BC/MPO/SERENA Scientific Objectives Anna Milillo and the SERENA team

BC/MPO/SERENA BC/MPO/SERENA Scientific ObjectivesScientific Objectives

Anna MililloAnna Mililloand the SERENA teamand the SERENA team

Hermean environmentHermean environment

(from Milillo et al., SSR, 2005)

SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008

Instrument package on board Instrument package on board BepiColombo/MPOBepiColombo/MPO

SERENA SERENA NPA-ISNPA-ISSSearchearch forfor E Exosphericxospheric R Refillingefilling

and and EEmittedmitted N Naturalatural A AbundancesbundancesNNeutral eutral PParticle article AAnalysers - nalysers - IIon on SSpectrometerspectrometers

UnitsUnits::ELENAELENA: Emitted Low-Energy : Emitted Low-Energy

Neutral Atoms Neutral Atoms

STROFIOSTROFIO: Start from a ROtating : Start from a ROtating FIeld spectrOmeterFIeld spectrOmeter

MIPAMIPA: : Miniature Ion Miniature Ion Precipitation Precipitation AnalyserAnalyser

PICAMPICAM: : PlanetaryPlanetary Ion Ion CAMera CAMera


Main scientific Main scientific objectives objectives of each unitof each unitNPANPA::

ELENAELENA investigates the Hermean escaping investigates the Hermean escaping neutral gas (strongly linked to its surface), and the neutral gas (strongly linked to its surface), and the processes responsible of such a population.processes responsible of such a population.

STROFIOSTROFIO investigates the exospheric gas investigates the exospheric gas composition.composition.

ISIS:: MIPAMIPA investigates the plasma precipitation investigates the plasma precipitation

toward the surface of Mercury.toward the surface of Mercury. PICAMPICAM investigates the exo-ionosphere investigates the exo-ionosphere

extension and composition. extension and composition. SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008

SERENA vs Hermean SERENA vs Hermean environmentenvironment


TargetsTargets

Exosphere composition and spatial Exosphere composition and spatial distribution and dynamicsdistribution and dynamicsSearch for exo-ionosphere and its Search for exo-ionosphere and its relation with neutral atmosphererelation with neutral atmosphereSurface release processesSurface release processesAtmosphere/magnetosphere Atmosphere/magnetosphere exchange and transport processesexchange and transport processesEscape, source/sink balance, Escape, source/sink balance, geochemical cyclesgeochemical cycles


SERENA scientific objectivesSERENA scientific objectives

1. Chemical and elemental composition of the exosphere

2. Exo-ionosphere composition and distribution

3. Surface emission rate and release processes

4. Plasma precipitation rate

5. Particle loss rate from Mercury’s environment

6. 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


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)

Sc. Obj:1


Expected range of the ion/neutral densities in Mercury's close-to-planet environment

Sc. Obj:1


Neutral Species

Neutral Zenith Column density

cm–2

Neutral scale Height

km

Neutral density Range (observed) at 400 km

cm–3

Photo-ionization lifetime

s

Range of Ion density at 400 km cm–3

H 3109 1160 (1330) 410–2-200 (20) 5.1106 510–5 - 2.4 He 31011 500 (330) 5 - 2104 (2600) 1.7106 110–4 - 70 Li < 8.4107 190 810–4 - 4 4.1102 210–4 - 4 C 11011 96 310–1 - 1600 2.6104 110–4 - 70 N 51010 83 110–1 - 500 5105 210–6 - 810–2 O < 31011 72 (83) 310–1 – 1600 (160) 5105 410–7 -10 Ne 4.91010 58 210–2 - 80 5.6105 110–7 - 610–2 Na 21011 50 310–2 – 140 (14) 5.8103 110–5 - 7 Mg 3.91010 480 3.5 - 8103 7.2104 210–3 - 440 Al 3109 430 2.510–1 - 500 1.6105 110–5 - 16 Si 1.21010 414 1 - 2000 1.6105 2.510–4 - 72 S < 21013 36 210–1 - 900 8.9103 310–5 - 32 Cl 8.7106 330 110–3 - 1.5 1.6105 2.510–7-410–2 Ar 1.3109 290 310–2 - 140 3105 610–6 - 3 K 1109 30 110–5-110–2 (5 10–4) 4.2103 210–10 - 110–4 Ca 1.1108 290 110–2 – 20 (1) 1.6105 510–6 - 810–2 Fe 7.5108 210 510–2 - 100 2.3104 110–3 - 220 Ni 9.4107 200 510–3 - 10 1.6105 410–5 - 8 Kr 109 140 410–2 - 80 1.6105 110–5 - 1.610–1 Xe 7109 90 110–1 - 220 6.2104 210–5 - 4 H2 61011 600 10 - 10,000 1.7106 310–4 - 120 OH 1010 68 810–3 - 40 3.8105 110–7 - 410–2

Neutral density asymmetries

Sc. Obj:6

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.


Sodium observationsvariability

tail

Sc. Obj:1

Dawn-duskasymmetries

SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008(Schleicher et al. A&A, 2004)

(Potter et al., 1999)

(Potter et al., 2002)

Summary of scientific Summary of scientific requirements (1)requirements (1)


Scientific Topic

Signal Intensity @ 400

km

Energy Energy

resolution

Major Components

Angular/spatial coverage Angular

resolution

Time resolution

Observable region

Useful associated

observations

1. Chemical and elemental composition of the exosphere

105 cm–3 min req. 101 cm–3

< 1 eV Not req

H, He, O, Na, K,

Ca, H2, OH, Mg, Si, others

…

- Not req

Not req. Whole planet

6a. Neutral gas density asymmetries Latitude

105 cm–3 min req. 101 cm–3

< 1 eV Not req.

H, He, O, Na, K,


…

- Not req. T<15 m

Whole planet

6b, c. Neutral gas density asymmetries Day/night Dawn/dusk

105 cm–3 min req. 101 cm–3

< 1 eV Not req.

H, He, O, Na, K,


…

- Not req. T>orbit

Whole planet

6d, e. Neutral gas density asymmetries Altitude LT

105 cm–3 min req. 101 cm–3

< 1 eV Not req.

H, He, O, Na, K,


…

- Not req.


Altitude density profiles

variations

Summary of instrument performances Summary of instrument performances (1)(1)


Scientific Topic

Geometrical factor

Energy Energy

resolution

Mass resolution

FOV Angular

resolution

Time resolution

SERENA units

Synergies with other BC

instruments 1. Chemical and elemental composition of the exosphere

10–6

GF10–1 < 1 eV

NA >60

- NA

NA STROFIO MPO/PHEBUS

6a. Neutral gas density asymmetries Latitude

10–6

GF10–1

cm2 sr

< 1 eV NA

>60 -

NA T<15 m STROFIO

6b, c. Neutral gas density asymmetries Day/night Dawn/dusk

10–6

GF10–1

cm2 sr

< 1 eV NA

>60 -

NA T>orbit STROFIO

6d, e. Neutral gas density asymmetries Altitude LT

10–6

GF10–1

cm2 sr

< 1 eV NA

>60 -

NA NA STROFIO MPO/PHEBUS

Exo-ionosphere compositionIons 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.

Sc. Obj:2


Expected range of the ion/neutral densities in Mercury's close-to-planet environment

Sc. Obj:2


Neutral Species

Neutral Zenith Column density

cm–2

Neutral scale Height

km

Neutral density Range (observed) at 400 km

cm–3

Photo-ionization

lifetime s

Range of Ion density at 400 km cm–3

H 3109 1160 (1330) 410–2-200 (20) 5.1106 510–5 - 2.4 He 31011 500 (330) 5 - 2104 (2600) 1.7106 110–4 - 70 Li < 8.4107 190 810–4 - 4 4.1102 210–4 - 4 C 11011 96 310–1 - 1600 2.6104 110–4 - 70 N 51010 83 110–1 - 500 5105 210–6 - 810–2 O < 31011 72 (83) 310–1 – 1600 (160) 5105 410–7 -10 Ne 4.91010 58 210–2 - 80 5.6105 110–7 - 610–2 Na 21011 50 310–2 – 140 (14) 5.8103 110–5 - 7 Mg 3.91010 480 3.5 - 8103 7.2104 210–3 - 440 Al 3109 430 2.510–1 - 500 1.6105 110–5 - 16 Si 1.21010 414 1 - 2000 1.6105 2.510–4 - 72 S < 21013 36 210–1 - 900 8.9103 310–5 - 32 Cl 8.7106 330 110–3 - 1.5 1.6105 2.510–7-410–2 Ar 1.3109 290 310–2 - 140 3105 610–6 - 3 K 1109 30 110–5-110–2 (5 10–4) 4.2103 210–10 - 110–4 Ca 1.1108 290 110–2 – 20 (1) 1.6105 510–6 - 810–2 Fe 7.5108 210 510–2 - 100 2.3104 110–3 - 220 Ni 9.4107 200 510–3 - 10 1.6105 410–5 - 8 Kr 109 140 410–2 - 80 1.6105 110–5 - 1.610–1 Xe 7109 90 110–1 - 220 6.2104 210–5 - 4 H2 61011 600 10 - 10,000 1.7106 310–4 - 120 OH 1010 68 810–3 - 40 3.8105 110–7 - 410–2

Exo-ionosphere distributionNa+ distribution model by Leblanc foresees strong asimmetries

Sc. Obj:2


(Leblanc et al., 2004)


Scientific Topic

Signal Intensity

@ 400 km

Energy Energy

resolution

Major Components

Angular/spatial coverage

Angular resolution

Time resolution

Observable region

2a. Exo-ionosphere composition

102 cm–3

min req. 1 cm–3

>0 eV Not req.

H+, He+, Na+, O+, K+, others

…

- Not req.


2b. Exo-ionosphere spatial distribution

102 cm–3

min req. 1 cm–3

>0 eV E/E <30%

H+, He+, Na+, O+, K+, others

…

- Not req. T<2 m Whole planet


Summary of instrument Summary of instrument performances (2)performances (2)

Scientific Topic

Geometrical factor

Energy Energy

resolution

Mass resolution

FOV Angular

resolution

Time resolution

SERENA units


instruments 2a. Exo-ionosphere composition

10–1 cm2 sr >1 eV NA

>50 -

NA NA PICAM

2b. Exo-ionosphere spatial distribution

10–1 cm2 sr >1 eV E/E <

>50 -

NA T<15 m PICAM


Surface release processesDifferent 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.

Sc. Obj: 3


Particle release processes Particle release processes


TD PSD

IS MIV

Sc. Obj: 3

(Environment Simulation Tool (EST) at IFSI)

SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008

Energy distribution of sputtered Energy distribution of sputtered particles particles

by Wurz et al, SERENA Meeting in Pejo, 2006

H escape O escape

Ca escape

Fe escape

Ca O HFe

ELENASTROFIO

Sc. Obj: 3

Why we require detection of Why we require detection of neutrals at energies >10 eVneutrals at energies >10 eV


(EST@IFSI)

Ion-sputtering processELENA will map the location of the sputtering process on the surface and will image of the surface loss rate

Sc. Obj: 3

Surface sputtered signal

obtainable by ELENAwhen MPO pericentre is

in the day side

(Mura et al, PSS, 2005)SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008

Impulsive event (meteoroid 0.1 Impulsive event (meteoroid 0.1 m)m)

Frequency ~ 2 events/day

(Marchi et al, A&A, 2005)

Duration ~ 10-30 minAmplitude ~ 2000 km

(Mangano et al., PSS, 2007)

Sc. Obj: 3


Intensifications, durations and Intensifications, durations and spatial dimensions of a 10 cm MIV spatial dimensions of a 10 cm MIV

exosphere exosphere


METEORITE OF 10 cm Altitude: Species Na Mg Al Si S O K(*) Ca

Intensification I / d~ 3 n

~ 103 ~ 103 103 10 > 10--

< 104

Duration Δt 0 d300 n

1900 2000 ~2500 800 ~900--

3500

Extension d- d0º n

40º 50º 45º 25º 30º- d- n

50º

Altitude: Species Na(*) Mg Al Si S(*) O K(*) Ca

Intensification I- -

< 102 < 102 102 - < 10--

> 102

Duration Δt--

2700 ~ 2200 ~ 3200 - 1200--

3500

Extension d- d- n

100º 70º 80º 20º 20º- d- n

90º

Probability to detect 10 cm MIV Probability to detect 10 cm MIV exosphereexosphere




Scientific Topic

Signal Intensity

@ 400 km

Energy Energy

resolution

Major Components

Angular/spatial coverage

Angular resolution

Time resolution

Observable region

Useful associated

observations

3a. Localized surface emissivity induced by ion- sputtering

Up to108

(cm2 s sr)–1

min req. 106 (cm2 s

sr)–1

1-hundreds

eV min req. 20 eV v/v < 10%

H, Mg, Si, O, Na, K, Ca, others… min req.

light/heavy mass

discrimination

Order of RM on the surface s < 50 km

T< 3 m

Mainly dayside middle- latitude

Plasma precipitation

(4a) Surface

composition, mineralogy

and structure

3b. Average SW sputtering emission rate

Up to108

(cm2 s sr)–1

min req. 106 (cm2 s

sr)–1

1-hundreds

eV min req. 20 eV v/v < 10%


light/heavy mass

discrimination

Order of RM on the surface s < 100 km

T <10 m


3c. Surface vaporization micrometeorite impact

105 cm–3 min req. 101 cm–3

< 2 eV Not req.

Mg, Si, O, Na, K, Ca, others…

- Not req. T< 5 m

Whole planet

3d. PSD 105 cm–3 min req. 101 cm–3

< 1 eV Not req.

H, He, O, Na, K, others…

- Not req. T <10 m Dayside


Scientific Topic

Geometrical factor

Energy Energy

resolution

Mass resolution

FOV Angular

resolution

Time resolution

SERENA units


instruments 3a. Surface

emissivity induced by ion- sputtering

10–5

cm2 sr

<20 -100s eV v/v <

10%

Hydrogen/ heavy

particles discrimination

2ox60o

(nadir centred) < 8o

T< 3 m ELENA

STROFIO MIPA

MPO/MIXS MPO/MERTIS MPO/Simbio

Sys

3b. SW sputtering emission rate

10–5

cm2 sr

<20 -100s eV v/v <

10%

Hydrogen/ heavy


2ox60o

< 15o T< 3 m

ELENA STROFIO

3c. Surface vaporization micrometeorite impact

10–6

GF10–1 < 1 eV

NA >60

- NA T< 5 m STROFIO MMO/MDM

3d. PSD 10–6

GF10–1 < 1 eV

NA >60

- NA T <10 m STROFIO MPO/PHEBUS


SW precipitationThe 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.

Sc. Obj: 4

(Massetti et al., 2003)


(Delcourt et al., 2003)

Planetary ions precipitating from Planetary ions precipitating from the magnetosphere the magnetosphere

(Seki et al., 2006)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.

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)

Sc. Obj: 4



Scientific Topic


km

Energy Energy

resolution

Major Components


resolution

Time resolution

Observable region

Useful associated

observations

4a. Plasma precipitation rate: SW

108 (cm2 s sr)–1

min req. 106 (cm2

s sr)–1

0.5-10 keV E/E <30%

Mainly H+ 2 in the orbit

plane < 25o

T< 5 m Mainly dayside

Magnetic field

Fluxes and fields from

different v.p.

4b. Plasma precipitation rate: Heavy ions

106(cm2 s sr)–1

min req. 105(cm2 s

sr)–1

0.5-10 keV E/E <30%

Mainly Na+, O+

2 in the orbit plane

< 25o T< 5 m

Whole planet

Magnetic field

Fluxes and fields from

different v.p.


Summary of instrument Summary of instrument performances (4)performances (4)

Scientific Topic

Geometrical factor

Energy Energy

resolution

Mass resolution

FOV Angular

resolution

Time resolution

SERENA units


instruments

4a. Plasma precipitation rate SW

10–6

GF10–4

cm2 sr

0.5-15 keV E/E <30%

H identification

+

5ox180o FOV in the orbit

plane < 25o

T< 5 m MIPA MPO/MERMAG

MMO/MPPE MMO/MGF

4b. Plasma precipitation rate Heavy ions

10–5

cm2 sr

0.5-15 keV keV E/E <30%

>10

5ox180o FOV in the orbit

plane < 25o

T< 5 m MIPA

PICAM

MPO/MERMAG MMO/MPPE MMO/MGF


Loss rate from Hermean environmentThe 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.

Sc. Obj: 5


(Mura et al., 2006)

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.

Sc. Obj: 5

(Delcourt et al., 2003)SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008SERENA-HEWG meeting, Santa Fe, 12-14 May, 2008



Scientific Topic


km

Energy Energy

resolution

Major Components


resolution

Time resolution

Observable region

Useful associated

observations

5a. Particle loss rate from Mercury’s environment SW

sputtering

Up to108

(cm2 s)–1 sr)–1

min req. 106 (cm2 s)–1 sr)–1

1-hundreds

eV min

req.>20 eV

v/v < 50%


light/heavy mass

discrimination

Half planet s < 100 km

Not req.


Plasma precipitation

(4a)

5b. Particle loss rate from Mercury’s environment Exospheric

charge-exchange

107

1/(cm2 s sr)

min req. 5 105

1/(cm2 s sr)

500 eV-10 keV

v/v < 50%

mainly H, may be,

planetary major

components

Up to hundreds km above the

planet < 8o

Not req. Mainly close to horizon

c-e ENA from wider

FOV

5c. Particle loss rate from Mercury’s environment Loss of

planetary ions

107(cm2 s)–1 sr)–1

min req. 105(cm2 s)–1 sr)–1

500 eV-10 keV E/E <30%

Mainly Na+, O+ < 25o T< 5 m

Whole planet

Magnetic field


Scientific Topic

Geometrical factor

Energy Energy

resolution

Mass resolution

FOV Angular

resolution

Time resolution

SERENA units


instruments 5a. Particle loss rate from Mercury’s environment SW

sputtering

10–5

cm2 sr

<20 -100s eV v/v <

50%

Hydrogen/ heavy


2ox60o

(nadir centred) < 15o

NA ELENA

5b. Particle loss rate from Mercury’s environment Exospheric

charge-exchange

10–5 cm2 sr

500 eV-5 keV

v/v < 50%

Hydrogen/ heavy


2ox20o

(toward horizon) < 8o

NA ELENA MMO/MPPE

5c. Loss of planetary ions

10–1

cm2 sr

500 eV-10 keV

E/E < 30%

>50 Hemispheric

FOV < 25o

T< 5 m PICAM MIPA

MPO/MERMAG


Summary of ELENA scientific performances

Energy range <0.02- 5 keV (mass dependent)

Velocity resolution v/v Down to 15%

Viewing angle 2ox76o

Nominal angular resolution 2ox2o

Mass resolution M/M H and heavy species

Optimal temporal resolution 18 s

Geometric factor G 1. 10–5 cm2 sr

Integral Geometric factor 4 10–4 cm2 sr


Summary of STROFIO scientific performances

Energy range < eV

Viewing angle [deg] 20o x 20o

Mass resolution M/M 60

Mass range 1-64 dalton (AMU)

Sensitivity 0.14 (counts/s)/ (particles/cm3)

Temporal resolution 10 s


Summary of MIPA scientific performances

Energy range 10 eV – 15 keV

Energy resolution E/E 7%

Viewing angle 9o x 180o

Angular resolution (FWHM)

4.5° x 22.5° (inherent 4.5° x 8°)

Mass range, amu 1 – 50

Mass resolution, M/M ~5

Time resolution, sec 8 s, Full Azimuth – Energy cycle (8A x 32E)

Efficiency, e 1 – 10% (adjustable to decrease GF)

Geometrical factor 1.8·10-3 cm2 sr eV/eV w/o efficiency


Summary of PICAM scientific performances

Energy range 1 eV - 3 keV

Energy resolution E/E 7%

Viewing angle 3‑D, 2

Angular resolution ~22.5o

Mass resolution M/M >50

Mass range 1 ... ~132 AMU (Xe)

Time resolution 1 s ... 32 s

Geometric factor G = S 3.4 x 10–3 cm2 sr


SERENA new webpage: HomeSERENA new webpage: Home


http://www.ifsi-roma.inaf.it/enagroup/serena/index.php?categoryid=1

SERENA new web site: ScienceSERENA new web site: Science


SERENA new web site: TeamSERENA new web site: Team


SERENA new web site: SERENA new web site: ResourcesResources


SERENA Science team and SERENA Science team and thematic WGsthematic 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

Thank youThank you


BepiColombo key questionsBepiColombo key questions

Which are the Which are the composition, the composition, the origin and the dynamics of origin and the dynamics of

Mercury’s exosphere and polar Mercury’s exosphere and polar deposits?deposits?

Which are the Which are the structure and the structure and the dynamics of Mercury’s dynamics of Mercury’s

magnetosphere ?magnetosphere ?


Sodium and Potassium observations

Sc. Obj:1


(Killen et al. SSR, 2007)

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.

Sc. Obj:1


CalciumCalciumThe neutral Calcium was The neutral Calcium was observed by Bida observed by Bida et alet al. . (2000).(2000).

It is likely that Ca is It is likely that Ca is released in the molecular released in the molecular form, possibly as CaO. If so, form, possibly as CaO. If so, CaO could be dissociated in CaO could be dissociated in the atmosphere by Lythe atmosphere by Ly photons, giving the Ca atom photons, giving the Ca atom excess energy as observed excess energy as observed ((Killen et alKillen et al., 2005). ., 2005).


Documents

BC/MPO/SERENA Scientific Objectives Anna Milillo and the SERENA team