Science: After spending a full year on Mars, the Curiosity rover has confirmed its earlier finding that the planet’s atmosphere contains almost no methane. The finding is significant because methane is often a waste product of living organisms. The lack of the chemical in the atmosphere doesn’t disprove the existence of life on Mars, but it does make it less likely. And the finding challenges previous detections of possible localized methane pockets that then quickly disappeared. Those measurements came from orbiters and remote observers. Curiosity has much better detection ability and places the upper limit of methane in the atmosphere at 1.6 parts per billion. That is lower than expected if the previous localized methane blooms had dispersed through the atmosphere.