A5085824314- Astro and Planetary Science
- Planetary Science and Exploration
- Ionosphere and magnetosphere dynamics
- Geomagnetism and Paleomagnetism Studies
- Space Exploration and Technology
- Solar and Space Plasma Dynamics
- Dust and Plasma Wave Phenomena
- Isotope Analysis in Ecology
- Geology and Paleoclimatology Research
- Earthquake Detection and Analysis
- Stellar, planetary, and galactic studies
- Scientific Research and Discoveries
- Mass Spectrometry Techniques and Applications
- Astrophysics and Star Formation Studies
- Plasma Diagnostics and Applications
- High-pressure geophysics and materials
- Paleontology and Stratigraphy of Fossils
- Atomic and Molecular Physics
- GNSS positioning and interference
- Molecular Spectroscopy and Structure
- Laser-induced spectroscopy and plasma
- Geological and Geochemical Analysis
Swedish Institute of Space Physics
2015-2024
Imperial College London
2018-2022
Japan Aerospace Exploration Agency
2021
Uppsala University
2013-2017
Cassini discovered a plethora of neutral and ionised molecules in Titan's ionosphere including, surprisingly, anions negatively charged extending up to 13,800 u/q. In this letter we forward model the electron spectrometer response function unexpected ionospheric component achieve an increased mass resolving capability for species observed at Titan altitudes 950-1300 km. We report on detections consistently centered between 25.8-26.0 u/q 49.0-50.1 which are identified as belonging carbon...
During the six Cassini Titan flybys T83–T88 (May 2012 to November 2012) electron density in ionospheric peak region, as measured by radio and plasma wave science instrument/Langmuir probe, has increased significantly, 15–30%, compared previous average. These measurements suggest that a long‒term change occurred ionosphere of Titan, likely caused rise new solar maximum with EUV fluxes. We compare from TA, TB, T5, declining phase cycle 23 recent during 24, since irradiances those two intervals...
Abstract We present Cassini Langmuir probe measurements of the highest electron number densities ever reported from ionosphere Titan. The measured density reached 4310 cm −3 during T85 Titan flyby. This is at least 500 higher than observed before and 50 % above average for similar solar zenith angles. peak ionospheric not on this flyby, making maximum a lower limit. During we also report that an impacting coronal mass ejection (CME) leaves in magnetosheath Saturn, where it exposed to shocked...
The importance of the heavy ions and dust grains for chemistry aerosol formation in Titan's ionosphere has been well established recent years Cassini mission. In this study we combine independent situ plasma (Radio Plasma Wave Science Langmuir Probe (RPWS/LP)) particle (Cassini Electron Spectrometer, Ion Beam Neutral Mass Spectrometer) measurements selected flybys (T16, T29, T40, T56) to produce altitude profiles mean ion masses including develop a Titan-specific method detailed analysis...
Abstract We present the electron density ( n e ) altitude profiles of Saturn's ionosphere at near‐equatorial latitudes from all 23 orbits Cassini's Grand Finale. The data are collected by Langmuir probe part Radio and Plasma Wave Science investigation. A high degree variability in is observed. However, organizing them consecutive ranges revealed clear differences between southern northern hemispheres. shown to be more variable connected D‐ring below 5,000 km hemisphere compared hemisphere....
Effects of solar EUV on positive ions and heavy negative charge carriers (molecular ions, aerosol, and/or dust) in Titan's ionosphere are studied over the course almost 12 years, including 78 flybys below 1400 km altitude between TA (October 2004) T120 (June 2016). The Radio Plasma Wave Science/Langmuir Probe-measured ion densities (normalized by zenith angle) show statistically significant variations with respect to flux. Dayside increase a factor ≈2 from minimum maximum, while nightside...
Abstract Cassini’s Grand Finale orbits provided for the first time in-situ measurements of Saturn’s topside ionosphere. We present Pedersen and Hall conductivities top near-equatorial dayside ionosphere, derived from by Cassini Radio Wave Plasma Science Langmuir Probe, Ion Neutral Mass Spectrometer fluxgate magnetometer. The are constrained to at least 10 −5 –10 −4 S/m (or close to) ionospheric peak, a factor 10–100 higher than estimated previously. show that this is due presence dusty...
Abstract We use the Cassini Radio and Plasma Wave Science/Langmuir probe measurements of electron density from first 110 flybys Titan to study how Saturn's magnetosphere influences Titan's ionosphere. The data is corrected for biased sampling due varying solar zenith angle energy flux (solar cycle effects). then present results showing that in ionosphere, altitude range 1600–2400 km, increased by about a factor 2.5 when located on nightside Saturn (Saturn local time (SLT) 21–03 h) compared...
We combine derived ion–electron pair formation rates with Cassini Radio Plasma Wave Science Langmuir Probe measurements of electron and positive ion number densities in Titan's sunlit ionosphere. show that ionosphere can increase toward significantly lower altitudes than the peak despite effective recombination coefficient increases. This is explained by increased mixing ratios negative ions, which are formed attachment to neutrals. While such a process acts as sink for free electrons, ions...
Abstract We present statistical results from the Cassini Radio and Plasma Wave Science (RPWS) Langmuir probe measurements recorded during time interval orbit 3 (1 February 2005) to 237 (29 June 2016). A new improved data analysis method obtain ion density LP is used study asymmetries modulations found in inner plasma disk of Saturn, between 2.5 12 Saturn radii R S =60,268 km). The structure Saturn's mapped, peak, n max , shown be located at ∼4.6 not main neutral source region 3.95 . shift...
Some of the major discoveries recent Cassini-Huygens mission have put Titan and Enceladus firmly on Solar System map. The has revolutionised our view satellites, arguably matching their scientific importance with that host planet. While made big surprises in revealing Titan's organically rich environment Enceladus' cryovolcanism, mission's success naturally leads us to further probe these findings. We advocate acknowledgement science as highly relevant ESA's long-term roadmap, logical...
Current models of Titan ionosphere have difficulties in explaining the observed electron density and/or temperature. In order to get new insights, we re-analyzed data taken by Cassini Langmuir probe (LP), part Radio and Plasma Wave Science (RPWS) instrument. This is first two papers that present analysis method (current paper) statistics on whole dataset. We suggest between 2 4 populations are necessary fit data. Each population defined a potential, an temperature easily visualized dinstinct...
Abstract The ionosphere of Titan hosts a complex ion chemistry leading to the formation organic dust below 1,200 km. Current models cannot fully explain observed electron temperature in this dusty environment. To achieve new insight, we have re‐analyzed data taken by Cassini Langmuir probe (LP), part Radio and Plasma Wave Science package. A first paper (Chatain et al., 2021) introduces analysis method discusses identification four populations produced different ionization mechanisms. In...
Observations with Cassini's Electron Spectrometer discovered negative ions in Titan's ionosphere, at altitudes between 1400 and 950 km. Within the broad mass distribution extending up to several thousand amu, two distinct peaks were identified 25.8-26.0 49.0-50.1 amu/q, corresponding carbon chain anions $CN^-$ and/or $C_2H^-$ for first peak $C_3N^-$ $C_4H^-$ second peak. In this study we present spatial of these low from 28 Titan flybys favourable observations 26 October 2004 22 May 2012. We...
A surprising and unexpected phenomenon observed during Cassini's Grand Finale was the spacecraft charging to positive potentials in Saturn's ionosphere. Here, ionospheric plasma depleted of free electrons with negatively charged ions dust accumulating up over 95 % negative charge density. To further understand spacecraft-plasma interaction, we perform a three dimensional Particle-In-Cell study model Cassini immersed representative The simulations reveal complex interaction features such as...
Previous modeling studies of Titan's dayside ionosphere predict electron number densities that are roughly a factor 2 higher than those observed by the RPWS/Langmuir probe. The issue can equivalently be described as ratio between calculated production rates and square resulting in 4 effective recombination coefficient expected from ion composition temperature. Here we make an extended reassessment ionization balance, focusing on 34 flybys TA T120. Using recalibrated data set taking presence...
Abstract Between April and September 2017 in the final stages of Cassini Saturn Orbiter mission spacecraft executed 22 orbits passing planetward innermost ring, D‐ring. During all periapsis passes oscillations were detected azimuthal magnetic field components on typical time scales a few minutes. We argue that these time‐varying signals are also primarily plasma frame. Furthermore, we show nearly exhibit spatial feature, namely node near effective line equator. propose associated with Alfvén...
We study the effect of negatively charged dust on magnetic-field-aligned polarisation electrostatic field ( $\boldsymbol {E}_{\parallel }$ ) using Cassini's RPWS/LP in situ measurements during ‘ring-grazing’ orbits. derive a general expression for and estimate first time $\lVert \boldsymbol } \rVert$ (approximately $10^{-5} \, \text {V}\, {m}^{-1}$ near Janus Epimetheus rings. further demonstrate that presence close to ring plane $\vert {Z} \vert \lesssim 0.11 {R}_{s}$ amplifies by at least...
A significant difference in Titan's ionospheric electron density is observed between the T118 and T119 Cassini nightside flybys. These flybys had similar geometry, occurred at same Saturn local time while Titan was exposed to EUV ambient magnetic field conditions. Despite these similarities, RPWS/LP measured differed a factor of 5 passes. This present, similar, both inbound outbound. Two distinct peaks were present during T118, 1150 km 1200 km, suggesting very localised plasma production....
Abstract The Cassini spacecraft made in‐situ measurements of Titan's plasma environment during 126 close encounters between 2004 and 2017. Here we report on observations from the Radio Plasma Waves System/Langmuir probe instrument (RPWS/LP) which have observed, primarily outbound leg, a localized increase electron density by up to 150 cm −3 with respect background. This feature, appearing as an spike in data, is found 28 flybys. data RPWS/LP, spectrometer Spectrometer package , magnetometer...
The Cassini spacecraft's Grand Finale flybys through Saturn's ionosphere provided unprecedented insight into the composition and dynamics of gas giant's upper atmosphere a novel complex spacecraft-plasma interaction. In this article, we further study Cassini's interaction with using three dimensional Particle-in-Cell simulations. We focus on understanding how electrons ions, emitted from spacecraft surfaces due to high-velocity impact atmospheric water molecules, could have affected...
ABSTRACT Observations with spacecraft-mounted instruments are usually limited by their field-of-view and often affected the spacecraft's shadow or wake. Their extent though can be derived from geometry. In this work we present a robust method for calculating as well of spacecraft wake readily available CAD models. We demonstrate these principles on Cassini, where give examples vector-spacecraft intersection Cassini Langmuir Probe, Probe Plasma Spectrometer.
Some of the major discoveries recent Cassini-Huygens mission have put Titan and Enceladus firmly on Solar System map. The has revolutionised our view satellites, arguably matching their scientific importance with that planet. While made big surprises in revealing Titan's organically rich environment Enceladus' cryovolcanism, mission's success naturally leads us to further probe these findings. We advocate acknowledgement science as highly relevant ESA's long-term roadmap, logical follow-on...