In 2012, NASA’s Curiosity rover landed on Mars. Its investigations suggested that Mars was once a potentially habitable planet. Curiosity’s most exciting observation is the abundances of methane in Mars’s atmosphere. Curiosity builds a background signal of methane of 0.41 part per billion by volume. The periodic spikes have the potentiality to increase atmospheric methane to 21 ppbv.
All methane emissions have biological origins on Earth. Methane can be a biosignature on Mars. This can be a chemical trace produced by life. Scientists tried to rule out methane’s nonbiological origins.
Scientists investigated where methane emissions can take place. They used a method called “back-trajectory analysis.” They used models based on Mars’s atmosphere. They tried to track a parcel of air backward in time from the moment of its measurement. Scientists noted seven methane spike events by using a global climate model of Mars. This model stimulated how wind could transport methane around Mars.
Scientists stimulated the backward trajectory of each spike of methane. They based it on wind patterns from various seasons and times of a day. Scientists noted that the spikes originated from the same area which is the north western part of Gale crater. Scientists think this crater hold liquid water once.
But scientists have questioned Curiosity’s detections of methane on Mars. The European-Russian ExoMars Trace Gas Orbiter (TGO) has not detected the same abundance of methane in Mars’s atmosphere which Curiosity has detected from Mar’s surface. The TGO has been investigating Mars from orbit since 2016.
Scientists think it is geological mechanism. This mechanism quickly sequesters methane from the atmosphere. It can also be an atmospheric mechanism trapping it near the surface. Scientists will do further research on where the methane originates. Curiosity is continuing to make measurements of methane abundance to capture more methane spike events.