(AGI) Madrid, Dec 16 - Robotic rover Curiosity has detectedregular emissions of methane gas in the Martian atmosphere, butnot found its source. Scientists are working on what is causingthe gas, which could be microbial, and what is causing itslevels to vary so fast. Readings taken by a spectrometer and aSample Analysis at Mars laboratory on board Curiosity over 20months show that regular emissions in the Gale crater are lesssignificant than predicted, but continuous, according to areport to the annual American Geophysical Union meeting in SanFrancisco, said the magazine Science. The gas is believed to byproduced periodically by a source nearby. Methane is known forits biological activity, as almost everything in earth'satmosphere originates from it. Curiosity was able to takeprecise measurements: it identified baseline values ofconcentrated methane of around 0.7 parts per billion in volume,and confirmed spikes of up to 10 times this in a period of 60suns, or Martian days, which last 24 hours, 39 minutes and35.244 seconds. The fact that the jets of methane are sporadicmay suggest a correlation with environmental variables, such asthe relative humidity of air or environmental temperature. Onehypothesis is that rises in atmospheric pressure correspond tospikes in methane levels. Further research is required. (AGI) . .