3rd April 2015 Sol 945

The heavy noble gases argon, krypton and xenon are known for their non-reactive nature and on Earth used for many applications where a gas is needed to protect a surface from the reactive species in terrestrial air. Welding under argon atmosphere is one example, and krypton Kr or xenon Xe filled light bulbs for cars is another.

In nature the heavy noble gases are powerful tracers of atmospheric processes, such as loss to space and surface-atmosphere interaction.  For instance Kr and Xe have undergone much less loss to space over time than hydrogen or carbon, so the current heavy noble gas abundances can tell us about the original composition of the martian atmosphere, before much of Mars’ atmosphere was lost about 4 billion years ago.

Curiosity can measure the heavy noble gases in the current atmosphere with the quadrupole mass spectrometer (QMS in the image) in the SAM experiment. But before measuring the noble gases in the atmosphere, other constituents of the Martian atmosphere – such as the CO2 – need to be removed in order to purify the sample. The SAM instrument uses a series of scrubbers and getters to do this. A 2D schematic of the instrument is here: http://ssed.gsfc.nasa.gov/sam/2d/. SAM recently made heavy noble gas measurements – and the exciting news for our team is that one of us (my co-I Susanne P. Schwenzer from the Open University who is an expert in the field of noble gases) recently visited NASA Goddard, where she worked with Dr. Pamela Conrad (SAM Deputy PI) in her new noble gas laboratory and with the recent data.