Flight Laser Module Monitoring During ExoMars Raman Laser Spectrometer Environmental Testing

The flight units of the laser module for the Raman Laser Spectrometer (RLS) instrument of the ExoMars mission were manufactured, tested and finally delivered in March 2018. Based on the data collected during flight batch acceptance testing, FM and FS lasers were picked from that batch, and the former was subsequently tested at the next integration levels, i.e. RLS instrument, Analytical Laboratory Drawer (ALD) and ExoMars rover itself. As the system complexity increased, the data available for laser performance assessment became sparse due to shorter testing slots and to the basic information available through instrument telemetries and products. In order to assess the status of the laser module during these years of on-ground testing we have developed tools to extract as much information as possible from test sessions. Our starting inputs were some relevant house-keepings, such as laser optical power and temperature, and Raman spectra, from where laser spectral signature was obtained. Our analysis of the available on-ground test sessions at ALD and rover level show that the laser unit is working properly, but a fine tune of the working temperature setpoint may be required to provide optimal scientific return. The procedures developed will be also highly valuable for the definition of the laser performance assessment engineering tools during standard scientific operation in Mars.