Jess (falconry) Jess (falconry) A jess (plural "jesses") is a thin strap, traditionally made from leather, used to tether a hawk or falcon in falconry. Jesses allow a falconer to keep control of a bird while it is on the glove or in training, and allow a bird to be secured on a perch outside its aviary. Jesses come in various types: Jesses are generally made from strips of leather as thin as possible, for which purpose kangaroo leather has become increasingly popular over the years, as it is thin, light-weight and extremely durable with proper care. Jess size varies depending on
Momentum exchange tether field such as around the Earth, a conducting tether can be configured as an electrodynamic tether. This can either be used as a dynamo to generate power for the satellite at the cost of slowing its orbital velocity, or it can be used to increase the orbital velocity of the satellite by putting power into the tether from the satellite's power system. Thus the tether can be used to either accelerate or to slow an orbiting spacecraft without using any rocket propellant. When using this techniques with a rotating tether, the current through the tether must alternate in phase with