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Are Scientists Set to Discover Life Beneath Europa’s Underground Ocean?

Are Scientists Set to Discover Life Beneath Europa’s Underground Ocean?

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Europa is one of Jupiter’s 79 moons. It is one of four large moons that revolve around the planet, and is slightly smaller in size than our moon. Europa was discovered in 1610 by Galileo Galilei, and has the distinction of being the first moon found orbiting another planet in our solar system.

While Europa was the first of Jupiter’s moons to be discovered, it is also the most intriguing from the perspective of planetary scientists. Oxygen and water have been detected in its thin atmosphere, and it is known to have a massive ocean somewhere below the depths of its frozen surface. Estimates are that this ocean is 100 kilometres deep and has twice the volume of water of all the oceans on Earth combined.

And where there’s water, there could be life. Planetary scientists know this, and that is why they’ve identified Europa as a place worthy of exploring.

The Plumes of Europa

In 2014 and again in 2016, scientists observing images from the Hubble space telescope found confirmation of water on Europa, and in significant amounts. They were shocked and delighted to see vast, arcing plumes of liquid water spurting from the surface of the planet. Estimates are that these plumes were between 50 and 100 kilometres in length, and in each occasion they emerged from the same location on the planet’s surface.

Europa rotates around Jupiter in an eccentric orbit, with the same side facing Jupiter all the time (just as our Moon faces Earth exclusively on one side). The eccentric rotation creates motion in the ocean underneath the surface and tidal waves due to gravity changes, which may cause cracks to form on the moon’s surface. If some type of underwater disturbance (perhaps tectonic plates shifting or volcanic activity) created enough excess pressure, it might send plumes of water shooting up through those cracks and high into the low-gravity Europan sky.

Deep space geysers had been seen before, emerging from the surface of Saturn’s moon Enceladus. But seeing them on Europa, which has generated so much excitement and anticipation among planetary scientists seeking possible sources of extraterrestrial life, has helped spur interest in examining this fascinating moon more closely.

Submarines, Lander and Orbiting Spacecraft: NASA Has Big Plans for Europa

Plans have been underway to explore Europa for a long time.

In 2013, scientists from NASA’s Jet Propulsion Laboratory in California and the Angstrom Space Technology Centre at Uppsala University in Sweden proposed an innovative solution to exploring the depths of Europa’s subsurface ocean. They developed blueprints for a tiny submarine that could drill a hole through Europa’s surface ice and enter the water below to search for life.

Because its moons are bombarded by powerful radiation from Jupiter’s massive magnetosphere, life would not be able to exist anywhere close to Europa’s surface. Consequently, microbial life would likely be found at a depth of several kilometres, which a tiny unmanned submarine equipped with small-scale scientific instrumentation would be able to explore.

More recently (in 2017), a separate team of NASA scientists has requested funding for the development of a Europan lander . Modeled after the various Martian landers, such a mobile machine could travel across the Europa landscape taking photographs and collecting samples. This lander would be equipped with a scoop that could burrow into the ice to a depth of about 10 centimetres, in order to collect core samples for later examination.

With this mission, there would be no expectation of finding anything alive. But the ice samples might contain the remnants of life, such as the frozen bodies of dead microbes or organic compounds like amino acids and lipids. Even the way inorganic compounds were distributed in the ice might give indications of how life was functioning in the ocean below.

While missions to send a lander to Europa are currently on hold, the Europa Clipper is set to leave Earth for Jupiter sometime between 2022 and 2025. The Europa Clipper is a satellite-style spacecraft that will park itself in orbit around Jupiter, and then spend the next 28 months examining Europa during a series of 45 flybys. NASA plans to outfit the Clipper with a plethora of scientific instruments, which will measure the thickness of Europa’s surface ice, the depth and salinity of its ocean and the characteristics (primarily the moisture content) of its atmosphere.

Like the proposed Europan lander, the Europa Clipper will not search for life directly. But the data it collects will allow scientists to evaluate the moon’s overall suitability for life, based on existing knowledge about the requirements that must be met for organic evolution to take place.

There are several other moons in our solar system, including Enceladus (Saturn) and Ganymede (Jupiter), that may also have liquid oceans beneath frozen surfaces. If conditions are ripe for life to evolve on Europa, these other moons might be capable of hosting microbial lifeforms (or something even bigger) as well.

“All These Worlds are Yours Except Europa. Attempt No Landing There.”

It has long been speculated that life may exist in the subsurface ocean of Europa. In fact, this concept was a key plot point in Arthur C. Clarke’s 1982 novel 2010: Odyssey Two , as well as in the movie version of the book (both were sequels to the classic 2001: A Space Odyssey ).

“All these worlds are yours except Europa. Attempt no landing there.”

In Clarke’s novel, this was the ominous message received by the spacecraft sent to Jupiter to explore the planet and its moons. In the epilogue of the book, set 18,000 years in the future, Europa’s native lifeforms have evolved so far that they’ve left the moon’s oceans to live on land, and have even formed a primitive society. Apparently we were being warned away in the past because aliens monitoring developments on the planet were afraid we’d somehow disrupt or corrupt this evolutionary process.

As of now, we have no idea if any type of life actually does exist on Europa. But the influence of Jupiter’s gravity is believed to be strong enough to cause hot hydrothermal vents to form on the bottom of Europa’s ocean, and some scientists believe these types of vents are the wellsprings from which life first evolved on Earth. If Europa’s ocean is salty and rich in minerals on the sea bottom, this along with the presence of hydrothermal vents would create ideal conditions for the development of life, according to current theories about the origins of life and its subsequent evolution .

Given how complex life became on Earth, once it first appeared, the possibility that intelligent life might manifest elsewhere in our solar system is not so farfetched. Where there’s an initial spark, miraculous things can happen.

We can only hope that if life does exist on Europa, we will exercise great caution and a sense of moral responsibility in our interactions with it. We cannot possibly know its ultimate destiny, any more than aliens visiting Earth a billion years ago could have guessed the microbial species they discovered would someday turn into us.

NASA Is Sending a Lander to Discover Whether Life Exists on Europa

To the naked eye, Europa, one of Jupiter’s moons, might just look like a great big ball of rock and ice. But to NASA, this moon represents much more. It could contain what scientists have long been searching for – lifeforms that exist outside of our home planet. Through the Europa Mission, NASA plans to send a lander to Jupiter’s moon, which is believed to hold a vast ocean beneath it’s frozen crust. And where there is water, life is almost sure to follow.

The project is due to launch in either 2024 or 2025, when the lander would begin searching for lifeforms on the moon’s surface. If organisms are found, plans would develop for a more sophisticated craft to be sent to Europa in search of its underground ocean. Dr. Kevin Hand, one of NASA’s leading officials with the Europa Mission, explains the program’s investment towards these advancements:

For the first time in human history, we can actually build missions and design the instruments that could go out and answer this fundamental question of whether or not biology works beyond Earth. If we commit to getting these missions done, we could potentially find life in our own solar system’s backyard within the next 20 years. Technologically it is entirely possible, but it requires public support, excitement about this, so we look to you to help communicate and spread the word.

What we still need to land on Europa

Not only do scientists need to find a place on Europa's surface that will be worth studying, they also need to find a place to land that won't completely destroy the lander upon touch down, Jim Green, NASA's Director of Planetary Science, told Business Insider.

"Some recent research suggests there may be a lot of penitentes [on Europa]," Green wrote in an email. Penitentes are blades of ice shown in the image below. "Imagine landing on a vast field of tall sharp ice spikes, and remember that at the temperature of Europa ice has the strength of granite."

"Unlike Titan [which NASA landed Huygens on in 2005], Europa does not have an extensive atmosphere and therefore we are unable to use parachutes of any kind in the landing process," Green said in an email. "In order for a lander on Europa to be successful, it must have a completely new design of retro rockets with adequate fuel."

Scientists Discover Life's Common Ancestor, An Ancient Living Ocean

Ocean Spray &ndash Dirk Dallas (cc) 2015.

Almost every religious tradition has a creation mythology or genesis story about the triumph of order, light and civilization over the powers of confusion, darkness and wilderness. Though details differ from culture to culture and era to era, many of the themes are remarkably similar:

  • the churning waters of chaos in which all substances are intermingled and indistinguishable
  • the first divine act (a breath, a coupling, a hatching, a birth) that begins the process of separation
  • the death or dismemberment of a deity to create the very stuff of the universe.

As people living in a modern society informed by the discoveries of science, we have a tendency to think of these cosmogonic (literally, &ldquoorder-begetting&rdquo) myths as made-up stories that our ancestors turned to for explanation in their ignorance of the facts. Particular creation myths might be moving, beautiful or meaningful for us, and so true in some deeply metaphorical way, but most of us shy away from claiming that these stories must therefore be factual accounts of what actually happened. Instead, science offers us evidence in support of theories like evolution and the Big Bang to explain how the world came into existence and life evolved into the myriad species we see today.

But what if science uncovered evidence that these ancient creation stories might just have gotten some of the facts right after all? That&rsquos looking more and more likely, according to geneticists seeking clues to the origin of life on this planet in the shared genetic traits of plants, animals, bacteria and the microorganisms known as archaea. Piecing together the puzzle of evolution over the past several billion years, scientists now believe that our last common ancestor may have been a planet-wide &ldquomega-organism&rdquo so huge that it was the size of the sea itself.

Scientists Meet Mother Ocean

Ocean Sunset. photo by John Hilliard (cc) 2016.

From the beginning, evolutionary biologists have postulated that all of the organisms currently living on the planet must have originated from a single shared ancestor &mdash a theory that recent statistical analysis now confirms is more probable than there being multiple ancestors by a factor of 10^2860. Scientists call this great-great-grandparent organism from which all current life descends LUCA, or the Last Universal Common Ancestor, and estimate that it lived between 2.9 and 3.8 billion years ago.

Since very little evidence remains to show what kind of beings lived in the ancient seas of our young planet, genetic researchers have had to piece together the lingering traces of similarities in molecular structure shared among the three domains of life: single-celled archaea, bacteria and multicellular eukaryotes (plants, animals, fungi and the rest). The details get pretty technical (if you want to know more, check out this article in Science Daily), but the long and short of it is that scientists now have a pretty clear picture of what LUCA might have looked like.

What does that picture show? Something pretty startling. Billions of years ago, life existed as a primordial living soup that used the oceans as its medium, spanning the entire planet in what scientists are calling a &ldquomega-organism.&rdquo (Think: the leviathan from the Illuminatus! trilogy or, better still, the living ocean of the planet Solaris in the novel of the same name.)

The latest research suggests LUCA was the result of early life&rsquos fight to survive, attempts at which turned the ocean into a global genetic swap shop for hundreds of millions of years. Cells struggling to survive on their own exchanged useful parts with each other without competition &ndash effectively creating a global mega-organism.

LUCA&rsquos cells lacked the specialized molecular structures of cells today which allow them to efficiently and precisely control the production of the proteins they need for survival. However, those ancient cells did have primitive organelles and the basic enzymes necessary to break down and process nutrients, as well as the ability to build proteins in a clumsy, hit-or-miss kind of way. They also had &ldquoleaky&rdquo membranes that made the exchange of genetic material much easier, encouraging cooperation and coexistence rather than competition among cells.

That&rsquos why LUCA had to be cooperative, with any cells that produced useful proteins able to pass them on throughout the world without competition. This was a weird variation on what we know as natural selection &mdash helpful proteins could go from a single cell to global distribution, while harmful or useless proteins were quickly weeded out and discarded. The result was the equivalent of a planet-spanning organism.

This latest research puts a new twist on evolutionary biologists&rsquo assumptions about &ldquosurvival of the fittest&rdquo among primitive life on the planet. Rather than a single-celled organism that slowly evolved into a multicellular structure in order to gain the competitive edge over other early forms of life, it now seems likely that LUCA began as a vast, multicellular organism that thrived through cooperation and interdependence, breaking up into different entities as its parts became increasingly self-sufficient. Today&rsquos bacteria are not more complex or sophisticated than LUCA&rsquos cells they are actually simpler and more streamlined.

Ancient Myth Meets Modern Science

So what did the old creation myths get right? Almost every culture in the world has a cosmogonic story that shares one or more of these themes: the primordial waters of chaos, the separation of substances into their complimentary (and competing) opposites, and the dismemberment of a god or other being from which the world itself is made. Each of these three themes can serve as a pretty accurate metaphor for what scientists now believe to be the factual history of how life evolved on earth.

Chaotic Waters

Venus Virated. by Village9991 (cc) 2009.

The dark waters and murky depths of the ocean have long held sway over the human imagination as the realm of confusion, disintegration and mystery as well as the source of creation and life. The ancient Babylonian creation myth describes a primordial goddess of chaos named Tiamat, who held the other gods &mdash as well as the yet-unnamed sky and earth &mdash within her body where &ldquotheir waters were mingled together.&rdquo In the Judeo-Christian genesis story, the creator god Yahweh moves across the face of the roiling waters before speaking the single word that will part them to create heaven and earth. Similarly in ancient Egyptian mythology, life is said to have arisen out of the lifeless, watery abyss (deified as Nu), and in both Greek and Norse mythology the wellspring of creation exists within a dark void of nothingness from which the first waters of life spring.

In Japanese mythology, the story is told of how the two spouse-sibling deities Izanagi and Izanami plunged a jeweled spear into the thick soup of the ocean and stirred until the briny substance congealed into islands, forming the archipelago of Japan. Nearby in China, it is said the primordial giant P&rsquoan-ku formed inside a cosmic egg in which all the stuff of the universe was mixed up together, and that as he grew, he cracked the egg open and divided its shell and inner mixture into the opposites of yin and yang, earth and sky, male and female, and so on. In their own way, each of these myths evoke the sense of life appearing from the dark, chaotic depths of undifferentiated form where all substances mix and mingle together. One could hardly find a better description for what life must have been like in the earth&rsquos oceans some 3 billion years ago.

Separation and Competition

Venus. by Alice Popkorn. (cc) 2008.

In several of these myths, we can also see the recurring theme of the separation of these chaotic, intermingling waters into distinct elements that both compliment and compete with each other. Gods like Yahweh, P&rsquoan-ku and Atum are said to have divided this basic formless stuff of the world into opposites like heaven and earth, land and sky, male and female, light and dark, day and night, sun and moon. In Greek mythology, out of the void of Chaos comes Gaia (earth), along with Tartarus (abyss) and Eros (love) &mdash or in other words, both separation and space, and the potential for attraction and relationship between distinct beings.

Sometimes this separation is an act of masturbation, while other stories describe it as a birth. In some cases &mdash such as in the Chinese story of P&rsquoan-ku, the Hiraṇyagarbha (&ldquoGolden Egg&rdquo) of Brahma in Hindu cosmology, and in some versions of the Egyptian creation story &mdash the birth takes the form of hatching from the cosmic egg. In Polynesian mythology, the earth-goddess Papa creates the oceans when her belly swells so full of water that they suddenly burst forth, giving birth to the sea god Tangaroa, who proceeds to separate his mother earth from her lover, the sky (Rangi). Besides being a separation of the offspring from the mother, such a divine birth often results in the separation of primordial gods into male and female pairs. Egyptian mythology holds that Geb (earth) was joined in eternal sexual union with Nut (sky) until their offspring Shu (air, or emptiness) came between them and forced them apart. In Greek mythology, the machinations and betrayals of the father by a son who sides with his mother is a theme that recurs through several generations of deities.

These stories of separation, division and distinction strongly echo what scientists think might have been the reality of LUCA&rsquos fate, as this planet-sized, oceanic mega-organism broke apart into individuated, self-sufficient entities capable of surviving on their own. With this new independence came an end to the playground of free genetic exchange, and in its place arose competition and the more familiar process of natural selection as we know it today. Ancient myths of divine sibling rivalry and conflict seem especially poignant in light of such scientific theories.

Dismembered Gods

Finally, another common element in many creation stories is the dismemberment and scattering of a divine being&rsquos body to create the very stuff of the universe. In Norse mythology, the frost giant Ymir and the giant cow Auðumbla are both born of the commingling of opposite elements in the life-giving moisture called eitr, which formed when the congealed rime of the icy realm of Niflheim fell through the void into the fiery realm of Muspelheim where it melted and joined with sparks of flame. The sons of Auðumbla&rsquos offspring eventually rise up to kill Ymir and dismember his body to create the world. His blood becomes the sea, his bones make the mountains and his skull becomes the sky. In a similar story in Babylonian myth, the primordial sea-goddess and mother of creation Tiamat plots to kill her own descendants, but they discover her plans and eventually her great-great-grandson, Marduk, defeats her in battle, cutting her body in half. He uses one half to create the earth and the other to make the sky, while her tears became the source of the Tigris and Euphratus rivers. From the blood of her consort, Kingu, Marduk created the first human beings. Both of these creation myths are arguably further examples of the male and female separating from a single undifferentiated substance, with their divine offspring or descendants eventually rising up to set against the parents.

Another example of the dismembered god can be found in Hindu cosmology, which tells the story of Purusha, a primeval giant chosen by the gods as a sacrifice from whom they make the world. His feet become the earth and his head the sky, his breath is the wind, his eyes are the sun and his mind becomes the moon. The four castes of Indian society were also said to have been made from Purusha&rsquos body. And last but not least &mdash in ancient Chinese mythology, after being born in the nourishing soup of the cosmic egg and separating the elements into their opposites, our old friend P&rsquoan-ku finishes his act of creation by bursting apart his own body to create the ten thousand things: his eyes become the sun and moon, his head the sacred mountains, his blood makes the rivers, his hair becomes the grass, his breath the wind and his voice the thunder.

In these tales &mdash and in particular stories about how new living creatures and the very existence of human beings themselves are formed from the corpse of a god or giant &mdash we can see clear parallels with the literal &ldquodis-membering&rdquo of LUCA from a single mega-organism into disparate creatures of specialized and competing interests. From the ancient unity of this great mother ocean was born, quite literally, the ten thousand (and more!) things.

Ancestor Worship Just Got Nerdy

Mara, Goddess of the Sea by Prairie Kittin (cc) 2012.

Many modern Pagans and polytheists honor the ancestors of their bloodlines and homelands alongside the gods and goddesses of pre-Christian peoples. With the genetic theory of LUCA evolving (no pun intended!) in new and exciting directions, we can see how scientifically viable facts can sometimes support the poetry and insight of the old stories. The possibility of a living mother ocean as our Last Universal Common Ancestor not only blurs the lines between ancestor and deity reverence, but also challenges us to keep a more open mind about the ways in which science and religion can shape and inform each other.

So next time you&rsquore relaxing to the soothing sounds of the ocean&rsquos tides, or marveling at the amazing diversity and interdependence of life on this planet, take a moment to say a prayer for our vast and clumsy Grandmother LUCA, as old and deep as the sea.

What we still need to land on Europa

Not only do scientists need to find a place on Europa’s surface that will be worth studying, they also need to find a place to land that won’t completely destroy the lander upon touch down, Jim Green, NASA’s Director of Planetary Science, told Business Insider.

“Some recent research suggests there may be a lot of penitentes [on Europa],” Green wrote in an email. Penitentes are blades of ice shown in the image below. “Imagine landing on a vast field of tall sharp ice spikes, and remember that at the temperature of Europa ice has the strength of granite.”

What’s more: NASA doesn’t have the technology right now to land anything on Europa even if they wanted to, Green said.

“Unlike Titan [which NASA landed Huygens on in 2005], Europa does not have an extensive atmosphere and therefore we are unable to use parachutes of any kind in the landing process,” Green said in an email. “In order for a lander on Europa to be successful, it must have a completely new design of retro rockets with adequate fuel.”


1. Johnson, R.E. et al (2019) “The Origin and Fate of O2 in Europa’s Ice: An Atmospheric Perspective,” Space Sci Rev (2019) 215:20 DOI 10.1007/s11214-019-0582-1

2. Oza A P et al (2019) “Dusk Over Dawn O2 Asymmetry in Europa’s Near-Surface Atmosphere,” Planetary and Space Science 167 23-32

3. Hand, K. P., Chyba, C. F., Carlson, R. W., & Cooper, J. F. (2006). “Clathrate Hydrates of Oxidants in the Ice Shell of Europa,” Astrobiology, 6(3), 463–482. doi:10.1089/ast.2006.6.463 Davis, J C, (1975) “Minimal Dissolved Oxygen Requirements of Aquatic Life with Emphasis on Canadian Species: a Review,” J. Fish Res. Bd. Can. Vol. 32(12)

4. Danovaro, R., Dell’Anno, A., Pusceddu, A., Gambi, C., Heiner, I., & Kristensen, R. M. (2010). “The first metazoa living in permanently anoxic conditions,” BMC Biology, 8(1), 30. doi:10.1186/1741-7007-8-30

5. Greenberg, R., (2010) “Transport rates of radiolytic substances into Europa’s ocean – Implications for the potential origin and maintenance of life,” Astrogiology Vol. 10, Number 3, 2010. DOI: 10.1089/ast.2009.0386

6. Huang J, et all (2018) “The global oxygen budget and its future projection,” Science Bull.. v63:18 pp1180-1186

7. Vance, S. D., K. P. Hand, and R. T. Pappalardo (2016), “Geophysical controls of chemical disequilibria in Europa,” Geophys. Res. Lett., 43, 4871–4879, doi:10.1002/2016GL068547.

8. Clarke, A C. 2061: Odyssey 3. Ballantine Books, 1987.

Comments on this entry are closed.

“On the planet Ilmatar, under a roof of ice a kilometer thick, a team of deep-sea diving scientists investigates the blind alien race that lives below. . . ”
(“A Darkling Sea”, a sci-fi novel by James L. Cambias)

I’m betting on anaerobic unicellular life in Europa’s ocean Alex. I hope I live long enough to get an answer to this intriguing question. Do you write SF?

I’m betting that there is no any life on/in Europa, but me too want to live long enough to get an direct answer to this question …

@ Gary and Alex T. I too hope to get an answer in my lifetime. The discovery of life would be most exciting, but I suspect it may be absent. I still hold out some hope for life in Mars simply due to its history and proximity to Earth.

Me too , expect at least some news about finding on Mars life signs at least signs of Mars’s life existence in the far past.

Thanks for the Science. However, your fictional interludes remind me a bit of KS Robinson’s Mars Trilogy: you should write an equivalent for Europa (Icy/Green/Blue Europa?): I’d buy the book(s)!

@Gary, Supernaut. No, I don’t write any fiction at all. I don’t have the skill, patience, and dedication to write beyond very short pieces. A snippet of fiction is all I can manage.

That is why you need a co-author. :^)

White Europa: A frozen wasteland of a moon tackled by a few brave and hardy pioneers from Earth, some with questionable pasts. Their struggles, their passions, their political battles with a home world no longer theirs that still wants to control them and every other world in the Sol system. And far below, in the uncharted depths of the alien satellite they call home, hints that they are not alone….

Green Europa: The brave and hardy settlers, having successfully repelled a hostile takeover of their new home by Earth authorities, now plan to truly make Europa their world with an aggressive terraforming scheme. Yet there are some who oppose this effort in the name of the native beings who live in the deep global ocean depths – and may even be intelligent.

A brave young couple, whose families are on either side of the terraforming Europa divide, risk everything – including their growing love – to make contact with the mysterious Europans, who may hold the key to the survival of every living being on this alien moon.

The storm clouds of an ultimate confrontation between the two worlds and two species looms on their metaphorical horizon.

Blue Europa: The conflict between those who would turn Europa into another Earth and those who would keep Europa for the Europans finally comes to a head. Who will master this strange alien satellite, or will their greed and aggression destroy it? What will become of our young couple who now lives among the peaceful and enlightened Europans, who know the secret of their new alien friends that could save not only all those who call this moon home, but the cosmic destinies of every living being in the Sol system and beyond!

Even more importantly, will their epic story get a nice, juicy Hollywood contract?!

See? Easy. Now for when you write about that other life-promising moon with the water and geysers….

White Enceladus: A frozen wasteland of a moon tackled by a few hardy pioneers from Earth. Their struggles, their passions, their political battles with a home world no longer theirs that still wants to control them and every other world in the Sol system. And far below, in the uncharted depths of the alien satellite they call home, hints that they are not alone….

LOL. Have you tried pitching this to KSR wannabes? )
Now that I think about it, very few stories have been set on Europa… What about a story from the POV of the Europans – more James Tiptree Jr, maybe even Cordwainer Smith?

I have indeed considered a story set on Europa from the perspective of the natives. I think it will be rather short…

The intelligent beings of the alien moon called Europa have existed for eons in peace and harmony with their environment, a massive global ocean of liquid water many miles deep beneath the icy surface of the radiation-shrouded Galilean satellite.

Then one day an expedition of humans from the planet Earth arrives at their world and encounters the aquatic Europans. These strange bipedal creatures share their entire history using a medium the Europans are eventually able to decipher.

The Europans subsequently construct a giant black monolith and place it on the surface of their moon, where it broadcasts on a loop that their world is permanently off-limits to any and all talking primates hailing from Sol 3.

They also launch some fish-type animals from their ocean into orbit around the moon to distract the humans long enough so they can find an even deeper level to hide.

Excellent reading, thanks Alex. Regarding those ruddy red pigments that accompany the cracks on Europa, do we know if that is the same organic-rich material called tholins that occurs on many other deep space/ancient objects?

It would be interesting if the red material was like the tholins on comets. However, it seems it is more likely irradiated salts. This is why it is so important that we get samples from the plumes and eventually the surface to analyze.

Regarding the reddish brown lines on Europa, I remember reading an article about the possibility that microbes were responsible.

Here is the link, a bit dated but still interesting.

“Streaks of reddish-brown color highlight cracks in Europa’s outer layer of ice. Some scientists have speculated that microorganisms suspended in Europa’s ice may be the cause of these colorations”.

A thoughtful and thought-provoking piece. Thank you, Alex – and our host Paul.

If biological life as we know it is in consideration, then it may have a fastidiousness at its abiogenesis that precludes its appearance in austere environments. Energy would seem to be a critical issue, varying from too much too close to the host star to too little at a great remove. Whether or not forms of life that are less demanding at abiogenesis could exist, remains among the unknowns. Extending our biology to other parts of the solar system would be in consonance with its growth imperative.

Unless one is of the belief that terrestrial life (especially humans) is a cancer, then spreading our life to other worlds (and habitats) is a worthy goal, IMO. If we take a very long view, seeding the galaxy (and the universe?) with terrestrial life should give rise to incredible diversity as life evolves on different worlds in different ways. Our distant descendants could live in a galaxy with a huge diversity of life forms with varying levels of intelligence. Whether they could determine if it meant abiogenesis was common, or it was due to [directed] panspermia would be an interesting question, one that we may face ourselves when we start to obtain samples of life from exoplanets.

Just wondering if they used an angled surface for impingement and sputtering of ions as surfaces are rarely flat in the atomic world. Angled sputtering yields higher numbers of secondary particles, the surface of Europa is expected to also be very rough with sharp structures.

Pupil size surprisingly linked to differences in intelligence

A Harvard professor's study discovers the worst year to be alive.

The Triumph of Death. 1562.

  • Harvard professor Michael McCormick argues the worst year to be alive was 536 AD.
  • The year was terrible due to cataclysmic eruptions that blocked out the sun and the spread of the plague.
  • 536 ushered in the coldest decade in thousands of years and started a century of economic devastation.

The past year has been nothing but the worst in the lives of many people around the globe. A rampaging pandemic, dangerous political instability, weather catastrophes, and a profound change in lifestyle that most have never experienced or imagined.

But was it the worst year ever?

Nope. Not even close. In the eyes of the historian and archaeologist Michael McCormick, the absolute "worst year to be alive" was 536.

Why was 536 so bad? You could certainly argue that 1918, the last year of World War I when the Spanish Flu killed up to 100 million people around the world, was a terrible year by all accounts. 1349 could also be considered on this morbid list as the year when the Black Death wiped out half of Europe, with up to 20 million dead from the plague. Most of the years of World War II could probably lay claim to the "worst year" title as well. But 536 was in a category of its own, argues the historian.

It all began with an eruption.

According to McCormick, Professor of Medieval History at Harvard University, 536 was the precursor year to one of the worst periods of human history. It featured a volcanic eruption early in the year that took place in Iceland, as established by a study of a Swiss glacier carried out by McCormick and the glaciologist Paul Mayewski from the Climate Change Institute of The University of Maine (UM) in Orono.

The ash spewed out by the volcano likely led to a fog that brought an 18-month-long stretch of daytime darkness across Europe, the Middle East, and portions of Asia. As wrote the Byzantine historian Procopius, "For the sun gave forth its light without brightness, like the moon, during the whole year." He also recounted that it looked like the sun was always in eclipse.

Cassiodorus, a Roman politician of that time, wrote that the sun had a "bluish" color, the moon had no luster, and "seasons seem to be all jumbled up together." What's even creepier, he described, "We marvel to see no shadows of our bodies at noon."

. that led to famine.

The dark days also brought a period of coldness, with summer temperatures falling by 1.5° C. to 2.5° C. This started the coldest decade in the past 2300 years, reports Science, leading to the devastation of crops and worldwide hunger.

. and the fall of an empire

In 541, the bubonic plague added considerably to the world's misery. Spreading from the Roman port of Pelusium in Egypt, the so-called Plague of Justinian caused the deaths of up to one half of the population of the eastern Roman Empire. This, in turn, sped up its eventual collapse, writes McCormick.

Between the environmental cataclysms, with massive volcanic eruptions also in 540 and 547, and the devastation brought on by the plague, Europe was in for an economic downturn for nearly all of the next century, until 640 when silver mining gave it a boost.

Was that the worst time in history?

Of course, the absolute worst time in history depends on who you were and where you lived.

Native Americans can easily point to 1520, when smallpox, brought over by the Spanish, killed millions of indigenous people. By 1600, up to 90 percent of the population of the Americas (about 55 million people) was wiped out by various European pathogens.

Like all things, the grisly title of "worst year ever" comes down to historical perspective.

Where in the Solar System Are We Most Likely to Find Life?

Last week, NASA announced one of its most exciting missions in recent memory: a plan to visit Europa, one of Jupiter's largest moons. Previous research has shown that the moon is covered with water ice, and may contain a liquid ocean underneath its surface—raising the tantalizing possibility that Europa could harbor life.

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In recent years, the remarkable number of planets we've discovered orbiting distant stars (1780, at latest count) has shifted the focus of the search for extraterrestrial life to other solar systems. But these planets are far, far away, so it would likely take thousands of years to reach even the closest ones.

With the Europa announcement, it's worth remembering that there are a number of destinations here in our own solar system that we could visit (with unmanned probes) during our lifetimes and perhaps find life. Here's our rundown of the best bets:

A number of missions, including the 1995 flyby of the unmanned probe Galileo, have provided data on Europa that have led scientists to some interesting conclusions. Its surface is made of water ice, but is surprisingly smooth—it has a number of cracks, but very few craters—suggesting that the ice is likely of a relatively young age, and is continually reforming over time, erasing the effects of asteroid impacts.

A close-up of lineae on Europa's surface. (Image via Wikimedia Commons/NASA)

Moreover, analysis of Europa's lineae (dark fractures that crisscross the ice's surface) shows that they're gradually moving, perhaps evidence of tectonic activity or volcanic eruptions underneath. If true, this activity could provide enough heat to generate a liquid ocean underneath the ice.

The hypothetical combination of volcanic activity and liquid water has prompted some scientists to speculate that Europa could harbor life, perhaps similar to the ecosystems on Earth that crop up around seafloor hydrothermal vents and flourish in the absence of sunlight.

Last year, data from the Hubble telescope indicated that in some spots, enormous jets of water are actually shooting out through small holes in Europa's icy surface. If NASA really does send a probe to the moon sometime during the 2020s—still a big if, due to the realities of government spending on space—it could fly through these jets and collect samples to search for extraterrestrial life.

Enceladus, Saturn's sixth-largest moon, is also home to a liquid water ocean. (Image via NASA/JPL/USGS)

Saturn's moon Enceladus is tiny: Its diameter is about four percent that of Earth's, about the width of Arizona. But in recent years, scientists have become convinced that the minute moon is about as likely to harbor life as Europa, for largely the same reason—it appears to contain a liquid water ocean under a cover of ice. 

In 2008, NASA's Cassini-Huygens probe detected plumes of salty water vapor shooting out from the moon's south pole, and further analysis of the plumes confirmed the presence of organic molecules such as carbon, nitrogen and oxygen, thought to be necessary for life. Instead of a thick cap of ice, similar to the one found on Europa, Enceladus has a thinner coating of ice mixed with crust, and the speed at which these plumes were moving (upwards of 650 miles per hour) strongly suggest that they're being shot out from a liquid ocean present at the moon's southern pole.

The presence of liquid water—perhaps due to heating caused by the moon's natural radioactivity—along with rock, ice and vapor has led scientists to hypothesize the existence of a long-term water cycle, in which vapor is shot upward, settles back down to the planet's surface and condenses into a liquid, circulates deep into the moon's crust and then rises back to the surface over hundreds of thousands of years. This could hypothetically circulate the organic molecules over time, making the existence of microbial life on the tiny moon that much more likely. 

The Cassini-Huygens probe is schedule to pass by the moon several times in 2015, but there are currently no plans to send a specialized probe that could land on its surface, or sample the water vapor plumes for evidence of life.

Mars' thin atmosphere, as seen from low orbit. (Image via Wikimedia Commons)

Because of its close proximity, we know more about Mars than any of the other destinations on this list, and much of what we've found is encouraging. Data from the Curiosity rover and other unmanned probes have provided evidence that the planet once featured flowing liquid water and freshwater lakes on its surface. The planet currently has permanent ice caps on each of its poles that are largely composed of water ice, and the soil contains about one to three percent water by mass, although it's bound to other minerals and thus inaccessible. There's also some evidence that the planet's crust might feature traces of organic compounds.

The one thing we haven't found, though, is indisputable evidence of life, either current or historical. Previous claims of microbial fossils found on meteorites that originated on Mars have been debunked, and all the soil and rock samples that our probes have analyzed have failed to provide a clear signature of any life form. Other aspects of Mars that seem to make current life unlikely are its extremely thin atmosphere (too thin to substantially protect against radiation from space) and its extreme cold (average surface temperature: -82ºF), which prohibits liquid water from forming at the surface.

Still, some scientists believe that the historical evidence of liquid water suggests that Mars was once much more hospitable than it is today. Studies indicate that the planet likely once had a magnetic field, which could have protected against radiation and also helped preserve a thicker atmosphere against the erosional force of the solar wind. This atmosphere could have insulated the planet, raising temperatures to levels high enough to produce liquid water, the key to fostering microbial life.

We currently have two rovers exploring and sampling Mars, along with plans to send yet-more sophisticated probes and perhaps even a manned mission in the future. If life did once exist on Mars and left any evidence, with luck we'll eventually discover it.

Io, Jupiter's moon, has extremely high levels of volcanic activity, which could have provided the heat to sustain life sometime in the past. (Image via NASA / JPL / University of Arizona)

Jupiter's third-largest moon, Io is incredibly volcanic: With more than 400 active volcanoes, it's believed to be the most geologically active body in the solar system. All this activity has produced a thin gas atmosphere, mostly made up of sulfur dioxide, with traces of oxygen.

In some areas of the surface, it also produces heat. Regions near volcanoes have been found to be as hot as 3000ºF, while other areas average about -202°F, meaning that some areas could persist at a happy medium that's conducive to life.

Unfortunately, Io isn't nearly as likely to harbor life as Europa or Enceladus for a few reasons: It hasn't been found to have organic chemicals or water (either in a liquid or solid state), and and it orbits within a ring of radiation (called the Io plasma torus) surrounding Jupiter, formed by ionized gas from Io's own volcanoes, that would likely kill anything.

However, some scientists believe that Io could have harbored life long ago and that it could even persist deep under the moon's surface. Computer simulations of the formation of Jupiter's moons suggest that Io formed in an area with plentiful liquid water. This, combined with its heat, could have fostered the evolution of life. Io's plasma torus would have destroyed all life (and all surface water) within㺊 million years or so of the moon's formation, but it's possible that some could have migrated underground into the moon's lava tubes and been sustained by the energy released by volcanic activity.

If life does live on Io, it'll likely be some time before we can find it, as we'd need to land a probe on the moon's surface and drill into its interior to discover it. Building and successfully landing a probe that carries equipment to drill more than a few inches down is still far beyond our capabilities.

Titan, Saturn's largest moon, has a thick, chemically active atmosphere. (Image via NASA/JPL/Space Science Institute)

In terms of life, Titan—the largest moon of Saturn—has one thing going for it that none of the other destinations do: a thick, chemically active atmosphere. The moon's atmosphere is denser than Earth's, and the upper levels are mostly composed of nitrogen, with small amounts of methane and oxygen. This is encouraging, as life (at least on Earth) requires an atmosphere for protection from radiation and for the circulation of organic compounds.

For years, though, scientists dismissed the possibility of life on Titan because of its extreme cold. Distant from the Sun and without enough volcanic activity to significantly warm it, the moon's average surface temperature is �°F, far too cold to allow for liquid water, and life as we know it.

More recently, though, using the Cassini-Huygens probe, scientists have observed liquid lakes on the moon's surface, likely made of hydrocarbons such as ethane or methane. It would look radically different from life on Earth, but it's possible these lakes could harbor life that lives in a hydrocarbon medium instead of water.

There's even speculation that the moon's methane-rich atmosphere is actually the result of life: Normally, the chemical is degraded by sunlight, but if organisms on Titan emitted methane as part of their metabolism, as many microbes on Earth do, it could continually replenish the atmosphere's stock of it.

There has been some talk of sending a "splashdown" probe to explore the surface lakes of Titan, but there are no current plans to do more than examine it from afar with the Cassini probe.

About Joseph Stromberg

Joseph Stromberg was previously a digital reporter for Smithsonian.

Here’s Why We Need to Find Alien Life: Neil deGrasse Tyson Explains

Dr. Neil DeGrasse Tyson, director of the Hayden Planetarium and host of the recent Cosmos reboot, would like to know within 50 years if there’s any life in our backyard—Mars, Europa, Enceladus, Titan, etc.

It’s an ambitious goal, certainly, but it’s one that’s seconded by the foremost space agencies in the world, and is a major cornerstone of NASA’s astrobiology program.

And there’s every reason to be optimistic that Dr. Tyson’s hopes may be realized within the time frame he’s set. There’s been a frenetic spate of intensive astrobiological research throughout the solar system in recent years and the pace of activity is only set to increase as time goes on.

There are many robotic craft operating on (or in) orbit about Mars, the prime focus in the search for extraterrestrial life within our solar system the Curiosity rover expands our knowledge of Martian geology and history daily, and the twin rovers Spirit and Opportunity have been exploring the Red Planet for over 12 years.



Elsewhere, plans are in the offing for missions to explore whatever might lie beneath the shifting ice-plates of Jupiter’s moon Europa, or whatever sub-surface ocean feeds the ice-geysers of Saturn’s moon Enceladus and Saturn’s other intriguing moon, the smog-shrouded Titan, has long been a target for astrobiologists, with its weird weather, geology, and “hydrologic cycle” based on methane and ethane.

But for Dr. Tyson, the pursuit of alien life—and the discovery of a truly independent lineage of living things within our solar system—is one of the most important goals of modern science, and for a host of reasons.

A Diversity of Samples

Right now, our understanding of life is extremely limited, and that is because we have only one sample to study—our own, terrestrial life. We may marvel at the enormous diversity life has attained, in the multitude of permutations earthly life has expressed throughout the vast gulfs of geological time, and in the many different environments it has adapted to thrive in.

But it all has one thing in common—a single origin in deep time, and the use of nucleic acids to mediate replication and transmit heredity.



But if we could find a type of life within our solar system that was not “encoded”—that is, did not use DNA or RNA or any other macromolecule to register biological information—then we could be sure that this life possessed “an entire other genesis,” completely independent of terrestrial life.

“Can you even define your sample if it only exists as one?” Dr. Tyson asks. “Scientifically, generally you want multiple examples of something to say ‘here’s what they have in common, here’s what’s different, here’s what really defines it, and here’s what doesn’t.’”

In other words, life as we currently understand it is an anomaly, and almost impossible to truly define for lack of sufficient samples. Our definition of life amounts to…well, you know, things that are alive, and stuff.

But such a vague and nebulous answer doesn’t cut it with Dr. Tyson. He wants something scientifically rigorous and exact.



“Does life require liquid water?” he asks, rhetorically. “No, because this one is using liquid ammonia. Does it require a sun? No, because this one is getting energy from volcanoes—whatever! I’m making this up, of course.”

But he makes an important point.

“You can’t claim to fully understand your sample unless you have a diversity of kinds of samples.”

Perhaps, in the next fifty years, all our efforts will pay off, and we’ll finally discover—whether in a Martian crater, or in a Europan ocean, or in a frigid Titanian lake of hydrocarbons—one of Dr. Tyson’s extraterrestrial samples. And then we can get down to the business of figuring out what life really is.

Location Analog to Europa Found in Canada

Since a spacecraft meant to discover life on the Jovian moon Europa is in the works, testing to see which methods of doing this are the most efficient is essential for a successful mission. A location that provides a similar environment has been discovered at Borup Fjord Pass, in the Canadian High Arctic.

This location is a frozen fjord that features a highly-sulfurous environment, similar to what astronomers believe the icy Jovian moon has to offer. By studying how extreme bacteria survive here, experts may get an idea of what to expect when they visit the celestial body.

Discovering a place here on Earth where ice and sulfur come together was not an easy task. Chemical emissions in the Borup Fjord Pass were recently demonstrated to fulfill the necessary conditions for selection. From a satellite, the location displays a similar appearance to that of Europa's surface.

Both NASA and the European Space Agency (ESA) are currently in the process of preparing missions headed for Europa. Both will focus on finding biosignatures, subtle indicators that life either exists, or is possible, on the surface of the large moon.

&ldquoWe have discovered that elemental sulfur (S) can contain morphological, mineralogical and organic 'biosignatures' linked to bacterial activity. If they are found on Europa, this would suggest the possible presence of microorganisms,&rdquo expert Damhnait Gleeson tells SINC, quoted by Astrobiology Magazine.

Gleeson was the lead author of a new study detailing the findings, which is published in the latest issue of the Astrobiology Journal. He is currently a member of the Centro de Astrobiologia (INTA-CSIC).

Needle- and rhomboid-like sulfur shapes were found to contain the mineralized remains of microorganisms and some extracellular materials, and so scientists hope that they will find something similar on Europa as well. However, this will not be an easy task.

It could be that all microorganisms on the moon, if any, are located inside the alleged underground ocean that lies beneath tens of miles of granite-strength ice. Drilling all the way to this location is impossible with current technologies.

Europa is similar to other moons in the solar system &ndash a thick ice crust covering a supposed liquid ocean &ndash such as Saturn's Enceladus and Jupiter's Ganymede.