• Mars vs. Europa: Are we looking in the wrong place for alien life?

    NASA / JPL-Caltech / MSSS

    This graphic shows the relative sizes of Earth, Mars and Europa, an icy moon of Jupiter.

    By Alan Boyle, Science Editor, NBC News


    A British astrobiology conference has revived a years-old debate over the best place to look for life elsewhere in the solar system: Mars, or the moons of Jupiter and Saturn?

    "For reasons I don't really understand, the wider solar system and the potential for life there has not been high priority," The Telegraph quoted Robert Pappalardo, a senior research scientist at NASA's Jet Propulsion Laboratory, as saying on BBC Radio 4.

    Pappalardo's remarks were occasioned by this week's astrobiology conference at the UK Center for Astrobiology in Edinburgh, Scotland. The center recently established the International Subsurface Astrobiology Laboratory, or ISAL, half a mile (1 kilometer) beneath the surface in Yorkshire's Boulby mine. Biologists will use that facility to see how organisms hold up in extreme environments, learn about life's chemical signatures, and test instruments that could look for those signatures on other worlds.

    Someday, one of the worlds may well be Europa, an icy moon of Jupiter. With a diameter of 1,945 miles (3,130 kilometers), Europa is just slightly smaller than Earth's moon, and yet it is thought to contain more water than Earth's oceans beneath a miles-deep layer of ice. Researchers recently suggested that hydrogen peroxide in the ice could serve as an energy supply for simple forms of life in the ocean hidden below.

    Europa is the focus of Pappalardo's research, and for months he has been urging NASA to support a $2 billion mission to study Europa at close range. However, proposals for NASA missions to Europa have been losing out, in part because of the cost of missions to Mars. Last week's federal budget proposal for the next fiscal year provides no funding for a Europa mission, but it does fund Mars missions such as Maven (launching this year), InSight (launching in 2016) and a new science rover (launching in 2020).

    Kevin Hand (JPL-Caltech) / Jack Cook (WHOI) / Howard Perlman (USGS)

    If Europa's ocean is 100 kilometers (62 miles) deep, and all that water were gathered into a ball, it would have a radius of 877 kilometers (545 miles). This graphic compares that hypothetical ball of Europan water to the size of the Jovian moon itself, as well as all the water on planet Earth. Europa is thought to have two to three times the volume of water in Earth's oceans.

    At February's annual meeting of the American Association for the Advancement of Science, Pappalardo worried that NASA's study of the outer solar system would go "radio-dark" in 2017, when the Cassini mission to Saturn and the Juno mission to Jupiter are both due to end. He continued that theme in this week's BBC interview.

    "I worry that if Europa exploration is delayed, but then finally it happens some day, we might look back and say 'Why didn't we do that sooner?' Imagine 50 years from now, we get a lander there and find signs of life. All this time we'll have been looking in the wrong place," he was quoted as saying.

    Europa isn't the only moon that intrigues astrobiologists: In the Jovian system, Callisto and Ganymede also have icy shells and may hold hidden oceans. Meanwhile, Cassini has repeatedly observed geysers of water ice rising from the surface of the Saturnian moon Enceladus — suggesting that liquid water and perhaps life may lie beneath the surface. Saturn's largest moon, Titan, has a thick atmosphere and seas of hydrocarbon that some scientists think could harbor a totally alien kind of life.

    As for Mars, astrobiologists say hints of life could well lurk beneath the surface. To some extent, the Red Planet has been winning out over Europa and Enceladus because it's easier to get to. Moreover, NASA's vision calls for sending astronauts to Mars and its moons in the 2030s. NASA's robotic missions serve as precursors for those human voyages, as well as steps in a long-term program to learn about life in the universe.

    Europa's fans can take heart in the fact that the European Space Agency is planning its own mission to Jupiter's moons: The Jupiter Icy Moons Explorer, or JUICE, is due for launch in 2022 and arrival at the Jovian system in 2030. There's also talk of a sample return mission that would target Enceladus' geysers, and a proposal to drop a boat onto Titan's seas.

    So what if all of these worlds — Mars and Europa, Callisto and Ganymede, Titan and Enceladus — turn out to be lifeless? Charles Cockell, who heads the UK Center for Astrobiology, addressed that scenario in an interview with the BBC.

    "A lot of people think astrobiology is some sort of hunt for life, and if we don't find life, it will be a big disappointment," Cockell said. "But in fact, that's not the case. The discovery of many lifeless planets across the universe, the discovery that the Earth might be unique as a place for life, would be an astonishing discovery in itself. It would be a very lonely discovery, but it would be an astonishing discovery."

    More about the search for life:

    Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

  • Jupiter's icy moon Europa holds ingredient for life

    NASA / JPL / University of Arizona

    These global views of Jupiter's icy moon Europa were captured by NASA's Galileo spacecraft in June 1997. The image on the left shows Europa in natural color, while the right-side image has enhanced colors to bring out subtle color differences to show differences between pure water ice (white and bluish white) and non-ice components (red, brown and yellow spots).

    By Tariq Malik
    Space.com

    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.

    "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 waterand 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 analyzed near-infrared observations of Europa collected in September 2011 by the Keck II telescope atop the Mauna Kea volcano in Hawaii. [See photos of Jupiter's icy moon Europa]

    The study found that the highest concentration of hydrogen peroxide occurs on the leading side of Europa as it orbits Jupiter. The ice in those regions is almost pure water, and not contaminated by sulfur like other parts of Europa, NASA officials said.

    Hydrogen peroxide is created on Europa due to the intense radiation bombardment of the moon's surface as it moves through Jupiter's powerful magnetic field. At its most concentrated, the chemical was found with a peroxide abundance of about 0.12 percent compared to water. That's about 20 times more diluted than the bottles of hydrogen peroxide for sale in drug stores on Earth, NASA officials said.

     Hydrogen peroxide was first discovered on Europa by NASA's Galileo spacecraft, which studied Jupiter and its moons from 1995 to 2003. But Galileo's observations studied only a limited path of Europa. The new analysis covers a much broader region of Europa's surface.

    "The Galileo measurements gave us tantalizing hints of what might be happening all over the surface of Europa, and we've now been able to quantify that with our Keck telescope observations," Brown said. "What we still don't know is how the surface and the ocean mix, which would provide a mechanism for any life to use the peroxide."

    But the fact that so much peroxide exists on Europa is a boon for the potential habitability of the icy moon's water ocean. When mixed with water, peroxide releases oxygen.

    "At Europa, abundant compounds like peroxide could help to satisfy the chemical energy requirement needed for life within the ocean, if the peroxide is mixed into the ocean," Hand said.

    The research is detailed in a recent edition of the Astrophysical Journal Letters and was partially funded by NASA's Astrobiology Institute through its Icy Worlds team.

    Email Tariq Malik at tmalik@space.com or follow him @tariqjmalik and Google+. Follow us @Spacedotcom, Facebook and Google+.

    Copyright 2013 Space.com, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

  • 'Spikes of ice' may dot Jupiter's moon Europa

    NASA / Ted Stryk

    Europa, as viewed from NASA's Galileo spacecraft. Visible are plains of bright ice, cracks that run to the horizon, and dark patches that likely contain both ice and dirt.

    By Miriam Kramer
    Space.com

    THE WOODLANDS, Texas — The equator of Jupiter's icy moon Europa may be covered with huge spikes of ice, scientists say.

    Astronomers have known for some time that Jupiter's moon Europa is icy, and now scientists are trying to understand just what form that ice takes by using some of the coldest places on Earth as analogues. Huge ice spikes, known as penitentes, found on Earth could form on Europa, they said.

    "It's a pretty obscure geological feature on the Earth," Dan Hobley, an astronomer at the University of Virginia, told Space.com after he presented his findings at the 44th annual Lunar and Planetary Science Conference.

    The 3.3 to 16.4 foot (1 to 5 meter) spikes of ice only grow in certain parts of the Andes mountains on Earth, but those areas of the world serve as good proxies for what Europa's geology might be like, Hobley said. [Photos of Europa, Jupiter's Mysterious Icy Moon]

    It takes a very specific set of circumstances for penitentes to form, Hobley said. The angle of the sun has to hit the ice in just the right way to keep the spikes of ice standing on end and buried deep into the ground. The blades grow in very dry conditions and can thrive in dirt-filled or clean circumstances.

    As far as scientists can tell right now, all of those environments exist along Europa's equator, Hobley said.

    ESO / B. Tafreshi

    These bizarre ice and snow formations are known as penitentes (Spanish for 'penitents'). They are illuminated by the moonlight, which is visible on the right. On the left, higher in the sky, the Large and Small Magellanic Clouds can be faintly seen, while the reddish glow of the Carina Nebula appears close to the horizon on the far left. Photo by ESO Photo Ambassador Babak Tafreshi.

    Although Europa has been observed using radar and spectroscopy, scientists have not been able to understand exactly what the surface of this moon looks like. The geological features of Europa seem "basically random," Hobley said, but the existence of penitentes could offer an explanation.

    Scientists have found that Europa's equator is warmer than it should be, and penitentes could explain that mysterious temperature, Hobley said. The ice spines reflect heat onto one another, creating a warmer area because the sunlight gets trapped bouncing from ice spike to ice spike, Hobley explained.

    The scientist and his colleagues are interested in understanding what the surface of Europa looks like, partially because it's a first step toward designing a viable lander that could safely touch down on the moon's frozen surface.

    But it might not be that simple, Hobley said.

    The icy shell of Europa's surface might shift occasionally, displacing the area of the alien world that used to be its equator. Penitentes don't naturally form in higher latitudes, so if the shell does shift, that could create a problem for astronomers trying to map exactly where to set down a lander.

    "We're at the state where this is a good, solid guess," Hobley said.

    Follow Miriam Kramer @mirikramer and Google+. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.

    Copyright 2013 Space.com, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

  • Ocean bubbles up to surface of Jupiter's moon Europa

    NASA / JPL-Caltech

    Based on new evidence from Jupiter's moon Europa, astronomers hypothesize that chloride salts bubble up from the icy moon's liquid ocean and reach the frozen surface, where the salts are bombarded with sulfur from volcanoes on Jupiter's moon Io.

    By Mike Wall
    Space.com

    The huge ocean sloshing beneath the icy shell of Jupiter's moon Europa likely makes its way to the surface in some places, suggesting astronomers may not need to drill down deep to investigate it, a new study reports.

    Scientists have detected chemicals on Europa's frozen surface that could only come from the global liquid-water ocean beneath, implying the two are in contact and potentially opening a window into an environment that may be capable of supporting life as we know it.

    "We now have evidence that Europa's ocean is not isolated — that the ocean and the surface talk to each other and exchange chemicals," study lead author Mike Brown of Caltech in Pasadena said in a statement.

    "That means that energy might be going into the ocean, which is important in terms of the possibilities for life there," Brown added. "It also means that if you’d like to know what’s in the ocean, you can just go to the surface and scrape some off." [Photos: Europa, Mysterious Icy Moon of Jupiter]

    Studying Europa's icy shell
    Brown and co-author Kevin Hand of NASA's Jet Propulsion Laboratory in Pasadena scrutinized Europa's surface with Hawaii's powerful Keck II Telescope, which sports an adaptive-optics system to compensate for the blurring caused by Earth's atmosphere.

    Europa is tidally locked with Jupiter, meaning one hemisphere of the moon always leads in its orbit while the other one always trails. Keck detected a mysterious signal on Europa's trailing side that no other instrument had seen before, researchers said.

    “We now have the best spectrum of this thing in the world,” Brown said. “Nobody knew there was this little dip in the spectrum because no one had the resolution to zoom in on it before.”

    After much experimentation in the lab, Brown and Hand determined that the spectroscopic signal was caused by a magnesium sulfate salt called epsomite.

    "Magnesium should not be on the surface of Europa unless it’s coming from the ocean," Brown said. "So that means ocean water gets onto the surface, and stuff on the surface presumably gets into the ocean water."

    An Earth-like ocean?
    But the astronomers don't think Europa's ocean, which is believed to be about 62 miles (100 kilometers) deep, is rich in magnesium sulfate.

    That's because the epsomite signal comes only from Europa's trailing side, which is blasted with sulfur expelled by Jupiter's volcanic moon Io. If magnesium sulfate were bubbling up to the surface directly from the ocean, its signal should have been seen on the leading side, too, the reasoning goes.

    Europa's ocean, Brown and Hand say, can be only one of two types — sulfate-rich or chlorine-rich. With sulfate-rich off the table, the oceanic magnesium source is likely magnesium chloride (which gets broken apart on the surface by radiation, leading to the formation of magnesium sulfate on the moon's trailing side after exposure to sulfur from Io).  

    Other chloride salts are probably in the water as well, such as sodium chloride and potassium chloride, the scientists added. Indeed, previous work by Brown showed that atomic sodium and potassium are present in Europa's wispy atmosphere.

    The composition of Europa's ocean may thus be similar to that of Earth's seas, researchers said.

    “If you could go swim down in the ocean of Europa and taste it, it would just taste like normal old salt," Brown said.

    If that's the case, the 1,940-mile-wide (3,120 km) Europa would become even more intriguing to scientists searching for signs of life beyond our planet.

    "If we’ve learned anything about life on Earth, it’s that where there’s liquid water, there’s generally life," Hand said. "And of course our ocean is a nice salty ocean. Perhaps Europa’s salty ocean is also a wonderful place for life."

    The new study has been accepted for publication in the Astronomical Journal.

    Follow Mike Wall on Twitter @michaeldwall. Follow us @Spacedotcom, Facebook or Google+. This article was first published on Space.com.

    Copyright 2013 Space.com, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.