Show Date: June 28, 2006 
Pam Eastlick for THE DEEP on line

OCEANS IN SPACE

Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond. Join us each week on Newstalk K57 on Wednesday night from 7 to 8 p.m. for exciting live science expeditions or listen live on our web site www.thedeepradioshow.com

I’ve discovered over the years that one of the most popular space-related misconceptions is that Earth is the only planet, indeed the only place, in the solar system that has water. I am constantly amazed at the frequent news headlines that this robot or that scientist has made the astounding discovery that there’s water on Mars. This is, in fact, very old news. We’ve known for at least 200 years that the northern Martian ice cap is formed from water ice (the southern cap is mostly dry ice or frozen carbon dioxide).

Despite popular opinion to the contrary, water is extremely common in the solar system and Earth harbors only a small fraction of the compound that’s absolutely necessary for life-as-we-know-it. But the important factor for life-as-WE-know-it is that virtually all solar system water occurs in water’s solid form; ice.

The water ice we’re familiar with is called Ice 1. Because water is a polar compound, Earth’s water ice is chaotic in structure and less dense than the liquid form of water. This sole fact has allowed life to form on our planet. If Ice I was denser than water, the oceans would freeze from the bottom up and life-as-we-know-it could not exist. Our kind of life REQUIRES liquid water. For a great interview on the subject, CLICK HERE and scroll down to the interview where Dr. Cynan Ellis-Evans, from the British Antarctic Survey in Cambridge, discusses Lake Vostok which has remained sealed-off from the rest of the world for millions of years. What keeps the water of the lake liquid under the ice, does it contain life, and if so where did that life come from and what can it tell us about the prospect of finding life under similar conditions elsewhere in the universe ?

But frozen water comes in at least 12 different forms depending on the temperature and pressure at which it freezes. The water ices above Ice 3 have a crystalline form and are denser than liquid water. They can never naturally occur on Earth, it isn’t cold enough. These ices are not ice as we know it but water rocks. These ices can also take a molten or semi-solid form and we suspect that on some of the outer moons of the gas giants there are volcanoes that erupt molten water.

But that’s not all. Jupiter has four planet-sized moons. One of them, Io, is the most volcanically active body in the solar system and it’s made of silicate rocks. The other three, Europa, Ganymede and Callisto, are all made of solidly frozen water in one of its crystalline forms. But here’s the important part. All of them wobble as they spin around Jupiter, just as a raw egg wobbles when it spins, and this implies that they are not solidly frozen. Each of these enormous moons apparently contains a vast liquid water ocean. Europa’s ocean may be 30 to 40 miles deep and the ocean inside Ganymede (the solar system’s largest Moon) may be 300 to 600 miles deep. If these moons do contain liquid water, they harbor much more water than the seas of Earth.

We’re speculating about Europa, Ganymede and Callisto, but there is no more speculation about Enceladus, one of Saturn’s moons. Enceladus is the brightest moon in the solar system reflecting over 90% of the sunlight that falls on it. It’s that reflective because it’s a giant 300 mile wide frozen snowball. But the Cassini mission that’s orbiting Saturn right now has taken pictures of Enceladus erupting liquid water. There is no question that there’s liquid water inside this moon.

This week we will be talking about oceans on Earth and oceans in space. Can you have a liquid water ocean for 6 billion years and not have life in it? What kind of life would develop inside a moon? Join us as we journey from Earth’s oceans to oceans in space.
Artist’s view of an erupting water volcano on Enceladus

The Deep is broadcast on Newstalk K57 every Wednesday night at 7:00 p.m. You can also listen live from our web site www.thedeepradioshow.com. Join Jim Sullivan, Pam Eastlick, and Peter Melyan on the deepest radio show on Earth.