Where should future astronauts land on Mars? Follow the water

So you want to build a Mars base. Where to start? Like any human settlement, it will be best located near accessible water. Water will not only be essential for life-sustaining supplies, but will also be used for everything from agriculture to the manufacture of rockets, which astronauts need to return to Earth.

It would be expensive and risky to throw all the water to Mars. Therefore, since 2015, NASA has engaged scientists and engineers to identify deposits of Martian ice that may be within the space of astronauts on the planet’s surface. But water, of course, also has great scientific value: if the current microbial life can be found on Mars, it will probably be close to these water sources as well.

A new study appears in Natural Astronomy contains a comprehensive map outlining where ice most and least likely occurs in the northern hemisphere of the planet. The combination of 20 years of data from NASA’s Mars Odyssey, Mars Reconnaissance Orbiter, and the now inactive Mars Global Surveyor, is the work of a project called Subsurface Water Ice Mapping, or SWIM. The SWIM effort is led by the Planetary Science Institute in Tucson, Arizona, and is managed by NASA’s Jet Propulsion Laboratory in Southern California.

“The next frontier for Mars is that human explorers must come to the surface and look for signs of microbial life,” said Richard Davis, who is leading NASA’s efforts to find Mars resources to send humans to the Red Planet. . “We realize we need to make new maps of underground ice to improve our knowledge of where the ice is, both for scientific discovery and the local resources that astronauts can rely on.”

In the near future, NASA plans to hold a workshop for multidisciplinary experts to assess potential human landing sites on Mars based on this research and other scientific and engineering criteria. This mapping project could also inform recordings of future orbits that NASA hopes to send to the Red Planet.

NASA recently announced that, together with three international space agencies, the signing of a declaration of intent to investigate a possible International Mars Ice Mapper mission concept. The statement brings together the agencies to formulate a joint concept team to assess the mission potential as well as partnership opportunities between NASA, the Agenzia Spaziale Italiana (the Italian Space Agency), the Canadian Space Agency and the Japanese Aviation Development Agency.

Location, location, location

Ask Mars scientists and engineers where the ice is most accessible underground, and most will point to the area below Mars’ polar region in the northern hemisphere. On earth, this region is where you will find Canada and Europe; on Mars, it includes the plains of Arcadia Planitia and glacial valleys in Deuteronilus Mensae.

Such regions represent a literal middle ground between where most water ice (the poles) and where most sunlight and heat (the equator) can be found. The northern mid-latitude also offers favorable landing heights. The lower the altitude, the more likely a spacecraft is to slow down by decreasing friction of the Martian atmosphere as it descends to the surface. This is especially important for heavy land classes, as Mars’ atmosphere is only 1% as dense as Earth’s and therefore offers less resistance to incoming spacecraft.

“Ultimately, NASA gave the SWIM project the task of figuring out how close to the equator you can go to find ice on the surface,” said Sydney Do, the Mars Water Mapping Project leader at JPL. “Imagine that we have drawn a winding line across Mars that represents the ice boundary. With this data, we can draw the line with a finer pen instead of a thick marker and focus on parts of the line that are closest to the equator is. “

But knowing if a surface is hiding ice is not easy. None of the instrument data sets used in the study were designed to measure ice directly, said the Planetary Science Institute’s Gareth Morgan, co-principal of the SWIM project and lead author of the article. Instead, each orbital instrument detects different physical properties – high hydrogen concentrations, high radar velocity and the rate at which temperature changes on a surface – which may indicate the presence of ice.

“Despite 20 years of data and a fantastic range of tools, it’s hard to combine these data sets because they are all so different,” Morgan said. “Therefore, we assessed the consistency of an ice signal and showed areas where multiple datasets indicate that there is ice. If all five datasets point to ice – bingo.”

If only two of them say so, the team would try to figure out how consistent the signals were and what other material they could create. Although the different data sets did not always fit perfectly, they complemented each other. Current radars, for example, peek deep underground, but do not see the top 30 to 50 feet (10 to 15 meters) below the surface; a neutron spectrometer on board one orbit measures hydrogen in the upper soil layer, but not below. High-resolution photos have revealed ice thrown at the surface after recent meteoric impacts, providing direct evidence to supplement radar and other water ice distance detection indicators.

Next steps

While Mars experts are examining these new maps of subterranean ice, NASA is already thinking about what the next steps would be. First, blind spots can be resolved in the currently available data by sending a new radar mission to Mars that could house the areas that may be of greatest importance to human mission planners: water ice in the upper layers of the subsurface.

A future radar-focused mission on the near surface could also tell scientists more about the mixture of materials found in the layer of rock, dust and other material on top of ice. Different materials require special tools and approaches for digging, drilling and accessing water ice deposits, especially in the extreme Martian environment.

The mapping of efforts in the 2020s could help enable human missions to Mars as early as the 2030s. But for that, there will be a strong debate about the location of humanity’s first outpost on Mars: a place where astronauts will have the local water ice resources needed to sustain them, while also making valuable discoveries. about the evolution of rocky planets, habitability and the potential for life on extraterrestrial worlds.