Ion Temperatures Near the Martian Exobase
Abstract
The Mars Atmosphere and Volatile EvolutioN (MAVEN) has shown that the escape of charged particles to space has contributed significantly to the loss of Mars's atmosphere. Ions can be accelerated to escape energy by multiple processes, such as magnetic tension forces, ambipolar potentials, and wave heating, before leaving the Mars system through the ion plume or down the magnetotail. Some of these processes require that ions first be transported to high altitudes from their source regions in the upper atmosphere; however, the initial acceleration of ions in the vicinity of the exobase (~200 km altitude) is not well understood.
To address this outstanding question, we use data collected by the MAVEN SupraThermal and Thermal Ion Composition (STATIC) instrument. The elliptical orbit of MAVEN samples from several scale heights below to well above the exobase, allowing observations of the densities, temperatures, and velocities of different ion species over a large range of altitudes. By using several independent methods of calculating ion temperatures from STATIC measurements, we aim to construct a continuous temperature profile for each major ion species from MAVEN's periapsis near 150 km altitude, up to the regions from which ions can escape. Using these temperature profiles in combination with densities, velocities, and information about local magnetic topology, we begin to characterize the initial acceleration of ions at low altitudes, with the goal of understanding the physical processes responsible.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.P41B3443H
- Keywords:
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- 0343 Planetary atmospheres;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 6225 Mars;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS;
- 5405 Atmospheres;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 5445 Meteorology;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS