In a finding that has renewed talk about the possibility of life on Mars, NASA's Curiosity rover has detected "unusually high" levels of methane on the Red Planet.

Methane is an odorless, colorless gas that can be produced by simple geological processes as well as by microbes and other living organisms, so the new methane spike doesn't definitively prove that life exists or once existed on Mars.

"While increased methane levels measured by @MarsCuriosity are exciting, as possible indicators for life, it’s important to remember this is an early science result," Thomas Zurbuchen, associate administrator for the science mission directorate at NASA headquarters in Washington, said in a tweet on Saturday.

This image illustrates possible ways methane might be added to Mars' atmosphere (sources) and removed from the atmosphere (sinks). NASA/JPL-Caltech/SAM-GSFC/Univ. of Michigan

NASA said Curiosity scientists needed more time to analyze the new findings and to conduct additional methane observations. A spokesperson for the agency declined a request for more information.

"It's interesting, but we should wait a bit to be sure the data are confirmed," Dorothy Oehler, a senior scientist with the Planetary Science Institute in Tucson, Arizona, said of the methane spike in an email to NBC News MACH. Methane seeps from certain types of rocks on Earth and the same types exist on Mars, she said, "so while we cannot exclude a microbial origin for the methane peaks on Mars, that would not be necessary to explain the detections to date."

Major sources of methane on Earth include the production and distribution of fossil fuels; cattle and other domestic livestock, which produce methane during the digestive process; and the decomposition of waste in landfills and wastewater treatment plants.

The rover's laser spectrometer device detected the methane while the car-size rover was parked at the Teal Ridge site within Gale Crater, a 96-mile-wide dry lake bed that was created millions of years ago by an asteroid impact. Curiosity was sent to the crater in part because its watery past makes it a likely spot to find evidence of past life on Mars.

Previously, Curiosity detected carbon-containing molecules in ancient sediments on Mars as well as seasonal shifts in the levels of atmospheric methane. In a commentary published last June in the journal Nature, Inge Loes ten kate, an astrobiologist at Utrecht University in the Netherlands, called those discoveries "breakthroughs in astrobiology."

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