Scientists have argued for years over the ambiguous radar scans of Mars’ south pole. Do they reveal underground lakes of liquid water? Or something else? Two new articles published this week added even more intrigue to the controversy.
In 2018, a team of Italian scientists claimed to have discovered a subglacial lake near the Martian south pole using radar data from the Mars Express satellite. The discovery was met with skepticism, with other scientists suggesting alternatives like lumps of clay which could have produced the same thought patterns. It’s a fascinating debate, because of the implications of water for life. While most scientists agree that Mars was very wetthe remaining H2O seems to be all the ice cream.
The debate is reignited this week with new evidence from NASA’s Mars Global Surveyor satellite that supports the liquid water hypothesis. Radar signals from the 2018 study indicated a 12-mile-wide (20-kilometer) region about a mile below the surface, which the researchers interpreted as a subglacial lake or sheet of liquid water. In order to confirm this interpretation, a different team examined satellite data of the surface topography of the same region. Their analysis, published this week in Nature Astronomy revealed a 6 to 15 mile (10 to 15 kilometer) ripple made up of a depression and a corresponding uplifted area, similar to ripples found on subglacial lakes here on Earth.
The team then ran a computer simulation of ice flow that matches conditions on Mars, and the simulations generated ripples similar in size and shape to those seen on the surface of the Mars ice sheet. The study suggests that there is indeed an accumulation of liquid water under the planet’s southern polar cap. “The combination of new topographic evidence, results from our computer model and radar data makes it much more likely that at least one area of subglacial liquid water exists on Mars today,” said Neil Arnold, researcher at the Scott Polar Research Institute in Cambridge. lead author of the study, said in a statement.
But a separate new paper suggests that the liquid water radar data was actually the result of an interaction between different geological layers on Mars, producing a reflection pattern that could have been misinterpreted as liquid water. This studyalso published this week in Nature Astronomy, provides an alternative explanation for the 2018 discovery. The team behind this study created a simulation of layers made up of four materials – atmosphere, water ice, dioxide ice of carbon and basalt – and measured the interaction of the layers with electromagnetic radiation as it passes through them.
They found that depending on the thickness of the layers and their distance, they produced reflections similar to those seen in the 2018 radar data. “On Earth, such bright reflections are often an indication of liquid water, even buried lakes like Lake Vostok [under the surface of the East Antarctic Ice Sheet]said Dan Lalich, a research associate at the Cornell Center for Astrophysics and Planetary Science and lead author of the study, in a statement. “But on Mars, the prevailing view was that it should be too cold for similar lakes to form.”
“None of the work we’ve done disproves the possible existence of liquid water there,” Lalich added. “We just think the interference hypothesis is more consistent with other observations. I’m not sure anything less than an exercise can prove either side of this debate definitely right or wrong.
Temperatures on Mars can dip to around -220 degrees Fahrenheit (-140 degrees Celsius). These freezing conditions are the main argument against any liquid water flowing on the Red Planet. But the researchers behind the latest pro-water study say geothermal heat from the planet’s interior could be enough to keep water in liquid form.
Water is a primary ingredient of life on Earth, but that doesn’t necessarily mean our sacred life juice would sprout life forms elsewhere in the universe. The water debate, however, has implications for future crewed missions to Mars, especially if we are ever to establish a sustained presence there.
After: NASA is refining its strategy to get humans to Mars
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