Europa : Fact, Myth, Perspective
Ice or Ocean, Crete and Tyre, Dry to None
by Duane Dunkerson
Fact : Maybe
In 1610 both Galileo and Marius sighted the four
principal moons of Jupiter. Europa is one of the four
and is the smallest of the four. It is second in
position outward from Jupiter.
Europa had been a point of highly reflective light in
orbit about Jupiter until the spacecraft, Voyager,
showed mostly grooves and ridges on its water-ice
surface. Decades later the Galileo spacecraft has
confirmed what Voyager saw for us. Galileo has brought
more to our attention. We have become mostly interested
in the amount of water that may be present and in the
possibility of life below the surface in conjectured
vast seas of water.
Brother Guy Consolmagno hit upon both possibilities of
abundant water and life on Europa. His 1975 thesis
proposed that Europa was a moon with an icy covering and
an ocean below that frozen crust. In an appendix for
this thesis he touched lightly on the possibility of
oceanic life below the surface.
He pointed out that John Lewis in 1971 had noted that
the moons of Jupiter and Saturn were most likely of rock
and water ice. Their surfaces were bright. By the middle
1970's, infrared spectra of Europa had been obtained.
The spectra matched those of water ice. Father Guy
thought Europa's water was nearly all melted with a thin
icy crust. He proposed about 100 km of water.
He talked briefly with Carl Sagan at a scientific
conference about his thesis. Sagan coolly inquired how
life-giving energy could be provided without sunlight
penetrating the icy crust? Father Guy briefly thought
how about life by means of energy from a volcano? No one
had seriously heard of such a thing.
In the late 1970s oceanographers here on Earth found
volcanic vents under the Atlantic that had colonies of
life - living by means of energy supplied by the
chemical reaction between lava and the seawater into
which the lava flowed. In 1983, a group of scientists
also thought life was in Europa, that heat was supplied
by tidal action, and that lava flows gave life.
They were giving life in an underground ocean, second
to none in size for the Solar System. Vast quantities of
water could be available. We don't want distilled water.
We want salty stuff, a brine made up of dead cells from
a part of a living mass.
No taste tests have been done from the water in Lake
Vostok but many common and strange organisms have been
found in ice cores taken from above it. Lake Vostok, the
size of Lake Ontario, lies 4 km under the ice of
Antarctica. Apparently geothermal heat put the water
into liquid form. A Vostok-like ocean could be on
Europa.
Perhaps there is also a volcanic heat source on Europa.
If not, or in addition to it, there may be tidal
friction brought on by Jupiter's gravitational proximity
causing a tidal bulge that alters shape and position to
push-pull tidal forces.
A magnetometer on Galileo showed that a magnetic field
for Europa varies periodically. This can be explained by
an electrically conducting liquid like saltwater. Ice is
not a good conductor. Europa's magnetic field is a
secondary one induced by and responding to Jupiter's
magnetic field.
Galileo also got good looks at Thera and Thrace. They
are dark terrain that may be local meltdown of the ice.
They could be projecting from the interior or they could
be on their own, up in the ice floes of Europa's
surface.
Thin ice or thick ice? Lots of water? These and other
questions may have answers provided for by Europa
Orbiter. This proposed mission would have on board a
radar capacity to measure the thickness of the ice,
establish if there is water below the crust that is
liquid, and assess tidal forces on Europa- if Europa has
an ocean. There is talk of later missions to dispatch
remote-controlled undersea craft to seek life. (Europa Orbiter
remained a concept. The Europa Clipper is to launch in the fall
of 2024.)
Myth: Beautiful
Europa was the daughter of Agenor. He was a Phoenician.
The Phoenicians were ancient seafarers with a range all
about the Mediterranean. Europa is now immortalized on a
moon that may allow for seagoing voyages far beyond the
maritime dreams of those ancient Phoenicians. They
traded with Cyprus, Egypt, India, Spain, and Africa. A
famous dye, from the murex snail, was a hot item. The
Phoenicians also had an alphabet of 22 consonants. It
was contributory to the Hebrew and Arabic writing.
Carthage was theirs until 146 BC.
Cretans say, not they, but Zeus, as a white bull, took
Europa from her city of Tyre. She was taken by whatever
agent to Crete. Zeus gave her gifts. One of these gifts
was a javelin that, if thrown, never missed. We do not
have a name for the javelin. Zeus also gave her Laelaps,
a dog, which never missed its meat. Europa Orbiter could
be favorably named as Europa's Javelin or as Laelaps.
Perspective : Raspy Water
Not so long ago life was preposterous - beyond earth.
There was a greatness and a delicacy here that most were
sure could not be duplicated. Perhaps Mars, as the abode
of life as Lowell put it, in the time of the Mars mania,
cooled off a great many from any expectant stance for
life elsewhere in the Solar System.
Our telescopes and attendant apparatus could not find
life beyond us. Then spacecraft soared skyward and out
to Mars and Europa. A great deal of water may be at one
or both places.
We aren't ready for life-not-as-we-know-it. We eagerly
seek water there. Once all was dead but us. The needle
had gone over hard right, very conservative views of
life's elsewhere possibilities were stated. Now the
needle has pegged, it is slammed far left, there are
very liberal possibilities feeding on scraps of
information.
We may be anticipating more than the life there - we
may be dreading a badly burnt earthbound psyche. We see
ourselves parched, teetering on dry stack of rocks, with
a river in the distance. One river would not be enough
for the planet. The brilliant lies of the
anti-environmentalists can't provide enough room for us
on the banks of a single river. And so in the future….
The latest transport from Europa releases gigantic
splashes in the sky. Like baby robins in a nest we crane
our necks awkwardly with mouths agape, flopped out, for
a drop or two. We don't want anymore of what is not the
best of life, a grating, sandy water to drink.
We are all incomplete and deficient in the present.
Gone away into the past are the slender, not gaunt,
ones. We have elixirs, little better than what exudes
from sebaceous glands. We lick the water from the scales
of a fish.
No more water hazards, or water clock, sand in the
hourglass is most appropriate. Water wagons are
dismantled. The back-up beeper on the water truck has no
sound to make. Magical implications of a long, relaxing
shower are only read about.
We may need a bucket brigade from Europa. Never mind
the occasional exotic rotifer in the water. Drink it
down. Don't gulp, enjoy it for such a little while at
least.
There are no natural manifestations of aquatic purity,
no rapids, all are pools, simmering in the heat. No
breakers, no carafes one could scoop into the freshwater
surf.
What comes from the sky is a dry mist, insubstantial,
we camels of an enlarging desert see fullblown mirages
of a persistent oasis where the grass is not a painted
green collection of tiny sharp rocks. Super soaker,
wetlands, spillways, the smell of rain -all gone.
You don't splash any water on your face, what a waste.
It goes into the mouth. Better dirty than dead. Some
dislike the slogan and get to be too thirsty. Is that
what some said? I can't hear you…can't hear you…water's
running. In a dream.