By John Upton
Juliane Koepcke remembered the advice of her father, a biologist, when she woke on the floor of the Amazon following a mid-air plane explosion. The injured 17-year old needed to find civilization, so she followed the water. She hobbled along riverbanks for more than a week until she discovered a hut and was rescued.
It’s a common survival technique: If you want to find civilization, follow the water. In tandem with carbon, water is the quintessential chemical essence of life. Cities, towns and villages all around the world cluster around shorelines, rivers and lakes.
That’s what NASA scientists are doing with the landing of the latest Mars rover: They are following clues of water in their decades-old search for extraterrestrial life. [Update — Curiosity landed safely on Sunday night.]
Curiosity is a mobile laboratory the size of a car. It’s the biggest, most expensive and most sophisticated robot ever sent to explore Mars – that cold and windswept wasteland that’s one planet farther from the Sun than Earth.
Without water, there can be no life. At least, not life as as we understand it. Find water and carbon along with a source of energy, however, and you could find life. If we could find life or its fossils on Mars, we could investigate whether the self-replicating nucleic acids that form genes that code life sparked into existence right here on Earth. Or, whether our primordial ancestors rocketed here on a shooting star, perhaps after being dislodged from Mars or from a foreign galaxy.
Based on evidence gathered during previous missions, NASA has no doubt that Mars harbored substantial liquid water reserves in its ancient past. Its landscape has clearly been swished and swirled around. Maybe some of the water is still there, deep beneath the surface, providing shelter for exotic microbial wildlife.
But Curiosity isn’t looking for life.
Instead, the robot will inspect, pick up, zap and analyze rocks and soil in Gale Crater, which may once have been a lake bed, in its search for biosignatures – organic molecules and unusual textures that might have been produced by life. The task is daunting. Even if Mars was once teeming with wildlife, signs of that life may have long since weathered away.
“If we employ Earth’s early geologic record as a guide to prediction of biosignature preservation in the ancient Martian rocks to be sampled,” researcher John Grotzinger and his colleagues wrote in Space Science Review in December, “then we should prepare to be patient.”
Following water on Earth can save a life. Following a trail of evaporated water on an inhospitable planet in a quest for ancient organic compounds is both arduous and expensive (the Curiosity mission cost $2.5 billion, and it is landing at a time when the U.S. is slashing spending on intergalactic studies), but it could help eventually explain the very genesis of life.