Enceladus has been a magnet for investigation since 2005, when the Cassini spacecraft began to reveal the unusual activity at the moon’s south pole, where we subsequently learned that geysers of water ice and vapor laden with salts and organic materials were spraying into space from deeply fractured terrain. Subsequent studies have homed in on what is now believed to be a 10-kilometer deep ocean beneath an ice shell 30 to 40 kilometers thick.
Now we learn that evidence for hydrothermal activity — water reacting with a rocky crust in a process that warms and saturates it with minerals — has been found on Enceladus, drawing on a four-year analysis of Cassini data. The new paper, published in Nature, is one of two just out that paint a gripping picture of active processes on the moon. It uses computer simulations and laboratory experiments to make sense out of Cassini’s early detection of silicon-rich rock particles flung into space by Enceladus’ geysers.
Researchers working on data from Cassini’s cosmic dust analyzer instrument believe the particles are grains of silica, found in sand and quartz on Earth, but it was the consistent size of the grains (6 to 9 nanometers) that helped them pin down the process responsible. Lead author Sean Hsu (University of Colorado at Boulder) and Cassini scientist Frank Postberg (Heidelberg University) collaborated with colleagues at the University of Tokyo, whose laboratory work explained the conditions needed to form silica grains of the same size as those detected by Cassini. The environment to produce them is thought to exist on the seafloor of Enceladus.
Image: This cutaway view of Saturn’s moon Enceladus is an artist’s rendering that depicts possible hydrothermal activity that may be taking place on and under the seafloor of the moon’s subsurface ocean, based on recently published results from NASA’s Cassini mission. Credit: NASA/JPL.
The process outlined in the paper works like this: Water should infuse the core of Enceladus, where gravity measurements by Cassini have already indicated the rock is porous. Water warmed in the interior, laden with dissolved minerals, interacts with colder water as it moves upward toward the geyser regions at the south poles, with silica crystallizing along the way. We learn something about conditions inside Enceladus here, for temperatures of at least 90 degrees Celsius would be required for the silica grains to be produced. A relatively quick transit is implied (no more than several years), accounting for the uniform size of the grains.
The hydrothermal activity displayed here is not dissimilar to what we find on Earth when silica-rich super-saturated water experiences a significant drop in temperature, and scientists are already talking about the possible astrobiological implications. John Grunsfeld, associate administrator of NASA’s Science Mission Directorate in Washington, puts it this way:
“These findings add to the possibility that Enceladus, which contains a subsurface ocean and displays remarkable geologic activity, could contain environments suitable for living organisms. The locations in our solar system where extreme environments occur in which life might exist may bring us closer to answering the question: are we alone in the Universe.”
Geophysical Research Letters is the source of the second paper, which looks at methane in the plumes emanating from Enceladus’ south pole, suggesting that it too is the likely result of hydrothermal activity. The French and American scientists involved in this work have discovered that clathrates forming under high pressure in the moon’s ocean could trap methane molecules inside water ice, an efficient process for depleting oceanic methane.
The hydrothermal explanation for the abundance of methane in the plume is that hydrothermal processes cause the ocean to become super-saturated with methane, so that the methane is being produced faster than it can be converted into clathrates. This solution fits well with the hydrothermal activity suggested by the grains of silica described in the Nature paper. Another possibility is that the clathrates release their methane as they are forced up into the plumes. Both of these processes may be occurring on Enceladus, but the work on silica grains gives weight to the hydrothermal explanation.
Image: This illustration depicts potential origins of methane found in the plume of gas and ice particles that sprays from Enceladus, based on research by scientists working with the Cassini Ion and Neutral Mass Spectrometer. Credit: NASA/JPL.
In a Scientific American essay called First Active Hydrothermal System Found Beyond Earth, Lee Billings points to the significance of these two papers in relation to astrobiology:
One of the leading theories for the origin of life on Earth postulates that it began in hydrothermal vents at the bottom of the ocean, where seawater percolating through hot rocks created energy- and nutrient-rich environments favoring the formation of the first cells. Today, Earth’s active hydrothermal vents are seafloor oases, harboring ecosystems that flourish in the darkness, isolated from the surface world. Find someplace else beyond Earth where hot rock and water intermingle, and even if it’s far from the sun life might flourish there, too. Such systems may have been common early in the solar system’s history, when rocky planets and icy moons were still relatively hot and wet from their initial formation. But until now scientists had no evidence of ongoing hydrothermal activity anywhere beyond Earth.
Hydrothermal activity within Enceladus tells us that there is a heat source here beyond radioactive materials at the core, probably the result of the moon’s orbit around Saturn and the heat generated by the resulting interactions. Billings points to another possible process: serpentinization, in which chemical reactions between water and rock generate heat, all occurring in a fractured, porous core. He adds: “Enceladus’s sizzling core may actually be a bit like a broken heart, kept alive by tidal forces continually pumping seawater through its fractured veins.” That passage alone should make you want to read all of Billings’ essay.
The papers are Hsu et al., “Ongoing hydrothermal activities within Enceladus,” Nature 519 (12 March 2015), 207-210 (abstract), and Bouquet et al., “Possible evidence for a methane source in Enceladus’ ocean,” Geophysical Research Letters, published online 11 March 2015 (abstract). This NASA news release is helpful.
A few months ago, a paper came out claiming that Enceledus’ core was DIFFERENTIATED. Do these two findings confirm or deny this hypothesis? On the CONFIRMATION SIDE, expanding ice is a good way to FRACTURE rock. On the DENIAL SIDE, ice all the way through Enceledus would probably cool the core down to the point where temperatures of 90 C would be impossible ANYWHERE on Enceledus. I am trending toward DENIAL, but I strogly encourage other readers to argue for CONFIRMATION!
Sorry, I meant UNDIFFERENTIATED, NOT differentiated.
Stronger evidence that Ganymede has a global ocean of liquid salt water perhaps one hundred miles deep – 40 miles deeper than Europa and way more than all the water on Earth.
The only drawback in reaching this alien ocean is that unlike its Galilean neighbor, it is under an ice crust 95 miles thick.
HST site article here:
http://hubblesite.org/newscenter/archive/releases/2015/09/full/
To quote:
By watching the rocking motion of the two aurorae, scientists were able to determine that a large amount of saltwater exists beneath Ganymede’s crust, affecting its magnetic field.
A team of scientists led by Joachim Saur of the University of Cologne in Germany came up with the idea of using Hubble to learn more about the inside of the moon.
“I was always brainstorming how we could use a telescope in other ways,” said Saur. “Is there a way you could use a telescope to look inside a planetary body? Then I thought, the aurorae! Because aurorae are controlled by the magnetic field, if you observe the aurorae in an appropriate way, you learn something about the magnetic field. If you know the magnetic field, then you know something about the moon’s interior.”
Even if there isn’t life in such places yet, mightn’t we transplant Earthly hydrothermal vent biosystems to such places, to give life a jump start there?
It would be a nice thing to have left behind, if we happen to meet with a planet killer some time after.
@Brett Even if there isn’t life in such places yet, mightn’t we transplant Earthly hydrothermal vent biosystems to such places, to give life a jump start there?
On Earth, most vent life (macro) is oxygen breathing , requiring surface photosynthesis to supply the oxygen at depth. In Enceladus’ oceans, is there free oxygen, or is the life to be transplanted just chemotrophs?
If there is life in these icy moon oceans, I’m guessing that it would have to be anaerobic, or use another approach for higher energy metabolism.
Enceladus’ geysers throw out 200kg of water per second and recent models suggest the moon has probably lost around 30% of it’s mass since it was proto-Enceladus.
http://www.sciencedirect.com/science/article/pii/S0032063314002918
With both Enceladus and Titan presenting such rich targets for astrobiology and both seemingly being living and active worlds, I think it would be unacceptable not to have a mission to both of them in the next two decades.As I understand despite concepts being made nothing concrete is planned, hopefully this and the other research spurs the initiative to send a dedicated mission to both of these worlds in 2020s.
As a side note-I remember the terrible protests against Cassini and attempts to derail the mission. Can you imagine what a loss to our knowledge and science it would be if they had succeeded?
If the idea of long term, hot vents in Enceladus’ ocean pans out, then we have a potential warm environment for life to exist. If Enceladus is sterile, that might dent the idea of ease of life formation. It might also suggest that life as the form of the self-replicating von Neumann probes is less tenable.
What might be interesting is whether these vents could be exploited for energy for a colony below the ice.
I think the findings from the plumes of Enceladus are very significant . With the plans for Europa Clipper up in the air still there will be calls for a dedicated mission. The fact John Grunsfeld himself felt obliged to comment speaks volumes. Of course Europa has plumes too and also has long been suspected of having hydrothermal vents so I believe NASA are wisely using this as leverage for a mission to either Europa or Enceladus. Congress were keen and thus may just be the shot in the arm needed to swing the deal. Once SpaceX get their first successful Falcon Heavy under the belt this summer you can bet that they will push for a direct flight for this mission too. Big time. A “Heavy” to Saturn at less than $100 million is less than an ATLAS V or Delta Heavy multiple flyby and less than half the time ! Talk about a no brainer- two years to Jupiter and 4 max to Saturn. There is another New Horizons mission still to come over the next few years and with the much gentler radiation environment around Enceladus there would be enough cash for a decent payload for a dedicated Enceladus mission. I’m sure NASA will use this study to the extreme. It couldn’t be better timed.
Cassini is due to make three flybys of Enceladus this year, two in October and one in December. The one at the end of October in just 30 miles away. Hopefully it will go through a plume. The next nearest , mid October is about a thousand miles. The next New Frontiers round 4 commences this October too ironically. Of the five candidates one is a Saturn atmospheric probe. Whether this can be amended to a dedicated Enceladus mission I’m not sure. I would doubt it but you never know .. Due for launch in 2021, by which time the Falcon Heavy should have its flight licence and be on NASA’s itinerary Of launchers I’m sure. Five tonnes to Saturn if I recall .
The New Frontiers 4 cycle starts this October. Of the 5 contenders, one is a proposed Saturn entry probe and carrier/relay . It is due to launch 2021. Whether there is latitude to amend or modify this is unclear. The use of New Horizons technology would help reduce costs and ironically savings would be made by a direct flight via the Falcon Heavy as it is actually significantly cheaper than either the ATLAS V or Delta IV heavy proposed for the longer flyby route. A shorter mission length saves costs on maintaining a ground team too. NASA missions have the facility to add savings on launch vehicles to the overall mission cap. This can be up to $16 million for the cheaper Discovery mission so presumably more for the New Frontiers. Maybe this might allow an extended mission to include Enceladus, massively increasing the science return , something NASA like . Reusing proven New Horizons technology would further save costs .Certainly now is the time to push for It !
It seems to me that Enceladus is a much better candidate for astrobiological exploration than Europa — the radiation environment is much more benign, and it is far easier to sample its watery interior via its regular geysers. One could put a probe into orbit and routinely fly through geysers and analyze the results. Heck, one might even attach a fishing net, as we might get lucky.
Another possibility is a sample-return mission, as was discussed here:
https://centauri-dreams.org/?p=30713
A remote submersible would be a lot easier with accessible cracks for the probe to melt down into. I would personally like to try for Ceres first as it is much closer. We are also now approaching a time and target problem as there are now becoming more and more interesting targets to get to but also further away. But which ones to go for as we only have a limited amount of money.
Ok, the water chasers can officially bypass Europa already, please! It has now been 4 years since the Fukushima Daiichi nuclear disaster. There still aren’t any robots exploring the area in which 3 reactor cores vanished into smoking craters as the engineering which would allow electronic robots to function in such an environment does not exist. A “robot” has been prepared to explore the raging heart of unit 1 later this year, but my understanding is that this is an electromechanical device with a control cable – essentially a 40 meter colonoscope with the head driven by a set of crawlers:
http://www.world-nuclear-news.org/RS-Looking-inside-Fukushima-Daiichi-unit-1-1002154.html
The Russians solved a similar radiation problem at Chernobyl by sacrificing human “sponges” who picked up fuel rod fragments with their hands – and died shortly afterwards. That is not an option at Europa. On the other hand, the radiation environment at Enceladus is more manageable, while the H2O2 required to drive redox reactions (potentially an energy source for life) is still present. Why is the choice not obvious?
Would this proposed technique for Europa also work for Ganymede, or is its ice crust just too thick?
http://www.dailygalaxy.com/my_weblog/2014/06/scanning-europas-ocean-for-signs-of-life-with-jupiters-radio-waves.html
Here’s a mental excercise for you all! Assume that there IS life on Enceledus, and ALSO assume (see my ABOVE comment) that the rocky core IS porus (or even COMPLETELY undifferentiated). Then, the life-forms that emerged FIRST would be, ASSUMABLY extremely primative (i.e. NO ATP, or OTHER energy producer). Wouldn’t these life-forms migrate to the high energy environment of the inner core, instead of the low-energy ocean? Then, make ANOTHER assumption. To survive the early high radiation environment at the CENTER of the young Enceledus, they would have to MUTATE into an analog of Dieniochus Radiodurans. Now, let’s get into a purely science fictional scenario: These life forms not only survive in a high radiation environment, but actually start to CONSUME and STORE radioactive materials. As the migration proceeds to the center of ENCELEDUS, due to the COOLING of the core to a temperature where complex carbon chemicals are no longer destroyed, enough Uranium is transported to the center of Enceledus where critical mass is achieved and a nuclear detonation occurrs. Before completely dismissing this scenario, I encourage you all to read the science fiction story “The trelph is a solitary creature”!
Cassini Finds Evidence for Hydrothermal Activity on Saturn’s Moon Enceladus
By Paul Scott Anderson
The deep oceans on Earth are teeming with life, despite the cold and darkness, thanks to hydrothermal vents which provide needed heat and nutrients in an otherwise rather uncomfortable environment. Now, the first evidence has been found for current hydrothermal activity elsewhere in the Solar System – on the ocean bottom of Saturn’s moon Enceladus.
“These findings add to the possibility that Enceladus, which contains a subsurface ocean and displays remarkable geologic activity, could contain environments suitable for living organisms,” said John Grunsfeld, astronaut and associate administrator of NASA’s Science Mission Directorate in Washington.
“The locations in our solar system where extreme environments occur in which life might exist may bring us closer to answering the question: are we alone in the universe.”
Full article here:
http://www.americaspace.com/?p=78437
I think it safe to say that Enceladus, is not a prototypical Ice moon.
I was looking for the extent of tidal heating. Frankly I am surprised the
The icy moons eccentricity is only .0047 . The other thing that could cause heating is orbital tug from the interaction with Tethys, which is around 6 times the mass of Enceladus and comes as close as 56,000 Km. So maybe Enceladus is caught in a tug of war with Saturn Tethys. The orbital periods are 1.4 vs 1.9 days, which means that they are interacting often.
So what is the contribution from radioactive heating? Is this a case
where Enceladus just happens to be at the right position and just the right
size that allow minimal radio active decay to have a large influence? Because as we all know the other icy worlds about the Jupiter and Saturn do no behave this way.
If it turns out Enceladus’ heating ARE mostly the result of Radioactive decay, then I would theorize that it is a remnant of a much larger moon that was violently altered in the past. Or maybe it is host to the biggest Potassium-Uranium-Thorium Nugget in the solar system. (if it were true, what a colossal potential of industrial base, along with HE3 in Saturn’s Atmosphere)
Rob Flores: In reference to the SECOND of my above two comments, if you are looking for a way to CREATE that monster PUT nugget, DON’T RULE OUT BIOLOGY! Please read the story I mentioned above and tell me what you think. It’s one of my all-time favorite SF stories.
I think the source of heating in Enceladus is a big issue that seems to be swept under the rug while celebrating a new potential source of sea food.
The moon is probably too small for appreciable radioactive heating and tidal flexing should be minimal. The Saturnian moon system is odd and there are indications of something happening to the system at some point, which may have changed the orbits of a few moons, inducing tidal heating in Enceladus and Titan’s atmosphere. Perhaps Encleadus melted internally and it’s just now freezing up again… so it’s a nice sterile world.
In terms of Europa vs Enceladus – Europa has the greater potential for life and Jupiter is more accessible (quicker mission times for less money) than Enceladus.
If you want both, maybe move some of the money spent on always dead Mars towards these two moons.
@Alex Tolley, there could be plenty of oxidizing potential on Enceladus, from H2O2 in material returning from Saturn’s E-ring.
http://web.gps.caltech.edu/~jkirschvink/pdfs/Enceladus_OLEB_online_published_paper.pdf
@Harry R Ray, why refer to SF when the eminent physicist, Fred Hoyle, has put up such a good case that the Oklo reactors were ‘built’ by bacteria. Unfortunately, the U is now too depleted in 235 for anything like it to happen today.
I couldn’t agree more about Mars. Nasa and the ESA are obsessed with it to the detriment of other far more interesting targets. The main thing is that it is easy to reach and quickly . “Insight” is the epitome of a totally unnecessary mission given the numerous other Mars missions around the same time and on going rover missions. Half a billion that could have been used on the much more exciting Titan Mare Explorer. Or an Enceladus lander similar to Philae . Established technology with no expensive operations costs . Mars might be cheap to reach, but the cost of maintaining full time science and engineering teams over the years that some missions last is extremely expensive and often conveniently forgotten. With just the three days of intensive ,battery powered ,data collection costs would be minimal. This is why I’m such a fan of the new generation of heavy launch vehicles that bring Jupiter and Saturn and their interesting moons so much closer. The Falcon Heavy is even cheaper than the launchers for Mars missions so in effect makes Jupiter and Saturn much more cost effective. These Enceladus results demand a mission to the icy moons and soon. The Falcon should have its flight worthiness proven by 2017 and go on Nasa’s launcher inventory to be followed by the SLS next decade.
I think the issue which moon has the best chances of new seafood being available will be hotly debated among scientists in view of limited funds for missions.
Why would Europa have greater potential for life, I am curious?
As to accessibility, wouldn’t the need to protect probe from radiation at Jupiter offset the longer time needed to reach Saturn? Also the evidence of active plums makes it possible to collect samples without breaking through the ice.
Mars imho has possible life, but likely underground and which would require either a manned mission or sophisticated probes/drones to be deployed, which I don’t see happening before 30s at the earliest to be honest.
Also in its case its more likely to be simple bacteria, micro-organisms deep within the subsurface. Both Enceladus and Europe in theory could have something more complicated with ocean environment.
It would be also interesting to check if the lifeforms emerged on their own or were transported from original planet like Mars to other bodies in Solar System through lithopanspermia.
Joy: I am sorry, but if you are going to disseminate marginally relevant information like that, you have to at least keep it factual. Smoking craters? Where you see smoking craters, I see an intact building with a bit of steam coming out (http://en.wikipedia.org/wiki/Fukushima_Daiichi_nuclear_disaster#Investigation_Committee). There is no mention in the link you gave about any impact of radiation on the robot design, and I have not seen any evidence anywhere that radiation was a problem for robots, in Fukushima or elsewhere. As far as I can tell your story about Russians intentionally entering the reactor to pick up things in Chernobyl and then dying from it is pure nonsensical fantasy. You’d need to provide a credible reference, although I bet you can’t.
@RobFlores, I doubt that even a solid core of potassium of the maximum size allowed by Enceladus’ density could be that active, and if it had enough uranium to account for its current activity, it would have approached criticality and fried if formed more than a billion years or so ago.
@Wojciech, Europa has greater potential for life than Enceladus because of time. This current level of tidal heating on Enceladus should only be possible for a few million years every billion as the lunar resonances change with time (Saturn’s moons are not locked in a Laplace resonance as the Galileans are for Jupiter). The rest of the time it should be a solid ball of ice.
Rob Henry
“This current level of tidal heating on Enceladus should only be possible for a few million years every billion as the lunar resonances change with time (Saturn’s moons are not locked in a Laplace resonance as the Galileans are for Jupiter). The rest of the time it should be a solid ball of ice.”
That does seem to me like a lot of speculation,with “should” used quite often. As I understand we don’t even understand the current reasons for Enceladus being so warm.
In any case with such an attractive target, a mission to this moon is necessary.At best combined with a probe to Titan as well, something like the TSSM, perhaps with the re-purposed Europa Clipper design
http://en.wikipedia.org/wiki/Titan_Saturn_System_Mission
UPDATE:It seems members of the Cassini team are working on a new mission proposal and are using this discovery as one of the arguments.
This is what I found in Popular Mechanics
http://www.popularmechanics.com/space/deep-space/a14507/enceladus-saturn-moon-ocean/
“But Cornell’s Lunine says the question as to whether Enceladus’s ocean does or doesn’t contain life is one we could answer, and soon. All of the new information we’re gleaning about Enceladus (and all of Saturn’s moons) comes from the Cassini spacecraft, which was developed in the late ’80s and early ’90s. Despite carrying outdated tech and instruments, it’s revolutionizing the way we think about the possibility of life in other parts of the solar system. Lunine is currently working on a proposal for an update to the Cassini mission, using a new spacecraft with both modern day technology and specialized machinery designed to seek out the bio-signs of life.”
It would be interesting to see what they come up with. I would combine it with Titan probe as well, as there are many unexplained features requiring further study(like the vanishing and re-appearing island on one of its lakes).
I am still thinking along the lines of a decoupled ice mantle – core grinding against each other producing heat. Although there is little to no liberation of the moons surface it is possible to have the core oscillate back and forth inside the moon. There is simply not enough radioactive materials and limited eccentricity of the moon to get the amount of heat generated unless the eccentricity in the recent past was much higher.
Wojciech, even if we try to model Enceladus such that it might retain its current level of activity for much of its past, we run into mass loss problems. If we return most material through the E ring then, an already alarming loss of strategic volatiles, looks like it becomes critical. From memory, nitrogen is the worst of them.
Rob Henry, that might be true, but a model remains model until proven empirically. Enceladus poses various fascinating questions, that will remain unsolved until dedicated study is made using probes. The same with Titan.
Take these two together and Saturn system becomes one of the most fascinating subjects to study if not the most fascinating in our Solar System.
I agree that Enceladus and Titan merit special attention, although the distance is a serious difficulty. Not only do bioth worlds have direct bearing on the questions of the emergence of life and planetary habitabilty, but botha re damn interesting with the question of life ignored. They are also rather more accesable than the oceans of Europa and Ganymede.
@Eniac “As far as I can tell your story about Russians intentionally entering the reactor to pick up things in Chernobyl and then dying from it is pure nonsensical fantasy. You’d need to provide a credible reference, although I bet you can’t.”
Eniac, that is true and liquidators in Chernobyl were sent in to clean the highly radioactive debris from the roof because all the automated robotic vehicles and means did break down due to radiation. For instance all fire fighters who arrived first to the 4th reaction died due to sever radiation sickens. Beside, people were send in under the 4th reactor & inside. Even now scientists do time to time trips to the reactor inside to measure & observe. Do check up these videos on YT. Here is one that covers reasons of using liquidators. Per rules their work day should have had 30 second long as this was the dosage you got being in contact with the radioactive debris. The reality was no one paid attention to that unless one got seriously ill from radiation.
https://www.youtube.com/watch?v=0UbNDDqyk_Q
IceMole Drill Built to Explore Saturn’s Icy Moon Enceladus Passes Glacier Test
By Kasandra Brabaw, Space.com Contributor | April 07, 2015 08:00 am ET
For the first time, scientists have broken through the icy crust of a glacier in Antarctica and extracted an uncontaminated sample of water trapped beneath the ice for millions of years, potentially paving the way toward the exploration of icy bodies in the solar system.
The German Aerospace Center’s (DLR) Enceladus Explorer (EnEx) project has been working toward this moment for three years. In 2012, DLR developed a melting probe, or Icemole, meant to someday explore Saturn’s moon Enceladus, which hides an entire ocean underneath about 24 miles (39 kilometers) of ice.
But before the Icemole could be cleared for a journey to the Saturn system, it had to be tested on Earth.
Full article here:
http://www.space.com/28930-icemole-drills-glacier-saturn-moon-enceladus.html
To quote:
An entire ocean of liquid water lies under Enceladus’ crust of ice, and at the moon’s south pole, cryovolcanoes spew jets of icy water into space. When NASA’s Cassini spacecraft first flew over the icy spray in 2005, it detected organic compounds that hinted at a possibility of life.
But breaking through that crust will be more difficult than breaking through a glacier on Earth. Scientists at the German Aerospace Center say the EnEx Icemole must have a “robust, autonomous navigation process” to ensure the success of a future space mission.
“If EnEx is deployed on Enceladus, it will have to find its way from the surface to a water-bearing region in the ice crust of the Saturnian moon completely autonomously,” Oliver Funke, project manager at the German Aerospace Center, said in a statement.
So the jets of this moon may actually be walls of vapor and ice?
http://www.space.com/29330-saturn-moon-enceladus-geysers-curtains.html?hootPostID=93453da9792bddc430f895afe07c491a
Meanwhile the prospects for life on Enceladus continue to improve:
https://carnegiescience.edu/news/geochemical-process-saturn%E2%80%99s-moon-linked-life%E2%80%99s-origin