Why is liquid water on Mars necessary for life?

NASA revealed Monday that liquid water is present on Mars. Why is liquid water a prerequisite for life? 

NASA/JPL-Caltech/Univ. of Arizona
Dark narrow streaks, called 'recurring slope lineae,' hypothesized to be formed by flow of briny liquid water, emanate from the walls of Garni Crater on Mars, in this view constructed from observations by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter.

Yesterday, NASA revealed the “strongest evidence yet that liquid water flows intermittently on present-day Mars.” NASA's Mars Reconnaissance Orbiter (MRO) detected hydrated salts in the recurring slope lineae (RSL), the streaks that appear on the Red Planet’s slopes.

"We can look and see if we can determine if there is some sort of aquifer network that may be supplying these [RSL features]. We don't know that – there are other theories, other ideas – but that is actually the next step," Jim Green, director of NASA's Planetary Science division, said during the press briefing. "So if there is indeed those kind of resources that we can begin to probe, we might be able to answer that question pretty quickly."

Does the discovery of liquid water mean there is life on Mars? Not so fast.

"Finding evidence for flowing water is not the same as finding life," says National Geographic's Nadia Drake. "Right now, scientists don’t know where this water is coming from, or if the chemistry in these Martian seeps is even life-friendly."

Planetary scientists have long said that where water exists, life may also exist. “Water is essential at the molecular level to moving life beyond its basic building blocks; thus, searches for extraterrestrial life usually involve a search for liquid water,” writes NASA.

But what makes water the necessary liquid for sustaining life?

“Part of the reason is that we've never discovered an organism that's proven otherwise,” says Jonathan Attebery, science writer for “HowStuffWorks.” Water facilitated the beginning of life on Earth, “acting as a medium in which organic compounds could mix with one another.”

As a solvent, water allows vital chemical reactions to occur. “From the list of potentially abundant solvents in the universe, water looks to be the best candidate to support a complex ecosystem,” says Steve Nerlich of Universe Today in an article for io9.

Furthermore, liquid water “conveys vital substances like metabolites and nutrients from one place to another” and is also capable of “bending enzymes,” the proteins that catalyze chemical reactions, says Peter Tyson, editor in chief of NOVA Online.

"Given that life on Earth is so dependent on water, and given that water is so prevalent in the universe, we don't feel that we're going out on a limb to say that life would require liquid water," said Neil deGrasse Tyson, an astrophysicist and director of the Hayden Planetarium at the American Museum of Natural History, in an interview with PBS.

It isn’t impossible that lifeforms exist that don’t require water to survive, but they would not resemble life on Earth. Biochemistries based on other solvents “seem likely to be limited to cold, low energy environments where the rate of development of biological diversity and evolution may be very slow,” says Mr. Nerlich.

According to Mr. Attebery, “we simply don't have enough information to say whether or not life could exist without water. We know with certainty, however, that life on Earth definitely couldn't.”

You've read  of  free articles. Subscribe to continue.

Dear Reader,

About a year ago, I happened upon this statement about the Monitor in the Harvard Business Review – under the charming heading of “do things that don’t interest you”:

“Many things that end up” being meaningful, writes social scientist Joseph Grenny, “have come from conference workshops, articles, or online videos that began as a chore and ended with an insight. My work in Kenya, for example, was heavily influenced by a Christian Science Monitor article I had forced myself to read 10 years earlier. Sometimes, we call things ‘boring’ simply because they lie outside the box we are currently in.”

If you were to come up with a punchline to a joke about the Monitor, that would probably be it. We’re seen as being global, fair, insightful, and perhaps a bit too earnest. We’re the bran muffin of journalism.

But you know what? We change lives. And I’m going to argue that we change lives precisely because we force open that too-small box that most human beings think they live in.

The Monitor is a peculiar little publication that’s hard for the world to figure out. We’re run by a church, but we’re not only for church members and we’re not about converting people. We’re known as being fair even as the world becomes as polarized as at any time since the newspaper’s founding in 1908.

We have a mission beyond circulation, we want to bridge divides. We’re about kicking down the door of thought everywhere and saying, “You are bigger and more capable than you realize. And we can prove it.”

If you’re looking for bran muffin journalism, you can subscribe to the Monitor for $15. You’ll get the Monitor Weekly magazine, the Monitor Daily email, and unlimited access to CSMonitor.com.

QR Code to Why is liquid water on Mars necessary for life?
Read this article in
https://www.csmonitor.com/Science/2015/0929/Why-is-liquid-water-on-Mars-necessary-for-life
QR Code to Subscription page
Start your subscription today
https://www.csmonitor.com/subscribe