John E. Cochran, Jr.
Professor and Head
Department of Aerospace Engineering

Auburn University


Wednesday, March 28, 2001
Willet Science Center Room 101


            Tethered satellite systems (TSS) consist of two or more satellites, or other spacecraft, coupled together by lightweight, very flexible tethers.  The National Aeronautics and Space Administration has conducted several tethered satellite experiments and many uses of TSS have been proposed.  These include the generation of electrical power by using a conducting tether between two spacecraft that are moving through the Earth's magnetic field.   Another, more common place use proposed is a waste disposable system.  The concept is to downward deploy a ("garbage can") satellite containing waste material from a larger spacecraft into rather dense atmosphere.  During deployment the altitude of the larger spacecraft would increase.  When the tether is severed, the "garbage can" would re-enter the Earth's atmosphere and burn up, while the larger spacecraft would continue orbiting at a higher altitude.  Other uses of TSS include the transfer of payloads between spacecraft and long-term sampling of the properties of the upper atmosphere.  This presentation will focus on the some of the interesting and often confusing characteristics of TSS dynamics and on the problem of estimating the state of a two-satellite TSS by using observations of the motion of only one of the satellites.