Using motorized tethers for payload orbital transfer

The concept of symmetrical double-endedmotorized spinning tethers for use as orbital transfer vehicles is introduced. The orbital elements of a payload released from above and below a hanging, prograde librating and prograde spinning tether are derived and employed to evaluate the effectiveness of the three tether types along with their optimum configurations for payload transfer. A new ratio, the effciency index, is defined as the altitude gain or loss half an orbit after tether release per tether length. The motorized tether is found to perform best and also most effciently, improving by two orders of magnitude on the librating tether, which, in turn, improves on the hanging tether by a factor of two. A long motorized tether on a circular orbit can transfer an upper payload from a low to a geostationary Earth orbit by employing relatively high motor torque and a safety factor on the tether strength close to unit