NASA’s Mars rover InSight was retired over a year ago, but the data it transmitted back to Earth — specifically, the seismic velocity of Martian earthquakes — may contain the best evidence yet that liquid water exists on Mars.
NASA launched InSight, also known as the Interior Probe Using Seismic Surveys, Geodesy and Heat Transport, to explore the depths of Mars in 2018. The four-year mission ends in December 2022, but analysis of the data it collected is still ongoing.
According to a study published Aug. 12 in the journal Proceedings of the National Academy of SciencesA team of researchers from the Scripps Institution of Oceanography at the University of California, San Diego, led by geophysicist Vashan Wright, concluded that InSight’s data indicates the presence of liquid water in the Martian crust.
“Understanding the water cycle on Mars is important to understanding its climate, surface and interior evolution,” Wright said in a press release. “Determining where water is and how much there is is a useful starting point.”
Wright and his team didn’t just look at the chemical composition of the soil beneath InSight. They wanted to look deeper into the interior of Mars, so they analyzed data on Marsquakes – the seismic activity that periodically shakes the Red Planet. From the propagation speed of these quakes, the team was able to infer what materials exist beneath the surface. The most likely explanation for the data was the presence of liquid water in the crust. They acknowledged that their findings are not conclusive, but stressed that further study of Mars’ mineralogy is needed.
Decades of evidence have shown that both the North and South Poles of Mars are covered in frozen water, with the North Pole housing a huge reservoir 1.2 miles (2 kilometers) below the surface. The Martian atmosphere is much thinner than Earth’s, so liquid fresh water can easily turn into gas. But if water is extremely salty, it lowers its boiling point and allows it to remain liquid for longer. A 2016 paper concluded that dark streaks on the Martian surface could have been formed by water moving downhill.
If Wright’s team is correct, this could have a major impact on the theory that Mars was once home to microbial life, a theory that recently received a major boost from the Perseverance rover’s discovery of strange rocks. The presence of liquid water would also be a big plus for a human mission to Mars. More research is needed, and it’s hoped that future missions, both manned and robotic, will shed light on this very important open question.
