Don’t pack your bags for Mars just yet

Water is literally the elixir of life. Without it, no Earthly living organism can survive. It’s the reason that the Sahara and Atacama deserts are barren wastelands.

When humans began exploring our planet, each time they encountered a new island or valley, finding drinkable water was their first order of business. And as we turn our attention to the heavens, imagining a future in which intrepid explorers will search the solar system for places to live, the situation is pretty much the same. Celestial bodies with water will be the first places to be colonized.

Thus, the recent announcement that evidence of a lake of water was discovered on Mars has captured the imagination of anyone who has looked at our interplanetary neighbor and dreamed. If this discovery is verified, the possibility of successful human colonies on Mars has just taken a big step forward.

Media reports on the discovery are everywhere, occasionally with florid claims, prompting new speculation on the likelihood that we’ll discover life on Mars and renewing excitement about future manned missions to the Red Planet. So, which of these stories are reasonable and which are hype?

Well, the first thing to remember is that advances on the frontiers of scientific knowledge should be viewed with caution. This is one report, published by a solid and respectable team, but it would be wise to wait for confirmation before popping any bottles of champagne. And there is the disquieting fact the SHARAD probe, orbiting the planet on NASA’s Mars Reconnaissance Orbiter, found no water in the same region.

How did scientists make this discovery?

Using a radar instrument called Marsis on the Mars Express orbiter, researchers from the European Space Agency beamed radar waves at the Martian surface. Radar is able to penetrate the ground. In fact, similar technology has been used here on Earth to find ancient and dry riverbeds under the Sahara and remains of ancient civilizations that are invisible to explorers who walk over the ground.

As the satellite passed near the Martian south pole, they saw reflections from deep underneath the planet’s surface that indicated the presence of liquid water. This water isn’t easily accessible; it is located about a mile (1.5 kilometers) below the surface.

It is unclear just how much water is involved. Initial indications are that it is a body about 12 miles (20 kilometers) wide. It is not possible to know how deep it is, but it is at least three feet (one meter) thick. If these dimensions are right, this is a considerable amount of water.

The temperature of this water is also important. It’s extremely cold — -90 degrees Fahrenheit (-70 Celsius). Normally water at this temperature would be frozen ice, but the Martian surface has a plentiful reservoir of magnesium, calcium and sodium salts called perchlorates, which can keep water liquid at very low temperatures. Thus, this particular lake would be saltier than the Earth’s oceans. However, this isn’t an insurmountable problem for future explorers. If they can get to this water that is a mile underground, desalinization techniques exist.

The existence of water on Mars isn’t an enormous surprise. We have known for a long time that the surface of Mars was once much warmer and wetter. Chemical tests by earlier probes and images of complex dry river beds attest to that. Further, the existence of ice below the planet’s surface has been reported by surveys using other ground penetrating radar.

What does this say about the chances of Martian life?

Truthfully, not much.

Scientists have long suspected that Mars might have once harbored life, although this is by no means an accepted fact. However, the Martian climate has changed over the eons and the surface is now a dry and dead wasteland, with the surface constantly pummeled by deadly radiation from the Sun. It’s hard to imagine that we will find life on the planet’s surface.

But if Mars once did have a complex ecosystem, it’s easy to imagine that it would have retreated underground as conditions on the surface deteriorated. Here on Earth, we have found bacteria located in rocks a mile or two below the surface. And while salt kills most life (that’s why it’s such a good food preservative), there are so-called halophiles — salt-loving creatures who thrive in environments that are deadly to other organisms. In fact, there is a salty lake in Antarctica, which doesn’t freeze and is home to a thriving population of hardy bacteria.

So, while the existence of a salty lake deep underground on Mars is good news for those searching for alien life, we are no closer to knowing if that life actually exists. Xenobiologists and UFO enthusiasts will have to wait a little longer for their Martians.

Does this mean humans could colonize Mars?

Well, it’s clearly a positive sign. Water is crucial for a successful colony and, if a distant planetary body doesn’t host it, astronauts will have to bring it with them.

According to NASA, astronauts need about half a gallon of water per day, although this number depends very heavily on the water recycling and purification technology. Thus, the amount of water in these reports is a huge boon to future explorers. However, there are some very formidable technical obstacles to be addressed before accessing this water is anything other than a pipe dream. We would have to ship equipment capable of drilling a mile below the Martian surface and then bringing it to a complex desalination plant. This is a daunting and enormously expensive endeavor, although one that is probably solvable given the will and the resources to accomplish it.

It’s hard to say what the implications of this discovery will be. In the short term, if confirmed, it is an interesting scientific advancement and there are probably other similar lakes still to be found. What this discovery could mean for the future is a bit murkier. Liquid water on Mars does open the door to advancing our understanding of whether life exists elsewhere in the universe and maybe makes it reasonable to talk about colonizing the planet, But we’re a long ways away from making any additional and substantive advances.

This is the moment to congratulate the scientific team and the European Space Agency for their impressive accomplishment. Tomorrow we’ll start thinking about what to do next.