A5067990688- Planetary Science and Exploration
- Astro and Planetary Science
- Space Science and Extraterrestrial Life
- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Geomagnetism and Paleomagnetism Studies
- Space Exploration and Technology
- Laser-induced spectroscopy and plasma
- Space exploration and regulation
- Scientific Research and Discoveries
- Geological and Geochemical Analysis
- Methane Hydrates and Related Phenomena
- Geology and Paleoclimatology Research
- Atmospheric and Environmental Gas Dynamics
- Archaeological and Geological Studies
- High-pressure geophysics and materials
- Spacecraft Design and Technology
- Geophysics and Gravity Measurements
- Spaceflight effects on biology
- earthquake and tectonic studies
- Spacecraft and Cryogenic Technologies
- Archaeology and ancient environmental studies
- Pleistocene-Era Hominins and Archaeology
- Geological Modeling and Analysis
- Archaeological and Historical Studies
University of California, Berkeley
2018-2024
Goddard Space Flight Center
2024
West Virginia University
2021-2024
University of Cambridge
2023
Ida Darwin hospital
2020-2023
Laboratory for Atmospheric and Space Physics
2014-2021
University of Colorado Boulder
2014-2021
Pennsylvania State University
2021
Berkeley College
2021
Space Science Institute
2021
Coupling between the lower and upper atmosphere, combined with loss of gas from atmosphere to space, likely contributed thin, cold, dry modern Mars. To help understand ongoing ion Mars Atmosphere Volatile Evolution (MAVEN) spacecraft made comprehensive measurements ionosphere, interactions Sun solar wind during an interplanetary coronal mass ejection impact in March 2015. Responses include changes bow shock magnetosheath, formation widespread diffuse aurora, enhancement pick-up ions....
By com parison o f the methane m ixing ratio and carbon isotope (<513C ch4 ) in Arctic air w ith regional background, incremental input C H 4 an parcel source < 513C signature can be determined.Using this technique bulk soiuce arriving at Spitsbergen late summer 2008 2009 was found to -6 8 %o, indicative dominance a bio genic soiuce.This is close emissions from boreal wetlands.In spring, when wet land as frozen, th e sig n atu re ore enriched 13C -5 3 ± 6%o mass back trajectories indicating...
Abstract We present Mars' electron temperature ( T e ) and density n altitude profiles derived from the MAVEN (Mars Atmosphere Volatile EvolutioN) mission deep dip orbits in April 2015, as measured by Langmuir probe instrument. These had periapsides below 130 km at low solar zenith angles. The were above peak during this period. Using a Chapman function fit, we find that scale height projected of are consistent with models previous measurements. is slightly higher than earlier works. For...
Abstract Photochemical escape of atomic oxygen is thought to be one the dominant channels for Martian atmospheric loss today and played a potentially major role in climate evolution. Mars Atmosphere Volatile Evolution Mission (MAVEN) first mission capable measuring, situ, relevant quantities necessary calculate photochemical fluxes. We utilize 18 months data from three MAVEN instruments: Langmuir Probe Waves, Neutral Gas Ion Mass Spectrometer, SupraThermal And Thermal Composition. From these...
The Mars Atmosphere and Volatile Evolution (MAVEN) mission, during the second of its Deep Dip campaigns, made comprehensive measurements martian thermosphere ionosphere composition, structure, variability at altitudes down to ~130 kilometers in subsolar region. This altitude range contains diffusively separated upper atmosphere just above well-mixed atmosphere, layer peak extreme ultraviolet heating primary reservoir for atmospheric escape. In situ reveal previously unmeasured populations...
Abstract We utilize suprathermal ion and magnetic field measurements from the Mars Atmosphere Volatile EvolutioN (MAVEN) mission, organized by upstream field, to investigate morphology variability of flows, fields, forces in Mars‐solar wind interaction. employ a combination case studies statistical investigations characterize interaction both quasi‐parallel quasi‐perpendicular regions under high low solar Mach number conditions. For first time, we include detailed investigation temperature...
Abstract Measurement of the dense cold thermal plasma in planetary ionospheres via orbiting spacecraft is challenging because ion energies are small (0–4 eV), densities can vary by four orders magnitude, composition varies with altitude, charging time and must be measured very accurately, instrumental effects (e.g., detector dead‐time background) significant. The SupraThermal And Thermal Ion Composition instrument team has recently released a new set data products that contain density...
Research Article| July 01, 1983 Model for Archean plate tectonics E. G. Nisbet; Nisbet 1Department of Geological Sciences, University Saskatchewan, Saskatoon S7N 0W0, Canada Search other works by this author on: GSW Google Scholar C.M.R. Fowler Author and Article Information Publisher: Society America First Online: 01 Jun 2017 Online ISSN: 1943-2682 Print 0091-7613 Geology (1983) 11 (7): 376–379. https://doi.org/10.1130/0091-7613(1983)11<376:MFAPT>2.0.CO;2 history Cite View This Citation Add...
Abstract We use observations from the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission to show how superthermal electron fluxes crustal magnetic fields affect ion densities in nightside ionosphere of Mars. find that due impact ionization, high significantly increase CO , O + below 200 km but only modestly NO density. High also produce distinct peaks altitude profiles. are smaller near strong fields. Consequently, because they decay without being replenished by ionization. Furthermore,...
Abstract The first in situ nightside electron density and temperature profiles at Mars are presented as functions of altitude local time (LT) from the Langmuir Probe Waves (LPW) instrument on board Atmosphere Volatile EvolutioN (MAVEN) mission spacecraft. LPW is able to measure densities low ∼100 , a factor up 10 or greater improvement over previous measurements. Above 200 km, near‐vertical few hundred cubic centimeters were observed for almost all LT, with lowest highest temperatures...
Abstract On 26 December 2022 the solar wind density dropped by over an order of magnitude and remained low for about a day. We have utilized in‐situ plasma measurements made Mars Atmosphere Volatile EvolutioN mission to determine how this change affected Mars‐solar interaction. During time period, on inbound orbit segments, MAVEN sampled terminator ionosphere, which switched from magnetized unmagnetized state immediately following minimum in density. The magnetic field amplitude was...
Abstract We present Mars Atmosphere and Volatile EvolutioN observations of large‐amplitude magnetosonic waves propagating through the magnetosheath into Martian ionosphere near subsolar point on dayside planet. The observed grow in amplitude as predicted for a wave denser, charged medium, with amplitudes reaching 25 nT, equivalent to ∼40% background field strength. These drive significant density temperature variations (∼20% 100% amplitude) suprathermal electrons light ion species (H + )...
Abstract Recent results from the MAVEN Langmuir Probe and Waves instrument suggest higher than predicted electron temperatures ( T e ) in Mars' dayside ionosphere above ~180 km altitude. Correspondingly, measurements Neutral Gas Ion Mass Spectrometer indicate significant abundances of O 2 + up to ~500 altitude, suggesting that may be a principal ion loss mechanism oxygen. In this article, we investigate effects (which heating) heating on outflow loss. Numerical solutions show plasma...
Dust is common close to the martian surface, but no known process can lift appreciable concentrations of particles altitudes above ~150 kilometers. We present observations dust at ranging from 150 1000 kilometers by Langmuir Probe and Wave instrument on Mars Atmosphere Volatile Evolution spacecraft. Based its distribution, we interpret this be interplanetary in origin. A comparison with laboratory measurements indicates that grain size ranges 1 12 micrometers, assuming a typical velocity ~18...
Abstract We combine thermal electron densities in Mars' ionosphere with magnetic topology information to investigate the sources of nightside ionosphere. Thermal density is measured situ by Langmuir Probe and Waves experiment onboard Mars Atmospheric Volatile EvolutioN, while simultaneously inferred from suprathermal energy‐pitch angle distributions Solar Wind Electron Analyzer Magnetometer. Topologically closed regions inhibit impact ionization, allowing us isolate effects plasma transport...
Abstract On 10 September 2017, irradiance from a magnitude X8.2 solar flare impacted Mars while the Atmosphere and Volatile EvolutioN (MAVEN) orbiter was characterizing upper atmosphere. This largest to occur during MAVEN mission date, nearly tripling ionizing impacting in tens of minutes, provides an opportunity study planet's response extreme changes. letter reports situ observations topside ionosphere's this above 155 km made 1.67 hr after soft X‐ray peak. The observed plasma density...
Abstract This study assesses under what circumstances the Martian ionopause is formed on dayside, both in regions where there are strong crustal magnetic fields and areas these small (<30 nT). Multiple data sets from three MAVEN dayside deep dip campaigns utilized between periapsis 600–1,000 km, as well solar wind observations Mars Express. The identified a sudden decrease of electron density with increasing altitude simultaneous increase temperature variability below 400 km. physically...
Abstract An unusually low density solar wind event was observed in December 2022 moving past both Earth and Mars. The source traced back to a coronal hole active region on the Sun's surface. resulting lead development of co‐rotating interaction (CIR) trailing rarefaction that lasted for multiple rotations. Within this structure, conditions, including density, velocity, magnetic field magnitude orientation drastically changed. In study we analyze response Martian ionosphere using MAVEN data...
Abstract Ionospheric plasma density disturbances significantly affect radio wave propagation, impacting communication and planetary exploration. At Earth, sporadic E layers (Es) are commonly observed. They characterized by thin, high-density structures in the E-region ionosphere, primarily formed electromagnetic forces induced horizontal wind shears. Similar sharp vertical electron changes have also been observed topside of Martian ionosphere missions like Mars Global Surveyor, Express,...