After the discovery of of water on Mars, few weeks ago, the Curiosity rover is still performing this work. Actually, while the NASA was out due to the shutdown during 2 weekend, the +NASA 's rover analysed the Martian atmosphere. These analyses confirm that some meteorites that have dropped to Earth really are from the Red Planet.
A key new measurement of the inert gas argon in Mars' atmosphere by the laboratory on-board the rover, provides the most definitive proof yet of the origin of Mars meteorites while at the same time giving a way to rule out Martian origin of other meteorites.
The Curiosity measurements do not directly measure the current rate of atmospheric escape, but NASA's next mission to Mars, the Mars Atmosphere and Volatile Evolution Mission (MAVEN), is designed to do so. This mission is being prepared at NASA’s Kennedy Space Center in Florida for a launch around November 18th 2013.