expensive, especially on a quantity of 30 ribs. A better solution was found by using a bonding fixture to  precisely set the position for the root and tip rib, and then insert and bond the hinges in place. This fixture  also ensured all the ribs were identical to each other.  Design of the Antenna Deployment  A number of concepts were initially brainstormed for deploying the antenna, which included using springs,  cable and pulley systems, springs combined with cable and pulley systems, and gas-powered piston  systems. A major aid to developing the concept was creating a CAD drawing showing an outline of the  canister and folded ribs, and printing it out to scale. Deployment mechanisms could then be sketched on  this paper, as shown in Figure 3.  Figure 3. Original CAD templat e (left) and sketches made a t scale on th e template (center to right)  One of the major issues when working in CAD software is an unrealistic understanding of scale. By printing  out drawings  of the constraints,  and sketching  deployment  systems  to scale,  it was  quickly  realized  that  any type of cable and pulley system fitting in the volume would require very small components. In addition,  it would be hard to route cables in the small volume while also preventing tangling.   Springs alone were not a realistic system either because of the preload required to tension the mesh. While  the total preload needed was calculated to be 250 N at the end of deployment, this would result in a force  of at least  500 N when  the spring  was  stowed  prior  to deployment.  This  means  there  would  be a lot of  excess energy in the spring which would go into accelerating the antenna, resulting in a dynamic impact.  Therefore,  the most  reasonable  system  appeared  to be a gas driven  canister  as the primary  mode  of  actuating the deployment. As the entire system is stowed in a canister, it was convenient to also use the  hub as a piston. Pumping gas between the piston and the base would cause it to expand in the cylinder,  pushing  the antenna  out and deploying  it. If the gas could  be properly  metered,  the antenna  would  be  allowed to slowly deploy, and then pressure could be increased only at the end when the additional preload  was required. Given the 10-cm-diameter piston, operating in the vacuum of space, only 32 kPa (about 1/3rd  of atmospheric  pressure)  would be  required  to achieve  the 250-N  load.  Further,  no miniature  parts  were  required by such a pressurized system. To ensure the antenna would stay in the deployed state after the  gas-powered deployment, the fully deployed antenna would be latched in place  When  considering  the deployment  system,  beyond  pushing  the antenna  out of the canister,  the antenna  ribs also required deployment from their initial state. While originally multiple cable systems for rib actuation  were explored, and even tested, these were dropped for the same reasons they were not used for actuating  the antenna out of the canister; lack of space. It was determined the best approach was to have the root  ribs catch on the edge of the canister, leveraging them out to deploy. This ensured the root ribs, which react  a majority of the moment, could have a high preload when deployed. Each rib has two springs attached to  either side of it. These springs are all attached to one ring, which ensures all 30 ribs are synced together.  © 2018 All Rights Reserved. Government sponsorship acknowledged.  NASA/CP—2018-219887 365