“Now, you want to settle on Mars. Although it is somewhat smaller than Earth, it still has vast land . Where is the most suitable place to settle?”

NASA’s credo is to follow the water – they’re looking for evidence of the existence of life. It’s good advice for past and future humans. Water is heavy and nearly incompressible, so bringing it along to Mars is very expensive and difficult. That’s why finding water locally on Mars is the key to success. In addition, water is not just for drinking: it can be broken down into hydrogen and oxygen, which can make up for air and rocket fuel. Water is the most important thing for future humans on Mars.

Now, a group of scientists has marked possible water sources.

Mars is very cold – the maximum daytime temperature is usually -60°C, so the likely form of water is ice (with some exceptions deep underground). Frozen water sources have been tagged in different ways in different exploration operations, and most studies have focused on data from individual missions or on ice at isolated sites. Therefore, researchers have collected these information and called them SWIM: “Subsurface Water Ice Mapping on Mars Project” to observe data from many missions over a large area of Mars.

In 2008, the NASA Phoenix Landing excavated the surface of Mars. At Sol 20 (20 Martian days after landing), several ice clumps are visible in the lower left side of the recess (left picture, partial enlargement), but the ice evaporated (turned directly into gas) after 4 days. This proves that water can exist and persist below the surface at least at relatively high latitudes (68°N).

The goal of the project is to develop a system that can quantify the agreement of multiple independent observations so that reliable predictions of the location of water can be made. Note that we know that there is a considerable amount of water within the polar ice cap, but it is difficult for spacecraft to land – it is much easier to land near the equator or at mid-latitudes. Also, a depth of ice cannot be more than a few meters so that digging can be done. In other words, it needs to be accessible.

With this in mind, they studied observations extending northward from the Martian equator to about 60° N latitude, as well as observations covering about 80% of the longitude surface. These data were obtained by a variety of methods.The first one is neutron fluxes, which are absorbed by hydrogen in the water, so their can be used to map the location of ice. The second one is thermal inertia, which means at night rocks release heat caused during the day in a different way from ice, so they can be used to map the location of water. The third one is geomorphology, which means structures and features on the surface can indicate water is nearby, such as glaciers. The last one is radar , is can be used to map the location of water because of ice and rocks reflect radar pulses in different ways and as well.

On the map of Mars, location of the Arcadian Plain (left, at the arrow) and the sub-Nile Table Mountain group (right, at the arrow) .

By analyzing the data mathematically, they came up with a value called “ice consistency,” where positive values indicate the presence of ice and negative values indicate its absence. The higher the value, the higher the probability.

What resulted is a map of the available ice that may (and, importantly, may not) be present over a large area of the Martian surface.

The area with the highest values is Arcadia Planitia, which is a wide, flat plain of ancient volcanic flows, and the other area is the Deuteronilus Mensae, which is known to have glaciers. Both are located at mid-latitudes (around 45°N) ,therefore are relatively easy to reach.

In 2012, the Mars Reconnaissance Orbiter discovered a new impact crater in the mid-latitudes of Mars, where the impact has exposed ice from the surface.

One thing the team did to evaluate their predictions was to look at new impacts on the surface, where small asteroids are able to crash through the thin atmosphere onto the Martian surface. If the ice happens to lie below the surface, these impacts can dig it out and make it visible. In the past few years, a camera on an orbiting spacecraft has spotted 13 such craters. The team found that 12 of these sites are on maps that predict the likely presence of ice heights. The results are compelling.

NASA, other space agencies, and even private companies are looking to send people to Mars. I think they will read this paper with great interest.

With the rapid advances in technology, man walk on Mars doesn’t sound as sci-fi as it once did. The first person who will do it may be strolling on Earth right now. Now we can start planning where to put the first footprints.