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December 16 2013


Icy Europa May Be First Alien World With Active Plate Tectonics

Icy Europa May Be First Alien World With Active Plate Tectonics
Scientists may have spotted the first evidence for active plate tectonics on another world. Jupiter's moon Europa is covered in an ice crust bearing scars that may reveal movement similar to that of Earth's rocky plates

December 12 2013


200-Kilometer-High Jets of Water Discovered Shooting From Europa

200-Kilometer-High Jets of Water Discovered Shooting From Europa
Jupiter’s icy moon Europa may be showing us its insides. Data from the Hubble space telescope suggests that enormous plumes of water more than 200 kilometers tall (roughly twice as high as Earth's atmosphere) may be spurting intermittently from the ...

December 04 2013


More evidence there’s an ocean on Europa primed for life

An ocean below the surface of Jupiter’s moon Europa may have deep currents and circulation patterns with heat and energy transfers that are capable of sustaining life.

Scientists believe Europa is one of the planetary bodies in our solar system most likely to have conditions that could sustain life, an idea reinforced by magnetometer readings from the Galileo spacecraft detecting signs of a salty, global ocean below the moon’s icy shell.

Diameter comparison of Europa, Moon, and Earth. (Credit: CWitte/Wikimedia Commons)

Diameter comparison of Europa, Moon, and Earth. (Credit: CWitte/Wikimedia Commons)

Without direct measurements of the ocean, scientists have to rely on magnetometer data and observations of the moon’s icy surface to account for oceanic conditions below the ice.

Regions of disrupted ice on the surface, known as chaos terrains, are one of Europa’s most prominent features. They’re concentrated in the moon’s equatorial region and could result from convection in its ice shell, accelerated by heat from the ocean.

Scientists say the heat transfer and possible marine ice formation may be helping form diapirs—warm compositionally buoyant plumes of ice that rise through the shell.

As reported in the journal Nature Geosciences, a numerical model of Europa’s ocean circulation shows that warm rising ocean currents near the equator and subsiding currents in latitudes closer to the poles could account for the location of chaos terrains and other features of Europa’s surface.

Such a pattern coupled with regionally more vigorous turbulence intensifies heat transfer near the equator, which could help initiate upwelling ice pulses that create features such as the chaos terrains.

‘Ice giant’ oceans

“The processes we are modeling on Europa remind us of processes on Earth,” says Krista Soderlund, of the Institute for Geophysics at University of Texas at Austin, where a similar process has been observed in the patterns creating marine ice in parts of Antarctica.

The current patterns modeled for Europa contrast with the patterns observed on Jupiter and Saturn, where bands of storms form because of the way their atmospheres rotate. The physics of Europa’s ocean appear to have more in common with the oceans of the “ice giants” Uranus and Neptune, which show signs of three-dimensional convection.

“This tells us foundational aspects of ocean physics,” notes co-author Britney Schmidt, assistant professor at the Georgia Institute of Technology. More importantly, if the study’s hypothesis is correct, it shows that Europa’s oceans are very important as a controlling influence on the surface ice shell, offering proof of the concept that ice-ocean interactions are important to Europa.

“That means more evidence that the ocean is there, that it’s active, and there are interesting interactions between the ocean and ice shell,” says Schmidt, “all of which makes us think about the possibility of life on Europa.”

Soderlund, who has studied icy satellites throughout her science career, looks forward to the chance to test her hypothesis through future missions to the Jovian system.

The European Space Agency’s JUICE mission (JUpiter ICy moons Explorer) will give a glimpse into the characteristics of the ocean and ice shell through two flyby observations. NASA’s Europa Clipper mission concept, under study, would complement the view with global measurements.

Research funding was provided by the Institute for Geophysics, part of The University of Texas at Austin’s Jackson School of Geosciences.

Source: University of Texas at Austin

The post More evidence there’s an ocean on Europa primed for life appeared first on Futurity.

September 20 2013


Why Wait for NASA? Let’s Start Planning a Manned Mission to Europa Now

Why Wait for NASA? Let’s Start Planning a Manned Mission to Europa Now
A project launched this week called Objective Europa aims to create a detailed plan sending humans on a one-way trip to Jupiter's icy moon Europa. Sound a bit crazy? The idea is certainly out there, but the project's organizers hope ...

August 27 2012


One Astrobiologist’s Plan to Save the Search for Alien Life

A conceptual illustration of the Europa Jupiter System Mission, or EJSM, which consists of an orbiter for both Europa and Jupiter. Image: NASA/Michel Carroll

Jupiter’s moon Europa hides an ocean of water beneath its icy crust that might harbor extraterrestrial life.

Unfortunately, big dollar signs have kept alive the fictional decree in Arthur C. Clarke’s Space Odyssey series to leave Europa alone: No robot has ever landed on, drilled into or orbited the chilly world. Only a handful of spacecraft have flown by.

A panel of scientists determined in 2011 that NASA’s plans to explore the moon with a single spacecraft, called the Jupiter Europa Orbiter, or JEO, would cost about $4.7 billion. That amount of cash, they wrote, “is so high that both a decrease in mission scope and an increase in NASA’s planetary budget are necessary to make it affordable.”

But even before the panel slammed the mission’s financial feasibility, astrobiologist Pabulo Henrique Rampelotto of Brazil’s Federal University of Pampa was plotting to save exploration of Europa.

In a study published July 13 in Astrobiology, Rampelotto argues that nixing one large orbiter and instead sending three small spacecraft — two orbiters and a probe carrying surface impactors — could spread out both the cost and the risk while hitting all of JEO’s science goals, and then some.

“[T]he main advantages are the complete access to the habitability of Europa, simpler mission design and low cost for each mission,” Rampelotto wrote in an e-mail to Wired. “Europa is considered the prime candidate in the search for life in our solar system. Its ocean may be in direct contact with the rocky mantle beneath, where the conditions could be similar to those on Earth’s biologically rich sea floor.”

Both NASA and the European Space Agency hope to explore Europa and Ganymede, another of Jupiter’s moons, sometime in the next two decades because both bodies may hide a liquid ocean. In the joint space exploration plan, called the Europa Jupiter System Mission, NASA would launch JEO within this decade. Around the same time that spacecraft launches, Europe would rocket its own Jupiter Ganymede Orbiter into deep space.

Budget hawks, however, aren’t buying into NASA’s $4.7 billion dream. Accounting for other higher-priority missions, JEO would stretch further NASA’s shrinking annual planetary science budget of $1.5 billion.

“I believe you will not find someone who continues to support the $4.7 billion … mission concept,” Rampelotto said. “And that is interesting because before the release, no one was considering the possibility of an alternative mission concept.”

'Europa is considered the prime candidate in the search for life in our solar system.'
— Pabulo Henrique Rampelotto
Rampelotto beat the panelists to the punch by proposing his three-spacecraft mission.

If built and launched within the next few years, mission one — an orbiter to measure the thickness of Europan ice and see how deep its oceans go — could reach Europa between 2020 and 2025. A second orbiter would launch a few years later, map the surface in visible and infrared light, and determine if any organic chemicals are present.

“Mission two is technically easier than mission one and could be launched very soon too,” Rampelotto wrote. “After we have those results from missions one and two, mission three would be mature enough to be launched.”

That mission would pound the surface with impactors, penetrate between 3 and 33 feet of ice, and then beam data about the ice’s composition to Earth. It’s unlikely any impactor would reach the subsurface ocean, however, because the thinnest ice may be 1.8 miles thick. Even below that depth, only lakes of water far above the ocean may be locked in the icy crust.

“But, if delivered in potential landing sites where liquid water from the ocean could have recently reached the surface or near surface, we could analyze indirectly the ocean composition, including signals of life,” Rampelotto wrote.

Rampelotto’s plan to barnstorm Europa offers no concrete costs for each mission, which he said would require “advanced studies” to determine. So the idea isn’t without its critics. “NASA team leaders … have advised me that penetrators are difficult and risky to deliver and the best option continues to be a lander,” Rampelotto wrote.

Bob Pappalardo, a planetary scientist who studies Europa and is helping NASA develop future missions to the moon, said Rampelotto’s scheme is a logical one during tight budgetary times. But he noted saving money by splitting up a big mission into smaller ones brings about another issue: fear of commitment.

“The reality is that NASA is not going to want to fund or begin a program of missions, based on the reaction to the Mars sample return suggestion,” said Pappalardo, who wasn’t involved in Rampelotto’s study. “That went over like a lead balloon [at the White House], in terms of being a long-term budgetary relationship.”

Pappalardo hopes that, if there are signs of a recovering U.S. economy in the next few years, they will spur the current presidential administration to open its tight wallet.

“Right now the goal is to do anything at Europa,” he said. “I really hope we’ll come back to our senses soon. I don’t see the vision for planetary science that was present in the past.”

“We need to be planning on the future,” he said. “As it stands, in a few years, we won’t be launching anything. We’re in danger of losing our leadership in planetary science.”

March 08 2011


Experts Push NASA to Focus on Search for Life

The search for life in the solar system, whether in rocks from Mars or on a Jovian moon, tops the wish list of a panel of space scientists convened by the National Research Council. Mindful of shrinking budgets, the panel has issued hard-nosed recommendations that identify which planetary science missions NASA should fly in the decade beginning 2013. Even some top-rated missions should be either deferred or outright canceled if their estimated costs can’t be significantly cut, the panel says in a report released March 7.

sciencenewsAmong its big missions, the panel says, NASA should give highest priority to the Mars Astrobiology Explorer-Cacher. This project would be the first of three missions designed to collect Martian samples and bring them to Earth for analysis of any evidence of life forms. But the panel of space scientists recommends that the mission should go forward only if NASA’s cost can be limited to $2.5 billion; $1 billion less than the project’s estimated price tag in fiscal year 2015 dollars (adjusted for inflation). The European Space Agency and NASA, which will jointly run the mission, should work together to reduce the high cost, the report suggests. One possibility is to include one large robot instead of two.

“I’m ready to hit the ground running with Europe to see if we can do something with that first priority,” says Ed Weiler, NASA’s associate administrator for science in Washington, D.C.

NASA’s Jupiter Europa Orbiter also received a nod from the panel, which ranked the mission as the second-highest priority among large projects. The craft would carry a suite of instruments to determine if Jupiter’s moon Europa has an ocean — a possible haven for life — buried beneath its icy surface, as many scientists suspect. But the panel says the mission should fly only if the project’s current estimated cost of $4.7 billion is reduced and if NASA increases its planetary science budget. The panel did not say specifically how much to cut from the Europa mission in order to maintain funding of other projects, but did spell out a 5 percent boost to NASA’s planetary science research funding compared with fiscal year 2011. The panel also recommends that the planetary science budget should remain 1.5 percent above inflation for the remainder of the decade.

Exploring the structure, composition and atmosphere of Uranus with an orbiter and probe also earned a high mark from the panel, which rated the project third among NASA’s large missions. But the panel recommends the mission be reduced in scope or canceled if it rises above its estimated $2.7 billion cost.

The report also encourages NASA to fund two new midsize missions among five candidates but did not say which to choose. The five possibilities include a Venus lander, a probe that would descend though Saturn’s atmosphere, missions that would sample either the surface of a comet or a large basin at the moon’s southern pole, and a craft that would study the small objects that trail or lead Jupiter in its orbit around the sun. The cap on these missions should be raised slightly, from $1.05 billion including launch costs in fiscal 2015 dollars to $1 billion excluding launch costs, the panel recommends.

Among the least costly missions, the committee recommends that NASA continue to support the ESA/NASA Mars Trace Gas Orbiter, set for launch in 2016, as long as currently negotiated costs and responsibilities between the two space agencies remain unaltered.

The report also urged the National Science Foundation to complete the Large Synoptic Survey Telescope, which will not only probe the nature of dark matter and dark energy but aid in tracking near-Earth asteroids.

Previous reports recommending astrophysics and planetary science missions have been criticized for using cost estimates that were too low. As a result, NASA could not always fund the projects that scientists had pushed for, says planetary scientist Steve Squyres of Cornell University, who chaired the panel. This time both NASA and the National Science Foundation, which cosponsored the report, were specific about keeping recommendations and cost estimates in line with budget realities and requesting fallback options in case funding was less than expected.

“We took the marching orders very seriously,” Squyres said. “We tried very, very hard to be reasonable.”

Image: A National Research Council panel has recommended that NASA fund the proposed Jupiter Europa Orbiter, shown here, but only if scientists reduce the mission’s cost, now estimated at $4.7 billion. (JPL/NASA)

See Also:

February 10 2011


Rogue Planets Could Harbor Life

If a planet was ripped from the warm cradle of its solar system and plunged into the frigid depths of space, it could still hold on to a liquid ocean — and maybe life — beneath an icy crust.

Planet formation models suggest that small planets are regularly flung from their solar systems by close encounters with neighboring gas giants. The giants’ gravitational fields create an interplanetary slingshot effect, sending smaller planets on unstable orbits that quickly leave their star behind.

Prior to ejection, some of those planets could conceivably be like Earth, with continents, oceans and biospheres. A new model suggests that submarine aliens on such a planet could have a chance at survival.

“We originally started with the question, what if you turned off the sun?” said University of Chicago geophysicist Dorian Abbot, co-author of a paper submitted to Astrophysical Journal Letters and pre-published Feb. 5 on arXiv.org.

Along with fellow University of Chicago astrophysicist Eric Switzer, Abbot ran the numbers to see if an ocean could stay liquid without heat from a star. They called their rogue world a Steppenwolf planet, “since any life in this strange habitat would exist like a lone wolf wandering the galactic steppe.”

The pair assumed the planet was between 0.1 and 10 times Earth’s mass, with a similar amount of water and rock. Once the planet fled its warm, nurturing star, the ocean would start to freeze. But leftover heat from the planet’s formation and decaying radioactive elements in the rock could keep the ocean warm beneath a shell of ice. As long as the planet could keep the ice from freezing all the way to the core, the ocean should be safe.

Abbot and Switzer calculated that a planet 3.5 times as massive as Earth would be warm enough at the core to maintain a liquid ocean beneath an ice crust a few kilometers thick. The ocean could last for about 5 billion years.

“That’s a non-ridiculously-short timescale,” said astrobiologist Cynthia Phillips of the SETI Institute, who was not involved in the new work. “It seems like this thick ocean could actually persist for longer than you might assume, without going through the numbers.”

Phillips studies the possibility of life beneath the icy crust of Jupiter’s moon Europa, a world superficially similar to the hypothetical Steppenwolf planet. But unlike the rogue world, most of Europa’s heat comes from tides raised by Jupiter.

In a slightly more bizarre twist, the Switzer and Abbot imagined the Steppenwolf planet with volcanoes spewing carbon dioxide into the atmosphere. The gas would freeze and fall as snow almost immediately, covering the world with an insulating blanket of dry ice. In that case, planets as small as 0.3 times the mass of Earth could keep a liquid ocean.

“That I’m a bit more dubious about,” Phillips said. With only decaying radioactive elements providing heat, “it seems unlikely that you’d have serious volcanic activity going on, without any other energy present.”

Life on the planet could consist not only of organisms that survived the interstellar turmoil and adapted, but those that evolved later, around hydrothermal vents at ocean floors.

Abbot and Switzer declined to speculate what such life would look like, but they and Phillips agreed that it would almost certainly be microscopic.

“I would be very, very surprised if a planet like this could sustain big macroscopic life forms, just because the energy is so limited,” Phillips said.

If these inhabited, free-floating planets exist, they could have been a vehicle for bringing the seeds of life to Earth. If the planet came within about 0.01 light-years of Earth, it could even be observed from the ground, Abbot and Switzer suggest.

But the odds of that happening about one in a billion at best, Switzer says. The researchers mostly meant to muse on the extreme possibilities for habitable worlds.

“If you can imagine life on such an object,” Abbot said, “potentially there could be life in many sorts of weird situations that we haven’t thought of before.”

Image: Jupiter’s moon Europa, which could harbor life in a liquid ocean beneath an icy crust. NASA

See Also:

“The Steppenwolf: A Proposal for a Habitable Planet in Interstellar Space.” Dorian S. Abbot and Eric R. Switzer. arXiv.org, Feb. 5, 2011.

February 09 2011


With 30 Meters Left to Drill, Scientists Leave Subterranean Lake Vostok For The Winter, Amid Controversy

Lake Vostok Drilling Site Wikimedia Commons
Russian team investigating the Antarctic lake isolated for 14 million years may have polluted it as they left

Winter has stymied a Russian-led effort to drill into an Antarctic lake that has been buried for 14 million years, scientists said this week. Just 96 feet short of their goal, scientists had to put their tools away and wait out the rapidly approaching Antarctic winter. But they don't want to lose the progress they've made so far, so they're pouring kerosene down the borehole to keep it from freezing.

Meanwhile, the scientific community is worried the kerosene will taint the pristine, untouched lake and harm any strange life forms that might call it home.

The Russian team evacuated just in time - had they waited much longer, their airplane's hydraulic systems would have frozen, stranding them until spring, according to Science Insider. They left behind a 12,300-foot-deep borehole, just 29 meters (about 96 feet) from the lake. Teams had been working 24 hours a day in an attempt to reach the water-ice boundary.

Lake Vostok is interesting for its similarity to Europa and Enceladus, frozen satellites of Jupiter and Saturn, respectively. Astrobiologists are among those eager to uncover Lake Vostok's Miocene-era secrets.

Vostok Station, just above the lake, holds the distinction of experiencing the coldest recorded temperatures on Earth: -129 degrees F on July 21, 1983. If it makes you feel any better, that's the middle of winter on the continent. Incidentally, that is also much colder than the freezing point of kerosene, which is -54 degrees.

Efforts to reach the lake, which remains liquid because of the pressure of a more than 12,000-foot-thick ice cap, have been controversial since it was first discovered in 1993. Russian scientists drilled into it before but had to stop several times to satisfy international bodies tasked with protecting the lake. But the Antarctic Treaty Secretariat, set up to protect the continent, approved the team's drilling methods last month, giving them the green light to keep drilling. If all goes according to plan, once the drill breaches the ice boundary, the lake's water pressure will push the drilling fluid up into the borehole, where it will freeze. Another year after that, researchers will return to extract that ancient water and analyze its contents.

But some groups are not convinced the kerosene plug is safe. The Antarctic and Southern Ocean Coalition says contamination could destroy the very attributes that make Lake Vostok unique.

"If Russia continues to drill the lubricants and anti-freeze present in their borehole may taint the microorganisms they are trying to discover," the coalition argues on its website.

Now everyone will have to wait until at least next December, when the Antarctic summer allows scientists to return and switch on the drills once again.

[Discovery News]


Jupiter’s Moon Helps Peek Below Planet’s Belt

Astronomers have a new view of the chaos brewing beneath Jupiter’s cloud belt, thanks to some help from its icy moon Europa.

This new image, captured Nov. 30, 2010 with the 10-meter Keck II telescope in Hawaii, shows heat escaping from Jupiter’s interior, giving astronomers a peek into the roiling turmoil inside Jupiter’s missing red stripe.

The image shows Jupiter at four wavelengths of infrared light, which is beyond the range that human eyes can see. Three of those wavelengths show reflected sunlight. But one wavelength, 5 micrometers, can sense breaks in the cloud cover.

Jupiter’s famous red stripe mysteriously faded in late 2009 and vanished altogether by May, 2010. Observations with Hubble and other telescopes showed that the ruddy band was hiding beneath a layer of high, bright clouds made from icy ammonia crystals.

Last November, bits of the red band started coming back.

Astronomers wanted to use Keck’s thermal-sensing eyes to peel back the cloud layers. To get sharp pictures of the sky, Keck shines a laser on the sky to create a fake star and uses it to cancel out the blurring effects of the Earth’s atmosphere.

But Jupiter is so bright, it outshines the laser star. Astronomers needed another tiny light source right next to Jupiter to guide the telescope’s atmosphere-canceling system.

Jupiter’s icy moon Europa turned up at just the right moment.

“Because Jupiter is close to Europa in the sky, it will be experiencing similar distortions,” said astronomer Mike Wong of the University of California at Berkeley, who helped make the observations. “So if we can measure Europa’s distortions, those same distortions can be corrected for Jupiter.”

The resulting images show that the return of Jupiter’s cloud belt is happening at different speeds in each layer of the gas giant’s atmosphere.

“This shows us some of the 3D structure of what’s going on,” Wong told Wired.com. “Without the 5 micron observations, we wouldn’t know that the changes we’re seeing are isolated to individual cloud layers.”

Images: Mike Wong, Franck Marchis & W.M. Keck Observatory

See Also:

January 07 2011


Russians Will Be First To Explore Untouched Antarctic Lake Vostok, In Hunt For Weird Life Forms

The lake has been isolated and buried for 14 million years

An oxygen-rich lake, unreachable for the past 14 million years and buried beneath a thick sheet of ice, is about to be penetrated by a drill bit from a faraway place. It's possible that special life forms have adapted to live in this extreme environment, and scientists hope to learn more once they can analyze water samples.

No, sorry, it's not on Europa - it's in Antarctica. But the environment of Lake Vostok, which Russian scientists are about to drill open, is very similar to that Jovian moon and to Enceladus, a frozen satellite of Saturn. Astrobiologists are among those eager to uncover Lake Vostok's Miocene-era secrets.

The Antarctic Treaty Secretariat, a body set up to protect the frozen continent, approved a Russian team's process to extract water from the lake while preventing contamination, according to New Scientist. By the end of this month, a team from Russia's Arctic and Antarctic Research Institute (AARI) in St Petersburg expects to hit water.

The lake's water pressure will push the drilling fluid up into the borehole, where it will freeze. Next year, researchers will return to extract that ancient water and analyze its contents.

Efforts to drill into Lake Vostok have been stalled since 1998, when the treaty organization stopped the Russian team's work until further environmental studies could prove the lake would not be polluted. Later studies showed this would be tricky - in 2003, NASA astrobiologists said the lake's high nitrogen and oxygen levels would cause the water to fizz like a shaken soda can, opening the lake to possible contamination and even posing a threat to the scientists.

Lake Vostok has oxygen levels 50 times that of other freshwater lakes, so scientists believe life would have had to evolve protective enzymes or other adaptations to survive. If so, these extremophiles could have implications for life on Enceladus or Europa.

No one is sure where the ice-water boundary lies, so scientists are not sure when they'll break through.

[New Scientist via Wired UK]

December 14 2010


Canadian Microbes Give Clues for Life on Icy Moons

SAN FRANCISCO — A sulfur-loving microbe in the Canadian arctic could draw a blueprint for scientists searching for life on Jupiter’s icy moon Europa.

“Ultimately when we go to Europa, we’ll want to be able to tell if there’s any biological activity at all,” astrobiologist Damhnait Gleeson of NASA’s Jet Propulsion Laboratory told Wired.com here at the American Geophysical Union meeting Dec. 13.

Europa’s thick water ice crust may hide a dark liquid ocean, making the moon a favorite candidate for finding life beyond Earth in the solar system. The icy surface is crisscrossed with sulfur-rich, rust-colored lines, which could be cracks in the ice where liquid from the ocean below pushed its way to the surface.

“These geologic features on Europa indicate a plumbing system, so material gets from the bottom to the top of the ice layer,” Gleeson said.

If anything lives in the frigid subsurface brine, it could take in life-sustaining energy from chemicals brought down through the cracks, astronomers suspect. But to find these hardy bugs, astronomers need to know how to recognize them.

To get an idea of how sulfur-loving Europans might show signs of their presence, Gleeson and colleagues went to the most similar place on Earth: the Borup Fjord Pass in the Canadian arctic.

Pilots flying over the pass in the late 1990s noticed the ice was stained yellow with a pure form of elemental sulfur.

“It’s so unusual to find ice and sulfur together on Earth,” Gleeson said. “It’s really not what you’d expect to see.” On Earth, most pure sulfur reacts with oxygen to form the soft mineral gypsum. Finding so much elemental sulfur in Borup Fjord Pass suggested to Gleeson and colleagues that the supply of sulfur was being replenished, possibly by microbes. A trip to the site in 2006 confirmed their suspicions: The sulfur was built by microorganisms which derived energy from ripping electrons off another form of sulfur, sulfide.

Gleeson and colleagues brought the microbes back to the lab and let them grow on a diet of sulfide, then analyzed the elemental sulfur they produced. The researchers found that the microbe-built sulfur showed complicated sheets and filaments, structures that did not show up in microbe-free control samples.

“We can look at sulfur minerals that are formed by microorganisms, and we can tell they were formed by microorganisms,” Gleeson said. The results may help design instruments for future missions to Europa, like the proposed Europa Jupiter System Mission.

For now, though, the best observations of Europa come from the Galileo spacecraft, which orbited Jupiter from 1995 to 2003. Gleeson and colleagues combined their fieldwork with observations of Borup Fjord from space, to help provide “ground truth” for observations of Europa from afar. But for Gleeson, these comparisons just highlight the need to actually go to Europa and start digging.

“What we can see from orbit is such a simple picture compared to the surface,” Gleeson said. “From orbit it’s just ice and sulfur. We really have to go deeper to understand the system.”

Astrobiologist Kevin Hand of NASA’s Jet Propulsion Lab, who also spoke at the AGU meeting, agreed. “Observations from orbit can provide compelling evidence for life, but not convincing evidence,” he said. “To cross that threshold from compelling to convincing requires in-situ elements.”

Images: 1) The Borup Fiord Pass at Ellesmere Island, Canada, where the snow is stained yellow by sulfur. 2) Sulfur-rich lines crisscross the surface of Jupiter’s moon Europa. 3) Gypsum deposits mark a potential sulfur spring at Borup Fjord Pass. Gleeson et al. 2010/NASA

See Also:

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