Europa Archives

October 4, 2010July 20, 2018 by Nancy Atkinson

Acid Rain-Like Chemistry Could Occur in Europa’s Ice Crust

Europa, a moon of Jupiter, appears as a thick crescent in this enhanced-color image from NASA's Galileo spacecraft. Credit: NASA

A new look at how chemicals on Jupiter’s moon Europa may be reacting together could provide new insight to how chemical reactions could be occurring in the moon’s icy crust, despite frigid temperatures. Researchers have found that water and sulfur dioxide react together very quickly, even at temperatures hundreds of degrees below freezing. Because the reaction occurs without the aid of radiation, it could take place throughout Europa’s thick coating of ice. If this is occurring, it would revamp current thinking about the chemistry and geology of this moon and perhaps others.

Europa has temperatures around 86 to 130 Kelvin (minus 300 to minus 225 degrees Fahrenheit), and in those extremely cold conditions, most chemical reactions require an infusion of energy from radiation or light. On Europa, the energy comes from particles from Jupiter’s radiation belts. Because most of those particles penetrate just fractions of an inch into the surface, models of Europa’s chemistry typically stop there.

“When people talk about chemistry on Europa, they typically talk about reactions that are driven by radiation,” says Goddard scientist Reggie Hudson. “Once you get below Europa’s surface, it’s cold and solid, and you normally don’t expect things to happen very fast under those conditions,” said Reggie Hudson, from NASA Goddard’s Astrochemistry Laboratory.

“But with the chemistry we describe,” said Mark Loeffler, who is first author on the paper being published in Geophysical Research Letters, “you could have ice 10 or 100 meters [roughly 33 or 330 feet] thick, and if it has sulfur dioxide mixed in, you’re going to have a reaction.”

Spectroscopy shows there is sulfur in Europa’s ice, and astronomers believe it originates from the volcanoes of Jupiter’s moon Io, then becomes ionized and is transported to Europa, where it gets embedded in the ice. But originally, astronomers thought not much of a reaction could occur between water ice and the sulfur.

Loeffler and Hudson sprayed water vapor and sulfur dioxide gas onto quarter-sized mirrors in a high-vacuum chamber. Because the mirrors were kept at about 50 to 100 Kelvin (about minus 370 to minus 280 degrees Fahrenheit), the gases immediately condensed as ice. As the reaction proceeded, the researchers used infrared spectroscopy to watch the decrease in concentrations of water and sulfur dioxide and the increase in concentrations of positive and negative ions generated.

Even with the extremely cold temperatures, the molecules reacted quickly in their icy forms. “At 130 Kelvin [about minus 225 degrees Fahrenheit], which represents the warm end of the expected temperatures on Europa, this reaction is essentially instantaneous,” said Loeffler. “At 100 Kelvin, you can saturate the reaction after half a day to a day. If that doesn’t sound fast, remember that on geologic timescales-billions of years-a day is faster than the blink of an eye.”

To test the reaction, the researchers added frozen carbon dioxide, also known as dry ice, which is commonly found on icy bodies, including Europa. “If frozen carbon dioxide had blocked the reaction, we wouldn’t be nearly as interested,” said Hudson, “because then the reaction probably wouldn’t be relevant to Europa’s chemistry. It would be a laboratory curiosity.” But the reaction continued, which means it could be significant on Europa as well as Ganymede and Callisto, two more of Jupiter’s moons, and other places where both water and sulfur dioxide are present.

The reaction converted one-quarter to nearly one-third of the sulfur dioxide into different products. “This is an unexpectedly high yield for this chemical reaction,” said Loeffler. “We would have been happy with five percent.”

What’s more, the positive and negative ions produced will react with other molecules. This could lead to some intriguing chemistry, especially because bisulfite, a type of sulfur ion, and some other products of this reaction are refractory-stable enough to last for quite some time.

This new finding will certainly prompt new remote observations of Europa to see whether evidence of any reaction-based products can be found.

Source: JPL

July 22, 2010December 24, 2015 by Ryan Anderson

Europa Analog Deep-Sea Vents Discovered in the Caribbean

A team recovers the hybrid robotic vehicle Nereus aboard the research vessel Cape Hatteras during a partially NASA-funded expedition to the Mid-Cayman Rise in October 2009. A search for new hydrothermal vent sites along the 110-kilometer-long ridge, the expedition featured the first use of Nereus in "autonomous," or free-swimming, mode. Image credit: Woods Hole Oceanographic Institution

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White sand, blue water, sunny skies, pina coladas. When you think of “extreme environments” I doubt the Caribbean is high on your list. But a team of scientists from Woods Hole Oceanographic institute and NASA’s Jet Propulsion Laboratory, exploring the 68-mile-long Mid-Cayman rise deep beneath the surface of the Caribbean, have discovered the deepest known hydrothermal vent in the world, along with two other distinct types of vents.

The mid-Cayman rise is a much smaller version of the mid-ocean ridge system, a chain of submarine mountains that encircles the globe. These ridges form in locations where tectonic plates are pulling apart, allowing mantle rocks to melt and emerge at the surface as lava. Seawater, percolating through the hot rocks at these spreading centers, is superheated and emerges at vents, bearing a rich bounty of dissolved nutrients to support thriving ecosystems that can live without any sunlight.

“This was probably the highest-risk expedition I have ever undertaken,” said chief scientist Chris German, a Woods Hole Oceanographic Institution geochemist who has pioneered the use of autonomous underwater vehicles to search for hydrothermal vent sites. “We know hydrothermal vents appear along ridges approximately every 100 kilometers [62 miles]. But this ridge crest is only 100 kilometers long, so we should only have expected to find evidence for one site at most. So finding evidence for three sites was quite unexpected – but then finding out that our data indicated that each site represents a different style of venting – one of every kind known, all in pretty much the same place – was extraordinarily cool.”

In addition to the deepest hydrothermal vent yet discovered, at a depth of 5,000 meters (16,400 feet), the team also found a shallower low-temperature vent. Only one other vent of this type has been discovered: the famous “Lost City” vent in the Atlantic.

“We were particularly excited to find compelling evidence for high-temperature venting at almost 5,000 meters depth,” said Julie Huber, a scientist in the Josephine Bay Paul Center at the Marine Biological Laboratory in Woods Hole. “We have absolutely zero microbial data from high-temperature vents at this depth.”

The ecosystems encrusting the deep sea vents on the mid-Cayman rise provide valuable clues to how life could arise and thrive elsewhere in the solar system. “Most life on Earth is sustained by food chains that begin with sunlight as their energy source. That’s not an option for possible life deep in the ocean of Jupiter’s icy moon Europa,” said JPL co-author Max Coleman.

With an airless sky, intense radiation, icy crust, and no pina coladas, the surface of Europa is about as different from the Caribbean as you can get. But deep on the sea floor, they may be remarkably similar.

“Organisms around the deep vents get energy from the chemicals in hydrothermal fluid, a scenario we think is similar to the seafloor of Europa,” Coleman said. “This work will help us understand what we might find when we search for life there.”

An artist's depiction of a future Europa mission. Image credit: NASA

December 16, 2009December 24, 2015 by Nicholos Wethington

Could there be Life on Jupiter and Saturn’s Moons?

The plumes of Enceladus as imaged by the most recent Cassini flyby. Image Credit: NASA/JPL/Space Science Institute

The ongoing search for the existence of life that doesn’t call the Earth ‘home’ could potentially find that life right here in our own Solar System. There is considerable debate about whether evidence for that life has already been found on Mars, but astronomers might do well to look at other, more exotic locations in our neighborhood.

At the recent meeting of the American Geophysical Union in San Fransisco, Francis Nimmo, who is a professor of Earth and planetary sciences at UC Santa Cruz, said that the conditions on Saturn’s moon Enceladus, and Jupiter’s moon Europa may be just right to harbor life.

Nimmo said, “Liquid water is the one requirement for life that everyone can agree on.” The water underneath the icy crusts of Enceladus and Europa may just be teeming with alien fish and algae, or more basic forms of life such as bacteria.

Nimmo is one of a long list of scientists speculating on the existence of life on these watery moons. A discovery of any life form originating from a planet other than the Earth “would be the scientific discovery of the millennium,” Nimmo said. And even saying that is an understatement.

If life were able to exist in the watery oceans of the moons around Saturn and Jupiter, Nimmo said, it would mean that the ‘habitable zone’ around a star would extend much further out than previously thought, to moons that orbit large gas giants in other systems around faraway stars.

The possible ocean under the surface of Enceladus may receives its heat from the tidal forces of Saturn. That is, if there is an ocean under the surface of Enceladus, as that topic is still somewhat debated among astronomers. The constant tug of Saturn’s gravitational pull may stretch the interior of the planet enough to heat the water below the crust of ice, which is estimated to vary in thickness between 25km to 45km. Geysers of frozen water forced out of crack on Enceladus’ surface have been observed by the Cassini mission, and the craft has even flown through the plume of one of these jets.

Here’s a video of Carolyn Porco, who leads the imaging team on the Cassini mission, talking about the potential for life inside the moon, and some of the discoveries made by Cassini so far:

Evidence for the ocean under Europa’s icy skin comes from the Galileo mission, which passed by the moon in 2000 and took measurements of the moon’s magnetic field. Variations in the magnetic field have led astronomers to believe there is a vast ocean of water under the surface, leading to natural suppositions about the potential of its habitability.

Europa’s ocean is heated much in the same way as that of Enceladus: both moons have an eccentric orbit around their much more massive planets, and this orbit causes a shift in the way the planet tugs on their interiors, causing friction in the cores which in turn heats them up.

The core and surface of these moons both are possible sources of chemicals that are necessary for life to form. Impacts from comets can leave molecules on the surface, and light from the Sun breaks down compounds as well. Organic molecules and minerals may originate in the cores of the moons, streaming out into the watery ‘mantle’. Such nutrients could potentially support small communities of exotic bacteria like those seen around hydrothermal vents here on Earth.

Of course, just because these moons are habitable doesn’t mean that life exists there, as Nimmo and other planetary scientists are quick to point out. Cassini may still provide evidence of life on Enceladus, as the data from this last flyby of the plumes is still being analyzed. Future missions to Europa, such as the proposed ‘interplanetary submarine‘, may also give us an answer to the question of life’s existence elsewhere, and of course the quest continues for a mission to Mars that will finally give us some idea of its habitability now or in the past.

Until the data comes back from these missions, though, we’ll still have to wait and speculate.

Source: UC Santa Cruz press release

October 8, 2009July 20, 2018 by Nancy Atkinson

Europa Capable of Supporting Life, Scientist Says

Europa. CThe cracked, icy surface of Europa. The smoothness of the surface has led many scientists to conclude that oceans exist beneath it. Credit: NASA/JPLredit: NASA

The global ocean on Jupiter’s moon Europa contains about twice the liquid water of all the Earth’s oceans combined. New research by Richard Greenberg of the University of Arizona suggests that there may be plenty of oxygen available in that ocean to support life, a hundred times more oxygen than previously estimated.

The chances for life there have been uncertain, because Europa’s ocean lies beneath several miles of ice, which separates it from the production of oxygen at the surface by energetic charged particles (similar to cosmic rays). Without oxygen, life could conceivably exist at hot springs in the ocean floor using exotic metabolic chemistries, based on sulfur or the production of methane. However, it is not certain whether the ocean floor actually would provide the conditions for such life.

Therefore a key question has been whether enough oxygen reaches the ocean to support the oxygen-based metabolic process that is most familiar to us. An answer comes from considering the young age of Europa’s surface. Its geology and the paucity of impact craters suggests that the top of the ice is continually reformed such that the current surface is only about 50 million years old, roughly 1% of the age of the solar system.

Greenberg has considered three generic resurfacing processes: gradually laying fresh material on the surface; opening cracks which fill with fresh ice from below; and disrupting patches of surface in place and replacing them with fresh material. Using estimates for the production of oxidizers at the surface, he finds that the delivery rate into the ocean is so fast that the oxygen concentration could exceed that of the Earth’s oceans in only a few million years.

Greenberg says that the concentrations of oxygen would be great enough to support not only microorganisms, but also “macrofauna”, that is, more complex animal-like organisms which have greater oxygen demands. The continual supply of oxygen could support roughly 3 billion kilograms of macrofauna, assuming similar oxygen demands to terrestrial fish.

The good news for the question of the origin of life is that there would be a delay of a couple of billion years before the first surface oxygen reached the ocean. Without that delay, the first pre-biotic chemistry and the first primitive organic structures would be disrupted by oxidation. Oxidation is a hazard unless organisms have evolved protection from its damaging effects. A similar delay in the production of oxygen on Earth was probably essential for allowing life to get started here.

Richard Greenberg is the author of the recent book “Unmasking Europa: The Search for Life on Jupiter’s Ocean Moon.” He presented his findings at the 41st meeting of the American Astronomical Society’s Division for Planetary Sciences.

Source: AAS DPS

February 9, 2008December 26, 2015 by Nancy Atkinson

Testing a Europa Probe Prototype

While NASA doesn’t have any definite plans to send a probe to study Jupiter’s moon Europa, many planetary scientists consider the exploration of this enticing moon to be a high priority. Evidence from the Voyager and Galileo spacecraft suggests Europa contains a deep ocean of salty water under an icy outer shell. NASA is, however, helping to fund a prototype of an underwater autonomous vehicle to investigate ice covered lakes here on Earth, to demonstrate if such a vehicle could operate in an environment similar to Europa. The next test of the vehicle will take place Feb. 12-15, 2008 in Lake Mendota on the campus of the University of Wisconsin, Madison.

The Environmentally Non-Disturbing Under-ice Robotic Antarctic Explorer, also known as Endurance, will swim untethered under ice, and collect data to create three-dimensional maps of underwater environments. The probe also will look at the conditions in those environments and take samples of microbial life. Later this year, researchers plan to ship the probe to a permanently frozen lake in Antarctica for more operations. The probe is a follow-up to the Deep Phreatic Thermal Explorer, a NASA-funded project that completed a series of underwater field tests in Mexico in 2007.

“We’re using extreme environments on Earth as our laboratory,” says Peter Doran, associate professor at the University of Illinois at Chicago. “Ice-covered lakes are good, small-scale analogs to what we might find on Europa.”

Mendota Lake is only 25 meters deep, while the lake in Antarctica, West Lake Bonney is 40 meters deep. Scientists believe that Europa’s ocean could be up to 100 kilometers deep.

Hot water drills will bore a hole for Endurance to enter the water. If all goes well, the probe will be tested again in 2009.

But many hurdles remain before an underwater vehicle could possibly head to Europa. Presently, Endurance is too massive to send on interplanetary travel. Scientists will also have to come up with a way to drill through Europa’s icy crust and lower the sub safely through the ice.

And before a probe would be sent to land on Europa, many scientists feel that an orbiting spacecraft would be the best way to study the moon. The Jet Propulsion Laboratory is currently working on a concept called the Europa Explorer which would deliver a low orbit spacecraft to determine the presence (or absence) of a liquid water ocean under Europa’s ice surface. It would also map the surface and subsurface for future exploration.

Original News Sources: NASA Press Release, Washington University Press Release

August 29, 2007December 26, 2015 by Nancy Atkinson

A Submarine for Europa

Many planetary scientists believe that Jupiter’s moon Europa is our solar system’s best contender to share Earth’s distinction of harboring life. Evidence gathered by the Voyager and Galileo spacecrafts suggests Europa contains a deep, possibly warm ocean of salty water under an outer shell of fissured ice. In a paper published in the July 2007 Journal of Aerospace Engineering a British mechanical engineer proposes sending a submarine to explore Europa’s oceans.

Carl T. F. Ross, a professor at the University of Portsmouth in England offers an abstract design of an underwater craft built of a metal matrix composite. He also provides suggestions for suitable power supplies, communication techniques and propulsion systems for such a vessel in his paper, “Conceptual Design of a Submarine to Explore Europa’s Oceans.”

Ross’s paper weighs the options for constructing a submarine capable of withstanding the undoubtedly high pressure within Europa’s deep oceans. Scientists believe that this moon’s oceans could be up to 100 kilometers deep, more than ten times deeper than Earth’s oceans. Ross proposes a 3 meter long cylindrical sub with an internal diameter of 1 meter. He believes that steel or titanium, while strong enough to withstand the hydrostatic pressure, would be unsuitable as the vessel would have no reserve buoyancy. Therefore, the sub would sink like a rock to the bottom of the ocean. A metal matrix or ceramic composite would offer the best combination of strength and buoyancy.

Ross favors a fuel cell for power, which will be needed for propulsion, communications and scientific equipment, but notes that technological advances in the ensuing years may provide better sources for power.

Ross concedes that a submarine mission to Europa won’t occur for at least 15-20 years. Planetary scientist William B. McKinnon agrees.

“It is difficult enough, and expensive, to get back to Europa with an orbiter, much less imagine a landing or an ocean entry,” said McKinnon, professor of Earth and Planetary Sciences at Washington University in St. Louis, Missouri. “Sometime in the future, and after we have determined the ice shell thickness, we can begin to seriously address the engineering challenges. For now, it might be best to search for those places where the ocean has come to us. That is, sites of recent eruptions on Europa’s surface, whose compositions can be determined from orbit.”

The Jet Propulsion Laboratory is currently working on a concept called the Europa Explorer which would deliver a low orbit spacecraft to determine the presence (or absence) of a liquid water ocean under Europa’s ice surface. It would also map the distribution of compounds of interest for pre-biotic chemistry, and characterize the surface and subsurface for future exploration. “This type of mission,” says McKinnon, “would really allow us to get the hard proof we would all like that the ocean is really there, and determine the thickness of the ice shell and find thin spots if they exist.”

McKinnon added that an orbiter could find “hot spots” that indicate recent geological or even volcanic activity and obtain high-resolution images of the surface. The latter would be needed to plan any successful landing.

Slightly smaller than Earth’s moon, Europa has an exterior that is nearly craterless, meaning a relatively “young” surface. Data from the Galileo spacecraft shows evidence of near-surface melting and movements of large blocks of icy crust, similar to ice bergs or ice rafts on Earth.

While Europa’s midday surface temperatures hover around 130 K (-142 C, -225 degrees F), interior temperatures could be warm enough for liquid water to exist underneath the ice crust. This internal warmth comes from tidal heating caused by the gravitational forces of Jupiter and Jupiter’s other moons which pull Europa’s interior in different directions. Scientists believe similar tidal heating drives the volcanoes on another Jovian moon, Io. Seafloor hydrothermal vents have also been suggested as another possible energy source on Europa. On Earth, undersea volcanoes and hydrothermal vents create environments that sustain colonies of microbes. If similar systems are active on Europa, scientists reason that life might be present there too.

Among scientists there is a big push to get a mission to Europa underway. However this type of mission is competing for funding against NASA’s goal of returning to our own moon with human missions. The proposed Jupiter Icy Moon Orbiter (JIMO) a nuclear powered mission to study three of Jupiter’s moons, fell victim to cuts in science missions in NASA’s Fiscal Year 2007 Budget.

Ross has been designing and improving submarines for over 40 years, but this is the first time he’s designed a craft for use anywhere but on Earth.

“The biggest problem that I see with the robot submarine is being able to drill or melt its way through a maximum of 6 km of the ice, which is covering the surface,” said Ross. “However, the ice may be much thinner in some places. It may be that we will require a nuclear pressurized water reactor on board the robot submarine to give us the necessary power and energy to achieve this”

While Ross proposes using parachutes to bring the submarine to Europa’s surface, McKinnon points out that parachutes would not work in Europa’s almost airless atmosphere.

Ross has received very positive responses to his paper from friends and colleagues, he says, including notable British astronomer Sir Patrick Moore. Ross says his life has revolved around submarines since 1959 and he finds this new concept of a submarine on Europa to be very exciting.

McKinnon classifies the exploration of Europa as “extremely important.”

“Europa is a place is where we are pretty sure we have abundant liquid water, energy sources, and biogenic elements such as carbon, nitrogen, sulfur, phosphorus, etc,” he said. “Is there life, any kind of life, in Europa’s ocean? Questions don’t get much more profound.”

Written by Nancy Atkinson