Focus mechanism for EXOMARS mission: lessons learned from preliminary design to space flight model delivery

Abstract

The CLUPI (CLose-UP Imager) instrument is a high-resolution camera mounted onto the Drill of the ExoMars 2020 rover mission carried out by the European Space Agency (ESA) and Roscosmos. The CLUPI development is under the responsibility of Thales Alenia Space Switzerland whereas the Principal Investigator is Dr. Jean-Luc Josset from the Space Exploration Institute. In the frame of the development CLUPI instrument, the CSEM developed and delivered three models of a flexure-based Focus Mechanism. The CLUPI Focus Mechanism (CFM) design utilizes flexure guides to allow very accurate frictionless adjustment of the focal distance of the imager. Such design must also comply with very stringent requirement from the ExoMars mission, especially regarding the low Martian temperatures and the launch/landing load environment. This article presents the three main challenges encountered during the development of the mechanism and how these were addressed: resilience, performance and reliability. This article then draws the lessons learnt from this development including potential design improvements for a similar design and general rules to applicable to any development involving compliant mechanism.