Curiosity Rover Spots Clear Evidence of Ancient Water on Mars

The Mars Reconnaissance Orbiter snapped this picture of a distinctive ‘dragon scale’ pattern from Mars orbit. This arises from clay-bearing rock interacting with water, meaning the pattern likely formed billions of years ago.

Ius Chasma sits in Mars’ largest canyon, Valles Marineris. Researchers believe that water seeped out of the formation’s cliffs and evaporated before it could reach the canyon floor. The result is this artful geological formation.

MRO’s view of Saheki Crater on Mars reveals alluvial fans on the planet’s surface. Alluvial fans are gentle slopes formed by the flow of water. The fans also occur naturally on Earth, but on Mars they tend to be much, much older, given that water hasn’t been plentiful on the planet’s surface for ages.

European Space Agency (ESA) and NASA scientists recently teamed up to combine data from the Mars Express Orbiter and Mars Reconnaissance Orbiter, to make a map of where hydrated minerals are on Mars. The map offers a guiding document for where ancient water likely flowed. Note the amount of hydrous clays in Jezero Crater, in the map at top right. That’s why Perseverance rover scientists are exploring the crater’s river delta with such zeal. You can read more about the maps here.

This processed image from the HiRISE Camera on the Mars Reconnaissance Orbiter shows lineae (line) slopes, which could indicate where ancient water once flowed off this large ridge. Each line is about the length of a football field!

This false-color image of a slope in Mars’ Hale Crater shows slope lineae in a yellowish-brown, again where rougher terrain meets a more gradual slope.

This image from the MRO shows recurring slope lineae clearly, on the rim of Mars’ Garni Crater. Hundreds of feet long, the streaks indicate water once flowed down this sharp slope. Currently, Perseverance is investigating a delta on the western side of Jezero Crater, which also shows signs of ancient water flow.

The ice cap on Mars’ south pole shows that water is still on the planet—if only in a different state. In 2021, a team of researchers published a paper suggesting that liquid water may exist in subsurface lakes on Mars. “Either liquid water is common beneath Mars’ south pole or these signals are indicative of something else,” said Jeffrey Plaut, a research scientist at NASA’s Jet Propulsion Laboratory. But more recent work has challenged that hypothesis.

The raised remnant of a river delta on the western end of Jezero Crater, as seen by the Perseverance rover. The delta is thought to have carried water (as well as ancient Martian boulders and sediments) into a lake that once occupied the now-arid crater.

This map shows two paths NASA’s Perseverance team charted for the rover from its landing site (white dot at right). The rover ended up taking the blue path, and now sits at the base of the raised river delta at the center of the image. The delta is thought to have carried water from the west into the lake that occupied Jezero Crater, at right.

The same research noted earlier paid particular focus to the Perseverance rover’s area of study: Jezero Crater. The crater’s western end is dominated by carbonates and hydrated minerals. It’s one of several locations on Mars that show evidence of substantial water presence in the planet’s ancient past.

NASA is fairly certain that Jezero Crater was once filled with water. That would make the river delta that flowed into it a good place to search for signs of ancient microbial life, which may have looked something like the stromatolites that formed on ancient Earth (and still form in some parts of the world today.)

Read more: Abigail Allwood’s Hunt for Alien Fossils on Mars Has Begun