From Lava Lakes on Jupiter’s Moon, Io, Come Ideas About What Earth May Have Looked Like as a Newborn Planet
Investigations into lava lakes on the surface
of Io, the intensely volcanic moon that orbits Jupiter, may provide
clues to what Earth looked like in its earliest phases, according to
researchers at the University at Buffalo and NASA’s Jet Propulsion
Laboratory.
"When I look at the data, it becomes startlingly suggestive to me
that this may be a window onto the primitive history of Earth," said
Tracy K. P. Gregg, Ph.D., assistant professor of geology in the UB
College of Arts and Sciences.
"When we look at Io, we may be seeing what Earth looked like
when it was in its earliest stages, akin to what a newborn baby
looks like in the first few seconds following birth," she added.
Gregg and Rosaly M. Lopes, Ph.D., research scientist at JPL, gave
a presentation about Io’s volcano, Loki, on Tuesday (March 16,
2004) at the Lunar and Planetary Science Conference in Houston.
Scientists have been interested in Loki, considered the most
powerful volcano in the solar system, because of debate over
whether or not it is an active lava lake, where molten lava is in
constant contact with a large reservoir of magma stored in the
planet’s crust.
Using models developed to investigate temperature changes on
active lava lakes on Earth, Gregg and Lopes have concluded that
Loki behaves quite differently from terrestrial lava lakes.
Gregg suggests that Loki and other lava lakes on Io might be more
similar volcanologically to fast-spreading mid-ocean ridges on
Earth, like the Southern East Pacific Rise.
According to Gregg, plate tectonics on Earth make these features
long — as in thousands of kilometers — and narrow — as in less
than 10 kilometers wide. Io, on the other hand, has no plate
tectonics and a similar release of heat and magma would be circular,
like Loki.
"These lava lakes could be an Ionian version of mid-ocean ridges,"
functioning the way these ridges do on Earth, spilling huge amounts
of lava on its surface, thus generating new crust, she said.
During the most intense periods of its eruption cycle, Gregg said,
Loki churns out about 1,000 square meters of lava — about the
size of a soccer field — per second.
"All planets start out hot and spend their ‘lifetimes’ trying to get
cold," explained Gregg.
This effort by planets to "chill," she explained, is an attempt to
attain a similar temperature to that of outer space, which is 4
Kelvin, or minus 269 degrees Celsius.
On Earth, she explained, the shifting of the planet’s tectonic plates,
which focus the eruption of volcanoes at their boundaries, function to
cool down the planet’s surface.
Io never developed plate tectonics because it is stuck in an
incessant orbit between Jupiter and Europa, another of the Jovian
planet’s moons.
"Io just never grew up," she said, "since it’s continually being
pushed around by Jupiter and Europa."
But, she added, Earth only developed plate tectonics after it had
been in existence for perhaps 200 to 500 million years.
Gregg and Lopes analyzed data obtained by the Galileo spacecraft,
which orbited Jupiter for 14 years, finally disintegrating in Jupiter’s
atmosphere last fall.
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