scholarly journals Titan's ionosphere in the magnetosheath: Cassini RPWS results during the T32 flyby

2009 ◽  
Vol 27 (11) ◽  
pp. 4257-4272 ◽  
Author(s):  
P. Garnier ◽  
J-E. Wahlund ◽  
L. Rosenqvist ◽  
R. Modolo ◽  
K. Ågren ◽  
...  
Keyword(s):  
Plasma Wave ◽  
Significant Influence ◽  
Langmuir Probe ◽  
Cold Plasma ◽  
The Moon ◽  
Plasma Environment ◽  
Cassini Mission ◽  
Electrical Conductivities ◽  
Low Altitude ◽  
Detailed Picture

Abstract. The Cassini mission has provided much information about the Titan environment, with numerous low altitude encounters with the moon being always inside the magnetosphere. The only encounter taking place outside the magnetopause, in the magnetosheath, occurred the 13 June 2007 (T32 flyby). This paper is dedicated to the analysis of the Radio and Plasma Wave investigation data during this specific encounter, in particular with the Langmuir probe, providing a detailed picture of the cold plasma environment and of Titan's ionosphere with these unique plasma conditions. The various pressure terms were also calculated during the flyby. The comparison with the T30 flyby, whose geometry was very similar to the T32 encounter but where Titan was immersed in the kronian magnetosphere, reveals that the evolution of the incident plasma has a significant influence on the structure of the ionosphere, with in particular a change of the exo-ionospheric shape. The electrical conductivities are given along the trajectory of the spacecraft and the discovery of a polar plasma cavity is reported.

The martian plasma environment: electric field and Langmuir probe diagnostics

2003 ◽  
Vol 31 (6) ◽  
pp. 1232-1236
Author(s):  
L.G. Blomberg ◽  
J.A. Cumnock ◽  
A.I. Eriksson
Keyword(s):  
Electric Field ◽  
Langmuir Probe ◽  
Plasma Environment ◽  
Probe Diagnostics

scholarly journals COMPLEX WAVE NUMBERS IN THE VICINITY OF THE SCHWARZSCHILD EVENT HORIZON

2008 ◽  
Vol 23 (09) ◽  
pp. 1417-1433 ◽  
Author(s):  
M. SHARIF ◽  
UMBER SHEIKH
Keyword(s):  
Event Horizon ◽  
Plasma Wave ◽  
Cold Plasma ◽  
Dispersion Relations ◽  
Wave Numbers ◽  
Complex Wave ◽  
And Behavior ◽  
Wave Properties

This paper is devoted to investigate the cold plasma wave properties outside the event horizon of the Schwarzschild planar analogue. The dispersion relations are obtained from the corresponding Fourier analyzed equations for nonrotating and rotating, nonmagnetized and magnetized backgrounds. These dispersion relations provide complex wave numbers. The wave numbers are shown in graphs to discuss the nature and behavior of waves and the properties of plasma lying in the vicinity of the Schwarzschild event horizon.

scholarly journals Close Cassini flybys of Saturn’s ring moons Pan, Daphnis, Atlas, Pandora, and Epimetheus

Science ◽  
2019 ◽  
Vol 364 (6445) ◽  
pp. eaat2349 ◽  
Author(s):  
B. J. Buratti ◽  
P. C. Thomas ◽  
E. Roussos ◽  
C. Howett ◽  
M. Seiß ◽  
...  
Keyword(s):  
Optical Properties ◽  
Water Vapor ◽  
Thermal Infrared ◽  
Ring System ◽  
The Moon ◽  
Volcanic Plumes ◽  
Cassini Mission ◽  
Main Ring

Saturn’s main ring system is associated with a set of small moons that either are embedded within it or interact with the rings to alter their shape and composition. Five close flybys of the moons Pan, Daphnis, Atlas, Pandora, and Epimetheus were performed between December 2016 and April 2017 during the ring-grazing orbits of the Cassini mission. Data on the moons’ morphology, structure, particle environment, and composition were returned, along with images in the ultraviolet and thermal infrared. We find that the optical properties of the moons’ surfaces are determined by two competing processes: contamination by a red material formed in Saturn’s main ring system and accretion of bright icy particles or water vapor from volcanic plumes originating on the moon Enceladus.

Density spikes in Titan’s upper ionosphere

2020 ◽  
Author(s):  
Niklas Edberg ◽  
Jan-Erik Wahlund ◽  
Erik Vigren
Keyword(s):  
Langmuir Probe ◽  
Initial Result ◽  
Early Earth ◽  
Sudden Increase ◽  
The Moon ◽  
Plasma Properties ◽  
Density Peaks ◽  
Time Period ◽  
Upper Ionosphere ◽  
Measured Density

<p>Titan, the largest moon of Saturn, has a dense and nitrogen-rich atmosphere, which is similar to that of early Earth before lived evolved. Solar EUV radiation and energetic particles ionizes the atmosphere and thereby forming a layer of plasma, the ionosphere, in the uppermost part of the atmosphere. The Cassini spacecraft flew past the moon Titan 127 times during its 14-year mission in the Saturn system. During most of these close flybys Cassini entered the ionosphere and some reached the ionospheric peak, located at some 1400 km above the moon surface. With the Langmuir probe instrument, we could study the plasma properties, e.g. ion and electron density, temperature etc., and a very dynamic ionospheric structure was found. In particular, significant and apparently sporadic density spikes in the upper ionosphere were found. These density peaks are manifested as a sudden increase in the measured density by some 10-100 cm<sup>-3</sup> over a time period of roughly minutes. These have so far been left unattended in our studies of Titan. We will present some statistics on their appearance and initial result on the mechanism forming them.</p> <p> </p> <p> </p>

scholarly journals Electron density and temperature measurements in the cold plasma environment of Titan: Implications for atmospheric escape

2010 ◽  
Vol 37 (20) ◽  
pp. n/a-n/a ◽  
Author(s):  
N. J. T. Edberg ◽  
J.-E. Wahlund ◽  
K. Ågren ◽  
M. W. Morooka ◽  
R. Modolo ◽  
...  
Keyword(s):  
Electron Density ◽  
Cold Plasma ◽  
Temperature Measurements ◽  
Atmospheric Escape ◽  
Plasma Environment ◽  
Electron Density And Temperature

scholarly journals Real-time 3-D hybrid simulation of Titan's plasma interaction during a solar wind excursion

2009 ◽  
Vol 27 (9) ◽  
pp. 3349-3365 ◽  
Author(s):  
S. Simon
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Real Time ◽  
Plasma Flow ◽  
Time Scale ◽  
Hybrid Simulation ◽  
The Moon ◽  
Plasma Interaction ◽  
Plasma Environment ◽  
The Magnetic Field

Abstract. The plasma environment of Saturn's largest satellite Titan is known to be highly variable. Since Titan's orbit is located within the outer magnetosphere of Saturn, the moon can leave the region dominated by the magnetic field of its parent body in times of high solar wind dynamic pressure and interact with the thermalized magnetosheath plasma or even with the unshocked solar wind. By applying a three-dimensional hybrid simulation code (kinetic description of ions, fluid electrons), we study in real-time the transition that Titan's plasma environment undergoes when the moon leaves Saturn's magnetosphere and enters the supermagnetosonic solar wind. In the simulation, the transition between both plasma regimes is mimicked by a reversal of the magnetic field direction as well as a change in the composition and temperature of the impinging plasma flow. When the satellite enters the solar wind, the magnetic draping pattern in its vicinity is reconfigured due to reconnection, with the characteristic time scale of this process being determined by the convection of the field lines in the undisturbed plasma flow at the flanks of the interaction region. The build-up of a bow shock ahead of Titan takes place on a typical time scale of a few minutes as well. We also analyze the erosion of the newly formed shock front upstream of Titan that commences when the moon re-enters the submagnetosonic plasma regime of Saturn's magnetosphere. Although the model presented here is far from governing the full complexity of Titan's plasma interaction during a solar wind excursion, the simulation provides important insights into general plasma-physical processes associated with such a disruptive change of the upstream flow conditions.

scholarly journals A 1D coupled transport/cold plasma wave model for parallel ponderomotive density modification near RF actuators

2020 ◽  
Author(s):  
R. L. Barnett ◽  
D. L. Green ◽  
J. D. Lore ◽  
D. N. Smithe ◽  
J. R. Myra ◽  
...  
Keyword(s):  
Plasma Wave ◽  
Cold Plasma ◽  
Wave Model ◽  
Coupled Transport

scholarly journals Measurement and implications of Saturn’s gravity field and ring mass

Science ◽  
2019 ◽  
Vol 364 (6445) ◽  
pp. eaat2965 ◽  
Author(s):  
L. Iess ◽  
B. Militzer ◽  
Y. Kaspi ◽  
P. Nicholson ◽  
D. Durante ◽  
...  
Keyword(s):  
Gravitational Field ◽  
Total Mass ◽  
Radio Link ◽  
Interior Structure ◽  
The Moon ◽  
Final Phase ◽  
Cassini Mission ◽  
Formation And Evolution ◽  
Cloud Tops ◽  
Innermost Ring

The interior structure of Saturn, the depth of its winds, and the mass and age of its rings constrain its formation and evolution. In the final phase of the Cassini mission, the spacecraft dived between the planet and its innermost ring, at altitudes of 2600 to 3900 kilometers above the cloud tops. During six of these crossings, a radio link with Earth was monitored to determine the gravitational field of the planet and the mass of its rings. We find that Saturn’s gravity deviates from theoretical expectations and requires differential rotation of the atmosphere extending to a depth of at least 9000 kilometers. The total mass of the rings is (1.54 ± 0.49) × 1019 kilograms (0.41 ± 0.13 times that of the moon Mimas), indicating that the rings may have formed 107 to 108 years ago.

scholarly journals Short wavelength quantum electrodynamical correction to cold plasma-wave propagation

2006 ◽  
Vol 13 (10) ◽  
pp. 102102 ◽  
Author(s):  
J. Lundin ◽  
G. Brodin ◽  
M. Marklund
Keyword(s):  
Wave Propagation ◽  
Plasma Wave ◽  
Short Wavelength ◽  
Cold Plasma

Saturn lightning activity from a cyclone at 50°North latitude

2020 ◽  
Author(s):  
Georg Fischer ◽  
Jacob Gunnarson
Keyword(s):  
Radio Emission ◽  
Plasma Wave ◽  
Average Diameter ◽  
Upper Atmosphere ◽  
Electrostatic Discharges ◽  
Radio Emissions ◽  
White Spots ◽  
Cassini Mission ◽  
Almost All ◽  
North Latitude

<p>During the Cassini mission (2004-2017) the Radio and Plasma Wave Science (RPWS) experiment has recorded the lightning radio emissions from multiple thunderstorms in Saturn's atmosphere. Most of the storms were located in the storm alley at a planetocentric latitude of 35°South, and there was one extra-large storm at 35°North called "Great White Spot" (GWS), which emitted millions of SEDs. This is short for "Saturn Electrostatic Discharges", a widely-used synonym for the radio emission from Saturn lightning. Most lightning storms have also been observed by the Cassini cameras or by ground-based amateur astronomers as bright white spots with diameters around 2000 km ("smaller" storms in the storm alley) or as large as 10,000 km (GWS at 35°North).</p><p>In this presentation we focus on a cyclone at 50°North planetocentric latitude, which was observed by the Cassini cameras from 2007 until the end of 2013. Its average diameter was around 3000 km, and it also exhibited some weak SED activity. The first SED outbreak was in December 2010, at the same time when the GWS was raging further south. Due to the differences in longitude and SED rate of the 50°N cyclone compared to the GWS, it is partly possible to separate the SEDs emitted from the cyclone to those emitted from the GWS. The SED rate of the cyclone is rather low, typically a few SEDs per minute, whereas the GWS showed SED rates up to 10 SEDs per second. The SED activity of the 50°North cyclone was very intermittent, it usually lasted for a few weeks before disappearing again for several months. After the first outbreak in December 2010, there was some more activity in early 2011, autumn 2011, December 2011, spring 2012, July 2012, summer 2013, and finally autumn 2013. By comparing SED data from RPWS with images from the Cassini camera we will show that almost all SEDs taking place after the GWS had their origin in the 50°N cyclone, since the SED sub-spacecraft longitude range is consistent with the longitude of the cyclone. The last SED activity from this cyclone took place in November 2013, and it was also the last SED activity recorded by RPWS during the whole Cassini mission. No more SEDs were found from November 2013 until Cassini burned up in Saturn's upper atmosphere in September 2017.</p><p> </p>

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