131   Figure 19. Cross -Section of   Sample Tube and Glove in a   Sheath.               Left: Figure 20. Hermetic Seal Dispenser Cross -Section .  Right: Figure 21. Volume Station Cross -Section .                  Assembly and Test  Program  

Three ACA units were assembled to support ground testing and flight operations:  an Engineering Model  (EM), Flight Model 1 (FM1), and Flight Model 2 (FM2) . The EM unit was assembled first, consist ing of flight - like stations, and was used for early ground testing of the flight hardware design, including  algorithm  development of station interactions for flight software purposes . Successful first -time end- to-end operations  were conducted on the EM ACA in an Earth ambient environment . The EM unit was moved into a thermal  vacuum chamber where it is currently part of an SCS testbed for full end- to-end testing at Mars pressure  and temperature using analog samples . This testbed is known as QMDT, or Qualification Model Dirty  Testing, where dirty testing is conducted  to allow  for evaluation of hardware life and performance through  dust interaction. Drilling into rocks generates a lot of dust, whi ch can be monitored to understand where it  goes, and how well the mechanisms continue to operate over time in that  environment . This testbed is as  flight -like as possible, utilizing a QM (Qualification Model) Corer  attached to an QM Turret on an EM RA,  with the EM ACA . 

The FM1 ACA was assembled after the EM ACA and was the first ACA to be exposed to 3-axis random  vibration and thermal vacuum functional testing. Since station interaction sequences were not developed  in time for FM1 functional testing, only range of motion and aliveness checks were performed for active  mechanisms , and no passive mechanisms were tested, which would require robotic manipulation via the  SHA. The functional  check -outs were conducted before and after vibration testing, as well as at cold  temperatures ( -110°C and -70°C) and Mars pressure ( between 5 and 10 torr) in a thermal vacuum chamber  to verify functionality . Heat-to-use operations were verified below -70°C for  wet lubricated mechanisms .  Upon the completion of ACA -level testing, the FM1 ACA was installed in the flight Rover to support  Assembly, Test, and Launch Operations  (ATLO) testing with the flight vehicle. This testing included random  vibration and functional testing of the Rover in thermal vacuum at Mars press ure and temperature and is  part of validation for flight readiness . During the Rover thermal vacuum test campaign, limited station  interaction was performed on the FM1 ACA to validate force and position sensing of ACA hardware via  flight avionics, which was the only opportunity with the flight vehicle at Mars conditions prior to launch . Since  the entire Sampling and Caching System was available on the Rover during thermal vacuum testing, bit  exchange operations were conducted, which allowed for the flight R A to dock with the FM1 BC and the  Corer to remove and return bits to the carousel . The opportunity to test this functionality on the flight vehicle  Sample  Tube   Sheath   Sample  Tube Ball - Lock in  Sheath   Glove   Cover   Hermetic  Seal  Stack (7 

Advancing  Mechanism  for Seal  Dispensing   Volume  Probe