Every once in awhile, news about water on Mars pops up on science blogs and news outlets. In fact, the topic has been in the spotlight so much in recent years that many people just shrug when they read about it. What is the big deal; didn’t we find water on a half a dozen celestial bodies already? It is supposed to be a pretty common substance. We found traces of water on the Moon, on asteroids and comets, heck the entirety of Europa’s surface, Saturn’s largest moon, is comprised of mostly water—under a thick layer of ice. So why is Martian water so important? Well, the answer is quite interesting.
Everyone knows that water is an integral part of human life; in its liquid form, we need it for our everyday survival. We can also split water into oxygen and hydrogen and use the resulting elements as rocket fuel, to generate electricity or to produce breathable air. The role water plays in long-term manned space missions is fundamental, making this seemingly simple substance a crucial part of any future Mars initiative. But it is also a heavy substance! Carrying all the water astronauts will need on a years-long mission to Mars is expensive, even if we assume that most of it can be recycled. But what if much of the water needed would be readily available at the destination, therefore alleviating the need to ship it from millions of miles away? Such a case would significantly decrease the launch costs of manned Mars missions. Luckily, this precisely what seems to be the case as NASA has repeatedly demonstrated the existence of subsurface water ice. We also know that both polar caps consist of mostly said material, as well as the thin Martian clouds. To put it simply: Mars’ demonstrable water reserves bring us to the dream of a—at least partially—self-sustainable Martian outpost that much closer. But water has not only practical but tremendous scientific implications as well!
Life, as we currently understand it, requires liquid water. Although there is no liquid water on Mars today, we believe that, billions of years ago, water covered much of the surface. The Curiosity rover has even found evidence of ancient river beds where layers of sedimentary rocks and rounded pebbles point toward the presence of free flowing water. This is important for two reasons. On the one hand, it may give us clues about past life on Mars, if it ever existed, and I do not think I need to stress how important that would be. Signs of life on another planet would change forever how we think about life in the universe and our very place in it. But it could also help unravel one of the biggest mysteries of our own planet: of how life started here! The current consensus is that life began about 3.5 billion years ago, in conditions that are believed to be very similar to those of early Mars. The problem is that Earth has since undergone a tremendous amount of change—from erosion, heat, weather, etc—and evidence of that period is scarce at best. Mars, on the other hand, has changed very little over the eons. It is, essentially, an inactive planet where evidence of the distant past is still readily accessible. Mars is ripe for scientific investigation about the origins of life. So, ironically, it is entirely possible that clues about how life began on Earth may not be found in our backyard but on another planet, millions of miles away.
Of course, no one should expect Curiosity to come across fossil remains all of a sudden—it is not equipped to look for microbial life, which planetary biologists believe is as far as life could have gotten during Mars’ brief, hospitable period—but it can determine if Mars could ever have supported life while perhaps bringing us one step closer to answering the big questions about our origins. All of this would come at a time when the role of the Red Planet as the possible cradle of life is beginning to garner increasingly more attention.
* Illustrations are from the Wikimedia Foundation