page_title: Atmospheric escape
section_title: Sputtering escape
hierarchical_section_title: Atmospheric escape / Non-thermal (suprathermal) escape / Sputtering escape
caption_attribution_description: English: Charge exchange collision between ion and neutral
context_page_description: Atmospheric escape is the loss of planetary atmospheric gases to outer space. A number of different mechanisms can be responsible for atmospheric escape; these processes can be divided into thermal escape, non-thermal escape, and impact erosion. The relative importance of each loss process depends on the planet's escape velocity, its atmosphere composition, and its distance from its sun. Escape occurs when molecular kinetic energy overcomes gravitational energy; in other words, a molecule can escape when it is moving faster than the escape velocity of its planet. Categorizing the rate of atmospheric escape in exoplanets is necessary to determining whether an atmosphere persists, and so the exoplanet's habitability and likelihood of life.
context_section_description: Excess kinetic energy from the solar wind can impart sufficient energy to eject atmospheric particles, similar to sputtering from a solid surface. This type of interaction is more pronounced in the absence of a planetary magnetosphere, as the electrically charged solar wind is deflected by magnetic fields, which mitigates the loss of atmosphere.
caption: The fast ion captures an electron from a slow neutral in a charge exchange collision. The new, fast neutral can escape the atmosphere, and the new, slow ion is trapped on magnetic field lines.[7]
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