The US Space Agency, NASA, says the Mars exploration vehicle recently recorded a high level of methane on the planet. The discovery is exciting because the presence of methane gas can support the case for life on Mars.
NASA's Curiosity recently recorded the largest amount of methane ever measured during its seven-year Mars mission.
Methane has no color or odor. A special instrument on the curiosity Mars Science Laboratory recorded the increased gas level. The device, called a laser spectrometer, measures levels of chemical elements and gases in the martian atmosphere. In addition to methane, the instrument can record levels of water and carbon dioxide.
Almost all methane gas present in the Earth's atmosphere is produced by biological activity. It usually comes from animals and plants. But it can also be shaped by geological processes, such as the interaction between rocks and water.
NASA said the increased methane was measured at about 21 parts per billion volume (Ppbv). One ppbv means that if you take a volume of air on Mars, one billionth of the air volume is methane.
It was not the first time Curiosity has found methane in the martian atmosphere. About a year ago, NASA announced that curiosity had discovered sharp seasonal increases in gas.
This time, NASA said the measured methane gas level was clearly greater than previously observed. NASA officials even temporarily stopped the Curiosity's other activities to investigate further.
"It's exciting because microbial Life is an important source of methane on Earth, NASA says in a statement announcing the discovery.
The curiosity team, however, conducted a follow-up methane stimulus which showed a sharp decline in gas levels. The second survey showed that the level was less than a part per billion in volume. That number was "near the background curiosity looks all the time," NASA said.
The rise and fall of the methane gas levels left NASA researchers with more questions than answers. The researchers continue to study possible causes of the sudden increase.
"The methane mystery continues," said Ashwin Vasavada, curiosity project researcher at NASA's Jet Propulsion Laboratory in Pasadena, California. "We are more reasoned than ever, to measure and put our brains together to find out how methane behaves in the martian atmosphere. "
Curiosity has no instruments that can accurately identify whether the source of methane is biological or geological. A leading theory is that methane is released from underground areas created by possible life forms that have disappeared long ago.
Although Mars has no active volcanoes, scientists believe that methane can also be produced by reactions involving carbon and water.
A clearer understanding of the methane levels over time can help researchers determine where they are located on March, NASA said. Researchers hope that this understanding will come as curiosity continues to gather methane data in the search for possible life.
I'm Bryan Lynn.
Bryan Lynn wrote this story for VOA Learning English, based on reports from NASA and Agence-France Presse. Caty Weaver was the editor.
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Words in this story
mission – n. An important task, which usually involves traveling somewhere
geological – adj. related to the study of stones, soil and the physical structure of the earth
volume – n. the amount of something
microbial – adj. related to microbes (very small living things)
motivate – v. to get someone to act in a certain way
determine – v. to control or influence directly
locate – v. find or discover the exact position of something