Direct Detection of Biosignature Gasses Using Corrosion-Resistant QIT-MS Sensor for Planetary Exploration

We present a corrosion-resistant quadrupole ion trap mass spectrometer (QIT-MS) for the direct detection of biosignature gasses in chemically reactive planetary atmospheres, such as Venusian clouds. The system employs a Paul trap with hyperbolic titanium alloy electrodes and alumina spacers for chemical durability and precise ion confinement. An yttria-coated iridium filament serves as the thermionic emitter within a modular electron gun capable of axial and radial ionization. Analytes are introduced through fused silica capillaries and crescent inlets into a miniature pressure cell. The testbed integrates high-voltage RF electronics, pressure-regulated sample delivery, and FPGA-based control for real-time tuning. Continuous operation in 98% sulfuric acid vapor for over three months demonstrated no degradation in emitter or sensor performance. Mass spectra revealed H2SO4 fragmentation and thermally induced decomposition up to 425 K. Spectral variations with filament current and electron energy highlight thermal and electron-induced dissociation dynamics. Operational modes include high-resolution scans and selective ion ejection (e.g., CO2+, N2+) to enhance the detection of PH3+, H2S+, and daughter ions. The compact QIT-MS platform is validated for future missions targeting corrosive atmospheres, enabling in situ astrobiological investigations through the detection of biosignature gasses such as phosphine and hydrogen sulfide.