Want to see about 4 billion years of planetary evolution squeezed into less than two minutes? Take a look at this new simulation from NASA:
The music is cheesy, but otherwise the video is thought-provoking and even a little scary-on a geologic timescale, it's so easy for a healthy planet to turn into a rusty rock.
Mars may be endlessly fascinating, but it's not the kind of place you'd want to wake up on a bus with the driver telling you it's the end of the line. It is a freezing, nasty, nightmare version of the Atacama desert, exposed to killer radiation from space and covered in poison dust. A great place to send unmanned science rovers and crates full of copies of "E.T." for the Atari 2600, but not such a great place to visit.
But there are reasons to think that a few billion years ago, Mars had a much thicker atmosphere and warmer climate than it does today, with clouds in the sky and liquid oceans on the surface. Does this mean that if we traveled back in time a few billion years, we could live comfortably on ancient Mars? Not necessarily-but the more we learn, the more interesting the history of Mars becomes. For example, just this year scientists discovered that about 4 billion years ago (the time at the beginning of the video), Mars had an oxygen-rich atmosphere like we do. Where did the oxygen come from? On Earth, oxygen built up in the atmosphere as carbon dioxide was processed for photosynthesis by blooming populations of cyanobacteria (a.k.a. "blue-green algae") around the globe. So is the ancient Martian oxygen evidence that Mars was once covered in critters that ate light and CO2 and excreted molecular oxygen? Again, not necessarily-the oxygen buildup could also be explained by chemical reactions within the atmosphere of Mars. But there's an even more interesting question: Where did the atmosphere go? And could our atmosphere disappear in a similar way?
That's where the video comes in. It's sort of a teaser reel for NASA's Mars Atmosphere and Volatile Evolution (MAVEN) mission, which is currently planning to investigate exactly what happened to the Martian atmosphere with an orbital probe scheduled to arrive at the planet in September 2014.
Best of luck to them!