The present invention comprises apparatus and methods for using and
controlling electrodynamic tethers. The apparatus taught by the present
invention uses an interconnected multiwire (compared to the long, narrow
single wires of the prior art) conductive tether whose area maximizes
electrodynamic drag while simultaneously minimizing the Area-Time-Product
swept by the tether during its operating life. The preferred tether length
is two kilometers to five kilometers. The preferred tether mass is one
percent to five percent of the spacecraft mass. The methods of control
taught by the present invention comprise orienting the tether structure at
a preferred angle to the local vertical to maximize electrodynamic drag
and minimize tether instabilities. The angle of 35.26 degrees to the local
vertical line is preferred. The invention also includes useful methods of
controlling current flow in an electrodynamic tether to limit tether
dynamic instabilities including in plane libration, out of plane
libration, transverse instability and skip-rope instability.