437 this concern, “d irty” testing was performed as a dynamic functional test to ensure its full deployment  capability in such an environment.  The “dirty” environment was simulated via a media mixture designed to  simulate Martian regolith being blown into the CDPR.  Using nitrogen gas  (GN 2), 700 ml of this media was  distributed throughout the entire mechanism and around the mechanism revolute joints.  After 30 seconds  of circulating the media and thoroughly coating the mechanism, a cord connected to a manual pin (to  replace the pin- puller) was pulled to deploy the mechanism.   

This functional  test completed successfully by demonstrating full deployment capability under such “dirty”  condition with no signs of hindering.  This testing was performed prior to the development of the kickoff  spring. This showing that only the redundant torsion springs were sufficient to deploy the flexure and the  added kickoff spring only added  margin on top of this. To further demonstrate the robustness of the  mechanism, a worst -case scenario was also tested where the redundancy of the torsion springs was  eliminated and flexure deployment under the “dirty” condition was only driven by the lower and smaller  torsion spring.  With t hat, the CDPR st ill deployed its flexure successfully with no signs of any hindering.   See Fig.  11 for photos  of the test configuration.   

Figure 11. Showing the “dirty” test configuration: (a) showing the before the mechanism was coated with  the Mars regolith simulate media, (b) after media circulation and deployment. This test was for the fault  case with only the lower torsion spring having successfully deployed the flexure.  

Engineering Model Loaded Deployment Testing   From the rover descent simulation in ADAMS, it was determined that the CDPR would sustain  approximately 5.2 kN of residual load at the time just prior to pin-puller firing  (Fig. 3). Such amount of  residual  load would result in approximately 5 joules of potential energy being stored within the fully  restrained CDPR.  At DDR, this  led to a concern that once the pin- puller fires and the flexure becomes  unpinned, the then “open” system of CDPR could have an unpredictable and undesirable dynamic response  from the  sudden  release of the strain energy stored in the f lexure. To address this, another  dynamic   functional test was conducted where the CDPR would be deployed while under 1.2x peak load (6.2 k N  through the mechanism) . This “loaded deployment” testing employed a flight -like configuration using a  pneumatically driven pin- puller.  All springs, magnetic hardstop, and travel limit ers were present in this test   and in a flight -like configuration . See Fig. 12 for loaded deployment test configuration.  

Using a crane and load cell , a lateral load was applied to one side of a Ground Support Equipment ( GSE )  revolute joint to mock the d ifferential CDP, this in turn induced an equivalent load through the CDPR in the  opposite direction.  A total of five tests were conducted  with this setup . Since polarity of such residual load  in flight is not 100% certain, t he mechanism would be deployed under a tensile load and then a final