A huge lake of salty water appears to be buried deep in Mars, raising the possibility of finding life on the red planet.
The discovery, based on observations by a European spacecraft, generated excitement from experts. Water is essential to life as we know it, and scientists have long sought to prove that the liquid is present on Mars.
"If these researchers are right, this is the first time we've found evidence of a large water body on Mars," said Cassie Stuurman, a geophysicist at the University of Texas who found signs of an enormous Martian ice deposit in 2016.
Scott Hubbard, a professor of astronautics at Stanford University who served as NASA's first Mars program director in 2000, called it "tremendously exciting."
"Our mantra back then was 'follow the water.' That was the one phrase that captured everything," Hubbard said. "So this discovery, if it stands, is just thrilling because it's the culmination of that philosophy."
The study, published Wednesday in the journal Science, does not determine how deep the reservoir actually is. This means that scientists can't specify whether it's an underground pool, an aquifer-like body, or just a layer of sludge.
To find the water, Italian researchers analyzed radar signals collected over three years by the European Space Agency's Mars Express spacecraft. Their results suggest that a 12-mile-wide (20 kilometres) reservoir lies below ice about a mile (1.5 kilometres) thick in an area close to the planet's south pole.
They spent at least two years examining the data to make sure they'd detected water, not ice or another substance.
"I really have no other explanation," said astrophysicist Roberto Orosei of Italy's National Institute of Astrophysics in Bologna and lead author of the study.
Mars is very cold, but the water might have been kept from freezing by dissolved salts. It's the same as when you put salt on a road, said Kirsten Siebach, a planetary geologist at Rice University who wasn't part of the study.
"This water would be extremely cold, right at the point where it's about to freeze. And it would be salty. Those are not ideal conditions for life to form," Siebach said.
Still, she said, there are microbes on Earth that have been able to adapt to environments like that.
Orosei said, "It's tempting to think that this is the first candidate place where life could persist" on Mars.
He suspects Mars may contain other hidden bodies of water, waiting to be discovered.
Our planetary neighbour has a popular target for exploration, with rovers on its surface and other probes examining the planet from orbit. In May, NASA launched another spacecraft, the InSight Mars lander, that will dig under the surface after it reaches a flat plain just north of the Martian equator in November.
It’s been 11 days since InSight made its picture-perfect landing on Mars. Vivid new photos taken from the landing site are finally giving mission controllers a sense of the landscape around the stationary probe—and the early signs are very positive.
After six years of planning, $814 million in development costs, and a successful 300-million-mile journey to Mars, the key for NASA right now is to exercise patience.
InSight landed at Elysium Planitia, a flat plain located just north of the Martian equator, on November 26, which already seems like an eternity ago. We haven’t seen much from the probe yet, aside from a dusty photograph taken during the landing and a neat but subdued image of the probe’s immediate surroundings.
“Today we can see the first glimpses of our workspace.” We’re finally at the stage, however, when the mission operators can start to unfurl, very slowly and methodically, the probe’s various instruments, including its six-foot-long (2-meter) arm. The robotic appendage appears to be functioning normally, as does the Instrument Deployment Camera attached to its elbow. Eventually, the arm will be used to pick up science instruments from InSight’s deck, gently setting them down on the Martian surface. Once the mission is fully up-and-running, this tool will be the first robotic arm to shove instruments into the surface of another planet, including a seismometer and a heat flow probe.
For now, InSight’s Instrument Deployment Camera is being used to take photos of the terrain around the lander. And boy, did the probe ever land on a sweet spot. Just take a look at this picture:
“Today we can see the first glimpses of our workspace,” Bruce Banerdt, the mission’s principal investigator at NASA, said in a statement. “By early next week, we’ll be imaging it in finer detail and creating a full mosaic.”
Indeed, more images will be required to paint a full picture of InSight’s new digs, but this place looks amazing—especially for a probe designed to drill through the Martian surface. Photographs taken by the probe show a relatively flat, dusty surface, free of troublesome rocks. There was always the concern that the probe might land on top of a large, partially buried rock. Imagine, for example, if InSight had landed atop one of those boulders on the horizon, as pictured below.
InSight has another imaging tool, the Instrument Context Camera, which will gaze at the terrain immediately around and beneath the lander’s deck. Photos produced by this camera won’t be nearly as pretty, but they’ll serve a utilitarian function. Unfortunately, and despite a protective cover on the Instrument Context Camera, dust somehow managed to get into the lens, according to NASA.
“We had a protective cover on the Instrument Context Camera, but somehow dust still managed to get onto the lens,” said InSight project manager Tom Hoffman of NASA’s Jet Propulsion Laboratory (JPL). “While this is unfortunate, it will not affect the role of the camera, which is to take images of the area in front of the lander where our instruments will eventually be placed.”
NASA says InSight’s instruments may not be fully positioned and calibrated for another 30 to 60 days. One of these instruments, the Auxiliary Payload Sensor Subsystem, will eventually collect vital meteorological data, such as wind speed and air temperature. That said, the probe’s pressure sensor appears to be working, and it’s already detected a sudden drop in air pressure, a possible sign of a passing dust devil, said NASA.