"A cloud came and a cloud went," said Paul Mahaffy, who supervised the sample analysis of Curiosity at Mars (SAM) instrument, during a NASA Town Hall event at the Astrobiology Science Conference on Monday. "We are very confident in the measurement."
When the news of Curiosity's startling findings over the weekend was spread, many suggested that high methane could indicate the possibility of life on Mars. Methane is an important molecule on Earth and is excreted by many living organisms, including microbes.
Mahaffy explained that Curiosity found unusually high levels of methane in a routine experiment that investigated the concentration of molecules in the atmosphere last Wednesday. The data came back Thursday and showed a methane content of 21 parts per billion – about three times higher than ever before. Because of this, Curiosity's weekend plans were discarded to re-run the experiment.
"The methane cloud has disappeared … it is now sinking back below 1 part per billion," Mahaffy said, noting that the measurement was consistent with the previous one seen on Mars.that methane detection apparently came from a "temporary cloud" and Curiosity was not equipped with the appropriate tools to tell us whether the cloud was biological or biological geological origin.
What does that mean for life on Mars? Well, not much. Although the original findings have been confirmed, we are not yet closer to discovering its source – it depends on some spaceships orbiting the Red Planet and future Mars missions. In addition, the methane spike is certainly an unusual phenomenon that scientists have seen earlier.
"The methane puzzle continues," said Ashwin Vasavada, curiosity project scientist at NASA, in a statement. "We are more motivated than ever to continue measuring and putting our brains together to find out how methane behaves in the Martian atmosphere."