A5080914231- Planetary Science and Exploration
- Astro and Planetary Science
- Atmospheric Ozone and Climate
- Space Exploration and Technology
- Solar and Space Plasma Dynamics
- Space Science and Extraterrestrial Life
- Ionosphere and magnetosphere dynamics
- Atomic and Molecular Physics
- Geomagnetism and Paleomagnetism Studies
- Atmospheric and Environmental Gas Dynamics
- Atmospheric chemistry and aerosols
- Scientific Research and Discoveries
- Space exploration and regulation
- Astrophysics and Star Formation Studies
- Laser-induced spectroscopy and plasma
- Spacecraft and Cryogenic Technologies
- Advanced Chemical Physics Studies
- Spectroscopy and Laser Applications
- Quantum, superfluid, helium dynamics
- Gas Dynamics and Kinetic Theory
- Spaceflight effects on biology
- Spacecraft Design and Technology
- Geophysics and Gravity Measurements
- Plasma Diagnostics and Applications
- History and Developments in Astronomy
Wright State University
2010-2023
National Institute of Aerospace
2018
State University of New York
1990-2011
Stony Brook University
1988-2011
University of Virginia
1994
University of Minnesota
1994
Center for Astrophysics Harvard & Smithsonian
1979-1985
Smithsonian Astrophysical Observatory
1977-1984
Harvard University
1982
University of Illinois Urbana-Champaign
1981
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....
We present models of the low and high solar activity thermospheres ionospheres Venus for a background atmosphere based largely on VTS3 model Hedin et al. [1983]. Our consists 12 neutral species, we compute density profiles 13 ions 7 minor neutrals. find that peak production rates some ions, such as CO 2 + N , vary approximately flux some, whose parent neutrals are photochemically produced, O C show variations amplified over flux. The cycle variation at its is about factor 1.6, in good...
Abstract We report the results of observations ionosphere Mars by Neutral Gas and Ion Mass Spectrometer. These were conducted during first 8 months Atmosphere Volatile EvolutioN mission (MAVEN). revealed spatial temporal structures in density distributions 22 ions: H 2 + , 3 He O 2+ C CH N NH OH /CO HCO /HOC /N NO HNO HO Ar ArH CO OCOH . Dusk/dawn day/night asymmetries observed for nearly all ion species. Additionally, high‐density fluctuations detected on nightside may reflect effect...
The Mars Advanced Radar for Subsurface and Ionospheric Sounding aboard Express has been in operation over 2 years. Between 14 August 2005 31 July 2007, we obtain 34,492 ionospheric traces, of which 14,060 yield electron density profiles 12,291 acceptable fits to the Chapman model. These results are used study Martian ionosphere under changing conditions: presence or absence solar energetic particles, EUV flux, season, zenith angle, latitude. 2‐year average subsolar maximum n 0 is 1.62 × 10 5...
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...
The population of hot oxygen atoms in the Martian exosphere is reexamined using newly calculated O production rates for both low and high solar cycle conditions. are assumed to result from dissociative recombination 2 + ions. These calculations take into account vibrational distribution new measured branching ratios. Furthermore, these also consider variation cross section with relative speed participating ions electrons, rotational energy ions, spread ion electron velocities. were next used...
We have constructed low and high solar activity models of the Martian thermosphere/ionosphere for zenith angles from 60 to 90° in 5 degree increments. The fluxes that we adopted are those Solar 2000 v2.22 Tobiska (2004), without enhancements soft X‐ray fluxes. background neutral density temperature profiles similar recently presented (Fox, 2004). compute 14 ions nine species. For all models, present altitude photoionization rates, electron impact ionization total ion production predicted...
The escape rate of nitrogen from Mars is calculated to be 2.3×10 5 s −1 for low solar flux conditions and 8.9×10 high conditions. major source energetic atoms dissociative recombination ground state vibrationally excited N 2 + ions. measured 15 N/ 14 isotope ratio can reproduced by postulating an early dense atmosphere during which little differentiation occurred.
Abstract First results from the Neutral Gas and Ion Mass Spectrometer instrument on Mars Atmosphere Volatile EvolutioN (MAVEN) spacecraft reveal density profiles of protonated species that are mostly in good qualitative agreement with recent models Martian thermosphere/ionosphere. We present here first photochemical model which water ions ionosphere/thermosphere predicted. find computed peak densities OH + , H 2 O 3 fairly measured values. The column is predicted to be about 10 cm −2 mixing...
We have investigated the response of thermosphere and ionosphere Mars to enhanced fluxes solar soft X rays, such as those that been detected by SNOE satellite (e.g., Bailey et al. , 2000 ). constructed standard models adopting SC#21REFW F79050N from H. E. Hinteregger (private communication) (see also Torr 1979 ) for low high activity models, respectively. then X‐ray multiplying photon wavelengths below 200 Å a factor 3 at 6 activity. discuss effects larger rays on ion electron density...
Abstract The evolution of the atmosphere Mars and loss volatiles over lifetime solar system is a key topic in planetary science. An important process for atomic species, such as oxygen, ionospheric photochemical escape. Dissociative recombination O 2 + ions (the major ion species) produces fast oxygen atoms, some which can escape from planet. Many theoretical hot models have been constructed years, although number uncertainties are present these models, particularly concerning elastic cross...