The most recent expeditions to Mars has been NASA’s Mars Exploration Series which started with the Spirit and Opportunity rovers in 2004
Here are some highlights of their findings:
Opportunity found Hematite which typically forms in water. The opportunity found showed to have an acidic nature.
Spirit, on the other hand, found chemicals that indicate that Mars had a warm, wet history with a thicker carbon dioxide atmosphere where it landed. It also found signs of near-neutral water.
More information on their findings can be found here.
Next up in the series was the Curiosity rover in 2012.
Here are some of the key findings from Curiosity:
Found persistent liquid water in the past that would have been there for over a million years or longer.
Found the necessary chemistry needed for life (Sulfur, N, C, P, O). Soil samples showed not much evidence of salt which might suggest drinkable water.
Found a seasonally varying background level of atmospheric methane and observed a ten-fold increase in methane over a two-month period.
Special thanks to Colin Vendromin for the music also thanks to Zac Kenny for the logo!