Methane release from meteoritic material under Mars – like UV radiation

Abstract

Since the detection of Martian atmospheric methane in 2004, a lot of scientific debate has followed concerning the potential sources and mechanisms that cause its presence. The short photolytic lifetime of methane on Mars (Krasnopolsky et al., 2004) implies the existence of a constant emission source over or below the surface of the planet. Recommended geological and biological emission processes are confoundedly small and unable to explain the observed mixing ratio values.

Mars' location next to the asteroid belt exposes the planet to a heavy rain of meteorites; with some types like carbonaceous chondrites containing a few percent of organic material. Unlike Earth, the atmosphere of Mars does not have an ozone layer that filters a significant fraction of ultraviolet (UV) radiation. In this project it is shown that when a carbonaceous chondrite type (Murchison meteorite) is exposed to Mars surface like UV radiation levels, a part of its organic molecules interacting with UV is converted and outgassed as methane. By looking at the depth profiles of different elements through nanoSIMS analysis, an effort was made to investigate the solid carbon balance and distinguish the penetration depth of UV under the meteoritic surface.

The understanding of meteorite interactions with ultraviolet radiation can give a more thorough view of their contribution to the atmospheric composition of Mars, as well as to the primordial Earth.