Jupiter's Icy Moon Europa: Best Bet for Alien Life

Under a thick crust of ice, Europa might have an ocean warmed by tidal interactions with Jupiter. 

This tidal flexing could also produce a geologically active core that might in turn create hydrothermal vents on the ocean floor.

Credit: NASA/JPL/Ted Stryk

Jupiter's moon Europa doesn't look like a particularly inviting place for life to thrive; the icy satellite is nearly 500 million miles (800 million kilometers) from the sun, on average.

But beneath its icy crust lies a liquid ocean with more water than Earth contains. This ocean is shielded from harmful radiation, making Europa one of the solar system's best bets to host alien life.

That's one of the reasons Europa is so alluring to scientists. It has all the elements thought to be key for the origin of life: water, energy, and organic chemicals, the carbon-containing building blocks of life, scientists said at an event called "The Lure of Europa," held here last month.

"All the ingredients are there to make us think Europa is the next place to go," NASA Chief Scientist Ellen Stofan said at the event, which was organized by the Planetary Society, a nonprofit organization headed by scientist and TV host Bill Nye.



Just as a layer of ice over a pond allows the water beneath it to stay liquid through the freezing winter, Europa's icy crust shields its enormous ocean despite the moon's great distance from the sun.

As Europa travels around Jupiter, the massive planet bends and flexes the satellite, generating interior heat that keeps its water from freezing completely.

Beneath Europa's surface, active volcanoes may also heat the water, providing vents where bacterial life may thrive as it does on Earth.

"With that combination of volcanism and water, good things are going to happen," Stofan said.

NASA Considers Ambitious Mission to Jupiter's Icy Moon Europa by 2025

Under a thick crust of ice, Europa might have an ocean warmed by tidal interactions with Jupiter. 

This tidal flexing could also produce a geologically active core that might in turn create hydrothermal vents on the ocean floor.

Credit: NASA/JPL/Ted Stryk

NASA hopes to launch a mission to the Jupiter moon Europa, perhaps the solar system's best bet to host alien life, a decade or so from now, officials announced Tuesday (March 4).

The White House's 2015 federal budget request, which was released Tuesday, allocates $15 million to help develop a mission to Europa, which harbors a potentially life-supporting ocean of liquid water beneath its icy shell.

"Europa is a very challenging mission operating in a really high radiation environment, and there's lots to do to prepare for it," NASA chief financial officer Beth Robinson told reporters Tuesday. "We're looking for a launch some time in the mid-2020s."



The $15 million — which represents a tiny fraction of the $17.5 billion allocated to the space agency in the 2015 request — would fund very early "pre-formulation" work for a potential Europa mission, Robinson added.

"I know people have asked about the total size [of the possible mission], and we're frankly just not sure at this point," she said, adding that agency officials will reach out to the scientific community to help map out the mission.

Saturn Icy Moon Enceladus: Geysers Tied to Orbit

This photo of water geysers spouting from Saturn's moon Enceladus was taken by NASA's Cassini orbiter in October 2007

Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA

Steady geysers of water ice on one of Saturn's icy moons appear to erupt more strongly when the moon is farthest from its ringed parent planet, scientists say.

The warm vents at the south pole of Saturn's moon Enceladus emit vast plumes of water vapor and ice out into space.

While these plumes have been studied for some time, scientists have now observed a correlation between the intensity of the plume and the location of the moon in its orbit around Saturn.

Using data from the Cassini spacecraft, Cornell University research associate Matthew Hedman and a team of scientists found that when the 314-mile (505 kilometers) moon nears its farthest point from Saturn, the plumes seen in the Cassini data appear brighter.

This suggests that the vents in the southern portion of Enceladus are expanding, allowing more dust to escape the fissures at that point in the moon's orbit.

As the moon nears its home planet, however, the vents contract, making the plumes less pronounced.

Saturn's Icy Moon Dione Hides Watery Secret: A Subsurface Ocean

The Cassini spacecraft looks down, almost directly at the north pole of Dione. 

The feature just left of the terminator at bottom is Janiculum Dorsa, a long, roughly north-south trending ridge. Image taken March 22, 2008.

CREDIT: NASA/JPL/Space Science Institute

The plain-looking Saturn moon Dione may have once had a geologically active subsurface ocean, new images from NASA's Cassini spacecraft reveal.

Images of Dione's 500-mile-long (800 kilometers) mountain Janiculum Dorsa suggest that the moon could have been a weaker copycat of Enceladus, Saturn's icy geyser moon.

"There may turn out to be many more active worlds with water out there than we previously thought," Bonnie Buratti, who leads the Cassini science team at NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a statement.

Subsurface oceans are thought to exist on several bodies in the solar system, including Saturn's moons Enceladus and Titan and Jupiter's moon Europa.

These geologic hotspots have garnered the interest of scientists searching for the building blocks of life beyond Earth. If Dione turned out to have a liquid layer under its crust, that would increase the moon's chances of supporting life.

Cassini, which has been exploring Saturn since 2004, detected a weak particle stream coming from Dione with its magnetometer.

Images taken by the spacecraft suggest a slushy liquid layer might exist beneath its icy crust, as well as ancient, inactive fractures that now spew water ice and carbon-containing particles, much like ones seen on Enceladus.

Hydrogen Peroxide: Ingredient for Life Common on Europa, Jupiter's Icy Moon

A potential energy source for life appears to be common on Jupiter's icy moon Europa, a new study suggests.

An analysis of infrared observations of Europa revealed that hydrogen peroxide is abundant on the ice-covered Jovian moon. If the hydrogen peroxide finds a way beneath Europa's surface and mixes with the moon's liquid water ocean, it could be a vital energy source for any life that might exist there, scientists said.

Kevin Hand

"Life as we know it needs liquid water, elements like carbon, nitrogen, phosphorus and sulfur, and it needs some form of chemical or light energy to get the business of life done," study leader Kevin Hand, of NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a statement.

 "Europa has the liquid water and elements, and we think that compounds like peroxide might be an important part of the energy requirement. The availability of oxidants like peroxide on Earth was a critical part of the rise of complex, multicellular life."

Planetary scientist Mike Brown of the California Institute of Technology in Pasadena co-authored the new study, which analyzied near-infrared observations of Europa collected in September 2011 by the Keck II telescope atop the Mauna Kea volcano in Hawaii.

Jupiter's Moon Io: Watery Alien Planets Might be Stripped Dry by Gravity

Two sulphurous eruptions are visible on Jupiter's volcanic moon Io.

CREDIT: Galileo Project, JPL, NASA

Alien planets might experience tidal forces powerful enough to remove all their water, leaving behind hot, dry worlds like Venus, researchers said.

These findings might significantly affect searches for habitable exoplanets, scientists explained. Although some planets might dwell in regions around their star friendly enough for life as we know it, they could actually be lifelessly dry worlds.

The tides that we experience on Earth are caused by the gravitational pull of the moon and sun. Our tides are nothing compared to what we see elsewhere in the solar system — the gravitational pull Europa experiences from Jupiter leads to tidal forces roughly 1,000 times stronger than what Earth feels from our moon, flexing and heating Europa.

Heat is a major factor in how capable a planet might be of supporting life as we know it. What scientists call the habitable zone of a star is defined by whether liquid water can survive on its surface, given that life exists virtually wherever there is liquid water on Earth.

NASA - Saturn's Moon Enceladus Spreads its Influence

Chalk up one more feat for Saturn's intriguing moon Enceladus.

The small, dynamic moon spews out dramatic plumes of water vapor and ice -- first seen by NASA's Cassini spacecraft in 2005.

It possesses simple organic particles and may house liquid water beneath its surface.

Its geyser-like jets create a gigantic halo of ice, dust and gas around Enceladus that helps feed Saturn's E ring.

Now, thanks again to those icy jets, Enceladus is the only moon in our solar system known to influence substantially the chemical composition of its parent planet.

In June, the European Space Agency announced that its Herschel Space Observatory, which has important NASA contributions, had found a huge donut-shaped cloud, or torus, of water vapor created by Enceladus encircling Saturn.

The torus is more than 373,000 miles (600,000 kilometers) across and about 37,000 miles (60,000 kilometers) thick. It appears to be the source of water in Saturn's upper atmosphere.

Though it is enormous, the cloud had not been seen before because water vapor is transparent at most visible wavelengths of light. But Herschel could see the cloud with its infrared detectors.

"Herschel is providing dramatic new information about everything from planets in our own solar system to galaxies billions of light-years away," said Paul Goldsmith, the NASA Herschel project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

The discovery of the torus around Saturn did not come as a complete surprise. NASA's Voyager and Hubble missions had given scientists hints of the existence of water-bearing clouds around Saturn.

Then in 1997, the European Space Agency's Infrared Space Observatory confirmed the presence of water in Saturn's upper atmosphere. NASA's Submillimeter Wave Astronomy Satellite also observed water emission from Saturn at far-infrared wavelengths in 1999.

While a small amount of gaseous water is locked in the warm, lower layers of Saturn's atmosphere, it can't rise to the colder, higher levels.

To get to the upper atmosphere, water molecules must be entering Saturn's atmosphere from somewhere in space. But from where and how? Those were mysteries until now.

Build the model and the data will come.

NASA - Saturn's Moon Enceladus Spreads its Influence

Pluto's icy exterior may conceal an ocean

PLUTO could hide a liquid ocean beneath its icy shell. Indeed, other bodies on the solar system's frigid fringe could also harbour subsurface oceans, and these could provide the conditions to sustain life.

Temperatures on Pluto's surface hover around -230 °C, but researchers have long wondered whether the dwarf planet might boast enough internal heat to sustain a liquid ocean under its icy exterior.

Now Guillaume Robuchon and Francis Nimmo at the University of California, Santa Cruz, say there is a good chance it does. They calculate that an ocean depends on two things: the amount of radioactive potassium in Pluto's rocky core, and the sloshiness of the ice that covers it.

Density measurements suggest a rocky core fills 40 per cent of the dwarf planet's volume. If the core contains potassium at a concentration of 75 parts per billion, its decay could produce enough heat to melt some of the overlying ice, which is made of a mixture of nitrogen and water.

It should have at least that much potassium and probably more, says William McKinnon at Washington University in St Louis, Missouri. He points out that Earth, which probably formed with less of the volatile element due to its closer distance to the sun, has 10 times that concentration in its core.

But merely having a source of heat is not enough to maintain a long-lived ocean. Heat from the core will trigger convection in the surrounding ice, and if the ice churns too quickly, the heat will simply escape into space before it can do much melting.

If it flows substantially more slowly than Antarctic glaciers on Earth, however, then the top 165 kilometres of ice could provide enough insulation for a liquid ocean of the same depth to exist below, the team calculates (Icarus, DOI: 10.1016/j.icarus.2011.08.015).

The viscosity of the ice depends on the size of individual ice particles, with smaller grains flowing more easily. There is no way to measure this from Earth, but Pluto's shape could reveal evidence of an ocean, the team says. 

Pluto's spin is slowing down due to tugs from its large moon Charon. Fast-spinning objects bulge out at their equator, but a soft interior would allow the world to relax into more of a sphere as its spin slows down. NASA's New Horizons probe will image the dwarf planet's shape when it flies past in 2015.

Other distant icy bodies might also have oceans, which could mean that the outer solar system is potentially ripe for life. "It's very exciting to think that these dwarf planets could have astrobiological potential," says New Horizons lead scientist Alan Stern.

LCROSS almost missed the target

The Lunar Reconnaissance Orbiter recorded temperatures at the Cabeus crash site, shown here about 90 seconds after impact. 

The impact generated temperatures over 1340 degrees Fahrenheit (727 degrees Celsius), which appear as a tiny glowing dot near the center of the color swath. Credit: NASA/UCLA.

The existence of ice on the moon was revealed with a bang last year, when kamikaze spacecraft crashed into a crater at the lunar south pole, kicking up enough water for researchers to finally detect.

Today scientists in six separate studies announced new findings from the Oct. 9, 2009 LCROSS moon crash mission. They found, among other discoveries, substantial amounts of water ice at ground zero for the impact — water that could one day be key to the humanity's future in space.

But as successful as the mission proved in the end, the complicated affair was fraught with uncertainty and came perilously close to failure. Now scientists reveal the story of how they made their discovery and what challenges they faced along the way. [10 Coolest New Moon Discoveries]

Silver found in lunar rocks

Silver was found in small amounts in lunar rocks collected by the Apollo astronauts, and now its spectral signature may have been spotted by NASA's LCROSS mission (Image: T. A. Rector/I. P. Dell'Antonio/NOAO/AURA/NSF)

Enceladus Heat radiation: Warm fissure of Saturn's icy moon

The right-hand image shows a dramatically improved view of heat radiation from a warm fissure near the south pole of Saturn's icy moon Enceladus. It was obtained by NASA's Cassini spacecraft during its Nov. 21, 2009, flyby of that moon. The fissure, named Baghdad Sulcus, is one of four so-called "tiger stripe" features that emit jets of water vapor and ice particles.

The tiger stripe runs from the upper left to the lower right of the image. The infrared map, obtained by Cassini's composite infrared spectrometer, is nearly 10 times more detailed than the image on the left, which was the best previous map of heat from the fissures. That image was obtained in March 2008.

The new data show that broad swaths of heat previously detected by the composite infrared spectrometer are confined to a narrow, intense region no more than a kilometer (half a mile) wide along the fracture.

The thermal image also reveals that the strength of the signal varies considerably along the length of this fissure segment. The composite infrared spectrometer data indicate that the temperature along Baghdad Sulcus reached more than 180 Kelvin (about minus 140 degrees Fahrenheit).

The new map shows how the surface glows at 10 to 16 micron wavelengths of radiation along a 40-kilometer (25-mile) length of Baghdad Sulcus. This covers a region about 10 kilometers to 5 kilometers (6 miles to 3 miles) in width, with the smallest features on the thermal map measuring less than 1 kilometer (half a mile) across.