Mars Water Sources Are Underground

A bunch of years ago, I wrote a documentary for fulldome called MarsQuest. In it, our audiences explored the past, present, and future exploration of Mars. Over the years, I’ve watched many missions go to Mars, following the progression we imagined in our show. First, robotic explorers. Then, if all goes well, we send people to Mars to give it a close-up human touch.

Today, we’re at the stage of planning the first crewed missions to Mars. Right now, we’re using robotic probes and we’ve sent many of them. Joining them this week are the Hope mission, the Tianwen-1 mission, and the Perseverance lander with its tiny helicopter.

Exploration of Mars

Of course, people have already explored Mars in a limited way. And, we’ve always dreamed of walking its surface. But, dreams of exploration are only a first step. Unlike the explorers of old who circumnavigated Earth, people going to Mars will prepare for a most alien place. That complicates the exploration of the Red Planet quite a bit.

Humans Need Mars Water

What is the most important thing that Mars explorers are going to need? Obviously, air to breathe is one resource. So is water. The exploration of Mars has continually focused on looking for sources of water across the planet. As we all know, the surface has NO flowing water and likely hasn’t for billions of years. However, that doesn’t mean water doesn’t exist there. The upcoming missions to Mars arriving this week all will continue the search for resources, including water.

Yet, we DO know that Mars has water. That’s thanks to the spacecraft that are already “in situ” and have explored in the past. For example, the first images of Mars from the Mariners showed river beds and flood plains. Every imaging mission since that time has shown tantalizing hints of water across the planet, including the ice caps. Other missions have “sensed” the planet using radar and other instruments, looking for the chemical indications of water.

Combing the Mars Data for Water

Today, data from the Mars Reconnaissance Orbiter, Mars Odyssey, and Mars Global Surveyor missions are contributing to the mapping of water on Mars. In particular, they are chartingthe amounts of ice that we can’t see, but are buried underground.

Planetary Science institute scientist Gareth Morgan leads a team that is analyzing that data. They’re using new data-processing techniques to assess the possibilities for hidden water ice on Mars. Their system is called “Subsurface Water Ice Mapping” (SWIM). It provides maps of places around the globe that could harbor icy reserves. The science team is doing radar analysis of the surface features, which tells them something about how the features formed. They’re also using radar data to peer beneath the surface, and mapping periglacial features that indicate the presence of ice. All of these, plus several other techniques, combine to give a much clearer view of subsurface ice on Mars. All of this information will help future mission planners find the best places to land people on the planet.

Of course, water is important for sustaining life, but it’s useful in a variety of other ways. According to Morgan, the goal of his project is to provide maps of potential buried ice deposits. Such maps can support the selection of human landing sites. “The ice is a critical resource that has many uses, like the generation of water for human consumption, growing plants for food, and for the generation of methane fuel and breathable air,” he says. But the most important is to provide fuel for the return trip home to Earth. “Taking all the fuel you need for the round trip to Mars is basically not feasible. As a result, pretty much every mission concept study from the last 30 years considers exploiting the Martian environment for fuel.”

Mars: The Icy Planet

Despite the fact that it looks like a desert, Mars is actually quite an icy place, especially if you consider all the buried ice. So, it seems simple to just land near where the ice is. It may not be that easy to locate a good landing site that is also near embedded ice deposits. That’s why Morgan and the team are reassessing all the data, to locate all the icy reserves across Mars. It also matters how deeply the ice is buried. Deposits that are close to the surface are obviously going to be easier to “mine” than those deeper down. The current data sets show ice buried as shallow as a centimeter and as deep as a kilometer.

Using ice on Mars as a water resource is not a new idea. Of course, mission planners have to consider a lot of other factors when sending people to the Red Planet. Landing site safety (i.e. is the place free of giant rock piles, landslides, etc.), as well as solar and thermal specifications, have to be considered. But, finding stores of water ice is the first challenge for the crewed missions of the future. Giving them all the water they can use for life support as well as transport is important.

The next few missions to Mars: Hope (from the United Arab Emirates), Tianwen-1 (China), Perseverance (NASA-USA), will also focus on the search for water, among their other goals. This tells you how important water is — it’s the stuff of life, no matter where we go in the solar system. Understanding its history and existence on Mars is an important step toward eventual human exploration of the Red Planet.

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