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Astrobiology

Hydrothermal Activity in The Seas of Enceladus

By Keith Cowing
NASA Watch
April 13, 2017
Filed under , ,
Hydrothermal Activity in The Seas of Enceladus

Hydrothermal Activity in The Seas of Enceladus: Implications For Habitable Zones, Astrobiology.com
First posted on 11 April 2017 at 7:16 pm EDT. “On Thursday NASA will announce evidence that hydrothermal activity on the floor of an ice-covered ocean on Saturn’s moon Enceladus is most likely creating methane from carbon dioxide. The process is indicative of possible habitable zones within the ocean of Enceladus. But before we go any further, “habitable” does not mean “inhabited”. NASA bases this determination on the amount of hydrogen in plumes emanating from the moon’s south pole. The large amount of hydrogen is strongly suggestive of a constant hydrothermal process wherein the ocean under the surface of Enceladus is interacting with rock and organic compounds. The amount of hydrogen present is in disequilibrium i.e. if there was not a process that was constantly generating hydrogen the observed hydrogen levels would likely be lower than what is seen. Something is pumping it out.”
NASA News Conference on Oceans Beyond Earth, NASA
“NASA will discuss new results about ocean worlds in our solar system from the agency’s Cassini spacecraft and the Hubble Space Telescope during a news briefing 11 a.m. PDT (2 p.m. EDT, 18:00 UTC) on Thursday, April 13. These new discoveries will help inform future ocean world exploration — including NASA’s upcoming Europa Clipper mission planned for launch in the 2020s — and the broader search for life beyond Earth.”

NASA Watch founder, Explorers Club Fellow, ex-NASA, Away Teams, Journalist, Space & Astrobiology, Lapsed climber.

81 responses to “Hydrothermal Activity in The Seas of Enceladus”

  1. MarcNBarrett says:
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    In my mind, Enceladus has replaced Europa as the ideal place to go to find life outside of Earth. All the same conditions exist to make life possible (perhaps even likely), with lower gravity and maybe a thinner ice shell. It is also looking like plumes exist so that a probe might only have to fly through the plumes and take samples and possibly even find microscopic life blasted completely off the moon by way of the plumes.

    • TheBrett says:
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      Same here. An orbiter or flyby mission with the right equipment could probably find proof of methanogens and other biological activity in the plumes, whereas that’s not an option with Europa – finding evidence of life on Europa would almost certainly entail drilling into the ice and hoping remnant biological material got preserved deep enough so that Jupiter’s radiation didn’t destroy it.

      • fcrary says:
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        The Europa Lander study assumed they could find a thin spot in the ice, or at least a spot where subsurface liquids had recently reached the surface. They were talking about landing there and digging down as little as 10 cm (assuming that was deep enough to protect biotic material from the radiation.) That might be considered optimistic.

        Flying through a plume would be easier, but there is no assurance the plume source is in contact with the ocean. Some models of the plumes invoke a near-surface pocket of melted water. In the case of Europa, the neutral and dust (ice, really) composition almost require some communication between the plume source and an ocean. For the Europa plume, if it really exists, that’s not known.

        • TheBrett says:
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          I’ve often wondered if a nuclear aquatic lander could literally melt its way through the ice. The reactor itself would produce waste heat that would radiate outwards, maybe creating a pocket of meltwater surrounding the probe with it freezing above the descending craft while it melts the ice below it.

          If it only required drilling down 10 centimeters, that would be fantastic. I figured it would be several meters.

          • fcrary says:
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            I’m sure you could find a way to use nuclear power to melt through the ice. I do know of a study which found a RTG sitting on the surface would not. But that’s not engineered to direct all the heat in one direction (down) and a reactor rather than a RTG would produce more heat. The real question is, “What then?” You’ve gotten your probe into the ocean. The path back up to the surface will have refrozen shut. How do you get back up or send information back to the surface?

            As for the 10 cm number, that’s what the SDT report assumed. Well, they had a post-doc who knows quite a bit about energetic particles and their penetration into mater calculate it. But it depends on a whole lot of things. Meteorites mix, or “garden” the near-surface regolith. The timescale for this is poorly known. The time since subsurface material reached the near surface is an issue, and more-or-less anyone’s guess. Personally, I wouldn’t bet on 10 cm being deep enough.

          • Paul451 says:
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            The real question is, “What then?” You’ve gotten your probe into the ocean. The path back up to the surface will have refrozen shut. How do you […] send information back to the surface?

            As I recall the various proposals over the years, you unspool a cable connected to the lander as the penetrator sinks.

            However, ice is largely transparent to microwaves, “surfacing” to the bottom of the ice should be sufficient to reach an orbiter-relay. Particularly if you have a nuclear reactor for power.

          • fcrary says:
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            Those are possibilities, but we’re talking about kilometers, possibly dozens of kilometers, of ice. A cable isn’t a bad idea (you’ll need the spool on the decent probe, not on the surface, so you don’t have to pull or drag it along.) But even a thin wire adds up to about 10 kg/km, possibly more if you want to make sturdy enough not to risk breaking. Microwave is an interesting idea, but the key word is “largely” transparent. The opposite problem (surface penetrating radar) has been studied in some detail, and it doesn’t look like you can confidently plan on transmitting all the way through the ice layer. The problem is less ice itself as the possible impurities in the ice and the likely cracks, voids and irregularities. By the way, the transmitter needs to be at the ice/water interface. Otherwise you’re sending through salt water before you get to the ice.

          • Paul451 says:
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            you’ll need the spool on the decent probe, not on the surface, so you don’t have to pull or drag it along.

            T’was what I meant.

            By the way, the transmitter needs to be at the ice/water interface.

            T’was what I said.

            The opposite problem (surface penetrating radar) has been studied in some detail, and it doesn’t look like you can confidently plan on transmitting all the way through the ice layer.

            Imaging is a different requirement from communication. Submarines use ELF for low-bandwidth comms, but you wouldn’t try to image with it.

            (Unless you were just quibbling over “microwave”. In which case, I just meant RF as opposed to a cable. I’m not trying to specify an optimum frequency.)

          • Michael Spencer says:
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            How does one keep the ice from freezing around this kilometers-long cable? Would heaters be another justification for some sort of a nuke?

          • fcrary says:
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            I’d actually want to passage to freeze around the cable. With the spool on the descent probe rather than the surface element, all I want is for nothing to disturb the cable laid above the decent probe. Having the passage freeze would, in effect, cement it in place.

          • Daniel Woodard says:
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            Sounds like this could be simulated at the South Pole base; perhaps using an electrical heater instead of nuclear power.

          • fcrary says:
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            I’d say Antarctica, not the South Pole. There isn’t any liquid water below the Amundson-Scott station. Vostok would be a better choice for a test. There are some issues about biological contamination of subglacial lakes, but I agree that there are places where we could do terrestrial tests of the hardware.

          • TheBrett says:
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            I’m leaning towards transmitting microwaves through the ice, presumably to a surface lander partially buried above the ice crust before being relayed to the orbiter. A multi-kilometer cable sturdy enough to hold together through the descent and re-freezing of the ice might add a significant amount of mass to the lander (although if it’s carrying a nuclear reactor it’s going to be a heavy-lander regardless).

            It would be nice if we could communicate directly with the descending craft while it’s on the ocean floor, too, not just when it rises back up to the ice crust. I don’t know how we’d do that. Maybe it just wouldn’t be necessary, since we could sample the sea water directly for signs of life.

          • fcrary says:
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            Leave a relay at the icy-water interface and use sound for the probe-relay link. It depends on the transmitted power, but active sonar can be easily detected at a few dozen kilometers. Also, if you want to broadcast radio signals through the ice layer, I’d go for very low frequencies. Maybe in the few hundred kHz range (AM radio bands.) That should propagate better through many kilometers of ice. All that should give a low but reliable data rate. Dealing with limited data rates is a familiar and solvable problem for planetary scientists.

    • Salvador Nogueira says:
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      The problem is, Enceladus maybe very young. Some people argue Saturn’s rings are fairly recent (circa 100 million years ago) and some people argue the inner moons and the rings are the same age and are the result of the collapse of an earlier system of moons. If so, that may suggest Enceladus is too young for life. Cassini’s Grand Finale should put constraints on the age of the ring system though. If it turns out they, and Enceladus, are as old as Saturn, then I’ll agree Enceladus would be the most exciting place to look for life in our Solar System.

      • fcrary says:
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        On the other hand, we don’t know exactly how long it took life to appear on Earth. Within a few hundred million years of the Earth becoming habitable is consistent with current data and theories. So, if the young moons theory for Saturn is true, the presence or absence of life could be quite important. (Or, more likely, how far pre-biotic chemistry had advanced in so short a time.)

  2. ThomasLMatula says:
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    Sounds like time to switch the search for life from Mars and Europa to Enceladus. And this of course will require the SLS 🙂

    • fcrary says:
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      Maybe not. Life detection on Europa or Mars requires a lander, probably a lander at exactly the right spot. In the case of Enceladus, the subsurface water is flowing out of the South Pole. There have been proposals for Enceladus life detection missions, just by flying the spacecraft through the plume. And those were Discovery proposals and definitely did not need a SLS launch.

      • anirprof says:
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        Not commenting on any specific proposal, but my (layperson) sense is to be skeptical of Discovery-class missions to outer planets. There is so much overhead in launch weight/cost that you’ve got a pretty small science payload budget left after that. And the cycle time is very long to follow up on missions with the next ones that build on their discoveries (and mistakes, or that re-do outright failures). Good case for spending the big bucks to do such missions right, even if it means waiting several more years for funding to materialize.

        • fcrary says:
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          I’ve been pushing a concept for a Jupiter Discovery mission, so I’m afraid I disagree with you. Of course, a Saturn mission would be more difficult, but there are a great many things you can accomplish by getting a few, good instruments to the right place. As an example of a past Discovery mission, Genesis was a solar wind sample return, whose sole goal was to allow very, very accurate lab measurements of isotope rations in the Sun’s atmosphere.

          In any case, I don’t know of any Discovery missions which built on the results of previous ones, so I think that’s not an obstacle. And, for flagship missions, it isn’t a matter of waiting several more years. It’s waiting several more decades. Galileo and Cassini were about a decade apart, Cassini and Europa Clipper almost two decades apart, and people advocating Uranus or Neptune orbiters, or a Europa lander, are already in line ahead of a Enceladus flagship mission.

          • Michael Spencer says:
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            One doesn’t hear much about Uranus or Neptune orbiters other than some noise made in 2015.

            A question I’ve wondered about: given that the Hohmann orbit to Neptune is in the range of 40 years (or so I read on the inter webs), some sort of much higher energy transport combined with active braking appears to be needed.

            Do we know enough about Neptune’s atmosphere for any sort of atmospheric braking?

          • fcrary says:
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            Actually, there is a study Uranus/Neptune missions in the works. A summary was presented at the last OPAG meeting, http://www.lpi.usra.edu/opa
            You are entirely correct about the problem with the cruse phase. If it’s short (the current study was thinking of under 12 years), then you approach Uranus or Neptune at a high speed and it’s hard to stop. The study found that you could do it, and with only current launch vehicles and chemical propulsion. But that does limit the mission to a relatively limited payload.

            Aerocapture would certainly help. It adds some problems of its own, but probably solvable ones. (E.g. thermal control. A RTG is designed to radiate waste heat into space, but aerocapture implies keeping the spacecraft buttoned up inside a aerodynamic shell all the way to Uranus or Neptune.)

            But the real problem is that it would be a critical event of a completely new and untested technology. Since you’d have to get below escape velocity in one pass through the atmosphere, the vehicle would need very good, autonomous control of its path. If the atmosphere were less dense than expected (at that exact spot and time) it would have to maneuver deeper into the atmosphere. If the atmosphere were denser than expected, it would have to pull up before anything catastrophic happened. I think that would really scare some project managers, even for a well-understood atmosphere like Mars or Titan (or even the Earth…)

            This is something which we could practice. The same issues apply to going from a trans-lunar trajectory to low Earth orbit in a single pass. Or from going from orbit around Saturn to orbit around Titan, in a single pass through Titan’s atmosphere. But in both those cases, if you don’t slow down enough, you’re still in orbit around the Earth or Saturn, and you can try again.

    • Gerald Cecil says:
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      Should be in range of FH+departure stage with only a Jupiter slingshot to Saturn. No doubt Bob Farquhar could have designed a series of Titan aerobrake skims to tweak a probe into multiple passes through the plumes. NASA New Frontiers proposals are due April 28 w/ selections in November, and Titan/Enceladus is one solicited theme. Fingers crossed.

      • Bob Mahoney says:
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        Sure wish the Aeroassist Flight Experiment hadn’t been sucked away by ISS financial mismanagement back in the 90s…

      • fcrary says:
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        Yes and no. In a sense, you are describing Cassini. Launch on the heaviest lift launch vehicle available (a Titan IV for Cassini) a Jupiter flyby, and using Titan to make multiple Enceladus encounters (over 20 for Cassini.)

        But some of the details are off. A Jupiter flyby isn’t an option at the moment, and won’t be for another decade or two. The Jupiter-Sun-Saturn angle is not favorable for a Jupiter flyby. Aerobraking at Titan isn’t necessary. Cassini just used gravity assists from flybys. Of course, you would want different instruments from Cassini, and might want more plume-crossing Enceladus encounters. But a large number would have to be over the less interesting northern hemisphere. Otherwise the gravity assists from Enceladus would pump up the spacecraft’s inclination, and the best plume-sampling encounter geometry requires low inclination orbits around Saturn.

        • Gerald Cecil says:
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          Thanks for reality check that Jupiter is a tricky gateway to the beyond! So, if one were constrained to FH direct (not SLS fantasies), what might be a plausible Enceladus architecture?

          Or is Titan direct entry the only option for the New Frontiers theme, e.g. a Pioneer Venus-like bus dispensing multiple probes w/ parachute descent to various interesting spots including a paddle-boat for lakes/sea?

          • fcrary says:
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            Well, patients would help. The Jupiter-Saturn geometry varies with a 20 year period (19.85, if you care) and it’s a fairly broad opportunity. The details of the Jupiter flyby give you five or ten years of flexibility. So the 2020s aren’t a good decade to get to Saturn with a Jupiter flyby. But the 2030s will be.

            Other than that, you can do multiple Earth and Venus flybys. That quite isn’t as good as a Jupiter flyby and takes longer. But there have been Enceladus Discovery proposals (unselected) which took this approach. It limited them to a very focused, two-instrument payload.

            As for a Falcon Heavy, it isn’t clear what you could do with that. Certainly, you could get a more capable payload to Saturn than those Discovery proposals considered. But the Falcon Heavy doesn’t have a high-energy upper stage (or any upper stage, for that mater.) The details would depend on whether or not one was added, if so, what sort, or if you built in more propulsive capability into the spacecraft rather than the launch vehicle.

            Once you get a spacecraft to Saturn approach, the rest is pretty easy. The Saturn orbital insertion maneuver isn’t too large (500-1000 m/s) and repeated Titan flybys can get a spacecraft to the right orbit for Enceladus encounters. Cassini has averaged 600 m/s of free delta-v from every Titan encounter, and the total for the mission will be about 90 km/s.

          • Daniel Woodard says:
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            Very informative.

            There is some interest in low-thrust trajectories to Saturn but most include the Jupiter gravity assist. i.e. http://ccar.colorado.edu/as… and it would be interesting to see what benefit electric propulsion might provide without Jupiter. Of course that would still require a power source. I found this concept from Los Alamos pretty interesting: https://yellowdragonblogdot… Surely there must be a path to space nuclear power at a reasonable cost!

            If nuclear is off the table and the classic Homann trajectory is to be used, I agree the spacecraft needs an Earth departure stage, but with the performance of the Falcon variants continuing to evolve and the New Glenn coming on line in a few years, and at least the potential for a fuel depot in LEO (a simple concept that could have been implemented long ago), a variety of launch vehicle strategies are available. One can only hope politics won’t tie it to any particular launcher.

          • Michael Spencer says:
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            “a simple concept that could have been implemented long ago”

            I’ve wondered about that. If it’s so simple, why hasn’t it been done? I know about Soviet efforts, but by and large and from the POV of a layman the benefits seems so obvious.

            This is where the engineers jump in an explain things, I think.

          • fcrary says:
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            I don’t see any real, engineering issues for either a fuel tanker or a fuel depot. For a stand-along mission, however, it just doesn’t fit into the way NASA traditionally does planetary missions.

            A tanker would involve multiple launches and on orbit operations. If the tanker and the experience with on orbit operations were already available, they’d probably use it. But no single mission would want to absorb all that development and risk. The tendency is toward using a larger launch vehicle or developing a more mass-efficient spacecraft.

            I guess a depot has the same problem. No one is going to develop it on their own, without specific missions to support in the pipeline, and NASA is unlikely to seriously consider a mission which depend on non-existent infrastructure being developed.

          • Daniel Woodard says:
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            As I was trying to imply, wouldn’t a propulsion module for the ISS serve as a reasonable prototype, a useful standalone mission that would also test the hardware for automated docking and propellant transfer?

            Regarding the Falcon Heavy, there has been some DOD interest in a LOX-methane upper stage. Would this provide the needed impuls or is LH2 essential?

          • fcrary says:
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            I don’t see why a ISS propulsion module couldn’t be used to test most of this technology. But ISS seems to be getting by with its current capabilities, and you’d have some management issues. If the requirements are ISS-centric, the optimal design might not develop and test what you want.

            For the Falcon Heavy and planetary missions, oxygen-methane should do. Most of the advantage comes from adding propellent mass, beyond the current configuration, and _not_ dragging the empty second stage all the way up to injection onto a planetary transfer orbit.

          • Michael Spencer says:
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            There was a similar argument involving TDRSS, especially the satellite portion, as I recall. TDRSS has become essential.

          • fcrary says:
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            I think TDRSS was justified as necessary for safe operation of the Space Shuttle. In commercial terms, they found an anchor tenant.

          • Zed_WEASEL says:
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            Of course the Falcon Heavy got an upper stage. It is the same upper stage as the Falcon 9. Which is about 115 metric tons in mass with about 110 metric tons of propellants propelled by a Merlin Vacuum engine rated at 934 kN thrust with a specific impulse of about 348 sec and a burn time of 397 sec. The current SpaceX upper stage is roughly the equivalent of the much lighter Atlas V & Delta IV upper stages with HydroLox propellants.

          • fcrary says:
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            Well, technically, any multi-stage rocket has one stage higher up the stack than the others. So I guess every rocket has an upper stage. My point was that, to get to Jupiter or Saturn, you don’t need 64 tonnes on a low Earth orbit, or 27 tonnes on a geostationary transfer orbit. But those are the destinations the Falcon Heavy is designed for. It can (or will be able to) launch a planetary mission, but it isn’t all that efficient. Adding an additional stage (what I meant by an upper stage) would really improve the mass it could send to Jupiter or Saturn.

          • Michael Spencer says:
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            “the rest is pretty easy” !!

            We’ve learned an awful lot from Cassini.

          • fcrary says:
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            We did, and also from Galileo. But I shouldn’t have said “easy.” That’s unfair to all the work the Cassini NAV team has done. I should have said that, once in orbit around Saturn, an orbital tour with multiple Enceladus encounters is something we know is possible and know how to do.

          • Michael Spencer says:
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            I read the weekly Cassini email (and anyone else interested should as well). Lots of it is beyond my education, but not my interest; the results of the mission speak for themselves.

    • mfwright says:
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      I’m all for more non-Mars missions, rovers are interesting but drilling to Europa and Enceladus is really interesting (and really hard and I like to imagine getting pictures or video of the little fishes). There is the mention “when looking for life, go where the water is.” What about all that water on the Moon? Don’t need SLS for lunar missions.

    • Zed_WEASEL says:
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      No, the SLS is not required for sending large & heavy payloads to Jupiter and Saturn.

      A large outer Solar system orbiter mission could be assembled and top up with propellants in LEO with current and soon to be available US launch vehicles.

      • fcrary says:
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        It will be interesting to see which comes first, SLS or the orbital shipyard you suggest. I’m fairly sure which would cost less, but not the schedule. The capability to launch those orbital facilities, or at least a fuel tanker, will be available in a year or so (call it after the first, non-test launch of a Falcon Heavy.) But going from the capability to the actual existence of that infrastructure is a different matter.

        • Daniel Woodard says:
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          Particularly if it does not serve the purposes of the powerful by undermining the rationale for an existing program. Still, if Musk or Bezos can finance even a modest demonstration of fuel storage and transfer it could tip the balance, not to mention being of considerable use aboard the ISS. I would not limit it to hypergols. With reasonable insulation and refrigeration methane and LOX could be stored from the arrival of a tanker to the refueling and departure of the probe on its departure stage.

          I can’t forget the viewgraphs presented by Clark Covington at JSC on the Space Operations Center. Before Shuttle ever flew, before Powerpoint existed, the fueling and checkout of planetary probes prior to their departure was to be one of the primary missions of the Space Station.

          • fcrary says:
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            And we now have an example of the benefits. The Galileo mission was crippled by the failure of its high gain antenna to open. Think of how much more it could have accomplished, if the antenna had been opened before Galileo had left LEO and an astronaut could have given the stuck parts a tap.

          • Daniel Woodard says:
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            Or a swift kick.

          • fcrary says:
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            I’d be inclined to store water (it’s easier) and electrolyze it on demand. That makes the thermal issues easier, and also reduces drag on the tank farm due to the higher density (i.e. less orbital maintenance.) But that would imply a decent amount of available power.

          • Daniel Woodard says:
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            That could be done just by heating the water with a resistojet, although heating water provides less energy than LH2-LO2 combustion. However to get the high thrust possible with the latter you would still need equipment to liquify the hydrogen and oxygen and keep it liquid until the tanks were full. Zero-loss cryo storage has yet to be fully explored.

            Alternatively there are some new ideas in the nuclear-thermal arena that permit relatively high thrust when needed and still allow the reactor to be used for generating electricity.
            http://www.sciencedirect.co

        • Zed_WEASEL says:
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          Wasn’t thinking of anything as grandiose as a spacedock.

          More along the line of a fueled outer planet orbiter and a departure stage docking in LEO.

          After the departure stage get top up with propellants from follow on tanker flights after initial LEO deployment with partial propellant load.

          Alternatively the departure stage could be fully loaded with propellants like a 40 metric ton ACES stage and flown up to LEO with something like a Falcon Heavy or a New Glenn.

  3. TheBrett says:
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    As I said to you on Twitter, I’m really stoked about this. I’ve been waiting for a while for the results to be publicly released from the close pass on Enceladus on October 28, and it’s really awesome that it came back so strongly positive on the hydrogen detection. It makes it even more likely that there’s possible life down there.

    We should use this to build a strong case for Enceladus Life Finder for a future Discovery 15 or 16 mission, or maybe even a New Frontiers mission if we upgrade it further (I’m still disappointed that asteroid missions got both of the Discovery missions up for grabs last year). I’d even be willing to forgo a long-overdue Venus mission if we got this – it would absolutely be worth it if we ended up finding proof of methanogens in the geyser eruptions.

    • fcrary says:
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      The delay between the Enceladus encounter and this announcement was due to the difficulty of the hydrogen measurement. The Cassini instrument in question (INMS) had to take data in a rarely used mode, and one which has a lower signal-to-noise than other modes. The instrument team has spent the time making sure they are getting the details right and making sure this is a solid result.

  4. Dr. Dan says:
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    This is more than exciting! It is possible that the first fragments of DNA/RNA could of developed off the mineral patterns created by the hydro-thermal activity. The chimneys created in the thermal vents have fractal patterns that could be used as a template for creation of more complex compounds. It is possible this is the very origin of life itself.

    • muomega0 says:
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      Flexible path and an economic deep space transportation system based on reuse for both science and HSF are sound policies forward.

    • Alfredo Menendez says:
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      How can mineral patterns create the necessary information to make fully functional RNA and DNA, much less at the same time. You need to look at the complexity of RNA and DNA and see how mineral can make information. Check it out. You will be surprised how complicated life really is.

      • David Reich says:
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        Who said the first life had to use complex RNA and DNA? That is akin to saying that old watches couldn’t exist because they didn’t have batteries to power the quartz crystals. Current life is incredibly complex, but it would be a mistake to assume that primordial life would have been equally complex. To maintain the watch analogy, if current life is a “Smart watch” then primordial life would be more like an accidental sundial.

        • Daniel Woodard says:
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          The first life on Earth may have been based only on RNA. Although no one can rule out life based on other chemistries, the unique richness of carbon-based chemistry makes it the most likely candidate for life anywhere.

          • fcrary says:
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            I don’t think we have enough evidence to say the first life on Earth used RNA. It looks like that sort of life predated life using DNA. But something simpler than RNA but plausibly considered “life” may have been around before that.

          • Daniel Woodard says:
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            Whatever was there at the beginning may have left no trace, leaving no way to provide proof and requiring a recreation of the event to even demonstrate plausibility.

          • fcrary says:
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            I guess that was my point. Between amino acids and RNA-based life, we have no data. As a result, we can not preclude the possibility of some sort of “life” predating RNA- based life. We just don’t know.

          • Daniel Woodard says:
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            We can’t prove what happened, but we can demonstrate how it might have happened. However I am excited by the hyrothermal vents theory. Water at varying temperatures, minerals, and chemical energy sources are present. Can organics form spontaneously in these environments? Life has to have the ability to store and recreate complex information with a limited assortment of molecules. TMK only carbon chemistry has this versatility.

  5. Alfredo Menendez says:
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    I have a question. In a dark and very very cold ocean, even with some hydro thermal activity, and with some chemicals, how can the highly organized and sophisticated chemical coding of RNA and DNA come together? Doesn’t it take a lot of “information” to make a functioning RNA and DNA molecules that can be called life? Chemicals reacting with each other are not life as we all know. Sodium and water react and it does not make life. Can someone please give me a good scientific journal supported article on how life can form. Right now this is all wishful thinking. It is great to explore new worlds but for the right reasons. Not for sci-fy aspirations.

    • fcrary says:
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      There are some references in the linked astrobiology.com article. But the whole subject of the origin of life on Earth is not well understood and a matter of active research. At least as far as going from complex, pre-biotic chemicals to RNA or DNA is concerned. There are even recent theories that terrestrial life first appeared near ocean floor hydrothermal vents. That’s not too different an environment from that of the suggested hydrothermal systems on Enceladus or Europa. (Most of those oceans may be cold, but not near the vents.)

      • Alfredo Menendez says:
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        Is your point that chemicals coming together can form life? Again the structure of DNA and RNA, just to make one living cell, is so very very very complex that the idea that hot water and chemicals acting according to chemical laws can lead to living organizations is hard to fathom. Let just enjoy exploring the oceans of Europa to see unique landscapes and astrogeology. And be the first to do it!

        • fcrary says:
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          I may regret asking, but… If “hot water and chemicals acting according to chemical laws” isn’t enough to produce life, then what produced life on Earth? (And, I know there is a theological answer to that, which would be followed by the theological question, “And why not on Europa as well?” I hope this conversation isn’t going in that direction.)

          • Alfredo Menendez says:
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            I appreciate you being willing to answer my questions and comments in a civilized manner. Thank you. My point still stands: nobody can show you or me by using science how life can be formed. Lots of science journals postulating the beginning of life always have comments like “could or maybe this would” or “by some unknown process” or ???. Check them out. No scientist can write down the reactions that it would take to make one single living thing from some chemicals and then the next reactions that would have to be more complex until viola we have life. We have all been raised in this paradigm and its time to open our eyes and look for what is real. And life in a dark warm ocean at 5.24 AU is not there. LIke I said, lets explore to see what we have not seen before. Leave finding life out of it. It costs alot to build instruments to detect things that are not there.

            Question: What is the radiation environment around Enceladus. Do you know we will never visit Europa without some real thick lead suits. The possibility of life surviving that radiation environment is less than nil. Originally scientists wanted to send the Europa Orbiter but the radiation environment is so bad that now we have the Europa Clipper which will just flyby Europa thus minimizing it radiation exposure. I kinda of chuckled when Elon show one of his ships on Europa. He must not be scientifically informed on what goes on around Jupiter.

          • kcowing says:
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            I am a biologist. Are you?

          • Daniel Woodard says:
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            Fortunately for any potential lifeforms that might be there already, the thick layer of water above the hydrothermal vents would provide excellent protection against radiation. Although the origin of life on Earth remains unknown, the recent explosion in genetic data provides clues. Amino acids and various carbohydrates can form by abiologic processes, and presumably the simplest self relicating systems formed from RNA, with proteins and DNA coming later. It seems almost certain that life originated in the sea and was chemoautotrophic. Hydrothermal vents are considered an entirely plausible site for the first life, although no firm evidence exists.

          • fcrary says:
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            Yes, there is a really big, unknown step between complex organic chemicals and life. We know that that step did happen on Earth. We know the conditions on early Mars, and currently in the subsurface oceans of Europa and Enceladus could or should have taken organic chemistry up to that unknown step. If we want to understand that unknown step, then the oceans of Europa and Enceladus are very interesting places to look for life. If they contain no life, then we have learned something about that critical step. Something must have been present on the early Earth which is absent in those ocean worlds. If life is present there, then that unknown step is probably likely to occur under the right conditions.

            I’m personally not a great fan of bug hunts (sorry, life detection missions), and I’ve even joked that the Europa Clipper should be named “Pequod” (a fictional ship involved in an obsessive hunt for a whale.) But I do see the value of taking our current knowledge of the conditions required for life to begin, investigating other places with those conditions, and finding out whether those conditions are necessary or sufficient for life to begin.

            As for the radiation environment at Enceladus, it isn’t as bad as Europa. I have some raw data on my laptop, but I don’t have time to dig it up. Specifically, the radiation produces noise in a Cassini instrument I’ve worked on. From memory, that’s about the same at Enceladus’ orbit as it was when Cassini crossed the Van Allen belts during it’s Earth flyby. That makes the surface of Enceladus a fairly nasty environment, but a couple orders of magnitude less so than Europa. But that is the environment at the surface, and therefore irrelevant. Even ten meters of ice is enough to block that radiation. We’re talking about pre-biotic and biotic processes occuring below tens of kilometers of ice and water.

          • TheBrett says:
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            Finding strong evidence of life in either Europa or Enceladus (or both) would be a bigger deal for me than finding it on Mars. Enceladus life is virtually certain to be of local origin, whereas with Mars you have the possibility that the earliest organisms were getting moved around in the inner solar system by impacts – it would take more research to separate it decisively from Earth life.

          • fcrary says:
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            If it uses DNA, that can be used to date when the species diverged from terrestrial life. If it doesn’t use DNA, well, then it is independent of terrestrial life. Or, at lest, that divergence occurred before DNA-based life.

          • Paul451 says:
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            We don’t know…. so we shouldn’t look.

            Strange argument. Failing to find life at Mars, Europa, Enceladus, etc, would tell us more about the formation of life on Earth (by giving us data to rule out some ideas). And finding a second location in the solar system with life will obviously revolutionise all biology.

            We find something, it’s revolutionary; we don’t find anything, it’s more data. So what’s the down-side in looking?

          • Michael Spencer says:
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            “nobody can show you or me by using science how life can be formed”

            That point might seem relevant, but it really isn’t. Put yourself, for instance, into a point in history when many things now well understood were either unexplainable or, in the instance of, say, radio, beyond even imagination.

            Science is best viewed, not through the glasses of results, but through the spectacles of process. Science is simply a way of examining and understanding the universe that we find ourselves inhabiting, a methodology whose chief characteristic is believable, repeatable results.

            The issue of how life arose is indeed a perplexing one. But keep in mind that while many things are unknown, nothing is unknowable.

          • fcrary says:
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            Mentioning radio in the context of things which would have been unbelievable at one time, reminded me of one reaction to James Clerk Maxwell’s equations. At the time, some people criticized his formulation of electromagnetism because it implied invisible, electromagnetic waves all around of us. To some, the idea that such a thing could be true without anyone noticing was absurd.

          • Michael Spencer says:
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            I’ve been reading Krauss’ latest (The Greatest Story Ever Told). While it’s an heart essentially a history book, like all the others, he does go into some depth regarding Maxwell, making a nice leap from ‘invisible’ waves to quantum cats, explaining finally to this reader the equality between magnetism and electricity.

        • kcowing says:
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          OK, then were does life originate? All you seem to want to do here is wave your arms around.

      • Daniel Woodard says:
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        Good points. There is a substantial (and apparently completely independant) ecosystem around some hydrothermal vents in terrestrial oceans.

    • Salvador Nogueira says:
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      Well, I think it is safe to say, even though we don’t know how, that life is possible in the Universe. Since it is possible, it is very exciting to find a place so different from Earth where life similar to Earth’s can proliferate. If it is there or not, that’s something future research can answer. What is the sci-fi in that?

      • fcrary says:
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        Not necessarily science fiction, but looking for extraterrestrial life is not the only thing about Enceladus which is worth studying. There is a tendency to think astrobiology is the most important issue, and to say that research funding needs to be prioritized. That may be true, but it doesn’t mean numbers two to ten on the priority list should be neglected. Studying a lifeless, extraterrestrial ocean would be of great scientific value.

        • Alfredo Menendez says:
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          Agree with you there about studying an extraterrestrial ocean. Lots to learn.

        • Salvador Nogueira says:
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          Of course I agree with you. But how do you know you are studying a living or a lifeless ocean, other than looking for signs of life?