Jess (falconry) anklet worn by the bird, which is itself formed of another rectangular strip of leather, bound together at the ends by a grommet (usually of brass), prevented from slipping through the grommet by the knobbed end. Often, another slit is placed near the thin end of the jess cut about one inch long and running lengthwise, through which a special type of swivel is fitted, preventing the whole arrangement from twisting or tangling about itself or the bird when a leash is threaded through the other end. Their intent is more to prevent the risk of the bird deciding to
Momentum exchange tether than the orbital velocity of the tether and the upper endpoint is moving faster. The word is a portmanteau derived from the words "rotor" and "elevator". If the tether is long enough and the rotation rate high enough, it is possible for the lower endpoint to completely cancel the orbital speed of the tether such that the lower endpoint is stationary with respect to the planetary surface that the tether is orbiting. As described by Moravec, this is "a satellite that rotates like a wheel". The tip of the tether moves in approximately a cycloid, in which it is momentarily