For years, scientists thought the Earth was unique in that it was the only body in our solar system to harbor water. Well, the more we explore, the more we realize that we live in a soggy solar system. Water lurks on nearly every body in our cosmic neighborhood. Earlier this week, NASA announced that our closest neighbor, Mars, has liquid water on its surface.
One of the most common questions to this news is "can we drink this water?" The short answer is yes; however, it’s a bit more complicated than that. Right now, we know that water doesn’t really flow on the surface of Mars, it seeps – think more like wet dirt. As the Curiosity rover and various other Martian landers have taught us, the Martian soil is rich in a type of hydrated salt called perchlorate. The presence of these salts is what makes the presence of liquid water possible.
In the extremely harsh Martian environment, pure water cannot survive on the surface for any period of time. The addition of the salt from the soil alters the temperature at which water freezes or evaporates, thus allowing the water to stay in liquid form longer. Future astronauts living and working on the Red Planet would not be drinking the briny water we currently see on the surface. Instead, we need to find the source of the water, as it will lead us to a drinkable supply.
We know more about than Mars than any other body in our solar system (aside from Earth), since we’ve spent the last 50 years studying it. As a result, scientists have a pretty good idea of what Mars’ interior looks like. We also know that at the poles there are frozen polar caps of water underneath layers of carbon dioxide. The Martian soil is incredibly moist, and loaded with elements such as carbon, hydrogen, phosphorus, sulfur, oxygen, and nitrogen.
According to Jim Green, NASA’s planetary science division director, the key to finding drinkable water on Mars will be to locate freshwater aquifers below the Martian surface. Based on data collected so far, we know they exist, but we aren’t sure how extensive they are and where exactly they are located. Green says our best chance of mapping these aquifers is with the upcoming Mars 2020 rover. Equipped with ground-penetrating radar, the rover will provide centimeter-scale resolution of the geologic structure of the subsurface. Dubbed the Radar Imager for Mars' Subsurface Experiment (RIMFAX), the Norwegian-built instrument will tell us where the aquifers are located and also give us details about Martian geology.
While an official landing site has yet to be determined for the robotic explorer, scientists will have to use caution when making their selection. The Mars 2020 rover is equipped with a radioisotope thermoelectric generator (RTG) – basically, a nuclear power source. As explained in a recent article, rovers are not allowed to roam the Red Planet all willy nilly; there are specific guidelines governing where they can and cannot go. Since Mars 2020 will rely on nuclear power, it will need to land in an area void of any potential habitable conditions or liquid water. This is a safety precaution in case of a crash landing – they don’t want to wipe out any potential habitable areas.
Mars 2020 will not only help lead us to the water, it will also test out technologies needed for future human missions, but on a smaller scale. Stay tuned for more details as this mission is still in development.