BepiColombo MMO Payload

Mercury Dust Monitor(MDM)
1st Meteor and Dust meetingat National Astronomical Observatory of Japan

3 July 2007

BepiColombo Mercury Dust Monitor ( MDM )P.1

BepiColombo MMO Payload

Mercury Dust Monitor(MDM)
K.Nogami ---Dokkyo Medical University
M.Fujii--- FAM Science Co., Ltd.,
H.Ohashi ---Tokyo University of Marine Science and Technology
T.Miyachi --- Waseda University
S.Sasaki --- National Astronomical Observatory of Japan
H.Yano--- ISAS / JAXA
A.Fujiwara --- ISAS / JAXA
H.Shibata --- Kyoto University
S.Minami --- Osaka City UniversityS.Takechi --- Osaka City University
T.Iwai--- University of Tokyo
G.Kuraza --- Waseda University
T.Ohnishi --- Osaka City University
E.Grün--- Max Planck Institute for Nuclear Physics, Germany
R.Srama --- Max Planck Institute for Nuclear Physics, Germany
BepiColombo Mercury Dust Monitor ( MDM )P.2

Microparticles inthe solar systemB) Cometary dust trail(trail)A) Interstellar dustE) Interplanetary dust
CometC)  meteoroids

SunMercuryD) Hermean dust
Cruising Phase
Spin Axis

SunBepiColombo Mercury Dust Monitor ( MDM )P.3

Historical dust mission of inner solar system

BepiColombo Mercury Dust Monitor ( MDM )4

Scientific Objectives
Dust Types

Scientific Interests

Dust flux within theInner Solar System

Confirm the flux and size distribution as a function of theheliocentric distance. In-situ measurement to constrain
zodiacal dust cloud distribution model.

Cometary Dust

Possible encounters with the cometary dust trails and highly
eccentric trajectories.

Beta Meteoroids

Direct flux measurement in the vicinity of Mercury (0.31-0.47
AU) help to understand mechanism and location.

Interstellar Dust

Possible detection of large interstellar dust (>>1 micron)intruding so close to theDust to Mercury(V orbit = 47.5 km/s)

Investigation of temporal and directional variations of dust influx
throughout Mercurian orbit to identify the key meteoroid
sources. Estimate external mass accretion rate to the
Mercurian surface Constraint to space weathering effect on the
Mercurian surface. Assessment of meteoroid impact
contribution to the formation of the tenuous Na-K atmosphere.

Dust from Mercury(V esc.= 4.25 km/s)

Search for Mercurian dust ejection (e.g., temporal dust cloud?)by meteoroid impacts, similar to the Jovian satellites. Possible
interaction with the magnetic field, similar to the Jovian satellite
dust stream.

BepiColombo Mercury Dust Monitor ( MDM )5

Dust flux near Mercury
from Mann et al. 2003

10-2Flux ( impact / m2 s1 )







10-

6

0.1

0.3(AU)

BepiColombo Mercury Dust Monitor ( MDM )

1.0
P.6

BepiColombo Mercury Dust Monitor ( MDM )P.7

MDM-S 4 PZT sensors set in the frame
PZT:4cm4cm2mm

Circuit board & sensor frame

BepiColombo Mercury Dust Monitor ( MDM )Van de Graaff dust accelerator

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flight time: t velocity: v = L/tcharge: q = cV, induced voltage V and capacitance 1pF.
energy: mv2/2 = qU, acceleration voltage U
mass: m = 2qU/v2

10

Experiment chamber of thedust accelerator at HIT

BepiColombo Mercury Dust Monitor ( MDM )P.11

PZT sensor in the dust
accelerator chamber

BepiColombo Mercury Dust Monitor ( MDM )P.12

Typical waveform (MPI-K)
Change with velocity (Iron particles)
5.5 km/s
28 pg

Slow

25 km/s
29f g

High speed
7.2 km/s
5.5pg

9.7 km/s
1.2 pgMedium
BepiColombo Mercury Dust Monitor ( MDM )P.13

Particle mass vs. velocity by thevan de Graaf dust accelerator

BepiColombo Mercury Dust Monitor ( MDM )P.14

 

Vp vs momentum (Sample) 

P~12*Vp-6










    
BepiColombo Mercury Dust Monitor ( MDM )15

Rise time vs. velocity of single peaked pulse
High speed impact ( > 8 km/s )PZT ThicknessBepiColombo Mercury Dust Monitor ( MDM )P.16





SUN

BepiColombo Mercury Dust Monitor ( MDM )P.17

Installation of MDM and heat flow
Silver Plating(  PZT Element(1.2W/mK)White Paint(Hughson Z202:

CHO THRM1 (T500)(2.1W/mK)
Mg Frame(152W/mK)Side Panel

Welding

Cable Wire (Co-Axial #26)

Contact Area

Black Paint(Hughson Z306:

MLI

Total 600g
MDM-E
Lower DeckE
ContactArea

BepiColombo Mercury Dust Monitor ( MDM )P.18

Thermal mathematical calculationof the PZT sensor

193

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BepiColombo Mercury Dust Monitor ( MDM )P.19

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BepiColombo Mercury Dust Monitor ( MDM )P.20

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BepiColombo Mercury Dust Monitor ( MDM )P.21

( End )BepiColombo Mercury Dust Monitor ( MDM )P.22