The surface of Mars is a lifeless, repellent desert. However, under its red earth, the planet may still be alive – geologically.
In 2018, big space news broke out: with a ground radar aboard a Mars satellite, a group of scientists discovered a twelve-kilometer-long lake that lay thousands of feet below the Martian South Pole. Researchers have now presented a paper arguing that hot molten rock (magma) must be seeped near the surface when there is a substantial salt lake under that ice cap.
Such subterranean volcanism would have occurred in geological time several hundred thousand years ago or less.
"They need a heat source," said Ali Bramson, a scientist at the University of Arizona's Lunar and Planetary Laboratory and co-author of the new paper, in an interview.
"What could cause this heat source?" Bramson asked. "The only thing we can think of is a subterranean magma chamber that has had to be active lately."
The first leading theory was that this lake contained abundant amounts of salt. Salts lower the freezing point of water, leaving the water molecules fluid.
That's pretty reasonable. "There's salt all over Mars," said Kirsten Siebach, Mars geologist and Assistant Professor of Rice University's Earth, Environmental, and Planetary Sciences.
But in the new study published this week In the Geophysical Research Letters magazine, Bramson and her team found that not enough salt was sufficient. "Salts alone are not enough to explain the liquid water," Bramson said. There had to be some warmth, and one of the most plausible ideas is that Mars itself has provided the inner furnace.
This raises a question of continued scientific intrigues: is Mars – an externally long-dead planet – geologically alive? That is no small matter. It would mean that magma (underground lava) moves in certain sections of the interior and possibly receives other waters.
"It would be unlikely, but not impossible," said Siebach, who played no role in the study.
"There is potential for Mars to be active in some places in this way," added Siebach.
In this case, however, the hot rock would have to appear near this ice cover. The chances are not too high.
"It would have to be a lot of conditions to have liquid water," Siebach said.
But when Mars has heat, or remnants of recent geological heat, about four or five miles below its surface – planetary scientists will soon have a much clearer idea. In November NASA's InSight probe landed safely on Mars. The Martian probe will probe the interior of the planet and ultimately answer the imminent alien dilemma: is Mars alive or dead?
"That's a big motivation for InSight," Bramson said.
"The issue of today's heat flow not only provides insight into current processes, but also into Mars' earliest history," added Sue Smrekar, NASA's chief investigator for InSight Email.
To answer the question, InSight drills a hole almost three meters deep into the Martian soil to study the planet's temperature. It will measure heat at distances of up to 1,500 miles (300 km) in locations believed to have experienced volcanism in the last 10 million years, said Smrekar.
Although Mars may have been volcanically active hundreds of thousands of years ago, there is no direct, compelling evidence of such subterranean volcanism today. Between 2011 and 2014, scientists used sophisticated telescopes to detect volcanic gases emanating at various points on the Martian surface. They found little of these telltale gases in the atmosphere.
"The resulting absence of such atmospheric gases precluded the presence of greater outgassing on today's Mars," said Alain Khayat, a senior scientist at the Planetary Systems Laboratory at NASA's Goddard Space Flight Center and lead author of the report, e-mailed ,
However, Khayat found that Mars is home to long-lived volcanoes such as Olympus Mons – the largest volcano in the solar system – which has probably been active for two or three billion years. This long, rich volcanic history increases the likelihood of finding chambers of hot magma beneath the ground that could have melted ice beneath the Martian South Pole, he said.
Maybe Mars lived in geological time and possibly even today.
"One thing we can guarantee when we send a new mission to Mars is that we will be surprised," said Siebach.