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The DEMETER mission: Objectives

and first results M. Parrot

LPCE/CNRS

3A, Avenue de la Recherche

45071 Orléans cedex 2,

France

E-mail: mparrot@cnrs-orleans.fr

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Outlines

The project

Case studies

Statistic with the ELF/VLF electric field

Statistic with the ES turbulence during seismic activities

Conclusions

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The Project

The DEMETER micro-satellite has been launched on June 29, 2004 by a Dnepr rocket from Baïkonour.

The plate-form is under the CNES responsibility and the scientific payload was provided by scientific laboratories.

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The scientific objectives

The scientific objectives of the DEMETER micro-satellite are related to the study of ionospheric perturbations in relation with the seismic and volcanic activities.These perturbations are interesting because they can be considered as short-term precursors (they occur between a few hours and a few days before a quake).

The same payload will allow to survey the ionospheric perturbations in relation with man-made activities.

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The scientific payload

The scientific payload of the DEMETER micro-satellite has several experiments:- A set of electric sensors to measure the 3 components of the electric field from DC to 3.5 MHz (CETP),

- A three orthogonal search coil magnetometer to measure the magnetic field from a few Hz up to 20 kHz (LPCE),- Two Langmuir probes to measure the density and the temperature of the electrons (ESTEC),- An ion spectrometer to measure ion composition (CETP),- An energetic particle analyzer (CESR).

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The operations

The orbit of DEMETER is polar, circular with an altitude of 710 km.DEMETER record data in two modes: a survey mode all around the Earth with low resolution, and a burst mode with high resolution above main seismic zones.The seismic parameters received from IPGP are merged with the orbital parameters in a special file of events.

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d1d3

d2 d4

Earthquakeepicenter

Conjugate point of the epicenter

South conjugate pointof the epicenter at the satellite altitude

North conjugate point of the epicenter at the satellite altitude

DEMETER orbit

dm

dmcN

dmc

dmcS South conjugate pointof the epicenter at the satellite altitude

North conjugate point of the epicenter at the satellite altitude

DEMETER orbit

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The wave experiment

• NEURAL NETWORK – number of whistlers and dispersion.

• BURST MODE– waveforms of 3 electric components up to 15 Hz,– waveforms of 6 components of the EM field up to 1.25 kHz,– waveforms of 2 components (1B + 1E) up to 20 kHz,– spectra of one electric component up to 3.5 MHz,– spectra of 2 components (1B + 1E) up to 20 kHz,– waveforms of one electric component up to 3.5 MHz

(snapshots).

• SURVEY MODE– waveforms of 3 electric components up to 15 Hz,– spectra of 2 components (1B + 1E) up to 20 kHz,– spectra of one electric component up to 3.5 MHz.

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LPCE(IMSC, RNF, BANT)

DEMETER DATA ACQUISITION

ARCHIVE(Science data L0, QL, L1; Earthquake data;

Ancillary data)

WEB DATA SERVER(Data L0, QL, L1, L2; Earthquake events; Ancillary data products;

Mission information)

Science PL TM packetsPL TC

PLAN

SCIENCE PL PROGRAMMATION

GENERATION

CONTROL CENTER

PHYSICAL VALUES PROCESSING [L1]

ANCILLARY DATA - Orbit Parameters - TM station Pass-Planning

- Events (orbit, satellite) - Attitude - HK

OPERATIONBOARDOPERATION

BOARD

DEMETERMISSION GROUP

(Experimenters,CNES)

DEMETERMISSION GROUP

(Experimenters,CNES)

Scienceoperationcoordination

PL and MCevents

Memoryhandling

BURST zones

LPCE(MC)

CETP(IAP, ICE)

8 GHz

SCIENTIFICUSERS

SCIENTIFICUSERS

Science PLTM packets « back-up »

QUICK-LOOKPROCESSING [L0']

PRE-PROCESSING [L0](Decommutation, Good Health)

TM

CESR(IDP) ESTEC

(ISL)

IPGPSEISMIC DATA

Calibrationvalidation

Instrumentconfiguration

2 GHz

CNES

EXCHANGE FILE SERVICE

ANCILLARY DATAPROCESSING

INSTRUMMENT CALIBRATIONS

High resolutiondisplay [L2]

PL status

OPERATIONCOORDINATION

GROUP

OPERATIONCOORDINATION

GROUP

The DEMETER mission center

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One day in the DEMETER life (August 12, 2004)

d = 2800 km

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Case studies

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Sarkar et al., JASTP, submitted, 2007.

Central Iran22 Feb. 200502:25:26 UT

M = 6.4d = 42.4 km

Lat = 30.7°N, Long = 56.8°E

The Results: DEMETER data

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Sarkar et al., JASTP, in press, 2007.

6 days before 4 days before 2 days before

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Sarkar et al., JASTP, submitted, 2007.

Electron Density Variation of Ion Density

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23 Jan. 200520:10:11 UT

-1.22°S 119.82°EM = 6.2

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23 Jan. 200520:10:11 UT

-1.22°S 119.82°EM = 6.2

2.5 daysbefore

140 Hz

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Statistical analysis with the ELF/VLF electric field

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15 months of data4385 hours of measurements

Electric field data organized by

- Frequencies (16) below 10 kHz- Magnetic local time (2)- Geographic positions (bin of 4° in longitude, 2° in latitude)- Kp classes (3)- Seasons (2)

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Electric field map

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Application of the central limit theoremProbability density functionof the wave intensities

in a bin

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2628 earthquakes with M > 4.8 and d < 40 km

Distance between

epicenter and track of the orbit

< 700 km

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2628 Earthquakes with random position and time

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3346 earthquakes with M > 4.8 and d < 40 km

Aftershocks have been removed and data set extended (Feb.2007)

2111 earthquakes with M > 5.0 and d < 40 km

Night time

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random

Aftershocks have been removed and data set extended (Feb.2007)

2111 earthquakes with M > 5.0 and d < 40 km

Night time

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Statistical analysis of the electrostatic turbulence

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22 Nov. 200420:26:25 UT

-46.57°S 164.83°EM = 7.3

1 day before

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M = 5.25 days before

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Estimation of the power law (f –α) during a ‘Survey’ mode with ICE

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Examples of global maps of the slope

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Examples of global maps of the slope

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Method of superposed epochs

- 4626 earthquakes of magnitude > 4.8 ; period 2004/08 – 2005/08;

- Distance between the projection of the orbit on the Earth’s surface and the epicenter < 2000 km

- Data selected in the time interval 3 days before the earthquakes and 1 day after the earthquakes.

- Comparison between the current data during the seismic activity and the average background data at the same location during the same condition

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Decimal logarithm of the ratio between the current values of the power density and the ‘‘background’’

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EQs

Random

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Ratio between the current values of the slope and the ‘‘background’’

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EQs

Random

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Method of superposed epochs

- 2173 earthquakes of magnitude > 4.8 ; period 2004/08 – 2005/12; aftershocks have been removed.

- Distance between the projection of the orbit on the Earth’s surface and the epicenter < 2000 km

- Data selected in the time interval 3 days before the earthquakes and 1 day after the earthquakes.

- Comparison between the current data during the seismic activity and the average background data at the same location during the same condition

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Decimal logarithm of the ratio between the current values of the power density and the ‘‘background’’

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EQs

Random

Average changeat maximumequal to 2(100.8-0.52)

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Average

Histogram

Comparisonbetween

twomethods

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Ratio between the current values of the slope and the ‘‘background’’

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Random

EQs

Average maximumchange = 18%

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Histogram

Average

Comparisonbetween

twomethods

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Conclusions (1/3)

The main points revealed by the statistical studies are:

-The values of the parameters when the satellite is far from the earthquakes are similar to the values obtained when a random data set of events is used. Therefore this study shows that there is an influence of the seismic activity on the ES turbulence at an altitude of 700 km both before and after the earthquakes.

-The perturbations are observed until 2 days before the earthquakes. There is a clear change right after the earthquakes.

- The perturbations are real but they are weak and only statistically revealed. Up to now nothing can be said about the possibility to predict earthquakes with the analysis of the ES turbulence.

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Conclusions (2/3)

Statistical analysis are in progress with other parameters:

- Electron density and temperature- Whistler dispersion- Energetic particles- VLF Transmitters

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Conclusions (3/3)

Operations will continue until the end of 2008.

Altitude was decreased in December 2005 (660 km).

The web site of the mission: http://demeter.cnrs-orleans.fr