Transcript CGS
Future China Geomagnetism Satellite Mission (CGS) Aimin Du Institute of Geology and Geophysics, CAS 2012/11/18 Taibei OUTLINE 1- Promoting of the CGS mission 2- A brief introduction to the Constellation 3- Open discussion about the science object of the CGS mission Grenoble Workshop about CGS On April 11, 2011 To Promoting the CGS Mission In 2012, China Spacesat Co. Ltd. to design the CGS It is confirmed that the Chinese companies have ability to product the small satellites and suitable rockets for the CGS mission. Why are Chinese interested in geomagnetic satellite missions? It is related to Chinese history. Magnetic Declination in China Needham has shown that the credit for the discovery of declination must go to the Chinese. Needham has tabulated eighteen recorded Chinese compass observations of declination covering the period about 720-1829. These are of interest not only to historians but also to geophysicists, for they represent the earliest recorded direct observations of the Earth's magnetic field. The question of their validity is therefore of great importance. Petrus Peregrinus (1269) Epistola de Magnete Compass CGS MagNet Swarm CHAMP Ørsted Magsat CONSTELLATION • One satellite is in an orbit close to the equatorial plane • Four satellites are in polar orbits separated by 45° Mass: 115 kg Inclination: 87.4° Altitude: Pre. rate: 450 km -0.34 °/day Spacecraft System Architecture Fluxgate Magnetometers Payload Advanced Stellar Compass Absolute Scalar Magnetometer Spacecraft Structure and Mechanism Subsystem Attitude and Orbit Control Subsystem Power Supply Subsystem Platform On-boardd Data Handing Subsystem Thermal Control Subsystem Communication Subsystem Combined GPS, GLONASS, Galileo and Beidou Occultation technique CGS Scientific Objectives Component Objectives Contribute to the long phase of synoptic Core monitoring of the core field Monitor flows in the core and their time changes Investigate the interplay between velocity and magnetic fields Mantle Perform 3D tomography of mantle Crust Construct the lithospheric magnetic map conductivity Environment Investigate the time-space structure of the magnetospheric and ionospheric sources on all time scales (Dominique and Jackson, 2010) 1. Core Field Dynamics of the Earth’s core, as estimated from the evolution of the magnetic field, evolves on a variety of timescales. 外核 2. Monitor of MagnetosphereIonosphere Current System 3. Atmosphere and ionosphere occultation technique GPS Atmosphere CGS Ionosphere 4. Crust Field Deep Structure of the Earth and Concentration of Metals in Lithosphere Considerations of the constellation concept are for: Good coverage in spatial, local time and seasons. Separating of the core field, crust field, induced field. Equatorial satellite is for monitoring the daily variations and equatorial current system. 80% data for single satellite were lost Kp < 2; LT ~ 21:00 - 03:00 Equatorial satellite monitoring mid-low latitude currents by the assimilation method • Ring current: Storm-time geomagnetic disturbance • Sq current: ionospheric dynamo • Eqatorial ElectroJet (EEJ): cowling current • Cross tail current: Substorm current • Magnetopause current: Solar wind ram pressure LONGITUDINAL PROFILE OF Bj FROM MAGNETOSPHERIC CURRENTS 1 Dst N N H j cos j 1 B j j Local Time 18 00 06 12 B o o 12 o o Dst (Le Guan et al., AG, 2004) EQUATOR CURRENT SYSTEM has a good longitudinal profile Sq C-F current Cross Tail current DEDUCE THE ELECTRIC POTENTIAL IN POLAR REGION THEN MAPPING TO THE MID-LOW LATITUDE MAGNETOSPHERE FOR EXAMPLE Geomagnetic Indices Ring Current Global profile in X component on the ground Magnetospheric Current System Auroral electrojet and Field-Aligned Current SUMMARY The constellation constellation with one nearequatorial orbit satellite and four polar orbit satellites should contribute to: Separating of outer source field (noise) from the satellite data. Modeling the magnetosphere-ionosphere current system (signal). Discovering the small scale and short term variation of core field. Constructing of mantle conductivity and lithosphere. Thanks！