The second Technology Demonstration Unit (TDU2) of the Spacecraft Atmosphere Monitor (S.A.M.) is a miniaturized gas chromatograph mass spectrometer (GC/MS) instrument for monitoring the chemical composition of cabin air for human spaceflight missions. TDU2 was delivered to the International Space Station (ISS) on November 9, 2023, with the SpaceX 29th commercial resupply services mission (CRX-29). TDU2 will continuously monitor the major atmospheric constituents (MCA) and trace organic volatiles (TGA) with relative abundances ranging from parts per billion (ppb) to parts per million (ppm). The TDU2 uses the quadrupole ion trap mass spectrometer (QITMS) sensor and includes a micro-electromechanical system (MEMS) preconcentrator, gas chromatograph, and microvalve system. The ruggedized miniature form factor allows the aisle deployment of TDU2 to monitor cabin air quality in different locations and during various crew activities. We will discuss the operational performance of TDU2 and report on its first onboard measurements of more than twenty TGA compounds identified as harmful to cabin crew during long exposures.
Madzunkov et al. (Sun,) studied this question.