We celebrate two giant birth anniversaries this week: Wednesday is the 453rd anniversary of Galileo and Sunday is the 544th anniversary of Copernicus’ birthday. Galileo proved by observation what Copernicus suggested as the structure of the solar system. Interestingly, 404 years ago, the Roman Catholic Church censored Galileo to keep him from distributing science truth to the general population in an attempt to maintain tight control over church doctrine.
We all agree Mars was warmer and much wetter in its past, but how? We’ve just assumed that Mars was like Earth early on. On Earth our atmosphere’s had enough CO2 as a greenhouse gas to keep the planet warm enough for water to exist on the surface as a liquid. Studies of rocks by Curiosity at Gale Crater and analysis from orbit indicate there isn’t enough carbonate rock to indicate there was enough CO2 in Mars’ atmosphere to keep the surface warm enough for liquid H2O to exist as the rock record shows. So what heating mechanism? There are other greenhouse gases (methane, SO2, NO) but they don’t last very long.