Search Publications
Cryoclastic origin of particles on the surface of Enceladus
Manga, M.; Degruyter, W.
Analogous to volcanic deposits on Earth, we can infer eruption characteristics on Enceladus from the relationship between particle size and distance from the vent. We develop a model in which ice particles feeding plumes are accelerated by the gas. We consider two cases: drag-limited and collision-limited acceleration, which link particle size to …
Observational evidence of alpha-particle capture at Mars
Fedorov, A.; Barabash, S.; Futaana, Y. +3 more
Solar wind alpha-particles are suggested to be the most important source of helium in the Martian atmosphere. Recent hybrid simulations show that as much as 30% of the alpha-particles passing through the planetary cross section can be lost from the solar wind due to charge-exchange processes associated with the Mars/solar wind interaction. We use …
Post-equinox periodicities in Saturn's energetic electrons
Krupp, N.; Krimigis, S. M.; Mitchell, D. G. +1 more
Since Saturn's vernal equinox in August 2009 (day 223), energetic electrons (110-365 keV) have exhibited a variety of periodic and aperiodic behavior within a spectral window of 5-15 hours. From late 2009 through the end of 2010, when the observed at dusk, a single period near 10.7 hours dominated the Lomb spectra of these particles. Near the end …
ENA periodicities and their phase relations to SKR emissions at Saturn
Gurnett, D. A.; Krimigis, S. M.; Mitchell, D. G. +2 more
Cassini orbits during days 200-366 in 2004 afforded the opportunity to continuously observe energetic neutral atom (ENA) emissions from long range (>50 RS, 1 RS = 60268 km) on Saturn's dawn side. Images of energetic neutral hydrogen (25-55 keV) and oxygen (90-160 keV) were projected onto the noon-midnight plane, corrected …
Cassini magnetometer observations over the Enceladus poles
Persoon, A. M.; Russell, C. T.; Wei, H. Y. +5 more
In 2009 and 2010, the Cassini spacecraft made seven targeted Enceladus flybys along trajectories parallel to the equatorial plane. The magnetometer on board Cassini made a complete set of vector field distribution measurements on these tracks and observed significant perturbations that further constrained the location of the momentum-exchange regi…
Conjunction of anti-parallel and component reconnection at the dayside MP: Cluster and Double Star coordinated observation on 6 April 2004
Wei, Y.; Dunlop, M. W.; Bogdanova, Y. V. +7 more
Previous theoretical and simulation studies have suggested that the anti-parallel and component reconnection can occur simultaneously on the dayside magnetopause. Certain observations have also been reported to support global conjunct pattern of magnetic reconnection. Here, we show direct evidence for the conjunction of anti-parallel and component…
Tidal variations in the Martian lower atmosphere inferred from Mars Express Planetary Fourier Spectrometer temperature data
Grassi, D.; Kasaba, Y.; Formisano, V. +4 more
We report on the characteristics of tidal variations in the Martian lower atmosphere (<45 km) using the Mars Express (MEX) Planetary Fourier Spectrometer (PFS) temperature data for about three Martian years (between the ends of MY26 and MY29). The PFS data, which widely cover local time, enable us to investigate diurnal variations in the atmosp…
Correction to “Are the basins of Titan's Hotei Regio and Tui Regio sites of former low latitude seas?”
Moore, Jeffrey M.; Howard, Alan D.
Abstract Available from http://www.agu.org
Anomalously low solar extreme-ultraviolet irradiance and thermospheric density during solar minimum
Woods, Thomas N.; Didkovsky, Leonid V.; Solomon, Stanley C. +2 more
Solar activity during 2007-2009 was very low, and during this protracted solar minimum period, the terrestrial thermosphere was cooler and lower in density than expected. Measurements from instruments on the SOHO and TIMED spacecraft, and by suborbital rocket flights, indicate that solar extreme-ultraviolet irradiance levels were lower than they w…
Initial results for the north pole of the Moon from Mini-SAR, Chandrayaan-1 mission
Kirk, R. L.; Neish, C. D.; Butler, B. J. +27 more
We present new polarimetric radar data for the surface of the north pole of the Moon acquired with the Mini-SAR experiment onboard India's Chandrayaan-1 spacecraft. Between mid-February and mid-April, 2009, Mini-SAR mapped more than 95% of the areas polewards of 80° latitude at a resolution of 150 meters. The north polar region displays backscatte…