Scientists Absorbed by Unique Ways and Wonder of Water

Water, the stuff of life. Scientists search for it everywhere, and it’s the first thing they look for when exploring new worlds.

Recently, Mars Pathfinder scientists went bananas over new evidence that ancient martian floods may have rivaled Noah’s. They think--and hope--that frozen water still lurks under Mars’ bone-dry surface and rejoiced when Pathfinder spotted fluffy early morning clouds.

Meanwhile, the National Aeronautics and Space Administration wants to send a probe to Jupiter’s frozen moon Europa--hoping to find (you guessed it) oceans underneath its cracked icy crust. Researchers go bonkers over water frozen into the heart of comets, water drifting about in outer space, water in snowballs supposedly pelting the Earth (did they fill our oceans?).

What is it about water, anyway?

Water is arguably the most interesting chemical on Earth, an elusive elixir brutal enough to wear down mountains and nurturing enough to spawn life.

Water is the only kind of matter that can exist as solid, liquid and gas all at the same temperature. (Think of frozen landscapes, with a stream running through packed snow, vapor rising into the still air.)

Water is also the only substance that expands when it turns from liquid to solid. Everything else shrinks from the cold, as molecules huddle closer together, and expands in the hyperactivity of heat, as molecules careen around with more and more energy.

Not water. Just above the freezing point, water molecules join in a kind of lattice with airy spaces in the middle, fluffing up like a souffle. Soda cans left in the freezer explode when the watery liquid inside expands, as the metal contracts, and there’s nowhere else to go.

The good news is: Airy ice is lighter than water, and it floats. Thick ice coats lakes and ponds with a blanket that allows life to carry on even in the depths of winter, locking in warmth from the sun.

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Water can do this trick in part because it’s electrically lopsided. The familiar H2O molecule looks like Mickey Mouse ears, with a large head (oxygen) carrying a negative charge, and two small ears (hydrogen) sticking out with positive charges. The molecule has two poles, like a magnet, and attracts like a magnet--grabbing onto just about anything in its path. The mouse ears meet the head at exactly 105 degrees-- the same geometry that sculpts snowflakes--as one water molecule joins another in a precisely repeating crystal pattern.

This magnet-like property means that the molecules grab onto each other with such strength that they form a skin--substantial enough to serve as a floor for some insects that walk on water. Raindrops have such a thick skin they fall like bullets, shattering rocks and whittling mountains.

But water is more than performance art.

Because it sticks to anything, it climbs up glass tubes and stalks of celery, adheres to edges so it can creep up, defying gravity--keeping blood flowing in capillaries and sucking nutrients high into the tallest trees.

And because it’s so promiscuous, it joins with other molecules to create an infinite variety of combinations. Water is a universal solvent. Practically anything (except oil) falls apart in it.

That makes it the perfect soup in which to brew life. In the ocean’s watery caldron, compounds can arrange and rearrange themselves over and over, trying out new configurations, until something takes, comes alive.

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Lately, scientists have been discovering many new forms of water. In the high, thin atmosphere, for example, water molecules can join into clusters that form cages--and researchers have succeeded in trapping various kinds of atoms inside these soccer-ball-shaped spheres. The self-arranged clusters are probably common, scientists think, in the very cold, sparse layers of the atmosphere, 50 miles high, and may act as seeds for eerie, luminescent clouds.

Farther out into space, water gets too cold even to crystallize. Indeed, scientists now think that the vast majority of water in the universe exists as this flash-frozen form of “disorderly” ice.

Which all goes to show that sometimes the most astonishing tricks of nature are frequently found in the most ordinary things.