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Synergistic Science from the MAVEN Accelerometer and Mass Spectrometer

Presentation #307.02 in the session Characterizing the Martian Atmosphere, All the Way Up (Oral Presentation)

Published onOct 23, 2023
Synergistic Science from the MAVEN Accelerometer and Mass Spectrometer

On the NASA Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft, both the Neutral Gas and Ion Mass Spectrometer (NGIMS) and the accelerometer suite (ACCEL) sense the neutral atmosphere at the location of the spacecraft, but do so using two distinct measurement techniques. NGIMS arrives at the total mass density by measuring the number densities of the major atmospheric constituents, while ACCEL arrives at the total mass density by measuring aerodynamic drag on the spacecraft. These mass densities can be used to investigate the response of the lower thermosphere to changing solar conditions, seasons, and dust activity during the nine MAVEN Deep Dips, which are roughly weeklong low-altitude excursions executed by the spacecraft, and the aerobraking period, which was executed in 2019 to modulate the orbit of MAVEN about Mars. The thermosphere is the reservoir of gas which can be lost to space and thus must be thoroughly characterized to determine atmospheric escape rates in the current epoch and the processes responsible for this escape. Characterization of this region is also critical for our understanding of the energy balance of the upper atmosphere, the navigation of spacecraft like MAVEN, and the entry, descent, and landing of probes. The combination of the mass spectrometer and accelerometer data sets provides an excellent opportunity for intercalibration and for synergistic science using thermospheric densities and temperatures, with the objectives of greater confidence in the data and greater science return from the mission. The NGIMS/ACCEL ratio is found to be close to 1, but increases with increasing atmospheric density. At the high densities observed at MAVEN periapsis, the NGIMS total mass density is systematically larger than the ACCEL total mass density by up to approximately 30%. While agreement between the two data sets is relatively good, the slope in the NGIMS/ACCEL ratio remains unexplained, though various potential causes have been explored.

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