Article about possibilty of water and life on Europa
NASA's press release about Europa
Older artcles concerning Europa
PASADENA, Calif. (Reuter) - Space scientists said Wednesday they were confident life existed in the muddy waters of one of Jupiter's moons.
"I am sure there's life there," John Delaney of the University of Washington said in a reference to the
Jovian moon Europa. Delaney and the other experts spoke at a news briefing detailing results of pictures from the Galileo probe.
Pictures of Europa sent back by Galileo after its closest flyby of the moon in February and released by the National Aeronautics and Space Administration Wednesday showed a red-colored sea with a crust of ice about three feet thick in which huge icebergs several miles across were floating, the scientists said.
The images were taken as Galileo was 363 miles from Europa. Talking to reporters at NASA's Jet Propulsion Laboratory, the scientists said they believed all the ingredients for creating and sustaining life forms existed in Europa's waters.
Delaney, a professor of oceanology, said he and other scientists believed the waters under the ice crust were being warmed by volcanic activity and undersea research on Earth had shown that "volcanic activity supports life without sunlight."
Richard Terrile of the JPL, a planetary scientist, said he believed there was organic matter in sediment at the bottom of Europa's ocean and pointed out: "On Earth, these same ingredients in a million years gave presence to life."
Terrile said he would like to see a "machine exploration" of Europa during a future unmanned probe to the moon in the hope of confirming his beliefs.
Delaney said he was "very excited" by Galileo's pictures. "The bottom line is, it's about life. The discovery of life on another planet will surpass anything that has ever taken place in human history,"he said. He added that volcanic activity not only sustained life but encouraged it, saying when a volcano erupted under the ocean on Earth it caused bacteria to "bloom at a massive level."
In an effort to bolster their life-in-outer-space theory, scientists and engineers from around the world were meeting in Pasadena on Wednesday and Thursday to discuss an exploration of Lake Vostok, a subglacial lake under the ice in Antarctica which they believe has conditions similar to Europa's sea.
Michael Carr of the United States Geological Survey said there was evidence of movement and rotation by the icebergs which could not be explained by wind as Europa is in a vacuum. "The plausible cause for this motion is traction below which implies liquid below.
Dr Paul Geissler of the University of Arizona said the pictures showed the sea as a red-brown area on the surface of Europa. He speculated that the red-brown material in the waters indicated it was a "muddy sea," while Max Coon, a scientist with NorthWest Research Associates, Inc., concluded after studying the pictures that, "The ice features here (on Earth) look very, very like the ones on Europa."
Oceanographer Clark Chapman of the Southwest Research Institute said he believed Europa was still developing and the ice crust was about one million years old, "a mere day in geological terms."
The scientists, who make up the Galileo imaging team and whose task it is to interpret the pictures and data sent back from the spacecraft, also said it appeared that the ice crust was slowly melting because of the warmer waters below which were being heated by volcanic activity.
Galileo was launched by the shuttle Atlantis in October, 1989 and arrived at Jupiter to begin its exploration of the planet and its moons in December of 1995.
Headquarters, Washington, DC April 9, 1997
Jet Propulsion Laboratory, Pasadena, CA
NEW IMAGES HINT AT WET AND WILD HISTORY FOR EUROPA
Chunky ice rafts and relatively smooth, crater-free patches
on the surface of JupiterÕs frozen moon Europa suggest a younger,
thinner icy surface than previously believed, according to new
images from Galileo's spacecraft released today.
The images were captured during Galileo's closest flyby of
Europa on Feb. 20, 1997, when the spacecraft came within 363 miles
of the Jovian moon. These features, which lend credence to the
idea of hidden, subsurface oceans, also are stirring up
controversy among scientists who disagree about the age of
Dr. Ronald Greeley, an Arizona State University geologist and
Galileo imaging team member, said the ice rafts reveal that Europa
had, and may still have, a very thin ice crust covering either
liquid water or slush.
"We're intrigued by these blocks of ice, similar to those
seen on Earth's polar seas during springtime thaws," Dr. Greeley
said. "The size and geometry of these features lead us to believe
there was a thin icy layer covering water or slushy ice, and that
some motion caused these crustal plates to break up."
"These rafts appear to be floating and may, in fact, be
comparable to icebergs here on Earth," said another Galileo
imaging team member, Dr. Michael Carr, a geologist with the U.S.
Geological Survey. "The puzzle is what causes the rafts to
rotate. The implication is that they are being churned by
The new images of Europa's surface also have sparked a lively
debate among scientists. Galileo imaging team member Dr. Clark
Chapman is among those who believe the smoother regions with few
craters indicate Europa's surface is much younger than previously
believed. In essence, Chapman, a planetary scientist at Southwest
Research Institute, Boulder, CO, believes the fewer the craters,
the younger the region. Clark based his estimate on current
knowledge about cratering rates, or the rate at which astronomical
bodies are bombarded and scarred by hits from comets and
ÒWe're probably seeing areas a few million years old or less,
which is about as young as we can measure on any planetary surface
besides Earth," said Chapman. "Although we can't pinpoint exactly
how many impacts occurred in a given period of time, these areas
of Europa have so few craters that we have to think of its surface
Chapman added, "Europa's extraordinary surface geology
indicates an extreme youthfulness Ð a very alive world in a state
However, Carr sees things differently. He puts Europa's
surface age at closer to one billion years old.
"There are just too many unknowns," Carr said. "Europa's
relatively smooth regions are most likely caused by a different
cratering rate for Jupiter and Earth. For example, we believe
that both Earth's moon and the Jovian moon, Ganymede, have huge
craters that are 3.8 billion years old. But when we compare the
number of smaller craters superimposed on these large ones,
Ganymede has far fewer than EarthÕs moon. This means the
cratering rate at Jupiter is less than the cratering rate in the
Scientists hope to find answers to some of the questions
surrounding Europa and its possible oceans as the Galileo
spacecraft continues its journey through the Jovian system.
"We want to look for evidence of current activity on Europa,
possibly some erupting geysers," Greeley said. "We also want to
know whether Europa's surface has changed since the Voyager
spacecraft flyby in 1979, or even during the time of the Galileo
The craft will return for another Europa flyby on Nov. 6,
1997, the final encounter of Galileo's primary mission. However,
eight more Europa flybys are planned as part of Galileo's two-year
extended mission, which also will include encounters with two
other Jovian moons, Callisto and Io.
The Jet Propulsion Laboratory manages the Galileo mission for
NASA's Office of Space Science, Washington, DC.
Images and other data received from Galileo are posted on the
Galileo mission home page on the World Wide Web at URL:
NOTE TO EDITORS: Stills and animation of the Galileo spacecraft
are available by calling the JPL Public Information Office at
- end -
January 17, 1997 Web posted at: 11:00 p.m. EST
JOHNSON SPACE CENTER, Texas (CNN)
-- New pictures of Europa, taken by NASA's Galileo space probe, have scientists excited at the prospect of an ocean on Jupiter's moon. Pictures taken by the probe, which flew within 430 miles (692 km) of Europa on December 19 show a criss-cross of ridges, craters and ice floes stretching hundreds of miles long. Though they haven't been able to study the pictures in detail, planetary scientists are able to say they detect signs of ice-spewing volcanoes and shifts in the moon's icy crust that are not unlike earthquakes. The features provide evidence that water, heat and organic compounds may have combined to create an environment suitable for the start of life, Galileo scientists told a news conference at NASA's Washington headquarters. "I think Europa is an excellent laboratory for the existence of possible life," said Jim Brown, a planetary scientist at Brown University in Rhode Island. "It's got the ingredients." Scientists are eagerly awaiting Galileo's closer look at Europa. It will pass within 364 miles (587 km) of the moon on February 20. Galileo, which was launched in 1989 and arrived at Jupiter in 1995, is making a two-year tour of Jupiter. Reuters contributed to this report.
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January 17, 1997
ICE VOLCANOES RESHAPE EUROPA'S CHAOTIC SURFACE
Ice-spewing volcanoes and the grinding and tearing of tectonic
plates have reshaped the chaotic surface of Jupiter's frozen moon Europa,
images from NASA's Galileo spacecraft reveal.
The images, captured when Galileo flew within just 692
kilometers (430 miles) of Europa on Dec. 19, were released at a news
briefing today at NASA Headquarters, Washington, DC.
Although the images do not show currently active ice volcanoes
or geysers, they do reveal flows of material on the surface that probably
originated from them, said Galileo imaging team member Dr. Ronald Greeley
of Arizona State University, Tempe, AZ.
"This is the first time we've seen actual ice flows on any of
the moons of Jupiter," said Greeley. "These flows, as well as dark scarring
on some of Europa's cracks and ridges, appear to be remnants of ice
volcanoes or geysers."
The new images appear to enhance Europa's prospects as one of
the places in the solar system that could have hosted the development of
life, said Greeley.
"There are three main criteria to consider when you are looking
for the possibility of life outside the Earth -- the presence of water,
organic compounds and adequate heat," said Greeley. "Europa obviously has
substantial water ice, and organic compounds are known to be prevalent in
the solar system. The big question mark has been how much heat is generated
in the interior.
"These new images demonstrate that there was enough heat to
drive the flows on the surface. Europa thus has a high potential to meet
the criteria for exobiology," Greeley added.
"This doesn't prove that there is an ocean down there under the
surface of Europa, but it does demonstrate that it is a scientifically
exciting place," said Galileo imaging team member Dr. Robert Sullivan, also
of Arizona State University.
The images also reveal a remarkable diversity in the geological
age of various regions of Europa's surface. Some areas appear relatively
young, with smooth, crater-free terrain, while others contain large craters
and numerous pits, suggesting that they are much older.
The icy crust bears the signs of having been disrupted by the
motion of tectonic plates. "There appear to be signs of different styles of
tectonism," said Greeley. "In many areas we see that the crust was pulled
apart in a spreading similar to the processes on the sea floor on Earth.
This is different from the tectonic processes at work on, say, Jupiter's
moon Ganymede. This suggests that Europa's interior may be different from
Galileo scientists will have a better chance to understand
Europa's interior when the spacecraft gathers gravity data on another flyby
next November. The gravity field is measured by tracking how the frequency
of Galileo's radio signal changes as it flies past the moon. This was not
possible during the recent flyby because radio conditions were degraded as
Jupiter passed behind the Sun from Earth's point of view.
Europa is crisscrossed by an amazingly complex network of
ridges, said Sullivan. "Ridges are visible at all resolutions," he
explained. "Closely paired ridges are most common. With higher resolution,
ridges seen previously as singular features are revealed to be double."
Some of the ridges may have formed by tension in the icy crust:
as two plates pull apart slightly, warmer material from below might push up
and freeze to form a ridge. Other ridges may have been formed by
compression: as two plates push together, the material where they meet
might crumple to form the ridge.
In addition to ice flows and tectonics, Greeley and Sullivan
noted that some areas on Europa seem to have been modified by unknown
processes that scientists are still debating.
Greeley said that some areas, for example, seem to have been
modified by "sublimation erosion" -- the evaporation of water and other
volatiles such as ammonia and methane into the vacuum of space. "Something
is destroying the topography," said Greeley, "and this sublimation erosion
is a good candidate for what is at work."
During last month's encounter, Galileo flew more than 200 times
closer to Europa than the Voyager 2 spacecraft did in 1979. After a swing
past Jupiter next week in what mission engineers call a "phasing orbit,"
Galileo's next targeted flyby will take it again past Europa as it passes
within 587 kilometers (364 miles) on February 20.
The Jet Propulsion Laboratory, Pasadena, CA, manages the Galileo
mission for NASA's Office of Space Science, Washington, DC.