Alicia Chang, science writer for the AP, relays some interesting information discovered by Curiosity about the Martian atmosphere:
The Curiosity rover has tasted Mars’ air: It’s made mostly of carbon dioxide with hints of other gases. There was a small surprise: Viking found nitrogen to be the second most abundant gas in the Martian air, but Curiosity’s measurements revealed a nearly equal abundance of nitrogen and argon, a stable noble gas. Several years ago, telescopes on Earth detected a surprising and mysterious belch of methane in three regions in the Martian western hemisphere. On Earth, methane is mainly a byproduct of life — from animal digestion and decaying plants. The gas can also be produced by non-biological processes. Last year, the Curiosity team reported no definitive whiff of methane near the landing site. Since then, the rover has taken several more air samples. There are also plans to sniff the atmosphere for methane during the monthslong drive to Mount Sharp, a 3-mile-high mountain looming from the crater center. NASA in the fall is set to launch a Mars-orbiting spacecraft aimed at solving the methane mystery. Called Maven, the craft will target the Martian atmosphere. Scientists want to know if it actually exists, determine the abundance and whether that varies by year or location, said mission chief scientist Bruce Jakosky of the University of Colorado.