of the mesh. The mesh was attached to the ribs through a series of holes in the ribs, with nearly 2,000 hand  stitches attaching the two. The antenna then came off the mold in the fully deployed state.   The antenna was first RF tested to check the as-built tolerances prior to deployment, and found to achieve  42.5 dBi of gain, outperforming the gain requirement of 42 dBi. This indicated the RF design had adequate  margin and the antenna was built to better than required tolerances.  After the RF test, the antenna was stowed by carefully folding the ribs and sliding the hub down into the  canister. Then pressurized gas was inserted through the base plate, actuating the deployment, which  appeared to be successful as illustrated in Figure 5.   A B C D  Figure 5. Antenna Deployment Via Gas Power  After  deployment,  the antenna  was  taken  to the range  for RF testing.  When  mounting  the antenna  horizontally, it was noted  some  of the ribs were  folding  closed.  Further investigation showed  that the inflation  powered deployment had never latched the antenna. While the antenna was able to be manually latched  in place, and the RF test could be finished, in orbit this would have been a requirement critical failure as  the ribs would not be in the right location to achieve high gain. RF testing also revealed after being manually  latched in place, the antenna only achieved 42.0 dBi of gain, just meeting the requirement.   Further investigation of the deployment video revealed that the spring ring and hub tilted to one side near  the top of the deployment  (Figure  5C).  This  angle  prevented  the ribs  from  properly  latching  in place.  Because gas was just pushing on the antenna during deployment, nothing was constraining the antenna to  ensure  it deployed  straight  and  vertical.  The  piston  consisted  of a thin plate  attached  to the hub,  and  therefore was free to rotate like a coin spinning its way down a pipe of similar diameter. While height could  have been added to the plate, there was not enough room to add as much length as the cylinder diameter,  which  would  mean  the L/D for a sliding  contact  would  be less  than  one,  putting  the design  at risk for  jamming.  While  this was  the first indicator  that  a gas-powered  deployment  would  not be suitable  for this space  deployable, several other complications arose. First, when looking for a gas system to operate in orbit, the  only commercially available parts that would fit in the system were small cold gas generators. Unfortunately,  these release pressure relatively quickly, and would result in an explosive deployment. Secondly, even if  the deployment  could  be controlled  by a gas-powered  system,  there  was  the added  complication  of a  canister of gas sitting in space. If it began to leak, even a small jet of gas would behave like a propulsion  system,  and could  potentially  cause  the spacecraft  to lose  control.  Finally,  residual  pressure  and launch  locks to resist residual pressure added further complications to the design. Because of this series of issues,  it was determined an alternate approach for the primary deployment system had to be found.   Developmen t of the Engineering Model  The engineering model began with a design process investigating alternatives to provide the main  deployment of the antenna ou t of the canister . After going back to the drawing board, a motor-powered  deploymen t with lead screws was investigated. This deployment approach was initially rejecte d during the  early trades because the mos t intuitive place to locate a lead screw was in the middle of the antenna,  conflicting with the waveguide. However, through further brainstorming, realization dawned : the antenna fit  © 2018 All Rights Reserved. Government sponsorship acknowledged.  NASA/CP—2018-219887 367