Patent ID: 7178763

Claim:
A deployment mechanism for expendable space tether applications comprising essentially a fixed single-layer tether winding cylinder ( 6 ), a multiple-layer tether winding central spool ( 8 ), an initial separation impulse mechanism ( 10 ) for passive tether deployment, and a tether deployment brake ( 12 ) of daisy-like shape; characterized in that said mechanism accommodates a first portion of tether ( 7 ), many kilometers in length, wound up on said inner multi-layer spool ( 8 ), followed by a second portion of said tether ( 7 ), many hundred meters in length, wound up in a single layer on said outer cylinder ( 6 ), in order to allow the passage of the tether ( 7 ) both on ground, during the required tether winding and preparatory operations, and on-orbit, during the actual deployment by the unwinding of its two types of tether windings, a surface cut ( 9 ) of said outer cylinder ( 6 ) of sufficient width and along most of its length is provided, in this way once the continuous space tether is deployed on orbit, the unwinding tether will pass through said cylinder cut ( 9 ) and will continue to unwind from said multi-layer central spool ( 8 ) till the end of deployment; said initial separation impulse mechanism for passive tether deployment comprises a central sinusoidal spring ( 10 ), mounted inside the core of said fixed multi-layer tether spool ( 8 ) and capable of storing the required energy for initial separation of the tethered masses; said separation spring ( 10 ) is kept in a compressed state, during ground operations and ground and space transportation and before on-orbit separation and deployment, by some, usually three, pyro-bolts ( 3 ) mounted on the mechanism cover ( 1 ) and its interface plane with the external surface ( 2 ) of the carrier spacecraft; at separation time, on command coming from ground through the carrier spacecraft telemetry and telecommand on-board system, said pyro-bolts ( 3 ) are actuated, said central spring ( 10 ) is released and the whole deployment mechanism, with its cover ( 1 ), spring ( 10 ) and full tether windings, will separate about the orbit local vertical direction from said carder spacecraft ( 2 ); and said passive tether deployment brake ( 12 ) of daisy-like shape and flexible material, incorporated within said centrally fixed multi-layer spool tether winding ( 8 ) and fixed on the spool central core mounting, will deploy On-orbit during tether deployment operation at the planned length of the deployed tether or distance of the tethered end-masses; the deployment of this device increases by the planned magnitude or amount the tether deployment friction resistance force, so that the decreasing of the tether deployment rate from the deployer mechanism is gradually provided and applied until the end of the deployment operation.