full deployment of the antenna.  While initially the deployment went as planned, the antenna suddenly stalled  about 2/3rds though the deployment. After trouble shooting, it was found the motor controller, which had a  poorly  design  thermal  path  to the chassis,  was  overheating.  The  motor  controller  had a thermal  limit  of  85°C,  but without  adequate  heat  conduction,  the heat  generated  by running  the antenna  caused  it to  overheat  at just 65°C.  Deploying  the antenna  at 55°C  eliminated  this problem.  While  the initial  thermal  range from deployment was 10°C to 50°C, the range was decreased to 10 to 40°C.  After  TVAC  testing,  the antenna  was  taken  to the RF range  for further  testing,  and  no changes  were  observed to antenna gain. However, another problem occurred when stowing the antenna. When driving  the antenna down, an odd noise was coming from the sun and planet gears. Investigation revealed the sun  gear was running at a slight angle. It appeared that during thermal vacuum tests, because the gear was a  300 series, or austenitic stainless steel, and the bearing was a 400 series, or matristic stainless steel, the  coefficient  of thermal  expansion  was  different  enough  to cause  the press  fit to become  loose.  As the  antenna was deployed with the loose press-fit at the high temperature, the sun gear worked its way off the  thin section  bearing.  Further  detailed  analysis  revealed,  depending  on the tolerances  of manufacturing,  when going cold the sun gear would likely crush the thin section bearing. The end solution was to increase  the diameter for the hole in the sun gear, and then bond the sun gear to the bearing, providing compliance  at the  thermal interface. Further, a 0.4-mm bond line with  EA9360 epoxy  helped to athermalize  the joint,  resulting in less stress on the gear and bearing.   After re-installing the sun gear bearing, the antenna was installed on the RADAR instrument assembly. The  RADAR instrument then went through a 6.1 G RMS workmanship vibe, which was the minimum required as  actual launch loads for RainCube are expected to be much lower, closer to 2 G RMS (given it is being stowed  with soft cargo to the International Space Station). After vibe, the antenna went through a second thermal  vacuum test, this time where it was deployed at 0°C.  The antenna behaved exactly as expected through  both tests.  However, about 3 months prior to installation of the antenna on the spacecraft, it was realized the spacecraft  (built by a vendor, Tyvak) would be supplying 12 V to the antenna, where previously the antenna operated  at 5.5 V during testing. This change warranted investigation, and revealed the antenna would be performing  fundamentally differently than before, and could generate a higher stall torque than observed  in the prior  test. As such, a current limiting feature was programmed in the motor controller to ensure the performance  on orbit was similar to the performance in the number of environmental and deployment tests on the ground.  The KaPDA antenna and RainCube instrument has been integrated int o the RainCube spacecraft at Tyvak,  the spacecraf t bus vendor. Assembly and EMI/EMC testing hav e been completed.   Current Status  The RainCube  spacecraft  assembly  is about  to undergo  environmental  testing  for a 3rd time  at the  spacecraft level, although this testing is much more benign than the level to which the Instrument Assembly  with the antenna was qualified. After environmental testing, the antenna will be deployed one last time to  verify  operation  before  it is stowed.  RainCube  is scheduled  to launch  in May  2018  from  Kennedy  Space  Center  and fly as soft cargo  to the International  Space  Station.  Once  there,  it will be deployed  from  the  station  via the NanoRacks  CubeSat  deployer.  After  approximately  one month  of bus checkout  tests,  the  antenna  will be deployed  for a final  time,  in low earth  orbit.  The  mission  and antenna  are designed  to  operate for approximately 1.5 years, before it reenters Earth’s atmosphere and disintegrates.    © 2018 All Rights Reserved. Government sponsorship acknowledged.  NASA/CP—2018-219887 370