WDS>1. The Curiosity rover detected time-varying methane concentration in Mars atmosphere, changing by factor>10 over a several-month period. They claim the usual "background" level is about 0.7+-0.25 parts per billion, but it has gone as high as 7.2+-2.1 ppb at least locally near Curiosity (these are 95% confidence intervals). Earth based telescope observations have been claimed to see Mars-wide changes in methane, spiking as high as 60 ppb. To put this in perspective, the total amount of methane (at background level) in the whole Mars atmosphere, is about 200 metric tons. Meanwhile the total amount in the Earth's atmosphere at any time is about 500,000,000 metric tons. 2. Also, it found chlorobenzene in a mudstone rock sample (something like dried clay). Chlorobenzene is the most abundant organic found in that sample (as well as the most complex; several chloro-alkanes were also found) with concentrations between 150 and 300 parts per billion. Chlorobenzene does not occur naturally on Earth but is present in pollution. <WDS Presumably there are microorganisms in the harshest terrestrial deserts. Could Curiosity detect these? I'm guessing the methane is primordial. It's looking really glum for life on Mars. --rwg