The methane rain that seems to have carved its surface would stop. Lakes, puddles and streams would dry up. Titan would lose its mystique and turn into just another satellite with thin air. Our understanding of geophysical, chemical and biological processes has helped narrow the field of possible sources on Mars, and many of the same arguments apply to Titan as well. Split by Sunlight The first step to answering the question is to determine the rate at which methane must be produced or delivered.
That, in turn, depends on how fast the gas is being removed from the atmosphere. At altitudes of 60 kilometers and higher above the Martian surface, solar ultraviolet radiation splits methane molecules apart. Lower in the atmosphere, oxygen atoms and hydroxyl radicals OH , which form when water molecules are broken apart by ultraviolet photons, oxidize methane. Without being resupplied, methane would gradually disappear from the atmosphere. On Titan, where solar ultraviolet radiation is much weaker and oxygen-bearing molecules are substantially less abundant, methane can last 10 million to million years which is still a short time in geologic terms.
They may be a sign that the gas comes from localized sources or disappears into localized sinks. One possible sink is chemically reactive soil, which could accelerate the loss of methane. If such additional sinks operated, it would take an even larger source to maintain the observed abundance. The next step is to consider potential scenarios for forming methane. The Red Planet is a good place to start because its methane abundance is so low.
For a year lifetime, a little over metric tons of methane would have to be produced each year to maintain a constant global average of 10 ppbv. That is about a quarter-millionth the production rate on Earth. As on Earth, volcanoes are most likely not responsible. Martian volcanoes have been extinct for hundreds of millions of years. Extraplanetary contributions also appear minimal.
Some 2, tons of micrometeoritic dust are estimated to reach the Martian surface every year. Less than 1 percent of their mass is carbon, and even this material is largely oxidized and hence an insignificant source of methane.
Comets are about 1 percent methane by weight, but they strike Mars only once every 60 million years on average. Thus, the amount of methane delivered would be about one ton a year, or less than 1 percent of the required amount. Could it be that a comet struck Mars in the recent past? It could have delivered a large amount of methane, and over time the abundance in the atmosphere would have declined to its present value. An impact of a comet meters in diameter years ago, or a comet meters in diameter 2, years ago, could have supplied sufficient methane to account for the currently observed global average value of 10 ppbv.
But this idea runs into a problem: the distribution of methane is not uniform over the planet. The time it takes to distribute methane uniformly vertically and horizontally is at most several months. Thus, a cometary source would result in a uniform methane distribution over Mars, contrary to observations. Smoke in the Waters That leaves us with two possible sources: hydrogeochemical and microbial.
Either one would be fascinating. Macdonald and Bruce P. Luyendyk; Scientific American , May ]. Please click here to see any active alerts. Methane CH 4 is a hydrocarbon that is a primary component of natural gas. Methane is emitted from a variety of anthropogenic human-influenced and natural sources.
Anthropogenic emission sources include landfills, oil and natural gas systems, agricultural activities, coal mining, stationary and mobile combustion, wastewater treatment, and certain industrial processes.
Methane is the second most abundant anthropogenic GHG after carbon dioxide CO 2 , accounting for about 20 percent of global emissions. All rights reserved. Share Tweet Email. Why it's so hard to treat pain in infants. This wild African cat has adapted to life in a big city. Animals Wild Cities This wild African cat has adapted to life in a big city Caracals have learned to hunt around the urban edges of Cape Town, though the predator faces many threats, such as getting hit by cars.
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These efforts, experts say, will be crucial not just for spotting leaks but also developing regulations and guiding enforcement — both of which are sorely lacking. Earlier satellites, such as the Japan Aerospace Exploration's Gosat launched in , were able to detect methane, yet their resolution wasn't good enough to identify specific sources.
But satellite technology is now advancing rapidly, boosting sensor resolution, shrinking size, and gaining a host of cutting-edge capabilities. Companies like French Kayrros are using artificial intelligence to enhance satellite imaging, paired with air and ground data, to provide detailed methane reports. In the past year, methane-hunting satellites have made a number of concerning discoveries. Satellites also observed sizeable releases from gas pipelines in Turkmenistan , a landfill in Bangladesh , a natural gas field in Canada , and coal mines in the US Appalachian Basin.
At any given time, according to Kayrros , there are about high-volume methane leaks around the world, along with a mass of smaller ones that add significantly to the total. Targeting emitters on a global scale from space, the European Space Agency says, provides "an important new tool to combat climate change". Now, Carbon Mapper is developing what it promises will be the most sensitive and precise tool for spotting point sources yet. The project aims to launch two satellites in , eventually growing to a constellation of up to 20 that will provide near-constant methane and CO2 monitoring around the globe.
Partners include Nasa's Jet Propulsion Laboratory, the California Air Resources Board, private satellite company Planet, and universities and nonprofits, with funding from major private donors such as Bloomberg Philanthropies. The impetus is the current global monitoring gap, says Riley Duren, a remote-sensing scientist at the University of Arizona and Carbon Mapper chief executive. The project's main focus is to find super emitters, Duren says.
Landfills produced the biggest share of the state's overall emissions in that survey, followed by agriculture and then oil and gas. The survey pointed out the need to "scale that up and operationalise it globally by going into space", Duren says. The orbiters will employ "hyperspectral" spectrometers designed by the Jet Propulsion Laboratory, which the project's website says will provide "unparalleled sensitivity, resolution and versatility.
When emissions are detected, subscribers to a rapid alert service will be notified within 24 hours by Planet , a private, San Francisco-based satellite operator that will build and manage the Carbon Mapper satellites. The satellites will enhance the California Air Resources Board's monitoring with wider and more frequent coverage, says Jorn Herner, who heads the board's emissions monitoring program. Monitoring now is done once a quarter, he says.
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