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BC/MPO/SERENA Scientific Objectives Anna Milillo and the SERENA team. Hermean environment. ( from Milillo et al., SSR, 2005 ). Instrument package on board BepiColombo/MPO. SERENA NPA-IS S earch for E xospheric R efilling and E mitted N atural A bundances
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BC/MPO/SERENA Scientific ObjectivesAnna Mililloand the SERENA team
Hermean environment (from Milillo et al., SSR, 2005) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Instrument package on board BepiColombo/MPO SERENA NPA-IS Searchfor Exospheric Refilling and Emitted Natural Abundances Neutral Particle Analysers - Ion Spectrometers Units: ELENA: Emitted Low-Energy Neutral Atoms STROFIO: Start from a ROtating FIeld spectrOmeter MIPA: Miniature Ion Precipitation Analyser PICAM: Planetary IonCAMera SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Main scientific objectives of each unit NPA: • ELENA investigates the Hermean escaping neutral gas (strongly linked to its surface), and the processes responsible of such a population. • STROFIO investigates the exospheric gas composition. IS: • MIPA investigates the plasma precipitation toward the surface of Mercury. • PICAMinvestigates the exo-ionosphere extension and composition. SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
SERENA vs Hermean environment SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
TargetsExosphere composition and spatial distribution and dynamicsSearch for exo-ionosphere and its relation with neutral atmosphereSurface release processesAtmosphere/magnetosphere exchange and transport processesEscape, source/sink balance, geochemical cycles SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
SERENA scientific objectives • Chemical and elemental composition of the exosphere • Exo-ionosphere composition and distribution • Surface emission rate and release processes • Plasma precipitation rate • Particle loss rate from Mercury’s environment • Gas density anisotropies • Remote sensing of the surface composition • Magnetosphere structure and dynamics • Planetary response to SW variations • ENA imaging (comparative solar-planetary relationship) • Heavy ion sputtering products SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Sc. Obj:1 Exosphere composition The estimate of the exospheric densities is derived from observations and models. The scale height for each species is derived by assuming a temperature T=500 K for volatiles and T=5000 K for refractory (Leblanc et al., 2004) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Sc. Obj:1 Expected range of the ion/neutral densities in Mercury's close-to-planet environment SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Sc. Obj:6 Neutral density asymmetries The measurements of the spatial distributions of the neutrals as well as ions are a possible way to understand the ejection processes that lead to these distributions and to have information about the history of the particles during their trajectories. Moreover, asymmetries induced by strong thermal variations, between different latitudes, day/night, dawn/dusk sides and perihelion/aphelion are expected in the Hermean exospheric density. STROFIO will observe these asymmetries. SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Sc. Obj:1 Sodium observations (Potter et al., 2002) variability tail (Potter et al., 1999) Dawn-dusk asymmetries (Schleicher et al. A&A, 2004) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Summary of scientific requirements (1) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Summary of instrument performances (1) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Sc. Obj:2 Exo-ionosphere composition Ions of planetary origin have been observed by MESSENGER in the magnetospheric tail. They are likely generated in the dayside hemisphere due to photoionisation and ion-sputtering processes. SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Sc. Obj:2 Expected range of the ion/neutral densities in Mercury's close-to-planet environment SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Sc. Obj:2 Exo-ionosphere distribution Na+ distribution model by Leblanc foresees strong asimmetries (Leblanc et al., 2004) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Summary of scientific requirements (2) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Summary of instrument performances (2) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Sc. Obj: 3 Surface release processes Different release processes can have different efficiencies as a function of latitude and longitude/LT at Mercury due to surface compositions and mineralogy togheter with external conditions, as solar irradiance or plasma precipitation. Among the release processes the ion-sputtering is particularly intriguing since the involved energies induce escape from the planet, with possible implication on its evolution. SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Sc. Obj: 3 Particle release processes PSD TD IS MIV (Environment Simulation Tool (EST) at IFSI) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Sc. Obj: 3 H escape O escape Ca escape Fe escape STROFIO ELENA Energy distribution of sputtered particles byWurz et al, SERENA Meeting in Pejo, 2006 Fe Ca O H SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Whywerequire detection ofneutrals at energies >10 eV (EST@IFSI) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Sc. Obj: 3 Ion-sputtering process ELENA will map the location of the sputtering process on the surface and will image of the surface loss rate Surface sputtered signal obtainable by ELENA when MPO pericentre is in the day side (Mura et al, PSS, 2005) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Sc. Obj: 3 Impulsive event (meteoroid 0.1 m) Frequency ~ 2 events/day (Marchi et al, A&A, 2005) Duration ~ 10-30 min Amplitude ~ 2000 km (Mangano et al., PSS, 2007) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Intensifications, durations and spatial dimensions of a 10 cm MIV exosphere SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Probabilitytodetect 10 cm MIV exosphere SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Summary of scientific requirements (3) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Summary of instrument performances (3) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Sc. Obj: 4 SW precipitation (Massetti et al., 2003) The SW ions (at energy about 1 keV) entering in the magnetosphere partially reach the planet surface causing ion sputtering, hence producing neutral atoms and ions. MIPA will monitor the SW precipitation. SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Sc. Obj: 4 Planetary ions precipitating from the magnetosphere • Planetary heavy ions precipitate toward the planet in the day side high latitudes and in the night side mid/low latitudes The precipitating planetary heavy ion fluxes are expected to be lower than the precipitating solar wind fluxes. Thus, they will be observed by MIPA and PICAM in the night side where the solar wind contribution is expected to be negligible. (Seki et al., 2006) (Delcourt et al., 2003) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Sc. Obj: 4 Loss cone angle The particle precipitates when V///Vn is high (i.e. the pitch angle is lower than the loss cone angle) (Nilsson et al. 1997) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Summary of scientific requirements (4) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Summary of instrument performances (4) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Sc. Obj: 5 Loss rate from Hermean environment The high-energy neutral products of the release processes as well as the charge-exchange ENA, are mainly created close to the surface and carried outward of the planetary environment due to their high velocity that exceeds the escape velocity (vesc= 4 km/s). Directional neutral measurements by ELENA will contribute in evaluating the mass loss from the Hermean environment. (Mura et al., 2006) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Sc. Obj: 5 Loss rate from Hermean environment The ions produced at thermal energies are energised and become part of the magnetospheric ion populations. Part of the magnetospheric plasma is eventually lost to the SW. PICAM high energy resolution will allow such an investigation. (Delcourt et al., 2003) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Summary of scientific requirements (5) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Summary of instrument performances (5) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Summary of ELENA scientific performances SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Summary of STROFIO scientific performances SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Summary of MIPA scientific performances SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Summary of PICAM scientific performances SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
SERENA new webpage: Home http://www.ifsi-roma.inaf.it/enagroup/serena/index.php?categoryid=1 SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
SERENA new web site: Science SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
SERENA new web site: Team SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
SERENA new web site: Resources SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
SERENA Science team and thematic WGs The SERENA science team is involved in the Hermean Environment WG. It has recently coordinated and participated to the paper on HE for the PSS special issue. It has participated also to the Surface and Composition paper in the same special issue SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Thankyou SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
BepiColombo key questionsWhich are the composition, the origin and the dynamics of Mercury’s exosphere and polar deposits?Which are the structure and the dynamics of Mercury’s magnetosphere ? SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Sc. Obj:1 Sodium and Potassium observations (Killen et al. SSR, 2007) SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008
Sc. Obj:1 Oxygen The small amount of observed atmospheric oxygen relative (<4. 104 cm-3) relative to the surface stoichiometry (≈50%) may indicate that atmospheric oxygen is bound in molecules, or it may indicate inefficient release (Morgan and Killen, 1997), or it may efficiently charge exchange with solar wind and magnetospheric protons. SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008