Tracing the Steps of Hydrothermal Activity in Hrad Vallis, Mars
Conditions that formed Amazonian age valleys may have been hospitable to microbial life.

Much of our planet’s recent history is documented in books, letters, photographs, and films. To supplement these human-made records and delve back even further, we rely on nature’s own relics—tree rings, geologic formations, and the evolving genetic makeup of animals—to better understand Earth’s history.

Human exploration of Mars has unfolded in much the same way. By observing the planet through telescopes, studying Martian rocks and meteorites, and collecting data via satellite missions, scientists across many disciplines have been able to piece together some of the natural history of the Red Planet, dating back millions of years.

On the basis of these types of records, scientists believe that at some point, flooding and volcanic activity formed a network of valleys across Mars. Knowing more about the magnitude and timing of these events could reveal more about the planet’s natural history and help identify regions that might be hospitable to microbial life.

Here Hamilton et al. studied a 370-meter-deep, 800-kilometer-long valley—a small subsection of this larger network—called Hrad Vallis. Named after the Armenian word for Mars, Hrad Vallis is young in terms of geologic time; scientists believe it formed during the Amazonian age, or roughly within the past 3 billion years.

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