Estimating Ion Escape from Unmagnetized Planets

TL;DR

This paper introduces a novel method combining observations and models to estimate ion escape rates from unmagnetized planets, exemplified by Mars, aiding understanding of planetary atmospheric loss.

Contribution

A new approach that integrates observational data with hybrid plasma modeling to estimate ion escape rates from unmagnetized planets.

Findings

Estimated Mars heavy ion escape rate: 2×10^{24} ions/sec

Method applicable to extreme solar wind conditions

Enables study of escape dependence on various parameters

Abstract

We propose a new method to estimate ion escape from unmagnetized planets that combines observations and models. Assuming that upstream solar wind conditions are known, a computer model of the interaction between the solar wind and the planet is executed for different ionospheric ion production rates. This results in different amounts of mass loading of the solar wind. Then we obtain the ion escape rate from the model run that best fit observations of the bow shock location. As an example of the method we estimate the heavy ion escape from Mars on 2015-03-01 to be $2\cdot 10^{24}$ ions per second, using a hybrid plasma model and observations by MAVEN and Mars Express. This method enables studies of how escape depend on different parameters, and also escape rates during extreme solar wind conditions, applicable to studies of escape in the early solar system, and at exoplanets.