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Future remote sensing of exoplanets will be enhanced by a thorough investigation of our solar system Ice Giants (Neptune-size planets). What can the configuration of the magnetic field tell us (remotely) about the interior, and what implications does that field have for the structure of the magnetosphere; energy input into the atmosphere, and surface geophysics (for example surface weathering of satellites that might harbour sub-surface oceans). How can monitoring of auroral emission help inform future remote observations of emission from exoplanets? Our Solar System provides the only laboratory in which we can perform in-situ experiments to understand exoplanet formation, dynamos, systems and magnetospheres.

As Rosetta was orbiting comet 67P/Churyumov‐Gerasimenko, the Ion and Electron Sensor detected negative particles with angular distributions like those of the concurrently measured solar wind protons but with fluxes of only about 10% of the proton fluxes and energies of about 90% of the proton energies. Using well‐known cross sections and energy‐loss data, it is determined that the fluxes and energies of the negative particles are consistent with the production of H− ions in the solar wind by double charge exchange with molecules in the coma., Key Points Double charge exchange of protons produces negative H ions in the solar windThe measurements agree with published laboratory cross sections and energy deficitsThe cross sections and energy deficits are estimated for the first time in the space environment

International audience; As well as this effort using in situ data, MAVEN can also constrain photochemical escape using remote sensing of the oxygen corona with the Imaging Ultraviolet Spectrograph (IUVS) [12, 13], the Solar Energetic Particle (SEP) instrument and the Solar Wind Ion Analyzer [14]. These multiple methods will eventually allow validation of photochemical escape from Mars and its dependence on solar and planetary conditions, enabling confident extrapolation back into the past

Observations of the coma near the nucleus of comet 67P/Churyumov-Gerasimenko (67P) made by the IES (Ion and Electron Sensor) instrument onboard the Rosetta Orbiter during late 2014 showed that electron fluxes greatly exceeded solar wind electron fluxes. The IES is part of the Rosetta Plasma Consortium. This paper reports on electron energy spectra measured by IES near the nucleus as well as approximate densities and average energies for the suprathermal electrons when the comet was at a heliocentric distance of about 3 AU. Comparisons are made with electron densities measured by other instruments. The high electron densities observed (e.g., ne ≈ 10–100 cm−3) must be associated with the cometary ion density enhancement created mainly by the photoionization of cometary gas by solar radiation; there are other processes that also contribute. Quasineutrality requires that the electron and ion densities be the same, and under certain conditions an ambipolar electric field is required to achieve quasi-neutrality. We present the results of a test particle model of cometary ion pickup by the solar wind and a two-stream electron transport code and use these results to interpret the IES data. We also estimate the effects on the electron spectrum of a compression of the electron fluid parcel. The electrons detected by IES can have energies as high as about 100–200 eV near the comet on some occasions, in which case the hot electrons can significantly enhance ionization rates of neutrals via impact ionization.

onization of neutrals by precipitating electrons and ions is the main source of Titan's nightside ionosphere. This paper has two goals: (1) characterization of the role of electron impact ionization on the nightside ionosphere for different magnetospheric conditions and (2) presentation of empirical ion production rates determined using densities measured by the Cassini Ion and Neutral Mass Spectrometer on the nightside. The ionosphere between 1000 and 1400 km is emphasized. We adopt electron fluxes measured by the Cassini Plasma Spectrometer-Electron Spectrometer and the Magnetospheric Imaging Instrument as classified by Rymer et al. (2009). The current paper follows an earlier paper (Paper I), in which we investigated sources of Titan's dayside ionosphere and demonstrated that the photoionization process is well understood. The current paper (Paper II) demonstrates that modeled and empirical ionization rates on the nightside are in agreement with an electron precipitation source above 1100 km. Ion production rate profiles appropriate for different Saturnian magnetospheric conditions, as outlined by Rymer et al., are constructed for various magnetic field topologies. Empirical production rate profiles are generated for deep nightside flybys of Titan. The results also suggest that at lower altitudes (below 1100 km) another source, such as ion precipitation, is probably needed. Fil: Richard, M. S.. University of Kansas; Estados Unidos. Benedictine College; Estados Unidos Fil: Cravens, T. E.. University of Kansas; Estados Unidos Fil: Wylie, C.. University of Kansas; Estados Unidos Fil: Webb, D.. University of Kansas; Estados Unidos Fil: Chediak, Q.. University of Kansas; Estados Unidos Fil: Mandt, K.. Southwest Research Institute; Estados Unidos Fil: Waite Jr, J. H.. Southwest Research Institute; Estados Unidos Fil: Rymer, A.. University Johns Hopkins; Estados Unidos Fil: Bertucci, Cesar. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: Wellbrock, A.. University College London; Reino Unido Fil: Windsor, A.. Benedictine College. Department of Physics and Astronomy; Estados Unidos Fil: Coates, A. J.. University College London; Reino Unido

We present Cassini Langmuir probe measurements of the highest electron number densities ever reported from the ionosphere of Titan. The measured density reached 4310 cm−3 during the T85 Titan flyby. This is at least 500 cm−3 higher than ever observed before and at least 50% above the average density for similar solar zenith angles. The peak of the ionospheric density is not reached on this flyby, making the maximum measured density a lower limit. During this flyby, we also report that an impacting coronal mass ejection (CME) leaves Titan in the magnetosheath of Saturn, where it is exposed to shocked solar wind plasma for at least 2 h 45 min. We suggest that the solar wind plasma in the magnetosheath during the CME conditions significantly modifies Titan's ionosphere by an addition of particle impact ionization by precipitating protons. Fil: Edberg, N. J. T.. Swedish Institute of Space Physics; Suecia Fil: Andrews, D. J.. Swedish Institute of Space Physics; Suecia Fil: Shebanits, O.. Swedish Institute of Space Physics; Suecia Fil: Agren, K.. Swedish Institute of Space Physics; Suecia Fil: Wahlund, J. E.. Swedish Institute of Space Physics; Suecia Fil: Opgenoorth, H. J.. Swedish Institute of Space Physics; Suecia Fil: Roussos, E.. Max Planck Institute for Solar System Research; Alemania Fil: Garnier, P.. University of Toulouse; Francia Fil: Cravens, T. E.. University of Kansas; Estados Unidos Fil: Badman, S. V.. University of Leicester; Reino Unido Fil: Modolo, R.. UVSQ/LATMOS-IPSL/CNRS-INSU; Francia Fil: Bertucci, Cesar. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: Dougherty, M. K.. Imperial College London; Reino Unido

International audience; The Diffuse X-rays from the Local Galaxy (DXL) mission is a sounding rocket mission for the study of Solar Wind Charge eXchange (SWCX) and Local Hot Bubble (LHB) X-ray emission. The mission was successfully launched from White Sands Missile Range, NM on December 12, 2012. It carried two large area proportional counters with thin carbon windows with roughly 1,000 cm2 area both in the ¼ and ¾ keV band. The mission successfully detected the spatial variation of the SWCX due to the He focusing cone. In this paper we will review the mission design and performance and present preliminary results from the December launch.

International audience; The Solar Wind Charge Exchange (SWCX) is one of the major contributors to the X-ray emission in the [0.3-0.9] keV band and possibly the strongest local component. SWCX is characterized by emission lines, however its intensity shows both temporal and spatial variations as it depends on the solar activity and on the relative positioning between the observer, the Sun, and the line of sight. SWCX is due to the interaction of the solar wind with neutrals and it is the superposition of two components, magnetosheat and heliospheric. The first one is varying on a very short time scale of hours to days, due to the interaction of solar wind with neutrals in our atmosphere, and can have very strong emission bursts. The second one is on average the dominant component. It varies more smoothly on a time scale of several days to months, due to the diffusion time of the wind through the solar system. An annual modulation due to distributions of interstellar neutrals (H and He) passing through the solar system is also present. The heliospheric emission is the focus of a Suzaku key project. Nearby 100 pc) high column density clouds absorb the X-ray contribution from distant sources and the leftover signal has local origin (and is expected to be dominated by SWCX). The project consists of a three year monitoring campaign of four high density clouds. Besides the high density the targets have been selected for their position in the sky, in order to maximize the latitude and longitude range and to model how SWCX depends on the distribution of neutrals. Three of the targets will be therefore observed once a year in order to characterize how SWCX depends on the solar wind (long term dependence). The fourth target will be observed twice a year, this allows to study also the annual modulation of SWCX. The targets shows a significant variation between the two Suzaku’s observing windows because the pointing partially goes through the He focusing cone in one window, but is far from it in the other. Here we present the preliminary results on the data taken during the first year of the project.

International audience; We describe current progress in the development of a prototype wide field-of-view soft X-ray imager that employs Lobster-eye optics and targets heliophysics, planetary, and astrophysics science. The prototype will provide proof-of-concept for a future flight instrument capable of imaging the entire dayside magnetosheath from outside the magnetosphere. Such an instrument was proposed for the ESA AXIOM mission

International audience; The Diffuse X-ray emission from the Local Galaxy (DXL) sounding rocket is a NASA approved mission with a scheduled first launch in December 2012. Its goal is to identify and separate the X-ray emission of the solar wind charge exchange (SWCX) from that of the local hot bubble (LHB) to improve our understanding of both. To separate the SWCX contribution from the LHB, DXL will use the SWCX signature due to the helium focusing cone at l = 185°, b = -18°. DXL uses large area proportional counters, with an area of 1000 cm2 and grasp of about 10 cm2 sr both in the 1/4 and 3/4 keV bands. Thanks to the large grasp, DXL will achieve in a 5-minute flight what cannot be achieved by current and future X-ray satellites

Plasma in Titan´s ionosphere flows in response to forcing from thermal pressure gradients, magnetic forces, gravity, and ion-neutral collisions. This paper takes an empirical approach to the ionospheric dynamics by using data from Cassini instruments to estimate pressures, flow speeds, and time constants on the dayside and nightside. The plasma flow speed relative to the neutral gas speed is approximately 1 m s‑1 near an altitude of 1000 km and 200 m s‑1 at 1500 km. For comparison, the thermospheric neutral wind speed is about 100 m s‑1. The ionospheric plasma is strongly coupled to the neutrals below an altitude of about 1300 km. Transport, vertical or horizontal, becomes more important than chemistry in controlling ionospheric densities above about 1200-1500 km, depending on the ion species. Empirical estimates are used to demonstrate that the structure of the ionospheric magnetic field is determined by plasma transport (including neutral wind effects) for altitudes above about 1000 km and by magnetic diffusion at lower altitudes. The paper suggests that a velocity shear layer near 1300 km could exist at some locations and could affect the structure of the magnetic field. Both Hall and polarization electric field terms in the magnetic induction equation are shown to be locally important in controlling the structure of Titan´s ionospheric magnetic field. Comparisons are made between the ionospheric dynamics at Titan and at Venus. Fil: Cravens, T. E.. University of Kansas; Estados Unidos Fil: Richard, M.. University of Kansas; Estados Unidos Fil: Ma, Y. J.. University of California; Estados Unidos Fil: Bertucci, Cesar. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: Luhmann, J. G.. University of California; Estados Unidos Fil: Ledvina, S.. University of California; Estados Unidos Fil: Robertson, I. P.. University of Kansas; Estados Unidos Fil: Wahlund, J. E.. Swedish Institute of Space Physics; Suecia Fil: Ågren, K.. Swedish Institute of Space Physics; Suecia Fil: Cui, J.. Imperial College London; Reino Unido Fil: Muller Wodarg, I.. Imperial College London; Reino Unido Fil: Waite, J. H.. Southwest Research Institute; Estados Unidos Fil: Dougherty, M.. Imperial College London; Reino Unido Fil: Bell, J.. Southwest Research Institute; Estados Unidos Fil: Ulusen, D.. University of California; Estados Unidos

When the Cassini spacecraft flew by Titan on 13 June 2007, at 13.6 Saturn local time, Titan was directly observed to be outside Saturn′s magnetopause. Cassini observations showed dramatic changes of magnetic field orientation as well as other plasma flow parameters during the inbound and outbound segments. In this paper, we study Titan's ionospheric responses to such a sudden change in the upstream plasma conditions using a sophisticated multispecies global MHD model. Simulation results of three different cases (steady state, simple current sheet crossing, and magnetopause crossing) are presented and compared against Cassini Magnetometer, Langmuir Probe, and Cassini Plasma Spectrometer observations. The simulation results provide clear evidence for the existence of a fossil field that was induced in the ionosphere. The main interaction features, as observed by the Cassini spacecraft, are well reproduced by the time-dependent simulation cases. Simulation also reveals how the fossil field was trapped during the interaction and shows the coexistence of two pileup regions with opposite magnetic orientation, as well as the formation of a pair of new Alfven wings and tail disconnection during the magnetopause crossing process. Fil: Ma, Y. J.. University of California; Estados Unidos Fil: Russell, C. T.. University of California; Estados Unidos Fil: Nagy, A. F.. University of Michigan; Estados Unidos Fil: Toth, G.. University of Michigan; Estados Unidos Fil: Bertucci, Cesar. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina Fil: Dougherty, M. K.. Imperial College London; Reino Unido Fil: Neubauer, F. M.. University of Cologne; Alemania Fil: Wellbrock, A.. University College London; Estados Unidos Fil: Coates, A. J.. University College London; Estados Unidos Fil: Garnier, P.. Swedish Institute of Space Physics; Suecia Fil: Wahlund, J. E.. Swedish Institute of Space Physics; Suecia Fil: Cravens, T. E.. University of Kansas; Estados Unidos Fil: Crary, F. J.. Southwest Research Institute; Estados Unidos

International audience; We present our analysis of the diurnal variations of Titan's ionosphere (between 1000 and 1300 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from eight close encounters of the Cassini spacecraft with Titan. Although there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ~700 cm−3 below ~1300 km. Such a plateau is a combined result of significant depletion of light ions and modest depletion of heavy ones on Titan's nightside. We propose that the distinctions between the diurnal variations of light and heavy ions are associated with their different chemical loss pathways, with the former primarily through “fast” ion-neutral chemistry and the latter through “slow” electron dissociative recombination. The strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes suggests a scenario in which the ions created on Titan's dayside may survive well to the nightside. The observed asymmetry between the dawn and dusk ion density profiles also supports such an interpretation. We construct a time-dependent ion chemistry model to investigate the effect of ion survival associated with solid body rotation alone as well as superrotating horizontal winds. For long-lived ions, the predicted diurnal variations have similar general characteristics to those observed. However, for short-lived ions, the model densities on the nightside are significantly lower than the observed values. This implies that electron precipitation from Saturn's magnetosphere may be an additional and important contributor to the densities of the short-lived ions observed on Titan's nightside.

TandEM was proposed as an L-class (large) mission in response to ESA's Cosmic Vision 2015-2025 Call, and accepted for further studies, with the goal of exploring Titan and Enceladus. The mission concept is to perform in situ investigations of two worlds tied together by location and properties, whose remarkable natures have been partly revealed by the ongoing Cassini-Huygens mission. These bodies still hold mysteries requiring a complete exploration using a variety of vehicles and instruments. TandEM is an ambitious mission because its targets are two of the most exciting and challenging bodies in the Solar System. It is designed to build on but exceed the scientific and technological accomplishments of the Cassini-Huygens mission, exploring Titan and Enceladus in ways that are not currently possible (full close-up and in situ coverage over long periods of time). In the current mission architecture, TandEM proposes to deliver two medium-sized spacecraft to the Saturnian system. One spacecraft would be an orbiter with a large host of instruments which would perform several Enceladus flybys and deliver penetrators to its surface before going into a dedicated orbit around Titan alone, while the other spacecraft would carry the Titan in situ investigation components, i.e. a hot-air balloon (Montgolfière) and possibly several landing probes to be delivered through the atmosphere. © Springer Science + Business Media B.V. 2008.

Solar extreme ultraviolet and x-ray radiation and energetic plasma from Saturn's magnetosphere interact with the upper atmosphere producing an ionosphere at Titan. The highly coupled ionosphere and upper atmosphere system mediates the interaction between Titan and the external environment. New insights into Titan's ionosphere are being facilitated by data from several instruments onboard the Cassini Orbiter, although the Ion and Neutral Mass Spectrometer (INMS) measurements will be emphasized in this talk. Measurements and comparisons with a model will be discussed for both the day and night on Titan. Electron impact ionization associated with precipitation of magnetospheric electrons (measured by the electron sensor on the CAPS spectrometer) seems the likely explanation for the nightside ionosphere but photoionization by solar radiation is the dominant source on the dayside. In this talk we will emphasize possible explanations for the temporal and/or spatial structure observed by the INMS and RPWS/LP (Radio and Plasma Wave – Langmuir probe) experiments during the T5 nightside pass, suggesting that temporal changes in the incident magnetospheric electron flux might be responsible for much of this structure.

The neutral nitrogen and methane measurements made by Ion and Neutral Mass Spectrometer during Cassini flybys TA , TB , and T5 in Titan's upper atmosphere and exosphere are presented. Large horizontal variations are observed in the total density, recorded to be twice as large during T A as during T 5. Comparison between the atmospheric and exospheric data show evidence for the presence of a significant population of suprathermal molecules. Using a diffusion model to simultaneously fit the N2 and CH4 density profiles below 1500 km, the atmospheric structure parameters are determined, taking into account recent changes in the calibration parameters. The best fits are obtained for isothermal profiles with values 152.8 ± 4.6 K for T A , 149.0 ± 9.2 K for T B , and 157.4 ± 4.9 K for T 5, suggesting a temperature ≃5 K warmer at night than at dusk, a trend opposite to that determined by solar-driven models. Using standard exospheric theory and a Maxwellian exobase distribution, a temperature of 20 to 70 K higher would be necessary to fit the T A , T B , and egress-T 5 data above 1500 km. The suprathermal component of the corona was fit with various exobase energy distributions, using a method based on the Liouville theorem. This gave a density of suprathermals at the exobase of 4.4 ± 5.1 × 105 cm−3 and 1.1 ± 0.9 × 105 cm−3, and an energy deposition rate at the exobase of 1.1 ± 0.9 × 102 eV cm−3 s−1 and 3.9 ± 3.5 × 101 eV cm−3 s−1 for the hot N2 and CH4 populations, respectively. The energy deposition rate allowed us to roughly estimate escape rates for nitrogen of ≃7.7 ± 7.1 × 107 N cm−2 s−1 and for methane of ≃2.8 ± 2.1 × 107 CH4 cm−2 s−1. Interestingly, no suprathermal component was observed in the ingress-T 5 data.

We present results of the cold plasma environment around Titan obtained during several Titan flybys primarily from the Cassini Radio and Plasma Waves Science (RPWS) Langmuir probe (LP) sensor. It shows that the magnetosphere of Saturn interacts strongly with this moon's ionosphere and exo-ionosphere. The altitude structure of the deep ionosphere during nightside conditions was found to be reproducible by a simple electron impact ionisation model. The dense and cold exo-ionosphere (from the exobase at 1430 km outward to several Titan radii from the surface), although partly affected by exospheric ionisation of impacting low energy electrons (30-50 eV), is dominated by induced magnetospheric forcing. The magnetospheric flow also seems to force a complicated dynamic situation below the exobase. The exo-ionosphere acts as a heavy mass- loading region for the magnetospheric flow resulting in draping of the magnetic field within Titan's induced magnetosphere. We illustrate the importance of UV ionisation on the sunlit side of Titan for the exo- ionospheric escape from this moon.

We present the results of two XMM-Newton observations of Jupiter carried out in 2003 for 100 and 250 ks (or 3 and 7 planet rotations) respectively. X-ray images from the EPIC CCD cameras show prominent emission from the auroral regions in the 0.2 - 2.0 keV band: the spectra are well modelled by a combination of emission lines, including most prominently those of highly ionised oxygen (OVII and OVIII). In addition, and for the first time, XMM-Newton reveals the presence in both aurorae of a higher energy component (3 - 7 keV) which is well described by an electron bremsstrahlung spectrum. This component is found to be variable in flux and spectral shape during the Nov. 2003 observation, which corresponded to an extended period of intense solar activity. Emission from the equatorial regions of Jupiter's disk is also observed, with a spectrum consistent with that of solar X-rays scattered in the planet's upper atmosphere. Jupiter's X-rays are spectrally resolved with the RGS which clearly separates the prominent OVII contribution of the aurorae from the OVIII, FeXVII and MgXI lines, originating in the low-latitude disk regions of the planet., 6 pages, 11 figures, Proceedings of the Symposium 'The X-ray Universe 2005', San Lorenzo de El Escorial, Spain, 26-30 September 2005. In press

International audience

As Rosetta was orbiting comet 67P/Churyumov-Gerasimenko, the Ion and Electron Sensor detected negative particles with angular distributions like those of the concurrently measured solar wind protons but with fluxes of only about 10% of the proton fluxes and energies of about 90% of the proton energies. Using well-known cross sections and energy-loss data, it is determined that the fluxes and energies of the negative particles are consistent with the production of H- ions in the solar wind by double charge exchange with molecules in the coma.