Sample Retrieval Lander Parachute System Deployment Test Campaigns: Modeling, Testbed Development, and Intermediate Results

A 24-meter Disk-Gap-Band (DGB) mortar-deployed parachute is being developed for the Sample Retrieval Lander as part of the proposed Mars Sample Return mission. This parachute will both larger and heavier than previous Mars missions, requiring a high mortar muzzle velocity to achieve a suitable bag strip ratio for successful deployment. A simple model was generated to predict the relative velocity between the parachute canopy and the deployment bag during bag strip. To reduce risk of canopy damage and better understand mortar velocity upper bound, the Dynamic Extraction Testbed originally used for ExoMars testing was revamped to simulate parachute deployment at high velocity. A test campaign was planned, using a 300-foot zipline and force device to accelerate a trolley above the maximum predicted velocity of 61 m/s and drop the parachute pack. This campaign has yet to been conducted, but all dynamic modeling is complete and ground support equipment has been designed. A separate mortar ground test campaign was developed to validate the deployment system and ensure that target muzzle velocity could be met. Two of the ten proposed tests have been conducted. Results from the first test indicate unforeseen dynamics associated with the larger system, leading to higher-than-predicted muzzle velocities. These findings were used to refine the mortar model, which then accurately predicted the velocity of the second deployment. A range of data was collected, including high-speed video, dynamic response of the test stand and mortar tube, pressure readings in the mortar tube and gas generator, reaction load, and bridle pin load. Future tests will focus on qualifying the system at temperature requirements.