66 Table 3: EQM and FM compliance to CFM performance requirement s  Requirement (measurement)  EQM  FM  Positioning  repeatability  of +/-20µm ~ At the limit    Positioning  resolution of 5 µm ~ At the limit    Mobile stage parallelism at rest position  better than 0.1°   < 0.034°   < 0.043°   Mobile stage concentricity at rest  position better than 50 µm  < 61 µm  Exceeded by ~ 20%  < 30 µm  Mobile stage parallelism stability along  stroke better than 0.1°   < 0.068°   < 0.12°   Exceeded by ~20%   Mobile stage lateral shifts along stroke  (concentricity stability) better than 20 µm  < 68 µm  Exceeded by x 4   < 114  µm  Exceeded by x 6  

It is worth noting that after delivery of the instrument to ESA, the optical performance was  assessed in the  instrument calibration campaign to be acceptable.  

Reliability   Reliability of systems  for space is an essential requirement: the system must  work reliably throughout  its  complete lifetime as no repair can occur after launch. In the case of the CLUPI mechanism the reliability of  the guiding structure was quite straight forward once on Mars and safely released from its launch lock,  since normal operation does not generate any stresses significant for fatigue consideration, the mechanism  is safe from any risk of failure. Considerable efforts were made to ensure that the actuator and sensors  were compatible to 300 sols in the Martian environment  [3]. Additionally,  all routing, soldering and contact  crimping was made according to the relevant ECSS standard.  

Thus , the major of risk of failure of the mechanism is  related to the launch lock system: if the launch lock  fails to release, the CLUPI instrument capability would be considerably reduced as the instrument would  only be able to image target at a fixed defined distance (about 26 cm). In order to reduce this risk, the  following mitigations wer e implemented:  

• The locked position of the optics  corresponds  to a working distance at which some critical operation  of the instrument can still be c arried out : while locked, the instrument is capable to image the drilled  core sample collected by the rover drill and placed into the sample drawer [ 1]. 

• The actuation system of the launch lock system is a space- qualified non- explosive actuator (NEA)  manufactured by Eaton.  

• Extensive testing of the launch locking system was carried out at breadboard level  in order to  ensure that the coating of the friction surfaces and the actuation forces were selected with sufficient  margin: not enough margin and the launch lock may not release; too much margin and the NEA  released energy propagates to the guiding struct ure and may damage it. This early testing included  many force measurements  to assess the friction coefficient best  and worst -case  values.  Furthermore,  high-speed imagery of the unlocking process allowed for a better understanding of  the propagation of the released energy onto the guiding structure [3]. 

Despite these efforts , the launch locking mechanism remained a very sensitive component with its  reliability  and efficiency excessively dependent  on the resetting procedure. Two important  observations were made  during the qualification of the EQM, one of which led to a partial failure during the thermal -vacuum   qualification test.