Curiosity Rover Traces Mars' Vanishing Atmosphere

Ashwin Vasavada, Mars Science Laboratory Deputy Project Scientist, gives a Curiosity Rover update. The Sample Analysis at Mars (SAM) instrument suite recently tested Mars' atmosphere, comparing the amount of argon-36 to a heavier form of the gas, argon-38. SAM found that the mix of argon at Mars today is heavier than in the Earth's atmosphere, the Sun, and in Jupiter. These measurements are evidence that Mars once had a thicker atmosphere, and much of it was lost long ago. This helps explain the evidence from rivers and lakes in the past, in spite of the cold and dry conditions today.