Sols 2894-2897: What's Up With Oxygen?

On Curiosity, we regularly look at the atmosphere with ChemCam using a “Passive Sky” observation. Among other things, this allows us to measure the amount of some trace gases in the atmosphere above us, including water vapor and oxygen. Those measurements, now spanning several Mars years, have revealed that oxygen abundances in Gale crater don’t always follow the expected seasonal variation. Possible explanations are that there may be unexpected local or distant oxygen sources or sinks, or unexpected chemical reactions.

Fortunately, the Atmospheric Chemistry Suite (ACS) instrument on the Trace Gas Orbiter is observing the atmosphere over Gale crater twice this month, giving us an opportunity to do some rare joint observations of oxygen abundance from the surface and from orbit. The ACS measurements will tell us how oxygen varies with altitude, down to about 10 kilometers above the surface. If their lowest altitude measurements are very different to what we measure with ChemCam, that might suggest lots of local surface-atmosphere exchange of oxygen is occurring, which would be exciting. We already had one pair of observations back on sol 2880, but a second pair will happen early on sol 2894. We’re hoping that - between these four observations - we’ll be able to understand better the oxygen variations we see.

For Sols 2894-2897 planning, we found out that there was an issue with the arm that prevented us from using it today, so we planned observations that don’t require it. These included three ChemCam LIBS targets (“Duachy,” a diagenetic nodule; “Duntulum,” and “Dervaig”), a ChemCam 12x1 RMI of “Housedon Hill” to finish up long-range imaging of the area, a ChemCam doc image of Dervaig, and a multispectral Mastcam image of the Duachy / Duntulum frame. Mastcam also looked at a clast survey area, to search for aeolian changes since we last looked there on Sol 2878 (see image). Finally, we included measurements of dust and water ice abundances and properties (with Navcam and Mastcam), searches for dust devils and clouds with Navcam, and the usual REMS, DAN, and RAD.