On February 18th, NASA's Perseverance rover https://interestingengineering.com/nasa-perseverance-rover-landing-on-mars">successfully landed on the surface of Mars. For the next two years of its primary mission, it will search the Jezero Crater (an ancient lakebed with a preserved delta fan) for possible biosignatures. This will include the first sample-return mission from Mars, where Perseverance will collect soil and drill samples and place them in a cache.
This will be picked up in a few years by a joint NASA-ESA mission, which will consist of a lander, rover, launch vehicle, and orbiter. These robotic elements will retrieve the sample cache and fly them back to Earth for analysis. In this, Perseverance and the sample-return mission are the latest in a long line of efforts to determine if Mars once supported life.
While the search for life on Mars has only been taking place for a few decades, our preoccupation with Martian life is centuries-old. Ever since scientists became aware that Mars was a planet much like Earth, the concept of Martians has fired our imaginations (and haunted our dreams!)
While much of the mythology of civilizations and "little green men" has been dispelled, there is still the possibility that life once existed on Mars (and perhaps still does). As our knowledge of the Red Planet has evolved, so too have our notions of what life on Mars could look like.
With the potential discovery of life just a few years away, perhaps it is time for a retrospective on what we expected to find.
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