A5062747295- Astro and Planetary Science
- Planetary Science and Exploration
- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Space Science and Extraterrestrial Life
- Space Exploration and Technology
- Earthquake Detection and Analysis
- Gas Dynamics and Kinetic Theory
- Atmospheric Ozone and Climate
- Laser-induced spectroscopy and plasma
- Plasma Diagnostics and Applications
- GNSS positioning and interference
- Scientific Research and Discoveries
- Space exploration and regulation
- Geophysics and Gravity Measurements
- Isotope Analysis in Ecology
- Magnetic confinement fusion research
- Spacecraft and Cryogenic Technologies
- Stellar, planetary, and galactic studies
- Advanced Thermodynamics and Statistical Mechanics
- Library Science and Administration
- Dust and Plasma Wave Phenomena
- Library Collection Development and Digital Resources
- High Altitude and Hypoxia
University of Michigan
2014-2023
National Research Centre
2016
Hungarian Academy of Sciences
2011
Austrian Academy of Sciences
2010
Planetary Science Institute
2007
Ann Arbor Center for Independent Living
2006
Michigan United
1961-2004
Jet Propulsion Laboratory
1997
Stanford University
1997
Goddard Space Flight Center
1982-1997
The theory and observations relating to electron temperatures in the F region of ionosphere are reviewed. review is divided into three basic parts. In first part concerning heating, cooling, energy transport processes reviewed, all relevant expressions updated. second behavior temperatures, as measured by satellites, rockets, incoherent scatter radars, discussed. This portion covers temperature variations with altitude, latitude, local time, season, geomagnetic activity, solar cycle. third...
Calculations have been made of photoelectron fluxes and energy spectra in the ionosphere for predawn sunlit atmospheres, taking account transport, elastic inelastic collisions, loss to ambient electrons. For models results indicate that a significant fraction incoming electrons are backscattered. By using recent measurements high-altitude incident electron flux, rates O I (6300 A) emission secondary ionization computed. An escape flux order 4.1×108 cm−2 sec−1 is calculated atmosphere. The...
A new computational model has been created to describe the interaction of auroral electrons with atmosphere. For energy greater than 500 eV, continuous losses and small angle deflections are combined in a Fokker-Planck diffusion equation that computes spectrums over all pitch angles throughout These fluxes then used determine rates secondary electron degraded (E < eV) primary production at heights. This information is compute upward downward hemispherical range 0–500 taking into account...
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....
An expression for the linear electromagnetic ion cyclotron convective growth rate has been derived, considering multiple ions in energetic anisotropic component of plasma (which provides free energy instability) as well cold plasma. This represents a modification recent treatments investigating rates which have considered only hydrogen component. Four major effects on and propagation characteristics result from inclusion heavy Some wave occurs at low frequencies below corresponding...
We present the results of model calculations, using our new, four‐species, spherical MHD model. Our are compared with relevant and limited available data. The resulting comparisons help us to increase understanding interaction processes between solar wind Martian atmosphere/ionosphere. This new a grid structure allowed use small (∼10 km) radial spacing in ionospheric region. found that calculated bow shock positions agree reasonably well observed values. vary interplanetary magnetic field...
The theory and observations relating to the ionospheres of terrestrial planets Venus, earth, Mars are reviewed. Emphasis is placed on comparing basic differences similarities between planetary ionospheres. review covers plasma electric‐magnetic field environments that surround planets, leading creation transport ionization in ionospheres, relevant observations, most recent model calculations. section includes a discussion ambipolar diffusion partially ionized plasma, fully supersonic flow,...
The time evolution of the ring current population during recovery phase a typical moderate magnetic storm is studied, using newly developed kinetic model for H + , He and O ions which includes nonequatorially mirroring particles. bounce‐averaged distribution function defined variables that are accessible to direct measurement, some useful formulas calculating total energy number density derived. equation solved, including losses due charge exchange with neutral hydrogen Coulomb collisions...
Voyager ultraviolet spectrometer (UVS) measurements provided the first unassailable evidence for particle precipitation in Jovian atmosphere. Strong Lyman and Werner band emissions at high latitudes indicate energy fluxes of about 10 ergs cm −2 s −1 . On other hand dayglow mid‐ low‐latitudes may additional on order 0.3 all latitudes. Such can have significant aeronomical effects thermsophere ionosphere. A one‐dimensional theoretical model is used to study these case electron precipitation,...
Our numerical model of the ring current‐atmosphere coupling (RAM) is further developed in order to include wave‐particle interaction processes. The calculates time evolution phase space distribution function region from 2 R E 6.5 , considering losses due charge exchange, Coulomb collisions, and plasma wave scattering along ion drift paths. spatial regions cyclotron instability are determined by calculating convective growth rates for electromagnetic (EMIC) waves, integrating them paths,...
The altitude distribution of the hot oxygen density was calculated for upper atmospheres Venus and Mars solar cycle maximum minimum conditions, respectively. values are in good agreement with observed about a factor twenty larger than at exobase.
Measurements of electron density and temperature by the Pioneer Venus orbiter probe (OETP) are used to describe dynamic behavior ionosphere begin relate this complex variations in solar wind ionosheath magnetic field, parameters that also measured instruments. The average ionopause height rises from about 330 km at subsolar point 700 dusk terminator 1000 dawn terminator, both cases exhibiting a stronger dependence upon zenith angle than reported Venera 9 10 occultation data. on dayside tends...
The energy distribution of “hot” oxygen atoms in the upper atmosphere Venus was calculated using two different numerical methods. approaches were based on 1) 2‐stream transport and 2) diffusion equation considerations. Dissociative recombination molecular ions charge exchange atomic with neutral hydrogen gas source terms considered; calculations show that dissociative term is dominant one. altitude hot above exobase also compared measurements by Pioneer Orbiter Ultraviolet Spectrometer....
The decay of the major ion species which constitute ring current is studied by solving time evolution their distribution functions during recovery phase a moderate geomagnetic storm. In this work, only equatorially mirroring particles are considered. Particles assumed to move subject E×B and gradient drifts. They also experience losses along drift paths. Two loss mechanisms considered: charge exchange with neutral hydrogen atoms Coulomb collisions thermal plasma in plasmasphere. Thermal...
This paper summarizes our present, preencounter understanding of the physical and chemical processes controling inner ( r < 1000 km) region cometary atmospheres. Special emphasis was attached to compiling a self‐consistent set governing equations. We are aiming this review at readers who want understand present status mantle coma regions and/or develop new, next generation models which will be needed as large volume new observational data become available in near future.
The solar wind interacts very strongly with the extensive cometary coma, and various interaction processes are initiated by ionization of neutrals. main mechanism far outside bow shock is photoionization extreme ultraviolet radiation. Electron distributions measured in vicinity comets Halley Giacobini‐Zinner instruments on VEGA ICE spacecraft, respectively, used to calculate electron impact frequencies. Ionization electrons comparable importance magnetosheaths Comets Giacobini‐Zinner....
A theory of photoelectron transport that includes both elastic and inelastic collisional processes has been developed to describe the behavior photoelectrons in upper atmosphere. Explicit solutions equations are obtained for a sunlit exponential atmosphere which local production occurs, predawn an influx arrives from magnetically conjugate region. The results indicate scattering significantly reduces rate escape while maintaining up/down isotropy higher altitudes than would be possible if...
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 The crustal remnant field on Mars rotates with the planet at a period of 24 h 37 min, constantly varying magnetic configuration interacting solar wind. Until now, there has been no self‐consistent modeling investigation how this affects wind plasma interaction. Here we include rotation localized in multispecies single‐fluid MHD model and simulate an entire day interaction under normal conditions. results are compared Global Surveyor (MGS) observations show very close agreement,...
Cassini's final phase of exploration The Cassini spacecraft spent 13 years orbiting Saturn; as it ran low on fuel, the trajectory was changed to sample regions had not yet visited. A series orbits close rings followed by a Grand Finale orbit, which took through gap between Saturn and its before destroyed when entered planet's upper atmosphere. Six papers in this issue report results from these phases mission. Dougherty et al. measured magnetic field Saturn, implies complex multilayer dynamo...