In-Situ Sounding of the Chemistry and Dynamics of the Turbopause: The Development of a Novel Cryogenic Time-Of-Flight Mass Spectrometer

The underlying physics of the Turbopause, from approximately 80-120 km, remains one of the most poorly understood topics in aeronomy today. However, the composition and dynamics of this region have a profound impact on the local and global climatological behavior of the thermosphere-ionosphere system. A detailed understanding of this region is critical to modern general circulation models and accurately predicting high-altitude weather systems within the mesosphere and lower thermosphere (MLT), which can have a detrimental effect on space and ground-based products. To improve our understanding of the Turbopause we propose the first modern measurements of O, O₂ , N₂, NO, CO₂, H₂O, O₃, and Ar spanning an altitude of 80 to 120 km. To achieve this, we present the Mass Spectrometry of the Turbopause Region (MSTR) program, a NASA HTIDES-funded technology development effort led by Orion Space Solutions (OSS) in partnership with the Southwest Research Institute (SwRI). MSTR is a novel, compact Cryogenically cooled Time-Of-Flight Mass Spectrometer (CTOF-MS) designed to integrate with a variety of aerospace platforms, including sounding rockets, small satellites, and advanced payloads. The flight prototype has a current SWAP of approximately 61 x 27 x 9 centimeters (volume: ~14800 cm3), 8 kg, and 20 to 25 W. MSTR is capable of sampling both ion and neutral elements and has demonstrated a resolving power at full width, half maximum of better than 3500 (predicted 5000), and a mass capability of 2u to 1500u. For integration with low-altitude sounding rockets, the instrument features an integrated 3D printed, liquid helium subcooled nosecone, to reduce and collapse the impinging bow shock experienced during supersonic flight. The MSTR CTOF-MS and cryogenic nosecone have undergone laboratory characterization and TRL advancement. The scientific objectives of the MSTR instrument are to provide simultaneous, in-situ, measurements of the chemistry and structure of the Turbopause as a function of altitude. The MSTR team plans to operate coincidentally with SABER overflights and ground-based LIDAR measurements to characterize the transport of NO across the Turbopause and compare measured CO₂ profiles to those retrieved by remote IR radiometry. Ultimately, the MSTR instrument hopes to improve our understanding of the complex temporal-spatial dynamics of the Turbopuase and MLT and provide valuable data to validate global circulation models.