Scientists have found what seems to be the oldest direct evidence of hot water flowing on Mars during its ancient past. The discovery could further indicate that the Red Planet, despite its arid and desolate appearance today, may have been capable of supporting life long ago.
The evidence was delivered to Earth and sealed within the well-known Martian meteorite NWA7034, found in the Sahara Desert in 2011. Due to its black, highly polished appearance, the Martian rock is also known as "Black Beauty."
At an estimated 2 billion years old, Black Beauty is the second oldest Martian meteorite ever discovered. However, the Curtin University team discovered something even older within it: a 4.45 billion-year-old zircon grain that harbors the fingerprints of fluids rich in water.
Team member Aaron Cavosie from Curtin's School of Earth and Planetary Sciences thinks this discovery will open up new avenues to understanding hydrothermal systems associated with the activity of volcanic magma that once ran through Mars.
"We used nano-scale geochemistry to detect elemental evidence of hot water on Mars 4.45 billion years ago," Cavosie said in a statement. "Hydrothermal systems were essential for the development of life on Earth, and our findings suggest Mars also had water, a key ingredient for habitable environments, during the earliest history of crust formation."
Cavosie added that the team identified specific elements in this unique zircon fragment through nano-scale imaging and spectroscopy, which allows the chemical composition of objects to be determined. These included the elements iron, aluminum, yttrium and sodium.
"These elements were added as the zircon formed 4.45 billion years ago, suggesting water was present during early Martian magmatic activity," Cavosie said.
Evidence of waterways and ancient lakebeds on Mars had previously led scientists to theorize that water was present on the Red Planet in liquid form and in great abundance around 4.1 billion years ago. This was during Mars' Noachian period, when the watery Martian surface was intensely bombarded by asteroids.
The Red Planet is thought to have lost its water billions of years ago, when the Martian atmosphere was stripped away by harsh solar radiation from the sun. The loss of the Martian atmosphere meant there was nothing to prevent water vapor from escaping into space anymore.
However, this new research implies that water in liquid form may have existed on Mars even earlier than previously expected in the planet's pre-Noachian period.
"A 2022 Curtin study of the same zircon grain found it had been 'shocked' by a meteorite impact, marking it as the first and only known shocked zircon from Mars," Cavosie said. "This new study takes us a step further in understanding early Mars by identifying tell-tale signs of water-rich fluids from when the grain formed, providing geochemical markers of water in the oldest known Martian crust."
The team's research was published on Friday (Nov. 22) in the journal Science Advances.
