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FT editor Roula Khalaf selects her favourite stories in this weekly newsletter.
The author is a science commentator
Another piece of the Mars puzzle is slowly falling into place. The surface of the Red Planet is riddled with grooves and channels that were long thought to be reminders of an ancient, wet past.
There is now evidence that there is liquid water beneath the surface of our neighboring planet, which is already known to have ice at the poles.
On Monday, US researchers announced that they had seen seismic signals indicating a reservoir of water buried deep beneath the Earth’s crust. In terms of volume, it is not a puddle, but an infinite pool, enough to cover the entire planet with an ocean at least one kilometer deep.
Since liquid water is a prerequisite for life as we know it, the underground reservoir, which could lie as much as 20 km below the surface, is an obvious target for the search for life. The discoveries will also give new impetus to future manned missions to Mars, which NASA hopes to realize by the 2030s.
This prospect is double-edged: we have a moral duty to look for life in our neighborhood if it exists, but when we discover it, we also have an obligation to protect it from the worst piratical instincts of our own species.
The data was collected by NASA’s InSight lander, which touched down on Mars in 2018. Over the next four years, its seismometer recorded the planet’s vibrations and rumbles, known as “Marsquakes,” and also detected signs of meteorite impacts. A team led by Vashan Wright of the Scripps Institution of Oceanography in San Diego ran the signals through a mathematical model that is also used to map underground aquifers and oil fields.
Their short paper, published Monday in the Proceedings of the National Academy of Sciences, contains a compelling conclusion: “The existing data are best explained by a midcrust composed of fractured igneous rocks saturated with liquid water.”
Planetary scientist Ian Crawford of London’s Birkbeck University, who was not involved in the research, said that confirming the existence of an underground aquifer would most likely require a new mission with special geophysical instruments.
Although there is ample evidence of a sculpted landscape, the whereabouts of Mars’ water has long been a mystery. There is water ice at the poles and traces of water vapor in the atmosphere, but that is not enough to explain what once flowed. One theory is that the liquid water disappeared when Mars lost its atmosphere about three billion years ago.
This latest finding suggests that at least some of it seeped into the crust. It’s not far-fetched to imagine that this watery subterranean kingdom of cracks and crevices harbors a form of microbial life similar to the “extremophiles” found on Earth. Resilient life forms thrive in the most unlikely terrestrial niches, from the driest deserts to the superheated, acidic high pressures of undersea volcanic vents.
Michael Manga, a team member at the University of California, Berkeley, says: “I don’t understand why [the underground reservoir] is not a habitable environment … deep, deep mines [on Earth] Home to life, the seafloor is home to life. We have not found evidence of life on Mars, but at least we have identified a place that could in principle host life.”
Chemists at Tufts University in Massachusetts have already shown that bacteria, including E. coli, can be grown on Mars’ regolith (the loose material on its surface) in the presence of water.
However, accessing the Mars aquifer presents an above-ground challenge: it is believed to lie somewhere between 12 and 20 kilometers below the surface.
This makes the search for extraterrestrial life a technical problem. Russia and China, two spacefaring nations with a penchant for technical skills, have the upper hand here.
Russia has already dug more than 12 km down and drilled the Kola super-deep well in the northwest of the country. China is currently drilling an 11 km long well in the Tarim Basin in Xinjiang. The well, called Shenditake 1, will be used to search for oil and gas and to study the Earth’s evolution.
Elon Musk would surely love being bored on Mars. The prospect of a water source will excite those like the brash tech titan who dream of unlimited colonization and control of the Red Planet. But the rules of the game have changed as the possibility has increased that there may be life on Mars, however rudimentary.
This requires a spirit of discovery rather than exploitation: we must continue the search for life beyond our own planet, and do so cautiously.
