October 19, 2015

Water, Water, Everywhere

by Anthony Carpi

We’ve long known that water was present in the atmosphere of Venus and that frozen water is trapped in the polar ice caps visible on Mars. However, it seems that there have been a slew of recent announcements about water being found on other planets and moons.

Artist’s rendition of a primitive ocean on Mars. ©NASA/GSFC

For example, in late 2013 NASA announced that its Hubble telescope found evidence for the existence of water on at least five massive exoplanets. In June of 2014, scientists analyzing data from NASA’s Cassini mission announced evidence of a salty ocean of liquid water inside of Saturn’s largest moon, Titan. This September, NASA announced that data sent back from its Mars Reconnaissance Orbiter strongly suggested that liquid water intermittently, and possibly seasonally, flows on that planet’s surface. And just last week, NASA announced that the Ralph spectral composition mapper onboard the New Horizons spacecraft had found evidence of water-ice deposits on the surface of Pluto.

Regions of Pluto with exposed water ice are highlighted in blue in this composite image from New Horizons’ Ralph instrument. ©NASA/JHUAPL/SwRI

Why the sudden rash of water findings? Is it suddenly raining down from the heavens? As it turns out, it really has more to do with our focus on looking for water. The vast majority of life forms that we know of need liquid water to thrive. Sure, there are things like cryptobiotic soils (which are actually communities of microbes) that can survive with very little water; there are certain microbes that produce spores that can survive for tens or even hundreds of years without water; and there are extremophiles that survive and even thrive in low water environments like the La Brea Tar Pits. However, these strange organisms need some amount of water, even if just a few molecules, to remain active, reproduce, and carry out other functions that living organisms do so well.

Water is so essential to our understanding of life that many scientists believe it is actually a prerequisite to finding life on other planets. And this helps explain our sudden finding of water in every nook and cranny of the solar system. Scientists are increasingly looking for the presence of water on objects other than Earth as a hint that life may exist outside of our own lusciously wet planet.

Instruments are increasingly being added to new space probes that could help detect water, and new techniques have been refined that not only look for water itself, but looks for signs of water through other clues. New spectral data is being collected by telescopes to look for the signature of water molecules; new geological information is being gathered to identify the presence of streaks that look like stream beds or minerals that we believe can only be produced in the presence of water; and even gravitational data is being used because the tides that can occur in massive bodies of water influence a planet’s gravitational pull. (See the NASA video below to learn how researchers investigate the characteristics of exoplanets, like size, composition, and atmospheric makeup, based on spectral data.)



Our sudden fascination with water in the universe is really a great example of how science works – scientific research is framed by our collective experiences, in this case our experience that life on earth is largely water-based. Does this mean we might overlook some exotic, non water-based form of life on a distant planet? No, but it may mean that it may take a bit longer to find those exotic life forms. As new data is collected and new technologies are developed, science expands its horizons – in this case these advances have led us to look more closely at the possibility of water existing on planets and moons other than our own. And as is common in science, or even in everyday life, once we focus our attention on something, we start seeing it pop up everywhere.

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Written by

Anthony is the founder and president of Visionlearning. He is a Professor of Environmental Toxicology at John Jay College of the City University of New York with extensive experience in teaching and educational research. He has authored articles for the Journal of Chemical Education and the Journal of College Science Teaching on the design and effectiveness of Web-based teaching resources. He is the recipient of two National Science Foundation grants for the development of online science teaching resources, and he was one of the designers of the HETS virtual plaza, an online education cooperative for Hispanic students. He has published extensively on the fate, behavior and toxicity of mercury as an environmental pollutant. In addition, he is active in research in the area of environmental forensics.

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