Inner Workings: Early Mars may have boasted a large ocean and cool climate
Nola Taylor Redd
PNAS December 15, 2020 117 (50) 31558-31560
.png)
Figure: For years, researchers have suggested that Mars once had an ocean, as depicted in this concept illustration. But the details about that ocean’s formation, disappearance, and impact on the Martian landscape remain hotly debated. Image credit: NASA/GSFC.
When Mariner 4 buzzed Mars in 1965, it revealed a dry, desiccated world that stood in stark contrast to the habitable planet dreamed of by decades of science fiction writers. Subsequent observations revealed the apparent scars of rivers and deltas, and even potential sea shorelines. The revelations brought hope that the planet had once been wetter. But the implications of these findings have remained unclear, with theories of potential climates falling into two camps. In the “warm and wet” camp, rainfall excavated Mars’ river-like features, and a large ocean stretched across its northern hemisphere. The “cold and frozen” camp credits melting ice with scooping out the valleys.
Now, new research (1) suggests that a large ocean was indeed required to form the features across the planet's surface. But rather than warm and wet, the planet would have been cool and semi-arid. This intriguing third hypothesis has started to garner attention as researchers continue to debate the particulars of the red planet’s early climate.
Falling between the “warm and wet” and “cool and dry” models of Mars, the new scenario provides a middle ground when it comes to understanding the planet's climate. It’s a picture that will be tested soon. When NASA’s Perseverance rover lands in February 2021, it should be able to probe how climate conditions changed at Jezero crater over time. “Having a rover there and having more information from different locations on Mars is going to help us,” Ramirez says. “It's going to be a game changer and will hopefully provide the impetus for later [human] exploration.”
Views: 281