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Articles 1 - 13 of 13
Full-Text Articles in Physics
Correlations Between The Rotations And Magnetospheres Of The Terrestrial Planets And The Sun's Formation In Our Solar System, Fred J. Cadieu
Correlations Between The Rotations And Magnetospheres Of The Terrestrial Planets And The Sun's Formation In Our Solar System, Fred J. Cadieu
Publications and Research
Correlations between the rotations of the terrestrial planets in our solar system and the magnetic field of the Sun have been previously noted. These correlations account for the opposite rotation of Venus as a result of the magnetic field of the Sun being dragged across the conducting core of Venus. Currently the Sun’s magnetic field is not sufficiently strong to account for the proposed correlations. But recently meteorite paleomagnetism measurements have indicated that during the Sun’s formation the magnetic field of the Sun was of sufficient strength to have resulted in the observed correlations. As a part of these correlations …
Vortices And Dust Devils As Observed By The Mars Environmental Dynamics Analyzer Instruments On Board The Mars 2020 Perseverance Rover, Brian Jackson
Vortices And Dust Devils As Observed By The Mars Environmental Dynamics Analyzer Instruments On Board The Mars 2020 Perseverance Rover, Brian Jackson
Physics Faculty Publications and Presentations
An important and perhaps dominant source of dust in the Martian atmosphere, dust devils play a key role in Mars' climate. Data sets from previous landed missions have revealed dust devil activity, constrained their structures, and elucidated their dust-lifting capacities. However, each landing site and observational season exhibits unique meteorological properties that shape dust devil activity and illuminate their dependence on ambient conditions. The recent release of data from the Mars Environmental Dynamics Analyzer (MEDA) instrument suite on board the Mars 2020 Perseverance rover promises a new treasure trove for dust devil studies. In this study, we sift the time …
Inferring Vortex And Dust Devil Statistics From Insight, Brian Jackson, Justin Crevier, Michelle Szurgot, Ryan Battin, Clément Perrin, Sébastien Rodriguez
Inferring Vortex And Dust Devil Statistics From Insight, Brian Jackson, Justin Crevier, Michelle Szurgot, Ryan Battin, Clément Perrin, Sébastien Rodriguez
Physics Faculty Publications and Presentations
The InSight mission has operated on the surface of Mars for nearly two Earth years, returning detections of the first marsquakes. The lander also deployed a meteorological instrument package and cameras to monitor local surface activity. These instruments have detected boundary layer phenomena, including small-scale vortices. These vortices register as short-lived, negative pressure excursions and closely resemble those that could generate dust devils. Although our analysis shows that InSight encountered more than 900 vortices and collected more than 1000 images of the Martian surface, no active dust devils were imaged. In spite of the lack of dust devil detections, we …
On The Relationship Between Dust Devil Radii And Heights, Brian Jackson
On The Relationship Between Dust Devil Radii And Heights, Brian Jackson
Physics Faculty Publications and Presentations
The influence of dust devils on the martian atmosphere depends on their capacity to loft dust, which depends on their wind profiles and footprint on the martian surface, i.e., on their radii, ��. Previous work suggests the wind profile depends on a devil’s thermodynamic efficiency, which scales with its height, ℎ. However, the precise mechanisms that set a dust devil’s radius have remained unclear. Combining previous work with simple assumptions about angular momentum conservation in dust devils predicts that �� ∝ ℎ1∕2, and a model fit to observed radii and heights from a survey of martian dust devils …
Seminal Evidence Of A 2.5-Sol Ultra-Fast Kelvin Wave In Mars’ Middle And Upper Atmosphere, Federico Gasperini, Maura E. Hagan, Jeffrey M. Forbes
Seminal Evidence Of A 2.5-Sol Ultra-Fast Kelvin Wave In Mars’ Middle And Upper Atmosphere, Federico Gasperini, Maura E. Hagan, Jeffrey M. Forbes
All Physics Faculty Publications
The structure and dynamics of Mars' middle and upper atmosphere is significantly impacted by waves propagating from the lower atmosphere. Using concurrent temperature and neutral density measurements taken by the Mars Reconnaissance Orbiter and Mars Atmosphere and Volatile EvolutioN satellites, we demonstrate for the first time that a 2.5‐sol ultra‐fast Kelvin wave is a prominent global‐scale feature of the low‐latitude middle (i.e., 30–80 km) and upper (approximately 150 km) atmosphere of Mars. Further, we present evidence of secondary waves arising from nonlinear interactions between this ultra‐fast Kelvin wave and solar tides, and based on their amplitudes we surmise that they …
Dependence Of The Martian Radiation Environment On Atmospheric Depth: Modeling And Measurement, Jingnan Guo, Tony C. Slaba, Cary Zeitlin, Robert F. Wimmer-Schweingruber, Francis F. Badavi, Eckart Böhm, Stephan Böttcher, David E. Brinza, Bent Ehresmann, Donald M. Hassler
Dependence Of The Martian Radiation Environment On Atmospheric Depth: Modeling And Measurement, Jingnan Guo, Tony C. Slaba, Cary Zeitlin, Robert F. Wimmer-Schweingruber, Francis F. Badavi, Eckart Böhm, Stephan Böttcher, David E. Brinza, Bent Ehresmann, Donald M. Hassler
Physics Faculty Publications
The energetic particle environment on the Martian surface is influenced by solar and heliospheric modulation and changes in the local atmospheric pressure (or column depth). The Radiation Assessment Detector (RAD) on board the Mars Science Laboratory rover Curiosity on the surface of Mars has been measuring this effect for over four Earth years (about two Martian years). The anticorrelation between the recorded surface Galactic Cosmic Ray-induced dose rates and pressure changes has been investigated by Rafkin et al. (2014) and the long-term solar modulation has also been empirically analyzed and modeled by Guo et al. (2015). This paper employs the …
Dust Devils And Dustless Vortices On A Desert Playa Observed With Surface Pressure And Solar Flux Logging, Ralph D. Lorenz, Brian K. Jackson
Dust Devils And Dustless Vortices On A Desert Playa Observed With Surface Pressure And Solar Flux Logging, Ralph D. Lorenz, Brian K. Jackson
Physics Faculty Publications and Presentations
Dust devils are convective vortices rendered visible by lofted dust, and may be a significant means of injecting dust into the atmosphere, on both Earth and Mars. The fraction of vortices that are dust-laden is not well-understood, however. Here we report a May/June 2013 survey on a Nevada desert playa using small stations that record pressure and solar flux with high time resolution (2 Hz): these data allow detection of vortices and an estimate of the dust opacity of the subset of vortices that geometrically occult the sun. The encounter rate of vortex pressure drops of 0.3 hPa or larger …
Comparisons Of Electron Fluxes Measured In The Crustal Fields At Mars By The Mgs Magnetometer/Electron Reflectometer Instrument With A B Field-Dependent Transport Code, Michael W. Liemohn, David L. Mitchell, Andrew F. Nagy, Jane L. Fox, Tamara W. Reimer, Yingjuan J. Ma
Comparisons Of Electron Fluxes Measured In The Crustal Fields At Mars By The Mgs Magnetometer/Electron Reflectometer Instrument With A B Field-Dependent Transport Code, Michael W. Liemohn, David L. Mitchell, Andrew F. Nagy, Jane L. Fox, Tamara W. Reimer, Yingjuan J. Ma
Physics Faculty Publications
We compare Mars Global Surveyor (MGS) magnetometer/electron reflectometer data with results from a B field–dependent kinetic transport code for ‘‘superthermal’’ electrons. The photoelectrons created on crustal field loops, when they are on the dayside, allow for the exploration of the magnetic topology and the upper atmospheric density structure. A case study of a typical orbit of the MGS satellite through the strong crustal field region in the southern hemisphere of Mars is examined. The results indicate that the low solar wind dynamic pressure during the selected orbit allowed for the expansion of the crustal field line to relatively high altitudes. …
On The Escape Of Oxygen And Hydrogen From Mars, Jane L. Fox
On The Escape Of Oxygen And Hydrogen From Mars, Jane L. Fox
Physics Faculty Publications
Escape rates of oxygen atoms from dissociative recombination of O2+ above the Martian exobase are computed in light of new information from ab initio calculations of the dissociative recombination process, and our recently revised understanding of the Martian dayside ionosphere. Only about 60% of the dissociative recombinations occur in channels in which the O atoms are released with energies in excess of the escape velocity. Futhermore, we find that the computed escape fluxes for O depend greatly on the nature of the ion loss process that has been found necessary to reproduce the topside ion density profiles measured …
Upper Limits To The Nightside Ionosphere Of Mars, Jane L. Fox
Upper Limits To The Nightside Ionosphere Of Mars, Jane L. Fox
Physics Faculty Publications
The nightside ionosphere of Mars could be produced by electron precipitation or by plasma transport from the dayside, by analogy to the Venus, but few measurements are available. We report here model calculations of upper limits to the nightside ion densities on Mars that would be produced by both mechanisms. For the auroral model, we have adopted the downward traveling portions of the electron spectra measured by the HARP instrument on the Soviet Phobos spacecraft in the Martian plasma sheet and in the magnetotail lobes. For the plasma transport case, we have imposed on a model of the nightside thermosphere, …
The Production And Escape Of Nitrogen Atoms On Mars, Jane L. Fox
The Production And Escape Of Nitrogen Atoms On Mars, Jane L. Fox
Physics Faculty Publications
We have computed the production rates and densities of odd nitrogen species in the Martian atmosphere using updated rate coefficients and a revised ionosphere-thermosphere model. We find that the computed densities of NO are somewhat smaller than those measured by Viking 1, but reasonable agreement can be obtained by assuming that the rate coefficient for loss of odd nitrogen in the reaction of N with NO is smaller at temperatures that prevail in the lower Martian thermosphere (about 130–160 K) than the standard value, which applies to temperatures of 200–400 K. We have also modeled the escape fluxes of N …
Mars And Beyond: The Solar System Beckons, Frank J. Redd
Mars And Beyond: The Solar System Beckons, Frank J. Redd
Faculty Honor Lectures
To space zealots, 1989 was the year the drought ended. The space shuttle was operational again; Voyager's grand reconnaissance of the Solar System climaxed with the glorious encounter with the planet Neptune and its startling moon, Triton; the launches of the Magellan spacecraft to Venus and the Gallileo to Jupiter broke a decade long hiatus in the launch of U.S. planetary missions; and, for the first time in over twenty years, a U.S. president announced a daring new initiative in human exploration with the goal of first returning humans to the Moon, then going on to Mars.
Nitrogen Escape From Mars, Jane L. Fox, Alexander Dalgarno
Nitrogen Escape From Mars, Jane L. Fox, Alexander Dalgarno
Physics Faculty Publications
The escape rate of nitrogen from Mars is calculated to be 2.3×105 s−1 for low solar flux conditions and 8.9×105 s−1 for high solar flux conditions. The major source of energetic atoms is dissociative recombination of ground state and vibrationally excited N2+ ions. The measured 15N/14N isotope ratio can be reproduced by postulating an early dense atmosphere during which little differentiation occurred.