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Exobiology

Life on Europa?

In August 2000, observations confirm the existence of an ocean covered under the ices of Europa, one of the moons of Jupiter. As science progresses, the focus on Europa raises because it is more and more a good candidate for extraterrestrial life. These pages will keep you informed.
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Europa news:

Hubble space telescope spots a water plume again on Europa:

A study published in The Astrophysical Journal Letters in April 2017 says that scientists using the Hubble Space Telescope again found what is likely a plume emitting from Europa.

After first spotting the apparent plume in 2014, scientists in 2016 saw it in the same spot, a particularly warm region of Europa where fissures occur in the icy crust.

Both studies are laying the foundation for the Europa Clipper mission, which is slated to launch in the 2020s. The mission will periodically fly past Europa to collect data and study the subsurface ocean.

James Green, NASA's Planetary Science Division Director, said "If there are plumes on Europa, as we now strongly suspect, with the Europa Clipper we will be ready for them."

Hubble space telescope spots possible water plumes erupting on Europa:

William Sparks of the Space Telescope Science Institute (STScI) in Baltimore, Maryland, USA, and his team, using NASA's Hubble Space Telescope imaged what may be water vapor plumes erupting off the surface of Jupiter's moon Europa.

Images showed finger-like projections while Europa passed in front of Jupiter.

The plumes are estimated to rise about 125 miles (200 kilometers) before, presumably, raining material back down onto Europa's surface.

Europa has a huge global ocean containing twice as much water as Earth's oceans, but it is under a layer of extremely cold and hard ice of unknown thickness.

The original goal of the team's observing proposal was to determine whether Europa has a thin, extended atmosphere, or exosphere. Using the same observing method that detects atmospheres around planets orbiting other stars. the team also realized if there was water vapor venting from Europa's surface, this observation would be an excellent way to see it.

The team observed Europa passing in front of Jupiter in 10 separate occurrences spanning 15 months, and observed the suspected plumes erupting on three of these occasions.

In 2012, a team led by Lorenz Roth of Southwest Research Institute in San Antonio, Texas, USA, had already detected evidence for water vapor erupting from the frigid south polar region of Europa and reaching more than 100 miles (160 kilometers) into space. Although both teams used Hubble's Space Telescope Imaging Spectrograph (STIS) instrument, each used a totally independent method to arrive at the same conclusion.

Sparks said: "When we calculate in a completely different way the amount of material that would be needed to create these absorption features, it's pretty similar to what Roth and his team found. The estimates for the mass are similar, the estimates for the height of the plumes are similar. The latitude of two of the plume candidates we see corresponds to their earlier work."

The plumes provide an opportunity for future missions to Europa to sample its ocean without having to drill through miles of ice.

Geoff Yoder, acting associate administrator for NASA's Science Mission Directorate in Washington, D.C., said:

"Europa's ocean is considered to be one of the most promising places that could potentially harbor life in the solar system. These plumes, if they do indeed exist, may provide another way to sample Europa's subsurface."

Confirmation of a liquid water ocean under the ice of Europa:

Data collected by NASA's Galileo probe shows that Europe, a satellite of Jupiter, does indeed have liquid water.

In a very active zone, the ice which covers the satellite carries out important exchanges with an ocean just below.

This result, in November 2011, reinforces the already admitted idea that life could be possible on Europa, say the researchers directed by Mary Voytek, chief of NASA's astrobiology program, in the scientific magazine Nature which publishes their study.

Russia wants to joins European mission to search for life on Jupiter's moon Europa:

The Interfax news agency, Moscow, reported on January 7, 2008, that Russia plans to participate in a European mission to investigate Jupiter's moon Europa and search for simple life forms.

The head of the Space Research Institute, Lev Zelyony, said the Federation of Russia is to participate in the Laplace project of the European Space Agency (ESA) for the years 2015 to 2025.

He said the main task is to explore Jupiter's satellite "Europa, on which under a thick layer of ice a liquid water ocean has been detected."

He suggested landing a craft in one of the fissures in Europa's icy crust, so that the craft would melt some of the ice and search for life forms.

He said: "Where there is an ocean, life could arise. In this respect, after Mars, the Europa satellite is probably the most intriguing place in the solar system."

A new idea boost chances for life on Europa:

February 27, 2003

Jerome Borucki, at the NASA Ames Research Center in California, and his colleagues, while simulating meteorite impacts on the frozen oceans of Europa have made a discovery which raises the chances of finding life on Jupiter's moon. They published their paper in the Journal of Geophysical Research - Planets, Vol 107, p 24.

They fired aluminum bullets into a block of ice and found that when the bullet impacted, sensors embedded in the ice detected an electric shock. A second, and much larger, electrical discharge was observed a few moments later.

A shell of ice many kilometers thick encases the surface of Europa and scientists speculate that liquid water - and therefore life - might lie beneath. Evidence for the presence of the molecular building blocks for life comes from the yellow-brown stains seen on the ice by the Galileo probe.

Ron Greeley, a planetary scientist at the Arizona State University, said: "Europa is a high priority target for exploration because the key ingredients for life seem to be there. But even if you have the ingredients, the question is, is there a spark that creates the first organic molecules?"

Borucki's bullet experiments suggest meteorite impacts might have provided that spark. He said the electric shock had gone undetected because no-one had put sensors below an impact crater before, he told New Scientist. The team thinks the current is caused by the movement of protons as the ice cracks.

In the 1950s, Stanley Miller, now at the University of California in San Diego, showed that shooting an electric current through a mixture of water, methane and ammonia created complex organic molecules. Amino acids, the building blocks of proteins, were among the products.

Methane and ammonia are likely to be present in Europa's ice and the energy pumped into the ice by a meteorite impact will melt it. Shock this mixture with electricity, says Borucki, and complex molecules should form.

But this still needs to be tested in the laboratory. So far the experiments have used only pure water ice, cooled to a chilly -196░C to simulate conditions on Europa.

The bullets used are about a centimeter across and were fired at the ice at a speed of six kilometers per second. This is the equivalent to a kilometer-sized asteroid crashing into the moon at about 24 km/s.

"We do see a handful of very large craters on Europa, and there would have been a lot of energy associated with those," comments Greeley. "These new results are exciting."

What's not included in this result's announcement:

The yellow-brown stains which are mentioned as evidence of the presence of basic organic compounds on Europe are not ordinary stains across the surface. Some are lengthened stains corresponding exactly to the many gigantic cracks which cross the ice layer of the surface of Europe and which by themselves are indicative of the presence of a liquid water ocean under the ice. This richer materials thus come from below the ocean and rushes towards the surface by the play of the plates of ice between them. This suggests that the most interesting things come from under the ice layer. (Another scientist went until suggesting recently that spectroscopy data of these dark scratches corresponds to that of bacterial remainders more than to that of basic compounds.)

This means that there is already an internal ice melting mechanism that heats the deep water layers, which are of liquid water and that meteoritic impact water melting is simply an additional ice melting mechanism.

Also, this heating mechanism and the cracks in the icy surface are almost for certain caused by the huge tidal forces to which Europe is subjected because of its proximity with the giant planet Jupiter. Europe is terribly deformed by tidal forces and get regularly elongated and roundish again. This could perhaps suffice so that piezoelectric discharges exist at the ocean's solid floor and may help create the complex molecules and amino acid the way Miller proposed.

Also, I think that a surface sample return mission, which would be much more easily quickly set up than those missions which propose to probe liquid water under the ice, if designed to specifically bringing back the darker materials deposited along the ice cracks, would be a daring but potentially very paying bet.

Europa

Left: In this false-color image taken by the Galileo spacecraft, reddish brown ridges and terrain indicate the presence of contaminants in the icy Europan surface.

This is sufficient proof that there are materials exchanged between the icy crust and the underlying ocean.

This is also sufficient proof that part of this material surfaces through the cracks in the ice layer and thus are originating from under the surface.

rock hunters bag five Mars meteorites:

Exploring the coldest and hottest places on Earth, space rock hunters have found five new meteorites from Mars, bringing the number of known stones from the red planet to 24. Planet scientists express keen interest in rare Martian meteorites, some of which have offered tantalizing clues about whether the planet once possessed oceans or life. The recent cache actually includes six specimens, but two are presumed to be chunks from the same meteorite. One of the pair weighs in at 30 pounds (13.7 kg), the second-largest Mars meteorite fragment ever recovered, NASA scientists said this week.

Scientists apply Earth hydrothermal plume dynamics to Europa:

The size of ice domes and movement of ice rafts on the surface of Europa are consistent with what one could expect of melting caused by a hydrothermal vent plume, or plumes, in an ocean beneath the ice, say oceanographers John Delaney of the University of Washington and Richard Thomson of Fisheries and Oceans Canada.

If hydrothermal vent plumes are contributing heat to Europa's ocean, Delaney and Thomson estimate that the frozen surface of the ocean actually may be 3 to 5 kilometers (2 to 3 miles) thick on average -- instead of the 20 kilometers (12 miles) some have estimated. And it makes it all the more possible that researchers may find microorganisms living in vent fluids on Europa, as they do here on Earth.

Delaney and Thomson's model, the first to take what's known about plume dynamics on Earth and apply them to Europa, was the subject of a paper last year in the Journal of Geophysical Research and a presentation at December's American Geophysical Union meeting.

The possibility of life on Europa has been part of Delaney's presentation, "Volcanoes, Oceans and Life in the Solar System," a lecture that was free and opened to the public.

Among scientists interested in Europa, a number think tidal forces generated by the gravitational tug-of-war between Jupiter, Europa and neighboring moons Io and Ganymede cause tidal flexing of Europa's icy crust, friction and then melting. Delaney, Thomson and others hypothesize that tidal flexing is at work on Europa's rocky core generating heat and magma.

Delaney and Thomson's model is the first:

If the melting at the surface of Europa is caused in part by plumes from magma-heated regions of the seafloor, it is feasible that some of the dark materials observed on the surface of Europa, thought to be salts and hydrated sulfuric acid, are remnants of particle-laden plumes originating from the seafloor.

Delaney says a better understanding of the links between plate-tectonic processes on our own planet and the microbial life that flourishes near faults, fissures, vent structures and beneath the Earth's crust will help us seek life on other planets and moons.

Extremophiles discovery published in "Nature":

Scientists have found a community of microbes unlike anything else on Earth. Conditions in this ecosystem could mimic those on Earth when life began, and might exist elsewhere in today's Solar System. While the news is not totally a surprise, it has been reported in "Nature" and adds up to the cause of exobiology.

Home to the microbes is a hot spring 200 meters beneath the US state of Idaho. Their lives owe nothing to the Sun. They generate energy by combining hydrogen from rocks with carbon dioxide, releasing methane as a by-product. These 'methanogens' belong to an ancient group related to bacteria, called the Archaea.

While drilling into a hot spring where there is no organic carbon to feed more conventional life, Frank Chapelle of the US Geological Survey in Columbia, South Carolina, and his colleagues identified the microbes living there from their DNA sequences.

They were shocked to find that more than 90% of the organisms in the spring were methane-producing Archaea. The technician "freaked out," recalls Chapelle, assuming she'd made a dreadful mistake. In most places, such microbes make up only 2 or 3% of microbial life.

Biologists have speculated for many years that hydrogen-powered ecosystems could exist beneath the ground. The methanogen community suggests they were right, says astronomer and astrobiologist Richard Taylor of the Probability Research Group in London.

"As long as there's subsurface water and enough chemical fuel, you can get microbial life," says Taylor. He thinks that life began in such environments: "It's life on the surface that's unusual," he says.

Many bodies in the Solar System and the Universe could harbor similar conditions. "I suspect it's going to turn out that life is extremely common," says Taylor.

Mars and Jupiter's moon Europa have both been suggested as places where life could exist on hydrogen, today or in the past. If this is so, says microbiologist Julian Hiscox of the University of Reading, UK, it will be several kilometers below the surface, well beyond the reach of any investigations so far. Probing these environments is going to cost "an awful lot of money", warns Hiscox. A cheaper alternative, he says might be to look for biologically produced methane in Martian meteorites on Earth.

Also, Hiscox says, the geological activity necessary to produce hydrogen may have stopped long ago on Mars, and be absent altogether on Europa.

The finding may give us an insight into life in time as well as space. Chapelle thinks that hydrogen may have been accessible and abundant enough on the young Earth to provide the energy for the earliest life.

See Chapelle, F. H. "A hydrogen-based subsurface microbial community dominated by methanogens", Nature, 415, 312 - 315, (2002).

Another evidence of water in Callisto too:

Robert Roy Britt publishes the space. com news brief that there More Evidence for Ocean on Jupiter's Moon Callisto:

"Punch a planet or moon on one side with, say, a giant space rock, and you'll create grooved and hilly terrain on the opposite side around a point called the antipode. The features are seen on Mercury and Earth's Moon and are created when seismic waves rattle into focus. Didn't happen, however, on Jupiter's Moon Callisto. Opposite a huge impact basin called Valhalla there is nothing but a flurry of small craters. No grooves. No hills. NASA scientists say this adds further evidence to the expectation that Callisto harbors a giant ocean under its frozen surface. The water dampens the quakes that would otherwise rattle the antipode. The finding was made recently by the Galileo spacecraft."

Extreme life under the ocean floor:

October 2001 studies of microbes living 300 meters below the Earth's ocean floors and literally eating glassy rocks have given scientists further evidence that life on Mars and Europa is a possibility.

The minimum requirements for life are pushed to the extreme in this ecosystem: these lithoautotrophs microbes have water, heat, and nutrients they digest from volcanic glass in the ocean floor. They absorb the silica nutrients and release acid generated by their metabolic processes. The microbes activities release substances that feed animals the next rung up on the food chain. Needless to say, the conditions are extreme in terms of pressure, temperature and absence of solar light. Although very primitive, such life forms are very enduring, escaping comet debris showers for example.

Obviously such poor conditions can be found on Mars and on Europa also. The DNA of the Earth microbes could be compared to any that is found on Mars or Europa, and reveal whether life forms, in the solar system at least, could have any common ancestry.

Extraterrestrial cells found in high atmosphere:

French scientific popularization magazine "Science et Avenir" points out and supplements a news already included in my site on 11.24.2000.

It tells of the discovery of bacteria of extraterrestrial origin in stratospheric air samples by collectors installed on balloons.

The collectors are designed by the Indian Space Research Organisation (ISRO), the sample were initially analyzed by a team of astronomers of the Indian Pune University, and Pr David Lloyd of the Cardiff University has also done and confirmed these analysis, which show, thanks to a fluorescent product containing cyanin, the presence of cells in our atmosphere at an altitude higher than 41 km. It is the distribution of the cells and their difference in size which constitutes for the researchers evidence of their extraterrestrial origin. They estimated that approximately a ton of such cell arrives in the Earth's atmosphere every three days.

The work was presented now by Pr Chandra Wickramasinghe to the congress of exobiology of San Diego.

It confirms the theory of panspermia worked out at the end of the 19th century by Lord Kelvin, which is that micro-organisms could travel through space as spores, it also might indicate that the warnings of certain scientists about risks of microbial catastrophe in the event of Martian sample returns could be unjustified, and that life is propagating freely at least inside the solar system, making more likely that at at least bacterial life thrives in suitable place such as like the ocean dissimulated under the ice layer of Europa, Jupiter's satellite.

Liquid water also under the ice of Callisto:

After the observation of a liquid water ocean under the frozen surface of Europe for example, Javier Ruiz of the Complutense University of Madrid publishes this month in "Nature" a study showing that Callisto also has liquid water under its surface.

Data are from the American probe Galileo which is traveling close to the four larger satellites of Jupiter, Europe, Io, Ganymede and Callisto since 1995. The probe now detected a variable magnetic field around Callisto, in conjugation with other data and measures it implies according to the study the presence of a salted underground stretch of water.

Europa Focus Group:

NASA Astrobiology Institute sponsored a meeting of the "Europa focus group" of planetary scientists, sea-ice experts, chemists and astrobiologists on February 1-2 at the NASA Ames Research Center to hail the Jovian natural satellite as a high priority target for life seeking exploration.

Workshop organizer, Ronald Greeley, planetary geologist at Arizona State University in Tempe said:

"We're dealing with a very interesting object here. Topped by a salty crust, Europa appears to sport a 160 kilometer thick shell of water. We don't know if it's liquid or not... but in volume, that's more water than on Earth's surface. There's a whole group of salt-loving organisms here on Earth. We haven't recognized their importance until just recently. Brine channels on Europa could be a pretty nifty niche for things to percolate in."

Jeff Kargel, a geologist with the U.S. Geological Survey in Flagstaff, Arizona, said:

"I'd say I'm cautiously optimistic about finding life on Europa, practically everywhere that we look, where there's liquid water we find life...and that includes some very harsh environments that resemble extreme scenarios several of us have painted for Europa. Europa is certainly forcing us to literally dig deeper and look in more problematic types of places where we, perhaps, wouldn't have looked before for life. Both Europa and Mars are having this effect."

08.29.2000 Life amidst glaciers:

Mark Schrope, from space.com, published the information that a new study shows that life can not only survive beneath tons of ice at the dark, near-freezing junctions between glaciers and Earth, but actually thrive there.

08.25.2000 From the JPL at NASA:

NASA researchers have the strongest evidence yet that one of Jupiter's most mysterious moons hides an ocean of water underneath its icy coat. This evidence comes from magnetic readings by NASA's Galileo spacecraft, reported in the Friday, Aug. 25, edition of the journal Science.

Europa, the fourth largest satellite of Jupiter, has long been suspected of harboring vast quantities of water. Since life as we know it requires water, this makes the moon a prime target for the search of exobiology - life beyond Earth.

This news item has been published in the homepage of the Jet Propulsion Laboratory web site.

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