Saturday 25th August Sol 19

In the next few days we are expecting the first measurements by the SAM mass spectrometer instrument (inlet on the top surface of Curiosity) of the Mars atmosphere.   The first situ measurements of the Martian atmosphere were made by Viking in 1976. Owen and Biemann published the first noble gas isotopic ratio obtained on the surface of another planet, argon-36 to argon-40, as 2750±500.  Viking also found upper limits for other noble gases and their ratios.  Three years later, the meteorite Elephant Moraine 79001 was discovered in Antarctica.  EETA 79001 belongs to the group of SNC meteorites, and there was debate that those young basalts might be from Mars.  This meteorite is composed of three different rock types, one of which is glass produced by high velocity impact on its parent body.  In this glass Bogard and Johnson in 1983 found noble gases that they compared to the Viking data.  Their findings supported earlier suggestions that EETA 79001 and other meteorites form the same group are from Mars.