So you want to go to Mars. It is smaller than Earth, but it still has a lot of real estate. Where is the best place to call home?
NASA’s mantra was to follow the water – look for evidence of past life, but for once and for future humans, it’s still a good idea. Water is heavy and almost incompressible, so it is very difficult and expensive to take it with you to Mars. That means finding her in situ, there on Mars, is key to success. Also, water is not just for drinking: it can be broken down into hydrogen and oxygen to make both breathable air and rocket fuel. It is the most valuable thing for a future human presence on the planet.
And now, a team of scientists has drawn the most likely place to be.
Mars is cold – a high daily temperature of -60 ° C is common – so any water is probably ice (with some deep exceptions). Frozen water has been mapped in different ways by different missions, and most research has focused either on data from a single mission or on ice in isolated places. So, the team brought together what I call SWIM: the Mars Subsurface Water Ice Mapping project, to analyze data from many missions in a large area of the planet.
The aim was to create a system that could quantify the consistency of several independent observations, so that it could make a robust prediction of where that water was. Beware, we know that there is quite a bit of blockage in the polar caps, but they are difficult to access on spacecraft – landing requirements make it much easier to land near the equator or in mid-latitudes. Also, the ice cannot be more than a few meters deep, so it is possible to dig it up. In other words, it must be accessible.
In view of this, they analyzed the observations that stretched from the equator of Mars to about 60 ° north, and around the planet covering about 80% of the surface in longitude. The data were obtained by various methods, including neutron flux (these subatomic particles are absorbed by hydrogen from water, so their prevalence can be used to map ice locations), thermal inertia (at night, rocks release heat accumulated during the day. a different way from water ice so that it can be used to map where water is), geomorphology (structures and features on the surface that indicate that water is nearby, such as glaciers), and radar (water ice). and the rock reflects radar pulses differently, again allowing water mapping).
Applying a mathematical algorithm to the data, they came up with a number that they call ice consistency, where a positive value is consistent with the presence of ice and a negative value inconsistent with it. Higher values mean stronger results.
The result: a map in which there may be accessible ice (and, most importantly, probably not) on a large sample of the Martian surface.
The places with the highest values are in Arcadia Planitia, a wide, smooth plain with ancient volcanic flows and in another region called Deuteronilus Mensae, which is known to have glaciers. Both are located at mid-latitudes (about 45 ° north), so they are relatively easy to access.
To evaluate their predictions, one thing the team did was to analyze the fresh impacts on the surface, where small asteroids managed to pass through thin air and hit the ground. If the ice is located just below the surface, these impacts can excavate it, which makes it quite obvious. In recent years, rooms aboard the orbiter have found 13 such craters. The team found that 12 of them were located where their maps predicted that ice would be highly reliable. It’s reassuring.
NASA, other space agencies and even private companies are looking to send people to Mars. I imagine they will read this paper with great interest.
Technology is advancing rapidly, and a human foot on Mars is not as scientific-fantastic as it used to be. It is possible that the first person to do this is already walking on Earth. And now we can realistically start planning where the first boot footprint can be.