Tag: Astrobiology

Fly or Die: How Life on Venus Might Survive

~ J.S. Pailly ~ 2 Comments

Hello, friends!

So I recently found this 100% totally legit JWST image of Venus, revealing some of the weird and scary chemistry that happens in Venus’s atmosphere.  As you can see, Venus sure does love chemicals.  Super noxious, super toxic chemicals.  With all those noxious and toxic chemicals in her atmosphere, you’d think Venus must be a pretty unlikely place to find life.

Now add in a runaway greenhouse effect that makes the surface of Venus hotter than the daytime surface of Mercury.  Now add in atmospheric pressure that rivals the deepest, most-submarine-crushing depths of Earth’s oceans.  Now add in some sort of volcanic activity (the specifics of which remain mysterious) that seems to sporadically spread fresh lava over nearly the entire planet’s surface.

So yes, Venus is an unlikely place to find life.  Venus is among the least likely places in the whole Solar System to find life.  And yet, the possibility of life on Venus does come up in the scientific literature from time to time.  So how would that work?  How could living things survive on a planet so infamously hostile to life?

Have you ever heard the expression “sink or swim”?  Well, if any sort of life exists on Venus today, its motto must be “fly or die.”  Everything about Venus is dangerous and deadly, but the most dangerous and deadly conditions are found at the planet’s surface.  So if you’re a Venusian life form, don’t go to the surface.  Stay aloft in the atmosphere.  At an altitude of about 55 kilometers up, you should be safe safe-ish.  The global lava floods (however frequently or infrequently that happens) will be far below you.  The extreme pressure and temperature will be far below you as well.  You’ll still have to deal with all those scary chemicals in the atmosphere, but if you’re clever (or rather, if evolution is clever for you) some of those scary chemicals might be usable to you as nutrients.

If the idea of perpetually airborne life—of life that never, ever touches the ground—seems farfetched, then I need to tell you that microorganisms can and do live in the upper reaches of Earth’s atmosphere.  That’s not an ideal environment for them.  They’d much rather be down on the ground, where water and nutrients are more plentiful.  But microbes can survive way up there, if they have to.  Earth has a whole “aero-biosphere” of airborne microbes that scientists are only just beginning to understand.

And if Earth has an aero-biosphere, then maybe (maybe!) Venus could have some sort of aero-biosphere, too.  It may not be likely, but it’s not totally impossible.

WANT TO LEARN MORE?

Here’s a link to diagram, originally from a paper on the possible habitability of Venus, showing what the life cycle of Venusian airborne microbes might be like.

And here’s a short press release from the Johns Hopkins Applied Physics Laboratory (A.P.L.) describing the so-called “Venus Life Equation,” which is sort of like the Drake Equation for life in the universe, but for just Venus.

And lastly, regarding the mystery surrounding Venus’s volcanic activity, we know Venus’s surface got “paved over” by fresh lava at some point in the recent past, but we don’t know how frequently this sort of thing happens.  It definitely happened at least one time.  Maybe it’s happened more often than that, or maybe it’s a continuing process that’s still happening today.  Here’s an article from the Planetary Society explaining why the global resurfacing of Venus remains such a big scientific mystery.

P.S.: Okay, I lied.  The image I used at the top of this blog post?  That’s not really from JWST.  Actually, I’m pretty sure JWST cannot safely observe Venus, due to Venus’s proximity to the Sun.  I drew that image myself.  And if you like my drawing of Venus, and if you want to do something to support what I do here on Planet Pailly, please consider visiting the Planet Pailly store on RedBubble.  There, you can buy my “Venus ‘Hearts’ Chemicals” drawing (and other drawings I’ve done) on a T-shirt, pillow case, spiral-bound notebook… personally, I think today’s drawing would look great on a little notebook, maybe for chemistry class!

Never Say Never: Life on Ancient Venus

~ J.S. Pailly ~ 9 Comments

Hello, friends!  Today’s post is about the planet Venus, but the real lesson today is this: never say never.

Could Venus have supported life at some point in the past?  Yes.  In theory, yes.  Despite being closer to the Sun than Earth, Venus still orbits within the so-called habitable zone of our Solar System (this depends a little on whom you ask; some sources say Venus is inside the habitable zone while others will tell you she’s skirting the habitable zone’s edge).  So it is plausible that, at some point in the distant past, Venus could have had more Earth-like temperatures and more Earth-like surface conditions.

But then something went catastrophically wrong.  Carbon dioxide gas somehow started accumulating in Venus’s atmosphere.  Carbon dioxide is naturally good at trapping heat, so rising CO2 levels caused the temperature to also rise.  Rising temperatures caused more CO2 to outgas from the planet’s crust.  The outgassing of more CO2 caused the temperature to rise further, which caused more outgassing of CO2, which caused temperatures to rise further, which caused more outgassing of CO2, which caused… you get the idea.  This process is known as a runaway greenhouse effect.

Cartoon of Venus, looking eager, and Earth, looking shocked, as Venus says, "Oh, Earth! I used to have 'organisms' crawling on me, too. But then I filled my atmosphere with CO2, triggering a runaway greenhouse effect. That killed everything!"

I don’t think anyone knows for certain what started the runaway greenhouse effect on Venus (or at least, I’ve read many different ideas about what the initial cause might have been).  All we know for certain is what Venus is like today: hell.  Insane heat.  Insane atmospheric pressure.  Insane levels of CO2 plus insane weather, most notoriously sulfuric acid rain.  I think it’s safe to say that no planet in the Solar System is more hostile to life as we know it than modern day Venus.

But the runaway greenhouse effect was not the only catastrophe to befall Venus.  Venus also experienced something called a global resurfacing event.  Resurfacing may sound like something you’d do to a parking lot, but when we’re talking about planets, resurfacing means spreading fresh lava over a planet’s surface, essentially paving over whatever surface features might have been there before.

So could Venus have supported life at some point in the past?  Sure.  It’s possible.  But this always seemed like an untestable hypothesis to me.  The runaway greenhouse effect would have killed everything (well, almost everything… see my post script), and the global resurfacing event would have paved over any fossils or other evidence of past Venusian life.  So if there ever was life on Venus, we’d never know about it.  Never.

We now come to the “never say never” part of today’s post.  On Venus, there are patches of rough terrain called tesserae (singular, tessera).  As longtime readers of this blog know, Venus is my favorite planet, so naturally I have heard about the tesserae on Venus before; however, I was previously led to believe tesserae were formed by thrust faults, volcanic eruptions, or some other relatively modern geological activity.  But recently, I read a research paper that mentioned, rather casually, that tesserae might also be the remnants of ancient continental crust jutting up above the otherwise smooth, resurfaced landscape.

So the tesserae we see today could be ancient Venus’s version of the Rocky Mountains, the Alps, or the Himalayas.  They are (or were) the highest of high elevation regions on ancient Venus—regions high enough to survive the global resurfacing event.  If true, then the tesserae of Venus may preserve some hard evidence of what Venus used to be like before the runaway greenhouse effect and the global resurfacing event wrecked the place.

So was there ever life on Venus?  It’s possible, but we don’t know for sure.  I once resigned myself to the belief that we could never know, but you should never say never.  Signs of ancient water and ancient life may be preserved on Venus after all, just waiting for us to discover.

P.S.: Some scientists believe there may be life on Venus today.  There is some very circumstantial evidence of microorganisms floating around in Venus’s upper atmosphere.  I do have some thoughts about that, but I’ll save that for another blog post.

Want to Learn More?

Here is the research paper I mentioned that casually mentions tesserae might be the remnants of ancient continental crust.

And here is a paper I found describing possible signs of water erosion on Venus’s tesserae.  Water erosion could not possibly happen on Venus today, so this would be further evidence that tesserae have preserved something of Venus’s ancient history.

And lastly, just because this “tesserae equals continental crust” idea is new to me, that doesn’t mean it’s new to science.  Here’s a paper from 1990 discussing the possibility.  Even if some of the information in this paper is out of date, I think it’s still worth a look, if only to see how much history this idea has.

That Time NASA Discovered Life on Earth

~ J.S. Pailly ~ 10 Comments

Hello, friends!

As some of you may already know, there is life on Earth.  NASA discovered that fact in 1990.  Let me explain.

In the decades prior to the Space Age, certain astronomers had claimed to observe vegetation growing on the Moon, artificial canals on the face of Mars, and some scientists even speculated that beneath the clouds of Venus (which were surely H2O clouds), we might find a world dense with jungle.  Writers and philosophers had long speculated about how other worlds might be populated by other people, and at least a few theologians argued that there must be life on other planets (for why would God create all these planets and then leave them empty?).

And yet, as both the Soviet and American space programs ventured farther and farther out into space, they found nothing.  No vegetation on the Moon (not even on the far side of the Moon).  No canals on Mars.  Definitely no jungles on Venus (and as for Venus’s clouds, it turns out they’re not made of H2O—they’re not made of H2O at all!!!).

I don’t want to make it sound like everybody expected to find life on the Moon, Mars, or elsewhere, but a lot of people were expecting to find life.  So what happened?  Why couldn’t our space probes find life on any of the other worlds of the Solar System?  There were two possible explanations.  Either there was no life out there to find, OR something was wrong with our space probes.  Maybe they weren’t carrying the right equipment to detect life, or maybe they weren’t performing their experiments properly, or maybe they weren’t sending the correct data back to Earth.

Which brings us to 1990.  NASA’s Galileo spacecraft was heading out to Jupiter, but for navigational reasons it needed to do a quick flyby of Earth first.  A certain scientist named Carl Sagan saw this Earth flyby as an opportunity.  What would happen if Galileo did a thorough scan of our home planet?  Could this fairly standard NASA space probe, equipped with a fairly standard suite of scientific instruments, detect life on a planet where we already knew life existed?

The results were published a few years later in a paper entitled “A search for life on Earth from the Galileo spacecraft.”  This “search for life on Earth” paper is my all time favorite scientific research paper.  First of all, for a scientific paper, it’s a surprisingly easy read.  Turns out Carl Sagan was a good writer with a knack for explaining science in a clear and accessible manner.  Who knew?  Secondly, the experiment itself is really cool.  And third, the results of the experiment are a little more ambiguous than you might expect.

Among other things, Galileo detected both oxygen and methane in Earth’s atmosphere.  If you didn’t already know there was life on Earth, it would be difficult to explain how those two chemicals could both be present.  Oxygen and methane should react with each other.  They should not exist together in the same planet’s atmosphere for very long—not unless something unusual (like biological activity) continuously pumps more oxygen and more methane into the atmosphere.

Additionally, Galileo noticed a strange “red-absorbing” substance widely distributed across Earth’s landmasses.  This mystery substance could not be matched with any known rock or mineral, suggesting a possible biological origin.  This red-absorbing mystery substance was, in fact, chlorophyll—the chemical that allows plants to perform photosynthesis.

And lastly, Galileo picked up radio transmissions.  Galileo couldn’t determine the content of these transmissions, but the transmissions were clearly artificial—an indication that there is not only life but intelligent life on Earth.

I’ve read this “search for life on Earth” paper several times over the years.  Like The Lord of the Rings or Ender’s Game, it’s one of those things I love to read again and again, and each time I feel like I get a little more out of it.  The main take away, I have come to believe, is that if there were anything similar—anything even remotely similar—to Earth’s biosphere on the Moon or Mars or anywhere else in the Solar System, we would know about it.  Our space probes would absolutely be able to detect something like that.

However, there’s still a lot of stuff here on Earth that the Galileo probe missed.  Some little details, for example: chlorophyll absorbs both red and blue light, but Galileo apparently didn’t notice the blue absorption.  Only the red.  And Galileo overlooked some big things, too.  Cities, roadways, the Great Wall of China?  Maybe a follow-up mission to Earth would find those things, but Galileo didn’t see any of that stuff.  And then there’s Earth’s oceans.  Galileo couldn’t detect anything beneath the surface of the water.  Water very effectively blocked all of Galileo’s sensors.

So our space probes are not fundamentally flawed, but they do have a few blind spots.  Today, no one expects to find jungles on Venus or canals on Mars.  Our space probes say those things aren’t there, and we can be confident that our space probes are working properly.  But there are a few niche environments out there were alien life might still be hiding.

WANT TO LEARN MORE?

Science communicators (myself included) dumb things down for their readers, which is why reading actual scientific papers has become an important part of my research process.  Dumbed down science is fine, provided it still says what the actual scientific research says.  But reading these sorts of papers is a skill, and it takes some time and practice to do it.  If you’ve ever wanted to start reading scientific papers for yourself, “A search for life on Earth from the Galileo spacecraft” by Carl Sagan et al. is a good starter paper.

Are We Alone in the Universe?

~ J.S. Pailly ~ 16 Comments

Hello, friends!

I have only recently returned to regular blogging, and in several recent posts I’ve alluded to the fact that I’m planning to take my Sci-Fi writing in a new creative direction.  A lot of things are changing for me right now.  A lot of the things I’m doing (or trying to do) are new.  With that in mind, I feel like this is a good time to restate some of my views and beliefs about science and the universe, starting with my views and beliefs about extraterrestrial life.

When people ask “Do you think we’re alone in the universe?” I get slightly annoyed by that question.  It’s too big a topic to reduce to a simple yes or no question.  In Humanity’s search for extraterrestrial life, there are really three kinds of life we might find out there:

Microbial Life: Almost as soon as Earth existed, terrestrial microorganisms existed, too.  Microbes developed so swiftly and so easily on this planet that the same thing must have happened elsewhere.  For this reason, I believe extraterrestrial microorganisms are plentiful across the cosmos.

Multicellular Life: Complex multicellular organisms—fish, plants, bugs, etc—exist on Earth due to a happy accident.  About 2.4 billion years ago, some of Earth’s microbes started burping up oxygen.  To those microbes, oxygen was a waste product, but that waste product could also be used in biochemical reactions to create energy.  Lots of energy.  Enough energy to make complex multicellular life possible.  If multicellular life requires this sort of happy accident in order to exist, then I suspect multicellular life must be rare across the universe.

Intelligent Life: I’m going to define intelligence as the ability of a species to make and use tools, to communicate complex ideas, and to generally improve upon its knowledge and technology over time.  As far as we can tell, life like that only evolved one time on our planet.  Given the vastness of the entire universe, I think intelligent life must exist elsewhere, but I also think it must be extremely rare.

Some time around 1950, nuclear physicist Enrico Fermi famously asked “Where is everybody?” in reference to alien life.  As Fermi saw it, advanced alien civilizations should be out there, and their activities in space should be obvious to us.  And yet when we look out into the universe, we see nothing.  This apparent contradiction—aliens should be everywhere, and yet they seem to be nowhere—is today known as the Fermi Paradox.

So I guess my answer to questions like “Where is everybody?” or “Are we alone in the universe?” depends on what kind of alien life we’re talking about.  If we’re talking about alien microorganisms, I think they’re plentiful, and I think it’s only a matter of time before we find evidence of alien microbes on Mars or on one of the icy moons of the outer Solar System.  If we’re talking about multicellular life, that sort of life is rare.  And intelligent life must be rarer still—so rare, in fact, that our nearest intelligent neighbors may be hundreds, thousands, or even millions of lightyears away.

But these are just my opinions.  My opinions about this topic have changed over time, and as I keep learning, my opinions and expectations will, no doubt, change again.

So, friends, what are your opinions and expectations concerning extraterrestrial life?  Do you think I’m on the right track, or is there something I’ve missed that you think I should learn more about?

Sciency Words: Flora and Fauna

~ J.S. Pailly ~ 11 Comments

Hello, friends!  Welcome to another episode of Sciency Words, a special series here on Planet Pailly where we talk about the definitions and etymologies of science or science related terms.  In today’s post, we’re talking about two words:

FLORA AND FAUNA

So this weekend, I was thinking about alien life, as I often do, and it occurred to me that the words “plant” and “animal” are woefully inappropriate words to apply to extraterrestrial organisms.  That got me wondering if maybe the words “flora” and “fauna” would be better.

This is hardly a revolutionary insight.  Arik Kershenbaum talks about this in his book The Zoologist’s Guide to the Galaxy.  You see, in the cosmic sense, when we’re considering life across the entire universe, the words “plant” and “animal” are highly Earth-specific terms.  Strictly speaking, plants are organisms belonging to the kingdom Plantae, and animals are organisms belonging to the kingdom Animalia.  These kingdoms are two branches of the tree of life—Earth’s tree of life.  Not Mars’s tree of life.  Not Proxima b’s tree of life.  Earth’s.

Extraterrestrial life forms would belong to the kingdom… who the heck knows?  I guess astro-taxonomists will have to figure that out if/when extraterrestrial life is discovered.  In the meantime, would it make sense to use the words “flora” and “fauna” as generic terms for plant-like and animal-like aliens?  Initially I thought it would, but after doing some research, I’m not so sure.

Definitions of flora and fauna: In ecology, the words flora and fauna refer to all the plants and animals, respectively, found within a particular ecological region.

Etymologies of flora and fauna: The word “flora” traces back to the Latin word for flower.  Fauna comes from the name of an ancient Roman goddess of fertility.

So the words flora and fauna are not exactly synonyms for plants and animals; however, they do include the words “plants” and “animals” in their definitions.  And extraterrestrials, no matter how plant-like or animal-like they may be, would still have to be categorized as something else.

I still feel like referring to alien life forms as flora and fauna is better than calling them plants and animals.  Or at least it’s less wrong.  But it’s still not perfect.  In a distant, Sci-Fi future, new terminology may need to be invented.

WANT TO LEARN MORE?

I highly recommend reading The Zoologist’s Guide to the Galaxy by Arik Kershenbaum.  Obviously we do not know at this point what alien life might be like, but, as Kershenbaum argues, we can make some educated guesses based on the way life on Earth does (or does not) work.

Sciency Words: Critical Zone

~ J.S. Pailly ~ 2 Comments

Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we take a closer look at the definitions and etymologies of science or science related terms, in order to expand our scientific vocabularies together.  In today’s post, our Sciency Word is:

CRITICAL ZONE

So I could make this post about climate change, but I won’t.  Certain people would just get angry with me in the comments, and I’m not in the mood for that today.  So instead, I’m going to talk about Earth’s “critical zone” as something that could be relevant to astrobiological research.

Definition of Critical Zone: In Earth sciences, the critical zone is the surface and near surface environment of our planet—in other words, it’s the part of our planet where life lives.  The proper scientific study of Earth’s critical zone will require an interdisciplinary approach, combining geology, biology, hydrology, and other related fields.

Etymology of Critical Zone: The term was first introduced in 1998 by American sedimentary geologist Gail Ashley.  She called it the critical zone because, in her words, “it’s critical for life” and also because it is “critical to know more about it.”  (Source: see the Eos article in the links below.)

Here’s a fun fact that I like to share at parties: there are somewhere between four and five thousand different minerals found here on Earth.  Four to five thousand!  Other planets in our Solar System are known to have only a few hundred, at best.

Why is Earth so mineralogically diverse?  Plate tectonics, for one thing.  Liquid water plays an important role as well.  Some minerals can only form in the presence of liquid water.  But the biggest factor, by far, is life.  Living things do lots of weird chemistry, and all that weird chemistry messed with the planet’s soil and bedrock. Earth’s biosphere affects Earth’s geology.  And Earth’s geology, in turn, affects Earth’s biosphere.  There’s a synergistic relationship between living things and non-living rocks on this planet—and that is what the concept of Earth’s critical zone is all about.

I feel this is a terribly important concept to understand as it relates to Earth.  It’s also something worth bearing in mind as we think about other worlds out there, worlds which may or may not support life of their own.

WANT TO LEARN MORE?

I’m going to recommend this article from Eos, entitled “Critical Zone Science Comes of Age.”  I think that article is a pretty good summary of how critical zone research started and how it’s going, and it includes some quotes from Gail Ashley explaining what she was thinking about when she originally coined this term.

I’m also going to recommend this brief article entitled “‘Critical Zones’ on Mars and Across the Solar System,” which attempts to adapt the concept of the critical zone for other worlds.

And if you want to read more about why Earth is so mineralogically diverse, here’s a piece from EarthDate.org entitled “Minerals Evolve, Too.”

Our Place in Space: Xanadu

~ J.S. Pailly ~ 4 Comments

Hello, friends!  Welcome to Our Place in Space: A to Z!  For this year’s A to Z Challenge, I’ll be taking you on a partly imaginative and highly optimistic tour of humanity’s future in outer space.  If you don’t know what the A to Z Challenge is, click here to learn more.  In today’s post, X is for…

XANADU

`Titan is the largest moon of Saturn.  It’s a very cold place.  It’s so cold on Titan that water is basically a kind of rock, and certain chemicals that we typically think of as gases (i.e.: methane and ethane) flow freely as liquids.  As a result, the surface of Titan looks surprisingly similar to some regions on Earth: a rocky landscape eroded by rain and rivers.  Except the “rock” is frozen water, and the rain and rivers are a mix of liquified methane and ethane.  One of the most curiously familiar “rock” formations on Titan lies near the equator.  It’s called Xanadu.

Xanadu is an Australia-sized region of craggy hills and mountains.  Due to Titan’s thick, hazy atmosphere, it’s impossible to see Xanadu (or any other surface feature on Titan) except in certain specific wavelengths, such as certain wavelengths of infrared.  When Xanadu is visible, it appears as a bright splotch on Titan’s surface, surrounded by much darker desert terrain.

It’s unclear how Xanadu came to be.  One hypothesis I read argues that Xanadu could be associated with some sort of giant impact event.  Perhaps a large asteroid or comet smashed into Titan, disrupting the icy crust, which then refroze as this jagged and craggy terrain.  Another hypothesis suggests that Xanadu was created by some sort of tectonic activity—a fascinating possibility.  At this point, Earth is the only world confirmed to have plate tectonics.

In this Our Place in Space series, I’ve tried to emphasize all the cool and exciting things humans could do in the distant future.  I have also mentioned, from time to time, my belief that humans in the distant future will learn to be good stewards of the Earth.  Space exploration can help us do that.  Titan is so curiously familiar, yet also so weirdly different from Earth.  Trying to understand why Titan is so different-yet-similar can teach us much about our own world—which, in turn, will help us figure out how to take better care of our planet.

But there’s a catch.  Just as we have a responsibility to take better care of Earth, we also have a moral responsibility to not mess up Titan.  Remember Titan’s thick, hazy atmosphere?  There are some weird chemicals forming in that atmosphere.  Organic chemicals.  Could those organic chemicals be associated, in one way or another, with biological activity?  Maybe.  Maybe not.  No one can say at this point.

In the next few years, NASA will be sending a robotic helicopter to explore Titan’s Shangri-La region, one of the dark-colored regions directly adjacent to Xanadu.  If we’re lucky, maybe that robo-helicopter will venture into Xanadu at some point.  I have confidence that NASA will thoroughly sterilize all of their equipment before sending it to Titan to ensure that we do not contaminate Titan with our Earth germs.

There will be many more missions to Titan in the future.  Just as Mars is crawling with Mars rovers today, Titan will be covered in Titan rovers, Titan helicopters, and Titan submarines in the future.  The place has too much in common with Earth, and we simply cannot leave it unexplored.  But humans in the distant future will not only be good stewards of the Earth; they’ll be good stewards of the Solar System.  And so, whether we’re exploring Xanadu or Kraken Mare or Shangri-La, or any other region on Titan that has a super cool name, strict safety precautions will always be a must.

Want to Learn More?

I had a really hard time finding information about Xanadu for this post.  I’m guessing that’s because very little information is available at this time.  More exploring needs to be done! What I did find came from these three scientific papers:

Our Place in Space: The Wilderness

~ J.S. Pailly ~ 8 Comments

Hello, friends!  Welcome to Our Place in Space: A to Z!  For this year’s A to Z Challenge, I’ll be taking you on a partly imaginative and highly optimistic tour of humanity’s future in outer space.  If you don’t know what the A to Z Challenge is, click here to learn more.  In today’s post, W is for…

THE WILDERNESS

All month long, I’ve been telling you about how, in the distant future, human civilization will spread out far and wide across the Solar System.  At the same time, I have rather casually been declaring various places in the Solar System should be off limits to humans.  I feel perfectly justified in doing that after reading a certain research paper titled “How much of the Solar System should we leave as wilderness?”

I’m not going to summarize that paper in its entirety.  If you want to learn more, you can check out the links in the “Want to Learn More?” section below.  The main point I want to talk about, based on what that “wilderness” paper said, is that the Solar System is absolutely ginormous.  You may think you understand how big the Solar System is.  However big you think it is, it’s probably bigger than that.

As a result, we can declare insanely large swaths of territory and resources “protected wilderness” without inconveniencing ourselves.  The paper advocates for establishing a one-eighth principle, meaning that our future space economy should be restricted to using only one-eighth of the resources in our Solar System.  The remaining seven-eighths would be off limits.  To quote from the paper:

We are required, as a point of social ethics, to accept reasonable constraints upon our self-interest in order to meet basic standards of justice between one another and (arguably) between ourselves and future generations.  This is a precondition of having any sort of stable and lasting human society.  However, we will take it that a livable ethic for society at large cannot ask for too much.  More precisely, a reasonable social ethic cannot ask for anything so demanding that it is impossible, inconsistent with what we know about human psychology, or otherwise so demanding that it belongs only in the domain of private sacrificial commitment of a sort associated with political and religious ideals.  The one-eighth restriction may seem to fall foul of this constraint.

Yes, the one-eighth principle sounds very demanding and restrictive at first glance.  But, as the authors of that paper go on to explain, the Solar System is really big.  Even if we make some highly optimistic assumptions about how fast the future space economy might grow, it would still take centuries to use up a full eighth of the Solar System.

This wilderness paper is now one of my all time favorite scientific research papers.  It does make some important warnings for the future, though, and if you’re a fan of the kind of futurism I’ve been touting in this Our Place in Space series, I’d encourage you to check out the links below.

In the meantime, I declare that the rings of Saturn should be off limits to mining operations.  Let’s preserve the natural beauty of those rings.  Parts of Mars should be off limits as well—if we find alien life on Mars, perhaps the whole planet should be off limits.  Same for many of the icy moons of Jupiter, Saturn, Uranus, and Neptune—especially Titan, Enceladus, and Ganymede—and most extra especially, Europa.  Seriously, nobody mess with Europa!

Want to Learn More?

Click here to read “How much of the Solar System should we leave as wilderness?”

Or click here to read an article from Live Science summarizing the paper’s main points in less technical language.

Our Place in Space: Callisto

~ J.S. Pailly ~ 18 Comments

Hello, friends!  Welcome to Our Place in Space: A to Z!  For this year’s A to Z Challenge, I’ll be taking you on a partly imaginative and highly optimistic tour of humanity’s future in outer space.  If you don’t know what the A to Z Challenge is, click here to learn more.  In today’s post, C is for…

CALLISTO

The major moons of Jupiter are Io, Europa, Ganymede, and Callisto.  In science fiction, Europa and Ganymede seem to get the most attention.  Sci-Fi writers often end up putting human colonists (or at least a handful of plucky human scientists) on the surfaces of one or both of these icy moons.  But today, I’m going to argue that Callisto would be a far more suitable home for future humans.

First off, and most importantly, there’s the issue of radiation.  The space around Jupiter is one of the most dangerous radiation environments in the entire Solar System.  As you can see in the highly technical diagram below, the radiation is most intense in the vicinity of Io.  The radiation levels get better in the vicinity of Europa and continue to taper off when you reach Ganymede.  You’re still soaking up a lot of radiation, though!  Callisto’s radiation levels, however, are fairly low.  You might even describe the radiation levels on Callisto as “survivable.”

Furthermore, planetary protection laws in the future may mean that both Europa and Ganymede are off limits to human settlers.  Scientists today are 99.99% sure that Europa has a vast ocean of liquid water beneath her surface, and (as you know) wherever there’s water, there may also be life.  There’s evidence suggesting Ganymede may have a subsurface ocean, too.  Europa is often said to be the #1 most likely place where we might find alien life here in the Solar System.  While the odds of finding life on Ganymede are considerably lower, the possibility of Ganymedean life shouldn’t be ignored.

There are already international agreements in place regarding extraterrestrial life.  Space agencies like NASA, the E.S.A., and others are legally obligated to do everything they can to protect suspected alien biospheres from our Earth germs (and also to protect Earth’s biosphere from any germs we might find in outer space).  For obvious reasons, these international agreements haven’t exactly been tested in court, and it’s a little unclear how they would be enforced.

But in a future where human civilization is spreading out across the Solar System, I’d imagine bio-contamination laws would become stronger, not weaker.  Europa would almost certainly be declared off-limits to humans, unless it is proven beyond a shadow of a doubt that no aliens currently live there.  Ganymede may end up being off-limits, too, for the same reason.

Meanwhile, we have Callisto.  Scientists who want to study possible biospheres on Europa and Ganymede could set up a research station on Callisto.  From there, they could keep a close eye on the other moons of Jupiter.  They could operate remote-controlled probes to explore Europa and Ganymede without risking contamination, or they could go on brief excursions to Europa and Ganymede themselves (taking proper safety precautions, of course).  While they’re at it, these scientist could also explore Io.  Io is the most volcanically active object in the Solar System.  There is virtually no chance that we’ll find life there, but studying Io’s volcanoes would still be interesting.

I’d be remiss if I didn’t mention this: Callisto might have liquid water beneath her surface, too.  Not as much liquid water as Ganymede, and nowhere near as much as Europa, but still… it’s possible.  Which means there’s a slim possibility that there could be life on Callisto.  But in Callisto’s case, it is a very slim possibility.  Based on what we currently know about Jupiter’s moons, Callisto still seems like the best place for humans to live.  The radiation levels are much lower, the risk of bio-contamination is negligible…  Yeah, if I were a science fiction writer, I’d put my human colonists on Callisto.

Want to Learn More?

In 2003, NASA published a plan to send astronauts to Callisto, with the intention of using Callisto as a base of operations to explore the other Jovian moons.  Click here to read that plan.  Some of the information is out of date, of course, but it’s still got some interesting ideas.  Maybe someday, something like this plan could work!

I’d also recommend this article on Planetary Protection Policy, covering some of the rules that are already in place to protect planets and moons where we might find alien life.

P.S.: If I were a science fiction writer…?  Wait a minute, I am a science fiction writer!  Click here if you want to buy my first book.  It’s not set on Callisto, unfortunately, but it’s still a fun story.

Arguing with Myself: The Search for Alien Life

~ J.S. Pailly ~ 24 Comments

Hello, friends!

So a certain argument has been playing out in the back of my mind for a long, long time now.  Whenever I write, there are really two different versions of me who do my writing.  On the one hand, there’s science enthusiast me.  On the other, there’s Sci-Fi author me.  And these two versions of me view science, space exploration, and the universe at large in dramatically different ways.  One of the biggest ongoing disagreements I have with myself involves alien life.

Science enthusiast me believes that extraterrestrial microorganisms are pretty common in the universe.  Science enthusiast me thinks we will find evidence of extraterrestrial microbes in the very near future, perhaps hiding under the ice on Mars or swimming around in the oceans of Europa, Enceladus, or even Titan.  (I almost wrote unambiguous evidence there, but science enthusiast me also expects that confirming the discovery of extraterrestrial microbes will be tricky—just ask the researchers who found (or thought they found) microfossils inside a Martian meteorite back in 1996).

As for complex multicellular life—plants and animals, or whatever the extraterrestrial equivalent of plants and animals might be—science enthusiast me is far less optimistic.  While microorganisms have proven again and again that they can survive almost anything, even direct exposure to the vacuum of space, multicellular organisms seem to be far more fragile, far less resilient.  Earth may be one of the very few worlds where complex, multicellular organisms like us are able to survive and thrive over cosmic timescales.

And intelligent life?  Science enthusiast me believes intelligent life must exist elsewhere in the universe—surely it must!  But the universe is an awfully big place.  Our nearest intelligent and communicative neighbors could be many galaxies away.  Humanity is not alone in the universe, according to science enthusiast me, but we may as well be.

Sci-Fi author me, however, sees things from a different perspective.

Sci-Fi author me wants to write stories where encounters with alien life are commonplace, almost routine—stories where the aliens are sometimes friendly and sometimes not so friendly—stories where all sorts of weird and wacky interspecies adventures are possible!  And Sci-Fi author me takes a particular and peculiar pleasure in handwaving away all the concerns and objections science enthusiast me might have, not just regarding alien life but also in relation to faster-than-light travel, time machines, cybernetics, et cetera, et cetera.  Part of the fun, for Sci-Fi author me, is thinking up clever excuses for why impossible things are now possible (in the context of the story world, at least).

So there is this ongoing argument happening in the back of my mind.  This argument is never going to end, and I’ve decided that that’s okay.  Not every argument needs to have a winner and a loser, nor do arguments necessarily need to end in compromises.  Sometimes a house divided can stand after all.  Science enthusiast me believes the universe is like this; Sci-Fi author me would prefer (for story reasons) if the universe were more like that.  And the tension between these two different versions of myself drives my creativity, both as a science blogger and a science fiction writer.

P.S.: For those of you who might be interested, both the “I Heart Science” and “I Heart Sci-Fi” designs in this post are available in my RedBubble store.  Click here if you heart science, or click here if you heart Sci-Fi.  And remember: nobody’s stopping you from clicking both if you heart both!