Liquid water may be lurking beneath Mars’ south polar ice cap, according to new evidence presented in Nature Astronomy.
Dark streaks and other surface patterns on the slopes of Mars indicate that billions of years ago, unforgiving worlds of dust underpinned lakes and oceans. It is believed that the loss of the atmosphere stripped the surface of the liquid, leaving Mars dry and barren. However, scientists believe that Mars still has water, but it is trapped in ice deposits and freezes in cold, dry areas.
Now, exciting data collected by spacecraft in past and present orbits suggests that liquid water may still flow on Mars. According to a paper published Thursday, an international team of astronomers led by the University of Cambridge has identified the ice cap of Mars’ south pole produced by the laser altimeter on NASA’s now-defunct Mars Global Surveyor satellite, and has studied detailed maps.
They found anomalies on the surface of the ice cap. There, ice forms ‘high benches’ and nearby ‘topographic depressions’, 10 to 15 km long that indicate the flow of liquid water beneath them. Then they ran a computer model that simulated the surface features of an ice sheet under which water flows and found that it produced unusually similar structures. The team believes that Mars is still geothermal active to generate the heat needed to melt its ice cap.
Previous radar measurements from NASA’s Mars Express Orbiter highlighted a particular bright spot where the area under the glacier in the same area was more reflective. Some astronomers believe that the high reflectance was a sign of liquid water under the ice sheet. However, some believe that the same signal might result from other effects, such as conductive ice or minerals in the Earth’s crust.
This latest study goes beyond initial radar results and provides more evidence for the presence of liquid water. “Combining evidence for new terrain, results from computer models, and radar data makes it very likely that there is at least one region of subglacial liquid water on Mars today, and that Mars maintains geothermal activity. There is still water under the liquid in the Ice Cap,” said lead author Professor Neil Arnold, Associate Professor at the Scott Polar Institute at the University of Cambridge.
Similar surface features exist on Earth. Rising and falling ice has been found in subglacial lakes, and the team believes these same patterns are present on Mars. This means that liquid water is hidden under the ice cap. While the evidence may look promising, scientists have yet to confirm that Mars has liquid water.
Co-author of the paper, Frances Butcher, a planetary scientist at the University of Sheffield in England, said the study narrows down the conditions Mars must have for the presence of water that scientists can look for.
“Liquid water is an essential component of life,” she said, making it difficult for microbes to survive. It gives you hope.®
