The European Space Agency (ESA) revealed today evidence gathered by the Mars Express spacecraft that shows an anomaly that could indicate the existence of a liquid water lake beneath the exoplanet's surface.
Radar properties matching water
Roberto Orosei, principal investigator of the MARSIS experiment and lead author of the paper said, “This subsurface anomaly on Mars has radar properties matching water or water-rich sediments,” in an ESA statement.
“This is just one small study area; it is an exciting prospect to think there could be more of these underground pockets of water elsewhere, yet to be discovered.”
The lake was discovered in the Planum Australe region using the MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) instrument. MARSIS is a low-frequency radar and altimeter that features operation altitudes up to 800 km above the Martian surface for subsurface sounding and up to 1200 km for ionospheric sounding.
We know from orbiters, landers & rovers that #Mars had a wet past, with its vast dried out river channels & minerals that can only form in liquid #water, but it is not stable on the surface anymore, so scientists are looking underground… pic.twitter.com/GBp8R8PSUE— ESA Science (@esascience) July 25, 2018
The scientists analyzed radar profiles, within a 200 km-wide area, collected between May 2012 and December 2015. They found that the south polar region of Mars is made of many layers of ice and dust down to a depth of about 1.5 km.
However, within a 20 km-wide zone a particularly bright radar reflection underneath the layered deposits is revealed. Further evaluation of the bright feature indicated an interface between the ice and a stable body of liquid water.
The #Mars Express radar investigation finds a subsurface feature spanning about 20km across under a 1.5km thick layer of ice & dust, interpreted as a buried pond of liquid water, which could be laden with salty, water-saturated sediments... pic.twitter.com/cjTSG9Cv9Q— ESA Science (@esascience) July 25, 2018
New techniques for better data
The presence of liquid water on Mars has long been suspected but thus far evidence from MARSIS remained inconclusive. The new discovery was a result of scientists working with the radar to develop new techniques of acquiring higher resolution data.
Until now evidence from the #Mars Express radar experiment MARSIS, the first radar sounder ever to orbit another planet, remained inconclusive. A new operating mode generating higher-quality data was needed to seek out better evidence for buried #water... pic.twitter.com/DMeGeMNeTX— ESA Science (@esascience) July 25, 2018
“We’d seen hints of interesting subsurface features for years but we couldn’t reproduce the result from orbit to orbit, because the sampling rates and resolution of our data was previously too low,” said Andrea Cicchetti, MARSIS operations manager and a co-author on the new paper. “We had to come up with a new operating mode to bypass some onboard processing and trigger a higher sampling rate and thus improve the resolution of the footprint of our dataset: now we see things that simply were not possible before.”
Research on the collected data was published in the journal Science today.