 520) when the spacecraft was in darkness at high northern latitudes (solar zenith angle, SZA >120°; latitude >60°), the Solar Wind Electron Analyzer (SWEA) instrument observed photoelectrons at altitudes below 200 km. Such observations imply the presence of closed crustal magnetic field loops that cross the terminator and extend thousands of kilometers to the deep nightside. This occurs over the weak northern crustal magnetic source regions, where the magnetic field has been thought to be dominated by draped interplanetary magnetic fields (IMF). Such a day‐night magnetic connectivity also provides a source of plasma and energy to the deep nightside. Simulations with the SuperThermal Electron Transport (STET) model show that photoelectron fluxes measured by SWEA precipitating onto the nightside atmosphere provide a source of ionization that can account for the O2+ density measured by the Suprathermal and Thermal Ion Composition (STATIC) instrument below 200 km. This finding indicates another channel for Martian energy redistribution to the deep nightside and consequently localized ionosphere patches and potentially aurora.Key PointsMAVEN SWEA instrument observed photoelectrons at altitudes below 200 km in deep nightsideIt suggests the presence of large cross‐terminator closed crustal magnetic field loops over the Martian northern hemisphereSuch topologies also provide new energy sources to the nightside ionospherePeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134075/1/grl54923.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134075/2/grl54923_am.pd