Methane - Extraterrestrial Methane

Extraterrestrial Methane

Methane has been detected or is believed to exist in several locations of the solar system. In most cases, it is believed to have been created by abiotic processes. Possible exceptions are Mars and Titan.

  • Venus – the atmosphere contains a large amount of methane from 60 km (37 mi) to the surface according to data collected by the Pioneer Venus Large Probe Neutral Mass Spectrometer
  • Moon – traces are outgassed from the surface
  • Mars – the Martian atmosphere contains 10 nmol/mol methane. The source of methane on Mars has not been determined. Recent research suggests that methane may come from volcanoes, fault lines, or methanogens, or that it may be a byproduct of electrical discharges from dust devils and dust storms, or that it may be the result of UV radiation. In January 2009, NASA scientists announced that they had discovered that the planet often vents methane into the atmosphere in specific areas, leading some to speculate this may be a sign of biological activity going on below the surface. Analysis of observations made by a Weather Research and Forecasting model for Mars (MarsWRF) and related Mars general circulation model (MGCM) suggests that it is potentially possible to isolate methane plume source locations to within tens of kilometers, which is within the roving capabilities of future Mars rovers. The Curiosity rover, which landed on Mars in August 2012, is able to make measurements that distinguish between different isotopologues of methane; but even if the mission is to determine that microscopic Martian life is the source of the methane, the life forms likely reside far below the surface, outside of the rover's reach. Curiosity’s Sample Analysis at Mars (SAM) instrument is capable of tracking the presence of methane over time to determine if it is constant, variable, seasonal, or random, providing further clues about its source. The first measurements with the Tunable Laser Spectrometer (TLS) indicated that there is less than 5 ppb of methane at the landing site at the point of the measurement. The Mars Trace Gas Mission orbiter planned to launch in 2016 would further study the methane, as well as its decomposition products such as formaldehyde and methanol.
  • Jupiter – the atmosphere contains about 0.3% methane
  • Saturn – the atmosphere contains about 0.4% methane
    • Iapetus
    • Titan — the atmosphere contains 1.6% methane and thousands of methane lakes have been detected on the surface In the upper atmosphere the methane is converted into more complex molecules including acetylene, a process that also produces molecular hydrogen. There is evidence that acetylene and hydrogen are recycled into methane near the surface. This suggests the presence either of an exotic catalyst, or an unfamiliar form of methanogenic life. An apparent lake of liquid methane has been spotted by the Cassini-Huygens probe, causing researchers to speculate about the possibility of life on Titan. Methane showers, probably prompted by changing seasons, have also been observed.
    • Enceladus – the atmosphere contains 1.7% methane
  • Uranus – the atmosphere contains 2.3% methane
    • Ariel – methane is believed to be a constituent of Ariel's surface ice
    • Miranda
    • Oberon – about 20% of Oberon's surface ice is composed of methane-related carbon/nitrogen compounds
    • Titania – about 20% of Titania's surface ice is composed of methane-related organic compounds
    • Umbriel – methane is a constituent of Umbriel's surface ice
  • Neptune – the atmosphere contains 1.6% methane
    • Triton – Triton has a tenuous nitrogen atmosphere with small amounts of methane near the surface.
  • Pluto – spectroscopic analysis of Pluto's surface reveals it to contain traces of methane
    • Charon – methane is believed present on Charon, but it is not completely confirmed
  • Eris – infrared light from the object revealed the presence of methane ice
  • Comet Halley
  • Comet Hyakutake – terrestrial observations found ethane and methane in the comet
  • Extrasolar planets – methane was detected on extrasolar planet HD 189733b; this is the first detection of an organic compound on a planet outside the solar system. Its origin is unknown, since the planet's high temperature (700 °C) would normally favor the formation of carbon monoxide instead. Research indicates that meteoroids slamming against exoplanet atmospheres could add organic gases such as methane, making the exoplanets look as though they are inhabited by life, even if they are not.
  • Interstellar clouds

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