A. Milillo, (INAF/Institute of Space Astrophysics and Planetology)

Transcription

1 A. Milillo, (INAF/Institute of Space Astrophysics and Planetology)

2 Hermean environment (from Milillo et al., SSR, 2005)

3 INTERPLANETARY SPACE Solar wind MAGNETOSPHERE Magnetospheric Ions Electromagetic fields EXOSPHERE Neutral gas Energetic Neutrals Planetary Surface

4 INTERPLANETARY SPACE MMO/MPPE Solar wind MPO/SIXS MPO/BERM MMO/MDM MMO/MPPE Magnetospheric MPO/SERENA Ions MAGNETOSPHERE MMO/PWI MPO/MAG Electromagetic MMO/MGF fields EXOSPHERE MMO/MSASI MPO/PHEBUS MPO/SERENA Neutral gas Energetic MPO/SERENA Neutrals MMO/MPPE MPO/MIXS MPO/MERTIS Planetary Surface MPO/SimbioSys

5 BepiColombo configura5on vs Mercury season

6 BepiColombo configura5on vs Mercury season LB EB C A ED LD

7 BepiColombo configura5on vs Mercury season

8 Focus: Winter and Summer MPO dayside Aphelion MTA = 180 Gas density latitudinal asymmetries Na day-night asymmetries Exosphere time variation in relation to solar and IMF conditions Planetary ions latitudinal distributions and time variation in relation to solar and IMF conditions Plasma precipitation in relation with solar and IMF conditions Solar wind back scattering in relation with solar and IMF conditions Reconnection processes Induction processes..

9 SW inside the Mercury s Magnetosphere Example: IMF ( 20, 0, 5) nt at aphelion precipitating (PA < 90) mirrored (PA > 90 ) PA distribution mid-latitudes PA distribution high-latitudes

10 Flux transfer events Near the dayside, MESSENGER magnetopause crossings observed 58 FTEs with extremely strong core fields on 90 orbits and many smaller FTEs. The FTEs alone contain at least 30% of the magnetic flux needed to drive a loading-unloading event at Mercury (2% at Earth). Whereas at Earth steady-state dayside reconnection is prevalent, multiple X-line dayside reconnection and associated FTEs at Mercury are a dominant forcing for magnetospheric dynamics (Imber et al. 2014)

11 MESSENGER cusps observa5ons In the cusps, H+ is mostly directed downward; 10-keV Na+ are observed mostly directed inward, while low-energy Na+ are directed outward (Raines et al, 2014) Cusp kinetics Energy-resolved pitch angle distributions for 77 cusps with most Na+ group Na+%group% H+% Ou\low% ~300eV%% LiXle% flow% toward% surface% Loss%cone% 24&Sep&2013& Flow%into%cusp% ~Isotropic% Jim&M.&Raines& 14&

12 Magne5c field models The southern parts of the magnetospheres produced by the Offset Dipole & Dipole+Quadrupole fields models differ greatly in topology and volume meanwhile their northern parts-are quite similar. (Richer, et al. 2012)

13 Sodium Exosphere and Earth ground based observa5ons Na Earth ground based observations have been done extensively and in a complementary way with MESSENGER in situ measurements. Statistical analysis of the THEMIS observations shows many possible Na distributions (Mangano et al. 2015). Nevertheless, the overall intensity does not change too much. HEWG Workshop, Rovaniemi, January, 2016

14 temporal coverage, observing the exosphere almost daily for over 16 Mercury ye It also provided unprecedented spatial resolution: altitude profiles of exosph emission resolve details down to the km scale (Figure 9). UVVS had the advantag not observing through Earth s atmosphere, but it had limitations, too. It was no imaging spectrometer, and its field of view (FOV) and observation geometries w restricted by the many considerations of spacecraft operations in a challeng environment. It also had a relatively poor spectral resolution compared to the grou based observations (~0.5 nm). Mercury s Na Exosphere from MESSENGER MASCS Two-temperature components: low-latitude dayside are K. Suggests photon-stimulated desorption is the dominant source process Figure 9. Altitude profiles of sodium emission observed above Mercury s subs point by the MESSENGER MASCS UVVS instrument. These were taken o several Mercury years (as indicated by the legend), but all were taken near the sa true anomaly angle, between in this example. Although the sodium exosph varies temporally, this figure highlights the seasonal repeatability of MAS observations. Most observations are year-toyear repeatable. This is despite episodic nature of theorized source processes and Some of the UVVS results are surprising in lightground of the decades of w published on Mercury s exosphere. In particular, ground observations (e.g. Mang observations. et al., 2013, above)based and models show a Na exosphere that is highly variable on time scale of hours. These sudden changes are thought to be in response to chang

15 More focus: Solar wind back scakering in rela5on with solar and IMF condi5ons Scientific Topic Localized surface emissivity induced by backscattering Targ et Instrument s/c location Pointing Energy Energy resolution Major Component s Angular/ spatial coverage Ang. res. Time res. SRN/ELEN ENA A surface x76 15 s Ion MPO fluxes SRN/MIPA Dayside Mainly zenith kev Mainly H + ~90 o x s ΔE/E <30% B average MAG - < 30 s field (σ< 10%) Ion kev MPPE/ Mainly zenith Mainly H + < 1 m fluxes MMO in ΔE/E <30% B field MGF the solar wind - PWI Average (σ< 10%) < 30 s < 30 s Possible only close to perihelion. What are the resource limitations?

16 Dayside coordinated measurements 1 MPPE MGF SERENA MAG Joint measurements of MPPE-MIA and MGF or PWI, on the MMO spacecraft and SERENA- ELENA and MIPA and MAG on the MPO spacecraft, will confirm plasma penetration inside the magnetosphere and surface backscattering of impacting ions.

17 Dayside coordinated measurements 2 MPPE MGF PWI SERENA MAG SIXS The addition of MPPE-MEA, -MSA, MGF and PWI, on the MMO spacecraft and SIXS, SERENA-PICAM on the MPO spacecraft, will allow to cover the whole spectrum with mass discrimination. The electromagnetic fields measurements will permit the ion flow direction determination.

18 Dayside coordinated measurements 3 MSASI PHEBUS SERENA MIXS Together with plasma penetration measurements described above, other dedicated instruments will observe the response of the planet in addition to the ELENA measurements of energetic neutrals for the surface. SERENA-STROFIO and PHEBUS and MSASI will observe the exospheric response of Mercury in terms of column density, composition and profile variations, while MIXS could observe the X-Ray emission of planetary aurorae.

19 Nominal science opera5on and interfaces Are all these measurements simultaneously possible? Are these objectives fulfilled by the nominal modes? Are these objectives fulfilled by nominal science operation planning? Which are the information to be shared among the two SGS and SSOC groups? Which are the best quick looks for a fruitful interaction?

20 SERENA Search for Exospheric Refilling and Emitted Natural Abundances Neutral and Ionized Particle Detectors for Hermean Environment Investigations S. Orsini (PI), S. Livi (CoPI-STROFIO), H. Lichtenegger (CoPI-PICAM), S. Barabash (CoPI- MIPA) A. Milillo (PI Dep., Sci. Coord.), P. Wurz (Sci. Coord.), A. Olivieri (ASI PM), E. Kallio (SGS), and the SERENA TEAM ELENA: Emitted Low Energy Neutral Atoms Neutral particle emission form Mercury s surface STROFIO: Exososphere Mass Spectrometer Exospheric density and composition PICAM: Planetary Ion CAMera Planetary ions composition and distribution! MIPA:Miniature Ion Precipitation Analyzer Solar wind ion precipitation INDUSTRY: OHB-CGS (Milano) & AMDL (Roma)

21 SERENA dayside nominal opera5on plan AA Orbit PL Mode STROFIO all M N ELENA all H N PICAM all L IM_HT_H R MIPA all H 5 CP Orbit PL Mode STROFIO all H N ELENA all H N PICAM 5/6 1/6 H MIPA all H Aphelion MTA = 180 MC_HR_LE MD_NR_H E 5

22 BepiColombo first 5mes (just for the dayside environment) For the first time north and south hemispheres will be closely observed; two spacecraft will measure at different vantage points in the dayside; two spacecraft will measure at different vantage points in dayside and nightside; two spacecraft will measure at different vantage points inside the cusps and in the unperturbed solar wind; a mass spectrometer, ENA detectors, PWI and will be operated at Mercury;

23 BepiColombo first 5mes (just for the dayside environment) For the first time ; a real comprehensive environment-investigation payload will provide the opportunity to measure simultaneously: Sun s radiation, solar wind, IMF, interplanetary dust, magnetosphere, solar wind inside the cusps, planetary ions just photo-ionised and energized from the exosphere, energetic neutrals from the surface, exospheric gas.

24 This is just a small part of the examples we can do for describing our outstanding science. To obtain the wished goals a careful analysis of science operations and coordination is required. We prepared a (distributed) handbook where major sensors performances and operation modes are summarized. we started focusing in some examples that thanks to your inputs are growing in number and definition.

25 Handbook outline Instruments involved in the Hermean Environment investigation MPO SERENA MERMAG PHEBUS MERTIS MIXS SIXS BERM MMO MPPE MGF MSASI PWI MDM Scientific Objectives and Requirements... Scientific performances and available model... Scientific modes... Nominal science operation plan... Summary of scientific requirements for MPO-MMO coordinated observations o Scientific requirements for MPO-MMO coordinated investigations o Scientific requirements for MPO-MMO inter-calibrations...

26 Thank you