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New Findings on Enceladus, Europa

Jim Green, who is director of the Planetary Science Division at NASA headquarters, clearly loves his job, and he got so excited during Thursday’s news conference that he kept interchanging Enceladus with Europa in his remarks. Both were in play during the discussion, and the context made it clear what he intended, but I always get a kick out of seeing that kind of enthusiasm showing forth in scientists and academics. It’s a reminder of why they got involved in the first place, and for that matter, what drew me into writing about the field myself.

The news delivered in the press conference and through two new papers involves two older space missions that are driving planning for yet a third, the Europa Clipper mission, a Jupiter orbiter that is still in the design and planning stages. And with Cassini in its final months of operation, it’s fitting that a Cassini flyby through the Enceladus plumes in 2015 should result in what Cassini project scientist Linda Spilker (JPL) called a ‘capstone finding.’ Hydrogen has turned up in the plumes, which turn out to be about 98 percent water vapor and 1 percent hydrogen, with a mix of carbon dioxide, methane and ammonia making up the rest.

Cassini’s Ion and Neutral Mass Spectrometer (INMS) instrument has, in other words, shown us, a potential pointer to what any Enceladus microbes might use to stay alive. For hydrogen must be entering the subsurface ocean because of hydrothermal activity on the seafloor.

We don’t know that life exists here, but provocatively enough, hydrogen can be a source of chemical energy, combining with carbon dioxide dissolved in the apparently abundant water beneath the surface of Enceladus. ‘Methanogenesis’ is the name of this reaction because methane is produced as a by-product. Add to this energy source the fact that we also have carbon, nitrogen and oxygen. If phosphorus and sulfur also exist in that ocean (and the prospects are good), then the case for Enceladus as a venue for life strengthens.

So we have powerful evidence that rock deep inside Enceladus is interacting with hot water. Think back 40 years to the arrival of the Viking landers on Mars and you’ll recall that at roughly the same time, oceanographers were finding unexpected life forms around hydrothermal vents on Earth. Hydrothermal fluids beneath the ocean floor were driving geochemical transformations in which minerals rich in iron react with water to form new minerals. Chris Glein (SwRI) said that the Cassini findings show that geochemistry is likewise active on Enceladus.


Image: The graphic shows water from the ocean circulating through the seafloor, where it is heated and interacts chemically with the rock. This warm water, laden with minerals and dissolved gases (including hydrogen and possibly methane) then pours into the ocean creating chimney-like vents. The hydrogen measurements were made using Cassini’s Ion and Neutral Mass Spectrometer, or INMS, instrument, which sniffs gases to determine their composition. The finding is an independent line of evidence that hydrothermal activity is taking place in the Enceladus ocean. Previous results from Cassini’s Cosmic Dust Analyzer instrument, published in March 2015, suggested hot water is interacting with rock beneath the ocean; the new findings support that conclusion and indicate that the rock is reduced in its geochemistry. With the discovery of hydrogen gas, scientists can now conclude that there is a source of chemical free energy in Enceladus’ ocean. Credit: NASA/JPL-Caltech/Southwest Research Institute.

It’s an exciting thought, though we don’t know if any parallels to life around Earth’s ‘white smokers’ far below the surface exist. We do know that forms of life can feed on chemical energy rather than sunlight, with that process of methanogenesis combining H with CO2 to produce methane and extract energy out of the process. As Glein pointed out, we’re now looking at the first calorie count in an alien ocean, with life as a geochemical possibility.

An older mission, the Galileo Jupiter orbiter that gave us our best imagery of Europa, accounted for the second discovery announced yesterday. This one was not a complete surprise, as we had already found evidence of a possible plume on Europa through observations from the Hubble Space Telescope. But the 2014 detection of a plume is now bolstered by a 2016 detection. The Galileo data are crucial here because thermal imagery of the area in question, taken by the spacecraft in the 1990s, shows a hot spot, a ‘thermal anomaly,’ as William Sparks (Space Telescope Science Institute) called it. The region also contains surface features that appear to be cracks in the moon’s ice crust.

“The plumes on Enceladus are associated with hotter regions, so after Hubble imaged this new plume-like feature on Europa, we looked at that location on the Galileo thermal map. We discovered that Europa’s plume candidate is sitting right on the thermal anomaly,” said Sparks.

It was Sparks who led the Hubble plume studies in both 2014 and 2016.


Image: These composite images show a suspected plume of material erupting two years apart from the same location on Jupiter’s icy moon Europa. The newly imaged plume, shown at right, rises about 100 kilometers above Europa’s frozen surface. The image was taken Feb. 22, 2016. The plume in the image at left, observed by Hubble on March 17, 2014, originates from the same location. It is estimated to be about 50 kilometers high. The snapshot of Europa, superimposed on the Hubble image, was assembled from data from NASA’s Galileo mission to Jupiter. Credit: NASA/ESA/W. Sparks (STScI)/USGS Astrogeology Science Center.

Finding a hot spot in the same place as the candidate position for the detected plumes gives us further evidence that the Europan ocean can communicate with the surface, although its activity is not as spectacular as the numerous venting jets we see at Enceladus’ south pole. The new plume rises about 100 kilometers above the Europan surface, about twice as high as the one observed in 2014, and both correspond to the thermal region imaged by Galileo.


Image: These images of the surface of the Jovian moon Europa, taken by NASA’s Galileo spacecraft, focus on a “region of interest” on the icy moon. The image at left traces the location of the erupting plumes of material, observed by NASA’s Hubble Space Telescope in 2014 and again in 2016. The plumes are located inside the area surrounded by the green oval. The green oval also corresponds to a warm region on Europa’s surface, as identified by the temperature map at right. The map is based on observations by the Galileo spacecraft. The warmest area is colored bright red. Credit: NASA/ESA/W. Sparks (STScI)/USGS Astrogeology Science Center.

Assuming a linkage between the plumes and the warm spot on the surface, researchers believe that liquid water being vented from below the crust could be warming the area around the plume. Another possibility is that water vapor being ejected from the plume falls back to the surface in a mist that changes the structure of local surface grains and lets them retain heat longer than the surrounding regions. We should learn a great deal more with Europa Clipper.

Planned for a launch in the next decade, Europa Clipper can draw on both sets of findings discussed yesterday. We can envision a probe that, like Cassini, can fly through the plumes of a distant moon, hoping to extract information about the ocean beneath. The spacecraft, which will make numerous close flybys of the moon, will carry nine major instruments. Its magnetometer should help us measure the size of the ocean, while ice penetrating radar can help us measure the thickness of the ice. We’ll also use thermal imaging, like Galileo, to look for other hot spots, and learn if there are cracks associated with these regions. Also in the works: A next generation version of Cassini’s Ion and Neutral Mass Spectrometer (INMS) instrument, and an ultraviolet camera to enhance the hunt for plumes.

Thus we learn, by a series of steps each leading to the next, mission building on mission to suggest the scope and shape of the mission to follow. We’re about to lose Cassini, but we lost Galileo in 2003 when it plunged into the atmosphere of Jupiter. Even so, its data continue to inform us how to interpret these new findings. Meanwhile, Hubble observations of Europa using its Space Telescope Imaging Spectrograph (STIS) continue to look for new plume activity. When Europa Clipper flies, it will be designed to answer questions earlier studies have raised.

The paper on Enceladus is Waite et al., “Cassini finds molecular hydrogen in the Enceladus plume: Evidence for hydrothermal processes,” Science Vol. 356, Issue 6334 (14 April 2017), 155-159 (abstract). The paper on Europa is Sparks et al., “Active Cryovolcanism on Europa?” Astrophysical Journal Letters Vol. 839, No. 2 (13 April 2017). Abstract available.


{ 57 comments… add one }
  • djlactin April 14, 2017, 11:27

    I am minded of Niven’s Gw’oth: https://en.wikipedia.org/wiki/Gw%27oth

  • Andrew LePage April 14, 2017, 11:29

    With even more evidence to back up the existence of Europan plumes, the prospects of a comparatively quick and inexpensive sample return mission using repeated flybys with an aerogel-based sample collector are improving:


    • Coacervate April 17, 2017, 6:07

      I am surprised that this idea didn’t receive more attention here. It seems so logical to run this low risk approach while maximizing return…if we’re looking for microbes that is.

  • john walker April 14, 2017, 11:43

    Intriguing announcements. Great work from the INMS team. And Dr. Sparks. Although I must say I found the press conference format itself more than a little irritating with its design completely devoid of quantitative data and anything above grade school level technical info. Sadly typical of an increased dumbing down at NASA events in recent years that they presumably regard as improving accessibility.

  • Harry R Ray April 14, 2017, 13:01

    Well, we now know where the Europa lander should land.

  • Andrew Palfreyman April 14, 2017, 13:44

    It takes so long and costs so much to get out to Jupiter and Saturn that one had best make the most of the visit (Cassini sure has!). Yet NASA is not talking about going straight for the prize here, which is to launch a sterilised penetrator directly through the ice.

    • Alan Mimms April 14, 2017, 16:45

      Or to launch a hundred (or more) of them, scattered around the moon, penetrating everywhere and sending telemetry and video and all other sorts of sensor data back to an orbiting relay that forwards the data at high speed back to us.

      • Robert G April 14, 2017, 17:57

        Or maybe a hundred chocolate landers and an orbiter with a good zoom lens on it. All we’d need to do is keep a good eye on the landers to detect any signs of nibble marks appearing — immediate proof of hungry Enceledans!

      • Robert G April 14, 2017, 18:12

        Happy Easter, all!

    • Andrew LePage April 14, 2017, 17:30

      > Yet NASA is not talking about going straight for the prize here, which is to launch a sterilised penetrator directly through the ice.

      That’s primarily because 1) the precursor missions needed to determine the properties of the ice layer (e.g. thickness, composition, structure, etc.) as well as the best sites to land have yet to be flown and 2) the technology to create such a device is still very much in its infancy. The proposed Europa Clipper will begin to address #1 (with more missions required depending on what it finds) while time and funding will be required to address #2. Even under the most optimistic scenarios, we are decades away from realistically mounting a penetrator mission that has any chance of succeeding.

      • Brett Bellmore April 16, 2017, 8:19

        “and 2) the technology to create such a device is still very much in its infancy.”

        Nonsense, Abner Perry cracked that problem back in the early 20th century, to say nothing of Tom Swift Jr’s later work in the field.

        Seriously, if the plumes are fed from the ocean underneath, any life in that ocean should be found in the plumes. It’s the plumes that need to be sampled, extensively, and analyzed in great detail. Burroughing down to the ocean can wait on that, and on the creation of a seismic network to map the ice; We might find an easy route that way.

        • Andrew LePage April 16, 2017, 10:49

          > Nonsense, Abner Perry cracked that problem back in the early 20th century, to say nothing of Tom Swift Jr’s later work in the field.

          ROFL!!! Yes, there are plenty of ideas out there and plenty of potential tools available to create such a penetrator. That is not the issue. But that technology is no where near mature enough to design and build an automated probe to land on the surface of another world which is bathed with high levels of radiation at temperatures hovering around 100 K then penetrate a couple of tens of kilometers of ice under vacuum conditions without any physical human assistance. Speaking as someone who has dealt with numerous review boards for government-funded space projects, *ANY* proposal to mount such a mission would fail to pass a NASA review board because the technology is too immature to ensure the success of a mission which would surely cost taxpayers tens of billions of dollars (a cost which would make such a mission unlikely to begin with).

          > It’s the plumes that need to be sampled, extensively, and analyzed in great detail.

          You are mixing apples and oranges. My comments are specifically about a building a “sterilized penetrator” *NOT* about how practical a plume sample mission would be. These are two completely different missions. In fact, others have already proposed a New Frontiers-class plume sample return mission for Enceladus and three years ago I discussed, in print, adapting this mission hardware for a Europa plume sample return mission:


          • Brett Bellmore April 16, 2017, 22:03

            I’m not actually dismissing the problems inherent in building a reliable penetrator, as the fact that I referenced *fictional* penetrators should have indicated. Just pointing out that reaching that ocean is, barring some evidence of life or interesting pre-life, a fairly low priority. First things first, the plumes have to be extensively sampled and analyzed. IF evidence of life, or complex pre-life, were found in the plumes, THEN, and only then, would it be justifiable to do the hard work of building something capable of reaching it.

            If we should find that there is no life there, perhaps we should try putting some there. But that would be even a longer term project.

          • DJ Kaplan April 17, 2017, 15:56

            Could the plume sample mission be piggy-backed with the ground survey mission that you mentioned? I’m over 50, thus the interest in piggy-backing missions… ;)

        • Alexander Tolley April 16, 2017, 11:41

          I agree that the Plumes are the first to analyze. If there are no life biosignatures in the plumes, then there is unlikely to be life in the ocean[s].

          The ice cover can be surveyed by radar and gravitometric mapping (as was done to Greenland’s glaciers) as a start. This will require an orbiter so that Enceladus will be the only target of the probe.

      • Harry R Ray April 18, 2017, 10:13

        NO NEED TO NOW! Unlike Enceladus, NO PLUME MATERIAL EVER ESCAPED EUROPA’S HIGHER GRAVITY! Everything falls back on the ground. A nuclear powered rover with a lead “turtle shell” should be able to scoop up any flash-frozen microbes(should they be there), photograph them under a microscope, analyze them for chemical content, transfer all good candidates to an Earth return capsule, blow off the “turtle shell”,and launch the return capsule to Earth. If(AND ONLY IF) this works, Europan life is confirmed on Earth(no “Calvins”, hopefully), then(AND ONLY THEN) do we send a FAR MORE ADVANCED “drill” mission with a submarine to look for COMPLEX life! In the mean time, the photograph of the “thermal anomaly” area should be split into small sections and each section MAGNIFIED and computer enhanced to bring out the ABSOLUTE MAXIMUM detail in hope of locating the vent(s)!

        • Harry R Ray April 20, 2017, 9:48

          I TAKE THAT BACK! Planetary geologists now estimate that the thermal anomaly is ONLY TWO KILOMETERS THICK, JUST LIKE THE RECENTLY DISCOVERED THERMAL ANOMALY ON ENCELADUS!!! Drilling there would be a piece of cake. A lander with onsite analysis capabilities of any water extracted would cost less and have a higher potential success rate than the surface sample return mission mentioned in my above comment.

          • Alexander Tolley April 20, 2017, 11:52

            The ice is still likely to be very hard and the radiation hasn’t gone away. More doable perhaps, but certainly not a “piece of cake” (or as Maxim Brailovsky might say, “piece of pie”).

    • Ashley Baldwin April 16, 2017, 18:05

      Good point. There is an ESA concept study of just such an impactor , AKON. Presentations and discussion on it have regularly featured at the NASA Outer Planets Assessment Group, OPAG, meetings over the last year or so but don’t in any way appear to have been picked up yet. Unlike a conventional lander , it could be launched from a flyby spacecraft and for much less cost. I understand from one of the AKON team that attempts are being made to gain ESA M class funding for potential inclusion with Clipper but haven’t come to much as yet. A high velocity penetrator must by its very nature be relatively high risk so whether the idea gains any momentum remains to be seen.

  • DJ Kaplan April 14, 2017, 14:24

    What’s the chance of a mission that drops probes onto both Enceladus and Europa? An orbiter could serve as the radio repeater for their signals and perform a sample-return fly-thru of both plumes if possible. Best bang for the buck, and if there ain’t no critters found at that point, well that would be a discovery in and of itself.

    • jonW April 14, 2017, 21:03

      Hmm, sounds like a lot of work, after settling into Europa orbit to drop a probe, to have to dig out of Jupiter’s gravity well and head on out to Saturn for Enceladus. It’s never been done and I don’t think it would be possible. A special planetary alignment of some kind would be needed (Jupiter overtakes Saturn only every 20 years or so).

      • Ashley Baldwin April 16, 2017, 19:14

        This idea was Ironically briefly explored for Cassini, with Uranus and Jupiter as potential “fly on” destinations. Theoretically possible with enough Titan et al flybys , but these would take years in their own right and the slow subsequent transfer to the new destination then decades longer. Not worth all the trouble and cost and with no guarantee of success. Better to wait for a bespoke direct ( and far more modern ) mission at a later date.( a Jupiter gravity assist mission to Uranus or Neptune launching around 2030 would take “just” 10- 12 years transfer respectively, less still using SLS ) Jupiter ‘s radiation environs around would also likely do for any spacecraft long before it could reach escape velocity anyway.

    • Ashley Baldwin April 16, 2017, 19:04

      It all comes down to delta V. And mass. To put a lander on either Europa or Enceladus requires firstly a large deceleration burn into orbit around their parent planets before either further substantial decelerations to orbit the moon . Then a further burn for landing. That’s a lot of fuel. It’s been shown for a posited 450 kg Europa lander would require a massive 16 tonnes of propellant . The biggest overall mission mass ever outside of the Apollo lunar missions, requiring even the mighty SLS to use gravitational assists to reach Jupiter.

      A fuel reducing alternative proposes multiple system moon deceleration flybys to achieve orbit around the target moon over a period of three years or so. Possible for Enceladus with Saturn’s relatively benign radiation environment , but three years of spacecraft operations time costs big money (even without any active science during that time ) . All added onto a multiple year transfer to Saturn . And unlike Europa , Enceladus will not have had detailed high res assessment of prospective landing sites first to reduce risk of catastrophic failure .That’s a lot of time and trouble for perhaps just a few months of science at best . Concepts have indeed been worked up by JPL for such missions , but they all come in at Flagship cost .

      The radiation environment around Jupiter’s Equatorial zone is hellish ( which is why JUNO avoids it ) and this is the area any flyby lander would have to operate and survive in for three years , prior to even attempting any ( still risky ) landing on Europa. Thus requiring substantial radiation shielding , more mass and thus more propellant still . Hence carrying 16 tonnes of propellant to start with is seen as much more realistic option.

  • Alexander Tolley April 14, 2017, 17:12

    “An indicator of biological origin may be the ratio of non-methane hydrocarbons to methane, which is very low (0.001) for biological sources but is higher (0.1 0.01) for nonbiological sources. Thus, Cassini’s instruments may detect plausible evidence for life by analysis of hydrocarbons in the plume during close encounters.” – source: The Possible Origin and Persistence of Life on Enceladus
    and Detection of Biomarkers in the Plume

    A nice paper: ENCELADUS LIFE FINDER: THE SEARCH FOR LIFE IN A HABITABLE M on a life detection mission to Enceladus as a follow up to Cassini.

    From the abstract of the Waite paper in Science: “The relatively high hydrogen abundance in the plume signals thermodynamic disequilibrium that favors the formation of methane from CO2 in Enceladus’ ocean.” However, their last statement in the paper: “Our analysis supports the
    feasibility ofmethanogenesis as an energy-releasing
    process that can occur over a wide range of geochemical
    conditions plausible for Enceladus’ ocean.
    This finding has implications for determining the
    habitability of Enceladus’ subsurface ocean (17), although
    the favorable thermodynamics alone are agnostic as to whether methanogenesis is actually occurring.”

    IOW, they are being very cautious whether the methane is due to geochemical or living processes.

    I would hope that we don’t need a multi-billion dollar probe to test for biosignatures in the plumes of Enceladus, but that this can be done with smaller probes at a fraction of the cost. It would be nice if we could also get those probes there more quickly than was done with Cassini and its multiple Earth-Venus gravity assists. With so much interesting exploration to be done in the outer system, it would be great if this could stimulate more aggressive development of new propulsion systems to reach those targets far more quickly so the experiments can be iterated much more quickly based on earlier findings.

    • Ashley Baldwin April 16, 2017, 18:29

      It’s likely that the former Discovery Encelaudus Life Finder ,ELF , submission will be rebadged for the New Frontiers 4 programme currently in process ahead of short listing and a 2024/ 2025 launch. It has already receive detailed feedback from the Discovery assessment process and involves a two instrument ( next generation mass spectrometers-100 times more sensitive than Cassini’s INMS ) payload on a space craft that will make up to eight science Enceladus flybys over 2.5 years as a primary mission. It was knocked back as a Discovery concept on two grounds, firstly that it wouldn’t fit within the $450 million budget and secondly that it was solar powered and the relevant array technology wasn’t deemed mature enough. It would clearly fit within the the larger NF $850 million budget envelope and the solar array technology involved has now reached NASA’s Technological Readiness Level, TRL 6 – the minimum necessary for consideration . The use of solar power at Jupiter with JUNO and Clipper obviously helps too in setting an outer solar system precedent . The ELF team includes most of the authors of the Eceladus plume paper ,most or all of whom are also heavily involved with Cassini already , so lots of experience . A factor that NF assessors prioritise along with a robust science case ( now assured ) and costing. And risks. So ELF must have a chance of atleast being shortlisted and hopefully following in the path of initially unsuccessful OSIRIS-REX in eventual selection to a programme based on lessons learned by its architects . Much less risky than any Venus lander, ( one of the major reasons that planet has been neglected in medium cost NASA programmes ). What we all need to hope meantime is that one or more of the new commercial heavy launchers gets onto NASA ‘s manifest to speed up transfer time to Saturn . Also that the solar electric power,SEP, required to Operate the NEXT ion thrusters available as “free” technology for NF4 reaches a level of maturity to further reduce transit time with additional “SEP” staging enroute . That was one of the aims of the largely terminated ARM mission concept , indeed the only bit of it to continue to receive some funding for that very purpose.

  • RobFlores April 14, 2017, 22:57

    If both of these icy moons are found to contain life,
    it should be interesting to compare their Structure/Organization.
    I wonder how likely it is that One will be the Source of the original lifeform
    and the other a recipient of an involuntary migration.

  • Michael Fidler April 14, 2017, 23:48

    NASA Approves Instruments for ESA’s ‘JUICE’ Mission:
    “JUpiter ICy Moons Explorer (JUICE).”


    The Radar for Icy Moon Exploration (RIME) experiment, an ice penetrating radar, which is a key instrument for achieving groundbreaking science on the geology, is led by the Italian Space Agency (ASI). NASA’s Jet Propulsion Laboratory (JPL), in Pasadena, California, is providing key subsystems to the instrument, which is designed to penetrate the surface of Jupiter’s icy moons to learn more about their subsurface structure. The instrument will focus on Callisto, Ganymede, and Europa, to determine the formation mechanisms and interior processes that occur to produce bodies of subsurface water. On Europa, the instrument also will search for thin areas of ice and locations with the most geological activity, such as plumes. The total cost of the NASA contribution is $30.8 million.

  • Robert Feyerharm April 16, 2017, 11:44

    I’m curious if the height of the plumes above Enceladus and Europa indicate the water is under some pressure – and if the exact pressure, and possibly depth of the subsurface oceans, can be estimated based on the height?

    Wouldn’t exposed water simply ooze out onto the surface and freeze rather than create a plume?

    • Michael April 17, 2017, 2:13

      If the water is warm it will vaporise almost instantly on reaching the vacuum of space and therefore reach high velocities.

  • ljk April 16, 2017, 18:24

    NASA Must Go Where No Man Will Ever Go: Europa

    Greg Autry, CONTRIBUTOR

    APRIL 15, 2017 @ 09:49 PM

    Visiting the Mission Control room of NASA’s Jet Propulsion Laboratory, I was shown a spot that former JPL Director Charles Elachi declared to be “The Center of the Universe.” It seemed to be a dubious assertion given the relative nature of space navigation, but that particular point in space commands a view across our solar system and beyond. Screens display astounding images and invaluable scientific information from the myriad of spacecraft, rovers and landers connected to NASA’s Deep Space Network. At my feet lay a marker inscribed, “Dare Mighty Things.” This motivational quote from Teddy Roosevelt’s is an understatement. JPL routinely achieves mighty things and it does that on a tiny budget.

    In his inaugural speech, President Trump called for “unlocking the mysteries of space” and his 2018 budget proposal reflects that commitment. While other departments received steep cuts, NASA’s budget remained at about $19 billion. To be clear, that’s less than one half of one percent of federal spending and JPL garners less than a tenth of that sliver but it is enough to begin an ambitious search for life in the ice-covered ocean of Europa. Europa Clipper will launch in 2022 on a mission to survey Jupiter’s sixth moon. However, a follow-on lander mission was conspicuously missing from the budget and media reports suggested that it had been cancelled.

    Not to worry, the Europa Lander is a personal favorite of John Culberson, Chairman of the Commerce, Justice, and Science (CJS) Appropriations subcommittee which oversees NASA’s funding. This conservative Texas Republican has a sincere passion for space science. I have found him to be deeply informed on the science, engineering requirements and cost constraints of space exploration. Scientists, engineers and directors at JPL hold him in the highest regard and jokingly refer to him as “Europa Mission Director.” Culberson’s connection to Southern California’s robot builders is also remarkably free of political self-interest. This Congressman doesn’t view space exploration as a pork barrel jobs program. His district borders Houston, home to the Johnson Human Spaceflight Center, 1,500 miles from JPL. Culberson really wants NASA to deliver answers to fundamental questions about our place in the universe.

    The existence of alien life is the biggest of those questions and the Chairman is fond of saying “I’ve made sure that the Europa Mission is one thing that NASA is required to do.”

    Full article here:


  • ljk April 16, 2017, 19:14

    “Ocean Worlds” discoveries build case for new missions

    by Jeff Foust

    April 14, 2017

    WASHINGTON — Discoveries involving two “ocean world” moons in the outer solar system announced April 13 are likely to bolster the case for planned and proposed spacecraft missions to those worlds.

    At a press conference, NASA announced that its Cassini spacecraft, orbiting Saturn, had detected hydrogen gas in previously-discovered plumes emanating from the surface of the icy moon Enceladus. Scientists suspect that the moon has an ocean of liquid water beneath the surface that provides the source material for the plumes.

    The hydrogen, scientists said at a briefing, is likely produced by hydrothermal activity, and could serve as an energy source for any life there. “Although we can’t detect life, we’ve found that there’s a food source there for it. It would be like a candy store for microbes,” said Hunter Waite, team lead for Cassini’s ion and neutral mass spectrometer, in a statement about the discovery.

    Full article here:


    To quote:

    Some scientists have questioned whether Enceladus, with its constant plumes containing chemical energy that could support life, may be a better initial target than Europa. Voytek noted that the presence of hydrogen in the plume indicates that it is not being consumed by any life that might exist in the oceans in Enceladus. “It means that there might not be life there at all, and if there is life, it’s not very active,” she said.

    She speculated that could be linked to the age of Enceladus, which may be much younger Saturn itself. Europa, by contrast, was formed at the same time as Jupiter, more than four billion years ago. “That’s a lot more time for life to have emerged and start taking advantage of these energy sources,” she said. “So my money, for the moment, is still on Europa.”

    • Ashley Baldwin April 17, 2017, 12:42

      This is based on a relatively recent paper that suggests that Saturn’s rings , along with all its moons interior to Titan , may have only been formed in the last 65 million years. It would explain the enigma of Enceladus’ seemingly high internal heat . Habitable potential , but not for long enough to be inhabited . Hence the high molecular hydrogen in the plumes , unconsumed by any ocean floor biosphere. Still worth investigating though as this is only one as yet unsubstantiated theory.

  • ljk April 16, 2017, 23:21

    From the invaluable space blog Future Planetary Exploration…

    Sunday, January 29, 2017

    Explorer of Enceladus and Titan


    Monday, August 22, 2016

    Selecting the Next New Frontiers Mission


    Friday, April 8, 2016

    Defining the Missions for the Ocean Worlds


  • Nick April 17, 2017, 0:46

    With the ocean being ~65 kilometers deep, could the extreme pressures at the ocean floor pose a challenge to the development of life?

    • Michael April 17, 2017, 9:58

      Due to the low mass of these moons such as Europa the actual pressure is relatively low, around 7 to 9 km’s of Earth water pressure at the 65 km suggested. Life has been found to survive these high pressures on Earth and so potentially there as well.

      • Ashley Baldwin April 17, 2017, 12:47

        That’s still a lot of pressure though. What would happen to any life form modified for such conditions on experiencing the rapid decompression of being released into a hard vacuum via a plume? Even before being captured by a spacecraft travelling at Km/s.

        • Alexander Tolley April 17, 2017, 17:24

          It becomes a race between absorbed gases expanding and the liquids freezing. On Earth, fish with swim bladders inflate badly when quickly hauled up from the depths, but simpler animals can survive the transition.

          Emerging into vacuum, any dissolved gases will start escaping, even at the low temperatures as they are ejected. But the water in the organism will quickly freeze, preserving it as a fairly intact specimen.

          [Historically bacteria have been found in teh stratosphere, and recently we found bacteria living on the outside of the ISS, so they can obviously survive in space.]

          My guess is that if life exists in Enceladus, we could find fairly intact prokaryotes and even intact, but dead, multi-celled eukaryotes. [Dyson used to talk about finding dead fish].

          The problem would be that even prokaryotes might not survive the ejection, and even if they did, we probably couldn’t culture them successfully. Even supposing we could capture a plume sample in an aerogel trap, any organisms would probably be mixed in a far greater amount of inorganic debris. (That would be useful for geologists.) So even locating a cell or organism might be very hard without being able to bring the sample back to Earth for study.

          Therefore the easiest thing is just assume that if organisms exist in Enceladus, that organic remains typical of life on Earth can be extracted and analyzed and hope for an unambiguous result.

          • Michael Fidler April 18, 2017, 9:06

            Of course, that’s where those raining fish and frogs came from, that Charles Fort documented so well! (“The Book of the Damned”). Seriously, Panspermia may have brought life from Venus to Earth when Venus was a water world. These plumes would be perfect to launch those little monsters – Tardigrade! These little Water Bears could be launch out of the oceans and over time evolve to be recycled thru the crust of Enceladus. As for handling the vacuum just breath out and empty your lungs as you enter the lower pressure. (Scuba Diving 101)!

            • Alex Tolley April 18, 2017, 14:11

              You well know that decompression from deep diving takes hours, otherwise you get the bends. Interestingly that happened to workers building the tunnels under the Hudson River for the Penn State Railroad in the 19th century (the tunnels were under pressure with airlocks to allow workers and equipment to enter and exit the tunnels under construction.)
              Exposure to vacuum is even worse. While our skins can temprarily hold pressure, eventually the blood both boilsand then freezes. Clarke’s point on this was famously shown in 2001: A Space Odyssey. He hated the instant exploding bodies depicted in SciFi movies. “The Expanse” shows the effect accurately too. But you do have to breathe out fast.

              Tardigrades have survived vacuum, but the experiment exposed pre-dehydrated tardigrades to vacuum, not active, hydrated ones. So we don’t quite have the sudden exposure to vacuum experiment we want. Would Enceladan sub-surface ocean organisms even evolve to handle dessication?

              • Robert G April 20, 2017, 18:59

                If a prokaryote bug (or a tardigrade, for that matter) was adapted for life on the sea floor around a mineral smoker, and then somehow got caught up in a thermal plume and pulled away toward the surface, might it not have time to do its cryptobiosis trehalose glassing-in trick and form a spore or ‘tun’ or whatever? If so, perhaps we might find such?

                I’m sure we could easily do some experiments on earth to see how our own known microorganisms handle it, and what their limits are.

                • Robert G April 20, 2017, 19:06

                  To clarify, there are several things that can trigger these states in earth organisms, and a serious departure from comfortable living conditions might be expected to do so for black smoker environment adapted life.

                  • Michael Fidler April 22, 2017, 11:15

                    The World’s Strangest Mammal Can Survive 18 Minutes Without Oxygen!
                    “There’s a lot of research and development that evolution has done”

                    So this is something that evolution developed to deal with major problems, but what about uses for this on long interstellar voyages. I keep thinking about the guru’s that were able to control there metabolism under scientific scrutiny. We keep looking from our viewpoint, but just imagine what all the bugs, bacteria and the trillion other living organisms can do if faced with major problems. Just think of the billions of bacteria in your gut producing all that gas, I bet handling the vacuum would be much easier!

    • Harold Shaw April 17, 2017, 11:46

      With the difference in mass, what depth on Earth would give the equivalent pressure of 65 km on Enceladus?

    • ljk April 17, 2017, 12:50

      The deepest region among Earth’s ocean floors is the Mariana Trench in the Pacific Ocean. You could drop Mount Everest into it and the whole mountain would sink out of sight with roughly two miles of ocean water sitting above its peak.

      As you can imagine, the water pressures at the bottom of the Mariana Trench are virtually unimaginable to us land lubbing dwellers. When the first manned submersible visited that place in 1960, named the Trieste, the tiny portholes they had to observe out from had two panes of glass each six inches thick. The outer pane cracked during the journey.

      Yet there is life in that place:


      Here is some very recent news on the subject of life way down there:


      Does this all mean that there IS life on Enceladus, Europa, and other such alien worlds? No, but it certain shows scientifically that such creatures could live in conditions that were considered not so long ago to be far too harsh for terrestrial type life.

      Here is a nice introductory site on the overall subject of deep sea marine life:


      In this site I found this interesting text on the discovery of the first hydrothermal vents which happened just 40 years ago! It is a good lesson in why any scientific expedition, be it in the deep ocean or in deep space, needs to have a crew and instruments with a diverse knowledge and background experience:

      Hydrothermal Vents

      “These amazing formations were first discovered in 1976 – 77 during a deep sea expedition with Alvin at a mid-ocean ridge near the Galapagos. At that time, only geologists were aboard, with the goal of directly observing seafloor spreading — the mid-ocean ridges being places where magma welling up underneath pushes two tectonic plates apart, creating a rift valley between them. Some geologists thought there might be geyser-like hot springs, as found in rift valleys on land (such as in Iceland), while others thought that high pressure would prevent such formations. However no one predicted any interesting biology. What they found not only revolutionized geology but biology even more so. These dives to depths of about 2,700 m revealed hot springs of far greater complexity and beauty than anyone had imagined: hot mineral-rich water spewing (like continuous geysers) from vents heated by magma, with metal sulfides precipitating in the cold surrounding seawater to form intricate, colorful and often towering chimneys.”

      This site gives a taste of how even a place like the very deep ocean, with no sunlight, incredible pressures, and very cold water, can create not an organic desert but life forms with an amazing range of sizes, shapes, and – most importantly – numerous ways to survive and reproduce:


      Now imagine what might exist in a truly alien ocean and we already know of several in our own solar system – and there are 400 billion solar systems in our galaxy alone.

  • Alexander McLin April 17, 2017, 10:58

    Since Enceladus is currently thought to be only about 100 million years old, if there is any life there, it would be at a much earlier phase of evolution or possibly even still working its way along the transition path from non-living matter to complex organized reproducing matter undergoing Darwinism selection.

    With that in mind, Enceladus may be a more attractive near-term target than Europa. That impression is furthermore enhanced when after researching references I see that radiation environment around Enceladus is less severe than Europa which should translate into much longer staying time at Enceladus.

  • Harry R Ray April 18, 2017, 10:19

    Paul Gilster: Is that crater directly below the “thermal anomaly” Pwill Crater. If it is, then the Conomora Chaos region with all of the icebergs is very nearby. RSVP.

    • Paul Gilster April 18, 2017, 12:12

      Not sure, Harry, but it would be interesting indeed if the Conamara Chaos region was that close!

    • Ashley Baldwin April 18, 2017, 13:30

      Good spot. And potentially relevant too. Looking at the Wikepedia Galileo maps the thermal anomaly is indeed located directly between and close to both Pwyll crater and the Conomarra chaos zone (which is just underneath the “X” created by the two liniae at the top of the image. )

      • Harry R Ray April 18, 2017, 17:42

        THOUGHT SO!!! THIS EXPLAINS EVERYTHING!!! The impactor that caused Pwill Crater must have BROKEN THROUGH THE 15 KM ice crust, the shock wave COLLAPSED the area of ice that became Conamora Chaos, AND, cracked the ice in the THERMAL ANOMALY region sufficiently to allow a vent to form! This explains why there are so FEW vents on Europa.

  • ljk April 25, 2017, 12:54

    ASTROPHILE 24 April 2017

    Icy Enceladus’s tiger stripes are a window on its watery depths

    Astrophile is Joshua Sokol’s monthly column on curious cosmic objects, from the solar system to the far reaches of the multiverse:


    To quote:

    Some mysteries still linger, though. For example, the water vapour that comes out of the fractures should turn solid when it hits the atmosphere, freezing the fractures shut in just a few years – yet they seem to have been active for at least half a century, and probably many millennia.

    The plumes on Enceladus are waning too, at least in the short term. For reasons that are unclear, they are half as active now as when Cassini arrived.

  • ljk April 29, 2017, 19:09
  • ljk May 10, 2017, 9:14

    May 9, 2017

    An ASU-designed ‘planetary stethoscope’ could help us find out what lies in Europa’s global ocean

    Jupiter’s moon Europa is definitely an odd place. Discovered in 1610 by Galileo Galilei, it was first seen in detail only in the late 1970s, after spacecraft visited the jovian system.

    Slightly smaller than our own moon, Europa could hardly appear more different. Both have interiors of rock and metal. But Europa is wrapped in a global saltwater ocean and covered by a bright shell of ice. The shell is scarred with cracks and faults and mottled places where the ice has been breached by liquid from below.

    Scientists have speculated for decades what lies within that ocean. It is larger in volume than all the oceans of Earth put together.

    A NASA-funded seismometer under development at Arizona State University holds the promise of landing on Europa’s ice shell — and listening to it.

    The seismometer would use Europa’s natural tides and other movements to discover the shell’s thickness, see whether it holds pockets of water — subsurface lakes — within the ice, and determine how easily, and how often, ocean water could rise and spill out on the surface.

    “We want to hear what Europa has to tell us,” said Hongyu Yu, of ASU’s School of Earth and Space Exploration. “And that means putting a sensitive ‘ear’ on Europa’s surface.”

    Full article here:


    To quote:

    Most seismometers, whether for use on Earth or other planets, rely on a mass-and-spring sensor concept to detect passing earthquake waves. But that type of seismometer, says Yu, has to be set down in an upright position, it must be put in place carefully with no major jolts or shaking, and the chamber where the sensor operates needs a complete vacuum to ensure accurate measurements.

    “Our design avoids all these problems,” Yu explains. The SESE seismometer uses a micro-electromechanical system with a liquid electrolyte as the sensor. “This design has a high sensitivity to a wide range of vibrations, and it can operate at any angle to the surface.

    “And if necessary,” he adds, “they can hit the ground hard on landing.” Yu notes that the team tested the prototype by hitting it with a sledgehammer. It survived.


    The team developing the SESE seismometer has its sights on Europa, but they are also looking beyond, because the design is robust and adaptable. This could let it become something of a universal instrument for seismology on other worlds.

    As team leader Yu explains, “With modification to fit local environments, this instrument should work on Venus and Mars, and likely other planets and moons, too.”

  • ljk May 10, 2017, 9:20

    I am very cautiously optimistic, because the political winds can change in an instant, especially these days.


  • ljk June 28, 2017, 9:02

    UTSA student finds new source of hydrogen in solar system’s moons, which could support alien life

    By Jesse Pound, Staff Writer

    Updated 2:44 pm, Tuesday, June 27, 2017

    A graduate student at the University of Texas at San Antonio has found that hydrogen can be produced between reactions between radioactive rock and water on spatial bodies within our solar system, potentially providing support for alien life.

    Physics doctoral student Alexis Bouquet, working at Southwest Research Institute as part of a joint program between the organization and the university, was part of a team that discovered that the crust of chondrites, such as moons and asteroids, contained radioactive material necessary to create hydrogen through a process called radiolysis, which is already a known reaction on Earth.

    “One of the best ways to advance planetary science in general is to take what has already been done here on Earth and apply it to bodies of the solar system,” said Bouquet, who was the lead author of the study.

    Full article here:


  • ljk August 24, 2017, 20:39

    Aug. 24, 2017

    NASA’s Webb Telescope Will Study Our Solar System’s “Ocean Worlds”

    NASA’s James Webb Space Telescope will use its infrared capabilities to study the “ocean worlds” of Jupiter’s moon Europa and Saturn’s moon Enceladus, adding to observations previously made by NASA’s Galileo and Cassini orbiters. The Webb telescope’s observations could also help guide future missions to the icy moons.


    To quote:

    For Enceladus, Villanueva explained that because that moon is nearly 10 times smaller than Europa as seen from the Webb telescope, high-resolution imagery of its surface will not be possible. However, the telescope can still analyze the molecular composition of Enceladus’ plumes and perform a broad analysis of its surface features. Much of the moon’s terrain has already been mapped by NASA’s Cassini orbiter, which has spent about 13 years studying Saturn and its satellites.

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