68th International Astronautical Congress (IAC), Adelaide, Australia, 25-29 September 2017. Copyright ©2017 by the International Astronautical Federation (IAF). All rights reserved. IAC-17-A6.4.4 DRAG ENHANCEMENT FOR SPACECRAFT USING NUMEROUS ULTRA-THIN WIRES ARRANGED INTO DRAG-WIRE WEBS OF VARIOUS 

The concept and design of a novel drag enhancement system called the Ultra-thin Wires Drag Enhancement System (UWDES), is presented. The UWDES uses numerous ultra-thin wires to form a three dimensional (3D) web through electrostatic charging. UWDES is designed with the objective of mitigating space debris, particularly in low altitude Earth orbits (LEOs) for pico/nano/micro-satellites by causing their rapid orbital decay. The ultra-thin drag-wires are stowed inside the container module of UWDES and at the end of spacecraft's mission life, deployed by releasing the container lid, followed by electrostatic charging. In comparison to drag sails, the UWDES drag-wires provide more effective area experiencing drag (EAED) for a given mass and size of the material used to fabricate the drag enhancing structure. For a unit cube of side 1 cm, (i) beaten into a square sheet of 1 micron thickness and (ii) drawn into a round wire of same thickness, the EAED for (i) is 1 m​ 2 and (ii) is 1.2732 m​2​. The ultra-thin drag-wires of the UWDES are held straight in a tuft with all strands fused together at both ends. When they are electrostatically charged, due to mutual repulsion on acquiring like charges, they unwind from spool and deploy out of container module to gradually arrange into a 3D web structure. With this, all the individual ultra-thin drag-wire strands are exposed to incoming atoms and ions of space atmosphere and thus augment the effective area experiencing drag (EAED) of the host spacecraft and the resultant aero drag. As the drag wires are electrostatically charged, they mutually repel with like-charged particles of space atmosphere that collide with them resulting in Coulomb drag. Hybrid-drag effect of both Aero drag and Coulomb drag are responsible for stretching the ceiling altitude for UWDES application up to 6000 km. Based on the amount of charges supplied to the wires, the UWDES is designed to arrange itself into various 3D configurations (boat-shape, spindle/pear, globe and flower), resulting in varying EAED. It may be argued that the deployment mechanism of UWDES, which involves a lid release relay followed by electrostatic charging, is simpler in operation and has a lesser chance of deployment failure compared to drag-sails that employ moving parts like motors. Varying in the way ultra-thin wires deploy from container, UWDES has two variants namely fixed-spool and deployable-spool. Also, based on​ ​charging,​ ​UWDES​ ​is​ ​categorised​ ​into​ ​passive-​ ​and​ ​active-charging​ ​variants. ​ ​IAC-17-​ ​A6.4. 4​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​​ ​Page​ ​1​ ​of​ ​13 68th​ ​International​ ​Astronautical​ ​Congress​ ​(IAC),​ ​Adelaide,​ ​Australia,​ ​25-29​ ​September​ ​2017. Copyright​ ​©2017​ ​by​ ​the​ ​International​ ​Astronautical​ ​Federation​ ​(IAF). ​ ​All​ ​rights​ ​reserved.