Mars, the Red Planet

Why We Study Mars

David Bowie wasn't the first person to ask "Is there life on Mars?" This question has intrigued humans for centuries. Early telescope observations in the 18th and 19th centuries seemed to show a planet not all that different from Earth, with ice caps, seasons, and features that were mistaken for seas and artificial canals. A few scientists even thought that Mars was inhabited by intelligent life.

We now know that Mars is very cold and dry, with no breathable atmosphere and no global magnetic field to protect it from the Sun's radiation. But it wasn't always that way. Space missions have shown us that Mars once had liquid water on the surface and could have been hospitable to life as we know it. Today, there may still be life beneath the surface, with access to water and protection from radiation and extreme temperatures.

We know Mars was habitable to life as we know it for at least some periods of time around 3 or 4 billion years ago. But we don't know whether the planet was warm and wet long enough for life to arise, or mostly cold and dry with only brief intervals that could have supported life.

How did Mars go from a potential life-supporting oasis to a cold, dry desert? Does life still flourish underground? The answers to these questions will teach us more about where we come from and whether we are alone in the cosmos.