ANITA Air Monitoring on the International Space Station Part 2: Air Analyses

After the launch to the ISS (International Space Station) with The Space Shuttle flight STS 118 13A.1 on August 9th 2007 and the accommodation in the US lab Destiny, the air quality monitor ANITA (Analysing Interferometer for Ambient Air) has been successfully put into operation. ANITA is a technology demonstrator flight experiment being able to continuously monitor with high time resolution the air conditions within the crewed cabins of the ISS. The system has its origin in a long term ESA technology development programme. The ANITA mission itself is an ESA-NASA cooperative project. ESA is responsible for the provision of the HW, the data acquisition and data evaluation. NASA's responsibilities are launch, accommodation in the US Lab Destiny, operation and data download. The ANITA air analyser is currently calibrated to detect and quantify online and with high time resolution 33 gases simultaneously with down to sub-ppm detection limits. In addition the system has automatic warning capabilities covering possible malfunctions, surprising gases, and gas concentrations above preset limits. However, owing to the experimental character of this ANITA mission, no measurement results are on-line visible to the crew. ANITA's standard, fully automatic mode of operation applies direct air sampling in front of the system. Whenever wanted, air samples for automatic analyses can be taken from any human-accessible position in the ISS or any connected spacecraft and fed to ANITA, applying gas bags and a hand pump. ANITA is an on-orbit test experiment and a precursor for a permanent continuous trace gas monitoring system on the ISS - ANITA II. It further represents a precursor system for future air monitoring in crewed vehicles being developed for the Human Space Exploration programme. This paper is part 2 in a series of two papers. The first paper describes the HW and the ANITA mission itself. This paper is dedicated to the data analysis, including the handling of special challenges and some measurement results. On the ISS, ANITA has measured several gases that, before now, have never properly been measured before, including one unexpected gas. And many gases have for the first time been measured with high time resolution. The observed gas dynamics clearly show effects from spacecraft visits to the ISS, crew activities, the number of crew present, and the functioning of the air revitalisation systems. ANITA gives detailed time resolved information on very different gases such as carbon dioxide and monoxide, methane, ammonia, perfluoro propane, sulphur hexafluoride, siloxanes, and alcohols. It was also demonstrated how ANITA was used to detect and quantify an unexpected gas in the ISS air, and how the system calibration could be updated from ground. The work described has been performed under contract of the European Space Agency.