ANITA2 – Multicomponent Air Analyser for ISS – 2 Years of Operation, Hardware Behaviour and Possible Improvements for Future Versions.

The ANITA2 (Analysing Interferometer for Ambient Air) instrument is a trace gas analyser on board the ISS to monitor cabin atmosphere. ANITA2 has been built in a contract between ESA, OHB and SINTEF and has been commissioned in Q1 of 2022. Since then, ANITA2 is monitoring the ISS gas environment, providing detailed analysis for more than 40 gases in real-time every six minutes. ANITA2 is running 24/7/365 and proved a reliable instrument, delivering more than 130000 data points for each gas over its lifetime. Throughout ANITA2’s operation, all down times (significant interruptions of the measurement cycle) were due to OPS constraints and not imposed by ANITA2.

This paper shows the two setups on board ISS in which ANITA2 has been operated since commissioning. It discusses possible life-limiting items and their aging, and the hardware performance, including opto-mechanical sensitivity, stability, and reliability. The concept for the next generation ANITA is presented and it is shown how lessons learned will be implemented. ANITA2 performance is not limited by optical stability of the instrument but by the fact that absorption spectra of gases are temperature-dependent. Since environmental temperature might vary significantly over time during cis-lunar missions (crewed and uncrewed phases), a concept for gas cell temperature control is proposed.