It’s hard to imagine dry and dusty Mars as a watery wonderland, but scientists have discovered a fascinating history of water on the red planet. One symbol of that legacy is a region called Caralis Chaos, home to Lake Eridania. The European Space Agency calls Lake Eridania “Mars’s largest lake.” The Mars Express spacecraft captured a new view of Caralis Chaos, showing the remnants of what had likely once been a spectacular body of water.
Mars Express has been studying the planet’s surface and geology from orbit since 2003. ESA released the new Caralis Chaos images on August 7. “We believe that water, and a lot of it, once existed here,” the agency said in a statement.
A large crater dominates the image. The ancient lakebed reaches across the lower right. A topographic image uses bright colors to highlight the features of the region. The lake area shows up in blue. “The old lakebed is now filled with lots of raised mounds, thought to have formed as ancient martian winds swept dust across the planet; this dust was later covered and altered by water, before drying out again and breaking apart,” said ESA.
Based on studies of the Lake Eridania area, ESA estimates it would have held more water than all other Martian lakes combined. In Earth terms, it could have filled the Caspian Sea almost three times. It would have been larger than any lake on Earth. Its heyday occurred about 3.7 billion years ago. Scientists suspect it was one giant lake at that time, but it slowly turned into a series of smaller lakes as the surface dried. Now, it’s an arid and enigmatic region of Mars.
Understanding the history of water on Mars is an important piece of a bigger puzzle. Scientists want to know if Mars was once home to microbial life. Water is needed for life as we know it, so exploring once-watery areas is a high priority for Earth’s space agencies. That’s why NASA’s Perseverance rover is cruising around Jezero Crater. Jezero was once home to a lake and river. NASA’s choice of landing site may pay off in a big way. The rover recently found possible evidence of ancient microbial life. However, scientists would need to get their hands on a sample of the rock in question for closer study.
The ESA images show more than just the remains of a lake. The many impact craters are also of interest. Formations along the left rim of the large crater may have been created by water after Lake Eridania dried out. The smaller crater to the left sports a series of gullies along its rim. Other features include faults that appear as long cracks and craters that were worn down over time until they became ghosts of their former selves.
Eridania may one day be a candidate for exploration, whether by robots or human visitors. The NASA Jet Propulsion Laboratory once described the area as “rough and dangerous,” which would make it a challenge for landing systems. Until then, orbiters like Mars Express will continue to study the intriguing region from afar.
