Mars Organic Molecule Analyzer (MOMA) Mass Spectrometer Status and Science Operations on the ExoMars Rover
Monday, 15 December 2014
The Mars Organic Molecule Analyzer (MOMA) investigation on the 2018 ExoMars rover will examine the chemical composition of samples acquired from depths of up to two meters below the martian surface, where organics may be protected from radiative and oxidative degradation. MOMA combines analyses of acquired drill fines via (i) pyrolysis gas chromatography mass spectrometry (GCMS) and (ii) Mars ambient laser desorption mass spectrometry (LDMS), enabled by a fast-valve capillary ion inlet system. This “dual source” approach gives MOMA unprecedented breadth of detection over a wide range of molecular weights and volatilities. Analysis of nonvolatile, higher-molecular weight organics such as carboxylic acids and peptides even in the presence of significant perchlorate concentrations is enabled by the extremely short (~1 ns) pulses of the desorption laser. Use of the MOMA ion trap’s tandem mass spectrometry (MS/MS) mode permits selective focus on key species for isolation and controlled fragmentation, providing structural analysis capabilities. The flight-like engineering test unit (ETU) of MOMA’s ion trap mass spectrometer has been put through a battery of tests to assure robustness of operation in the martian environment, to assess science performance, and to prepare for the flight model build under extremely sterile conditions as required by ExoMars. These tests have included coupling campaigns with advanced prototypes of the MOMA GC (provided by the University of Paris) and the MOMA tapping station, ovens, and laser (provided by MPS and LZH). Planning for science operations has expanded with the development of scripts for MOMA’s various parameterized modes, including MS/MS. Given the limited duration of the baseline mission (218 sols), MOMA will benefit from a thorough characterization of its performance with a variety of Mars analog samples and a careful comparison with current science results from the SAM experiment on MSL. Such preparation will enable efficient use of resources when MOMA analyzes unknown martian samples in conjunction with other ExoMars instruments such as the MicrOmega and Raman spectrometers.