GRADSAT: A DANISH GEOMAGNETIC GRADIENT MISSION

A proposal is given of a mission of two identical tethered micro satellites for simultaneous two-point mapping of the Earth's magnetic field and of the first space derivative of the field. Launch in the 2002 time frame into a low altitude near polar and approximately circular orbit, slowly drifting in local time. An approximately 3 month's lifetime in the tether mode (similar to METS), continuing as free flyer(s) for up to 2 years depending on the actual solar cycle atmospheric swelling. The Danish Ørsted Earth's field mapping mission brought Denmark into the international front in space magnetometry. A Danish Magnetic Gradient Mission will bring Denmark far ahead, and will consolidate our position in space magnetometry and advanced space technology. The proposed 600-400 km altitude polar orbit and the 20km gravity gradient extended tether are optimized for simultaneous observations of the field signatures and for the separation of the field sources below the orbit, from sources traversed by the satellites and from sources above the orbit.