The ongoing development for the European Space Agency (ESA) aims for long duration missions like the ISS (International Space Station). A longer term perspective would involve establishing a moon base and possibly missions to an asteroid and to Mars. A key factor to the success of such missions is the assurance of the health and safety of its crew. Continuous monitoring of the mission environment therefore plays an important role in the process. Together with OHB System AG, SINTEF developed an FTIR (Fourier Transform Infra-Red) system for ESA, which performs air quality monitoring through optical multi-gas measurements.
The system consists of off-the-shelf or modified FTIR hardware and specially developed analysis software. The software includes novel compensation methods for hardware imperfections and insufficiencies, allowing the successful simultaneous monitoring of over 30 frequently detected air contaminants in the presence of water vapour, carbon dioxide, and methane. In a blind sample test campaign for NASA, an early version of ANITA was ranked first with a significant lead over its competitors.
The launch of the latest prototype of ANITA to the ISS was performed in August 2007 by Space Shuttle Endeavour, flight STS-118. ANITA was installed for testing in the US lab Destiny in cooperation with NASA, and the system start-up took place in September. After an initial 10-day test phase, formally as a scientific experiment, the system was set to gather information on the indoor air quality on the ISS.
ANITA’s standard operation in space was fully automatic with a time resolution of 6 minutes. In addition, a few non-local air samples were taken manually, using a hand pump and a sample bag, and fed to ANITA for automatic analysis. Thanks to ANITA’s successful operation, giving new and very valuable information on the gas status and air dynamics in the spacecraft air, the operation was extended until august 2008. Further operation after that was no longer possible, because of a long-planned relocation of the indoor infrastructure on the ISS.
The data from ANITA achieved several “firsts” on the ISS. A few gases were for the very first time measured in air inside the ISS, or even sampled from the ISS. One of these gases was entirely unexpected to be present at measurable quantities. Many gases were for the first time measured onboard, i.e. without having to wait for air samples to be returned to ground for analysis. And even more gases were for the first time measured with high time resolution. The work was awarded the Wright Brothers Medal for 2009.
In the figure below, an example plot shows ANITA measurements on two accidental PFP (perfluoropropane) leakages on April 29 and May 23, 2008. Before ANITA, PFP was known to be in the air on the ISS because of its presence in Russian cooling systems, but it could never be measured. ANITA provided regular measurements as well as precise timing, size, and possible long-term effects of any leakages. ANITA also revealed that the countermeasures supposed to clean the PFP from the air were entirely unsuccessful, so that, as a consequence of the ANITA measurement results, the attempted countermeasures were just turned off.
The next version of the system, ANITA2, is currently under development. It is planned to perform air quality monitoring on the ISS from 2020.
Other possible application areas for such systems and techniques include monitoring of indoor air and industrial processes.
Graph from ANITA on PFP (perfluoropropane) measured on the ISS from April 26 to May 24, 2008. Two leakages of April 29 and May 23 are clearly seen. The first leakage quickly raised the ISS air concentration of PFP from 6 to 118 ppm (parts per million). The PFP oscillations that occur in periods of the time are also real, demonstrating a coupling between CO2 removal and PFP in the air that was previously unknown.