A5073704868- Astro and Planetary Science
- Ionosphere and magnetosphere dynamics
- Planetary Science and Exploration
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Space Science and Extraterrestrial Life
- Earthquake Detection and Analysis
- GNSS positioning and interference
- Space Exploration and Technology
- Atmospheric Ozone and Climate
- Spacecraft Design and Technology
- Geophysics and Gravity Measurements
- Space exploration and regulation
- Space Satellite Systems and Control
- Stellar, planetary, and galactic studies
- Plasma Diagnostics and Applications
- Mass Spectrometry Techniques and Applications
- Isotope Analysis in Ecology
- Atomic and Molecular Physics
- Spacecraft and Cryogenic Technologies
- Gamma-ray bursts and supernovae
- Ship Hydrodynamics and Maneuverability
- Light effects on plants
- Atmospheric chemistry and aerosols
- Radioactive contamination and transfer
Goddard Space Flight Center
2009-2020
Deleted Institution
2003
Pennsylvania State University
1968
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....
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...
Abstract The Mars Atmosphere and Volatile EvolutioN (MAVEN) orbiter has been gathering information on the upper atmosphere, ionosphere, solar wind interactions since its orbit insertion in September 2014. MAVEN's science goals are to understand processes driving escape of atmospheric gases space at present epoch, their variations with local heliospheric conditions together geographical seasonal influences. This introduction accompanying articles provide a selection key results obtained up...
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 Wavelike perturbations in the Martian upper thermosphere observed by Neutral Gas Ion Mass Spectrometer (NGIMS) onboard Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft have been analyzed. The amplitudes of small‐scale with apparent wavelengths between ~100 ~500 km Ar density around exobase show a clear dependence on temperature ( T 0 ) thermosphere. average amplitude is ~10% dayside ~20% nightside, which about 2 10 times larger than those Venusian low‐latitude region...
Abstract We present results from a global Mars time‐dependent MHD simulation under constant solar wind and radiation impact considering inherent magnetic field variations due to continuous planetary rotation. calculate the 3‐D shapes locations of bow shock (BS) induced magnetospheric boundary (IMB) then examine their dynamic changes with time. develop physics‐based, empirical algorithm effectively summarize multidimensional crustal distribution. It is found that by organizing model using...
Direct measurements of the pole-to-pole distributions topside thermal protons obtained with Ogo-4 ion composition experiment, near local midnight, reveal sharply structured variations plasmasphere boundary. With increasing L values proton density may exhibit a pronounced inner trough, in which ambient H+ concentrations decrease by an order magnitude L=2 and subsequently recover to midlatitude concentration levels before more persistent trough is encountered at higher positions. The time...
Abstract We study the solar wind interaction with Martian upper atmosphere during 8 March 2015 interplanetary coronal mass ejection (ICME) by using a global multifluid MHD model. Comparison of simulation results observations from Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft shows good agreement. The total ion escape rate is increased an order magnitude, 2.05 × 10 24 s −1 (pre‐ICME phase) to 2.25 25 (ICME sheath phase), this time period. Two major channels are illustrated:...
Abstract We report the first in situ detection of metal ions upper atmosphere Mars resulting from ablation dust particles comet Siding Spring. This was carried out by Neutral Gas and Ion Mass Spectrometer on board Atmosphere Volatile Evolution Mission. Metal Na, Mg, Al, K, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, possibly Si, Ca, were identified ion spectra collected at altitudes ~185 km. The measurements revealed that Na + most abundant species, remaining metals depleted with respect to CI (type 1...
Abstract Using data from the National Aeronautics and Space Administration Mars Atmosphere Voltatile EvolutioN European Agency Express spacecraft, we show that transient phenomena in foreshock solar wind can directly inject energy into ionosphere of Mars. We demonstrate impact compressive ultralow frequency waves on induced magnetospheres drive compressional, linearly polarized, magnetosonic ionosphere, a localized electromagnetic "ringing" at local proton gyrofrequency. The pulsations heat...
Abstract Understanding what processes govern atmospheric escape and the loss of planetary water is paramount importance for understanding how life in universe can exist. One mechanism thought to be important at all planets an “ambipolar” electric field that helps ions overcome gravity. We report discovery first quantitative extraterrestrial measurements such a planet Venus. Unexpectedly, despite comparable gravity, we show five times stronger than Earth's similar ionosphere. Contrary our...
From a thorough modeling of the altitude profile meteoric ionization in Martian atmosphere we deduce that persistent layer magnesium ions should exist around an 70 km. On basis estimated meteoroid mass flux density, peak ion density ∼10 4 cm −3 is predicted. Allowing for uncertainties all model parameters, this value probably within order magnitude correct density. Of these most sensitive to which determines source function Mg from ablating meteoroids. Unlike terrestrial case, where metallic...
Magnetic field structures are analyzed for both the ionospheric hole region and magnetosheath‐ionosphere interaction of nightside Venus, in search possible coupling between these two regimes. A magnetic coordinate system based on directions solar wind interplanetary (IMF) is found to order data reasonably well, allowing consistent superposition observational from individual passes Pioneer Venus orbiter. The main findings (1) holes form a zone ±45° latitude covering possibly entire width wake...
Saturation of the dc double-probe instrument on Explorer 45 has been used to identify plasmapause. Fifteen months these data resulted in a base sufficient size statistically study average position plasmapause over 14.5 hours magnetic local time (MLT) under differing conditions. The afternoon-evening bulge L coordinate versus was found be centered between 20 and 21 MLT during magnetically quiet periods shifted toward dusk as activity increased, but always postdusk. During near noon also seen,...
Light ion trough measurements near midnight made by the Bennett RF mass spectrometer on Ogo 4 operating in high-resolution mode reveal existence of irregular structure low-latitude side mid-latitude trough. By using two different relations between equatorial convection electric field, assumed to be spatially invariant and directed from dawn dusk, Kp (one based plasmapause other polar cap E field measurements) a model development was outer plasmasphere. The calculations produced multiple...
Abstract An important mechanism in the generation of polar wind outflow is ambipolar electric potential which assists ions overcoming gravity and a key for Terrestrial ionospheric escape. At Mars, open field lines are not confined to poles, electrons observed far into tail. It has thus been hypothesized that similar may be present at contributing global loss. However, no direct measurements this have made. In pilot study, we examine photoelectron spectra measured by Solar Wind Electron...
Abstract Interplanetary dust particles have long been expected to produce permanent ionospheric metal ion layers at Mars, as on Earth, but the two environments are so different that uncertainty existed whether terrestrial‐established understanding would apply Mars. The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission made first in situ detection of continuous presence Na + , Mg Fe indeed revealed non‐Earthlike features/processes. There is no separation light heavy with increasing...