Professor Umran S. Inan

Winter 1997-98

Date: Wednesday, January 14, 1998

Time: 4:15 PM Refreshments at 4:00

Location: Gesb 124 (Green Earth Sciences Bldg.)

Using Radio Tomography Imaging to Investigate the Earth's Magnetosphere

Dr. Robert Ergun

Space Sciences Laboratory, UC Berkeley


We discuss the concept of a multi-spacecraft mission that will provide two-dimensional high spatial and temporal resolution global images, and parameterized high-spatial resolution three-dimensional images of the plasma density, density turbulence, convection velocity, and magnetic field for investigation of the Earth's magnetosphere. The mission combines well established radio science techniques with computed tomography in an innovative fashion to form high resolution images of the magnetosphere. Also included are a radio sounder for nearby boundaries, a magnetometer, energetic ion and electron detectors, and a plasma wave receiver. Multi-point, in situ observations of energetic particles, plasma waves, and the vector magnetic field will allow one to link the global images to known dynamic processes and solar wind parameters. The primary scientific objectives are: (1) to provide a parameterized, three-dimensional baseline image of the plasma density, density turbulence, convection velocities. and magnetic field to ~30 Re, (2) to study in detail solar wind-magnetospheric coupling , the structure and dynamics of the bow shock, magnetosheath, and magnetopause, deriving the level of transfer across the magnetopause and locating and imaging disturbances on the magnetopause caused by reconnection, and (3) to study in detail the substorm process, focusing on the structure and dynamics of the plasma sheet and plasmapause, the thinning process associated with cross-tail current disruption, the tail expansion and dipolarization process, and exploring the possible formation of a neutral line inside 30 Re. We propose to develop a MIDEX level mission concept that makes tomographic images with a number of small (~30 kg) sub-satellites. All of the sub-satellites can be deployed with a single med-light vehicle. The mission requires mass reduction and the use of advanced technologies in spacecraft subsystems and instruments.