Life on Jupiter's Moon Europa ?

Article about possibilty of water and life on Europa

NASA's press release about Europa

Older artcles concerning Europa

Scientists Confident of Life on Jupiter Moon     4-10-97

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.

NASA press release:

Donald Savage

Headquarters, Washington, DC April 9, 1997

(Phone: 202/358-1547)

Jane Platt

Jet Propulsion Laboratory, Pasadena, CA

(Phone: 818/354-5011)

RELEASE: 97-66


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

Europa's surface.

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

as young."

Chapman added, "Europa's extraordinary surface geology

indicates an extreme youthfulness Ð a very alive world in a state

of flux."

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

Earth-moon system."

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 -

Older Europa news stories

New pictures of Europa suggest oceans, possible life

January 17, 1997 Web posted at: 11:00 p.m. EST


-- 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.





PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011

Contact: Franklin O'Donnell


January 17, 1997


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.


1/17/97 FOD