Zeitgeist Zephyr

Discovered by Galileo in 1610 and orbiting 670,000 miles away from Jupiter, the icy moon Europa beacons as one of the best possibilities for discovering extra-terrestrial life in our own solar system.  Massive amounts of data have been collected on the Jovian satellite in recent decades, much of this evidence increasingly indicates that there is some sort of liquid, most likely water, working beneath its ice covered surface.  If the evidence that water exists beneath the ice sheet on Europa is validated, the possibility of life goes up dramatically.How do we know it’s water?

Water is the only known substance in the universe that floats on itself in its frozen form.  Every other liquid as it freezes will fall to the bottom of what ever it is contained in.  In this case, it would be the rocky surface of Europa beneath the ice.  The reason that we know that it is in fact water and not some other liquid that has frozen all the way through is because of the presence Jupiter. 

The immense gravity of Jupiter acts on Europa in the same way that Earth’s moon acts on us.  As the moon orbits the Earth, the force of the Moon’s gravity (its tidal force) causes the oceans on Earth to experience tides.  The water is stretched out to where it doesn’t sit completely level on the Earth’s surface.  This is why the tides go in and out throughout the day in coastal areas.  The same thing is true with Europa.  The immense gravity of Jupiter causes tidal forces beyond what is observable in the Earth-Moon system.  Direct evidence of this is the next moon in from Europa, Io (pronounced eye - oh.)  Io is unquestionably the most volcanically active moon in the solar system, with massive geysers being observed on its surface from the earliest Voyager missions back in the 1970’s.

These same tidal forces would also affect Europa.  While the affects are slightly diminished due to its distance from Jupiter, they are a constant presence.  Volcanic activity on Europa would resemble the numerous underwater hydrothermal vents that have been discovered on Earth.  The heat coming out of a single vent can easily reach into the hundreds of degrees Fahrenheit.  With all of Europa’s volcanic activity occurring beneath the ice, it is not a stretch to realize that this would heat the liquid that causes the ice on the surface.

We also know that it is water because there is clear evidence that the ice on Europa shifts over time.  Zooming in on Europa, it becomes immediately apparent that there are large ridges on the surface.  These ridges have been observed to shift over time, indicating that whatever it is on the surface, it moves.  The closest analogies that can be found on Earth are found in the aerial photographs of sea ice covering the polar regions.  

Since the ice has to float to shift, and if only water allows its frozen form to float, then Europa has water.

Why would there be life on Europa?

As mentioned earlier, it is likely that hydrothermal vents exist on Europa’s ocean floor.  On Earth, it was once believed these environments would be inhospitable to life.  Turns out, they’re not!  At every hydrothermal vent known on Earth, there is some form of life.  Whether it exists in the form of microbes or more fantastic lifeforms ranging from tube worms to shrimp, life has adapted to survive on energy released from the heat of the vents.  Rather than depending on photosynthesis to fuel the most basic elements of the food chain in these communities, a process known as chemosynthesis drives these lifeforms.  Chemosynthesis is the conversion of carbon dioxide or methane as well as nutrients into organic matter than can be used as energy.

If there are hydrothermal vents on Europa, it is probable that communities of chemo-synthetic life exist on Europa as well.  While the life might not be highly evolved, it would be life nonetheless, and it would be life in our own solar system.  This is the “Holy Grail” of discovering extra-terrestrial life.  If life can exist on two worlds simultaneously around one star, and if one of those worlds is orbiting a gas giant (much like the ones discovered around other stars), then life must be an abundant phenomenon in the universe.  If that is the case, it might not be such a tragedy if life on Earth parishes (a tragedy for the universe, that is.)  

While NASA and ESA are considering their plans for the next joint mission to an outer planet, I would push for a Jupiter mission that would include a Europa lander.  Europa offers the best hope of finding extraterrestrial life in our own solar system.

_______________________________________________________

Sources:

“Europa (moon).” Wikipedia. 21 Apr 2008 http://en.wikipedia.org/wiki/Europa_(moon).

Picture Credits:

“Astronomy Picture of the Day.” NASA. 21 Apr 2008 http://apod.nasa.gov/apod/ap071202.html. 

“The Jupiter Icy Moons Orbiter: The Smooth and Bright Moon Europa.” Space Today Online. 21 Apr 2008   http://www.spacetoday.org/SolSys/Jupiter/EuropaInfo.html.

“The Microbial World.” University of Wisconsin - Madison. 21 Apr 2008 http://www.bact.wisc.edu/themicrobialworld/Hydrothermal_vent.jpg.

This new series of posts that I’ll post on a regular basis is called “Blogontology.”  Broken down, that’s blog and ontology (which is the study of the nature of existence.)  In essence, it’s a blogger’s attempt to understand the world and the nature of ’being.’  It’s become a part of my normal daily routine to read a passage by a philosopher during my daily prayers. 

Right now, I’m hooked on the two most well know American Transcendentalists, Henry David Thoreau and Ralph Waldo Emerson.  I’ve included links to databases of their work on my blogroll, as most of the time quotes that I use here will be referenced back to those sites. 

This first quote comes from Chapter 2 of Thoreau’s Walden and has been a significant guide for me this week.   

“Morning is when I am awake and there is a dawn in me. Moral reform is the effort to throw off sleep…To be awake is to be alive. I have never yet met a man who was quite awake. How could I have looked him in the face?

We must learn to reawaken and keep ourselves awake, not by mechanical aids, but by an infinite expectation of the dawn, which does not forsake us in our soundest sleep. I know of no more encouraging fact than the unquestionable ability of man to elevate his life by a conscious endeavor…

… I went to the woods because I wished to live deliberately, to front only the essential facts of life, and see if I could not learn what it had to teach, and not, when I came to die, discover that I had not lived.”

- Henry David Thoreau

The whole context of this passage can be viewed at the following page:

http://thoreau.eserver.org/walden02.html