NASA Spaceflight by Chris Gebhardt July 27, 2018
For the first time in human exploration of Mars, the presence of a stable, subterranean body of salty (briny) water has been strongly suggested by data returned by the European Space Agency’s Mars Express orbiter. Using measurements taken by the MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) instrument, a team of Italian researches announced this week the first (probable) discovery of a stable body of liquid water on Mars. But with this discovery comes a host of questions regarding future exploration of the Red Planet.
A stable, large body of liquid water on Mars:It’s the word “stable†that is the historic and big-ticket item here.
Prior to this week, liquid water on Mars’ surface had only been observed for very brief periods of time. Briny water droplets were briefly observed on NASA’s Phoenix Polar Lander and orbital terrain images have revealed new surface features carved by flowing water that quickly disappeared.
But never before had liquid water in large, stable quantities been found on – or beneath – Mars.
Nonetheless, the presence of liquid water underneath the Martian polar caps has long been hypothesized. In fact, it was first suggested as “possible†over 30 years ago, but conclusive data to either prove or disprove the hypothesis remained elusive.
Enter the European Space Agency’s (ESA’s) Mars Express orbiter, which has been at Mars since 25 December 2003.
Since then, it has been dutifully studying the Martian terrain, including its subsurface mysteries, with the Mars Advanced Radar for Subsurface and Ionosphere Sounding, or MARSIS, instrument – specifically, a region underneath Mars’ Planum Australe (south polar region) known as the South Polar Layered Deposits.
The evidence returned by MARSIS of a persistent liquid water deposit in this region came via a three and a half Earth-year observational period from May 2012 to December 2015, during which MARSIS conducted 29 different radar scans of a 200 km-wide (124 mile-wide), flat area of the Planum Australe.
The radar waves sent from MARSIS penetrated the top layers of the Martian terrain, extending a few kilometers underneath the surface. Those waves were then reflected back toward MARSIS when they encountered various rocks, sediments, and – in this case – liquid water.
More:
https://www.nasaspaceflight.com/2018/07/mars-water-discovery-martian-exploration/
