Methane on Mars could signal life New Scientist

Methane has been detected on Mars by three independent groups of scientists. And this could be a sign of life – indicating methane-producing bacteria. But scientists are advocating caution when interpreting the results, saying that the instruments looking for chemical signatures in the Martian atmosphere are not yet good enough to conclusively detect methane. Even if methane exists on Mars, the gas could be a product of non-biological processes such as active volcanoes.