A huge lake of salty water appears to be buried deep in Mars, raising the possibility of finding life on the red planet, scientists reported Wednesday.
|Artistic impression of the Mars Express spacecraft probing the southern hemisphere
of Mars, superimposed to a color mosaic of a portion of Planum Australe. The study
area is highlighted using a THEMIS IR image mosaic. Subsurface echo power is
color coded and deep blue corresponds to the strongest reflections, which are
interpreted as being caused by the presence of water [Credit: USGS Astrogeology
Science Center, Arizona State University, ESA, INAF]
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.”
|Artistic impression of the Mars Express spacecraft probing the southern hemisphere of Mars,
superimposed on a radar cross section of the southern polar layered deposits. The radar
cross section has been tilted 90°. The leftmost white line is the surface radar echo, while
the light blue spots along the basal radar echo highlight areas of very high reflectivity,
interpreted as being caused by the presence of water [Credit: ESA, INAF. Graphic
rendering by Davide Coero Borga – Media INAF]
The study, published 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 kilometers) reservoir lies below ice about a mile (1.5 kilometers) 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.
|ESA’s Mars Express has used radar signals bounced through underground layers of ice to find evidence of a pond of water
buried below the south polar cap. Twenty-nine dedicated observations were made between 2012 and 2015 in the Planum
Australe region at the south pole using the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument,
MARSIS. A new mode of operations established in this period enabled a higher quality of data to be retrieved than earlier
in the mission. The 200 km square study area is indicated in the left-hand image and the radar footprints on the surface
are indicated in the middle image for multiple orbits. The greyscale background image is a Thermal Emission Imaging
System image from NASA’s Mars Odyssey, and highlights the underlying topography: a mostly featureless plain with
icy scarps in the lower right (south is up). The footprints are colour-coded corresponding to the ‘power’ of the radar
signal reflected from features below the surface. The large blue area close to the centre corresponds to the main
radar-bright area, detected on many overlapping orbits of the spacecraft. A subsurface radar profile is shown in
the right hand panel for one of the Mars orbits. The bright horizontal feature at the top represents the icy surface of
Mars in this region. The south polar layered deposits – layers of ice and dust – are seen to a depth of about 1.5 km.
Below is a base layer that in some areas is even much brighter than the surface reflections, highlighted in blue,
while in other places is rather diffuse. Analysing the details of the reflected signals from the base layer yields
properties that correspond to liquid water. The brightest reflections are centred around 193°E/81°S in the
intersecting orbits, outlining a well-defined, 20 km-wide zone [Credit: Context map: NASA/Viking;
THEMIS background: NASA/JPL-Caltech/Arizona State University; MARSIS data: ESA/NASA/
JPL/ASI/Univ. Rome; R. Orosei et al. 2018]
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 neighbor has been 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.
Author: Emiliano Rodriguez Mega | Source: Associated Press [ July 25, 2018]