Our Place in Space: The Rocket Equation

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, R is for…


Are you bad at math?  That’s okay.  I’m bad at math too.  I try to avoid talking about math on this blog because I know a lot of my readers are still traumatized by high school math classes, but also because I don’t feel I’m qualified to explain math anyway.  So in today’s post, we’re going to talk about what the rocket equation means and why it’s so important without talking about what the rocket equation actually is or how it works.

As you know, you need fuel to go to space.  If you’re a rocket scientist, the rocket equation tells you how much fuel you need to reach any specific destination in space.  You want to travel from Earth to the Moon?  Plug some numbers into the rocket equation, and the equation will tell you how much fuel you need.  Want to go from the Moon to Jupiter?  Plug new numbers into the equation, and it’ll tell you how much fuel you need for that trip.  It always ends up being an absolutely ridiculous amount of fuel.

When you see space vehicles sitting on the launch pad, something like 85% to 90% of the mass of that space vehicle is fuel.  The rocket equation demands that it be so.  For the sake of comparison, fuel makes up about 30% to 40% of the mass of an airplane, or about 4% of the mass of a car.  NASA famously refers to this as “the tyranny of the rocket equation,” because NASA is the American space agency, and whenever Americans don’t like something that call it tyranny.

With a little creative engineering, rocket scientists can make marginal improvements to a rocket’s fuel efficiency—a 1% or 2% improvement, perhaps!  But that’s about it.  The rocket equation is unforgiving, and it offers very little wiggle room.  In other words, the rocket equation means that space exploration is super expensive, and it always will be, unless and until we invent some totally new Sci-Fi propulsion system that no longer requires rocket engines.

As a science fiction writer, I’m perfectly happy to dream up propulsion systems that ignore the rocket equation.  But for the purposes of this “Our Place in Space” series, I’m trying to stick to more realistic science, which means that the distant future we’ve been exploring in these blog posts is still very much constrained by the rocket equation.

We humans can still do a lot under those constraints.  We can get to the Moon (we’ve done it before!), and we can get to Mars and the asteroid belt as well.  Most of the outer Solar System is within our reach—in time, perhaps the entire outer Solar System could be ours.  But there are limits.  So long as we’re still using rockets for space travel, there will always be limits on how far humans can go.

Want to Learn More?

Check out NASA’s “The Tyranny of the Rocket Equation” article, which goes into more detail about why the rocket equation matters.  There’s also some colorful language in there about “revolting against tyranny.”

And for those of you who do want to see the math, here you go.  Enjoy!

Our Place in Space: Quaoar

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, Q is for…


Ceres is a dwarf planet located in the asteroid belt.  In early 2015, Ceres became the first dwarf planet ever visited by a space probe from Earth.  Later that same year, New Horizons conducted its now famous flyby of Pluto, making Pluto the second dwarf planet we’ve visited.  So that leads to an obvious question: which dwarf planet do we want to explore next?  Well, there’s a chance it might end up being Quaoar.

Quaoar (pronounced either as kwa-war or kwa-o-ar) was discovered in 2002 by astronomers at the Palomar Observatory in southern California.  It’s named after the Tongva god of creation, the Tongva being an indigenous people native to southern California.  At the moment, we know that Quaoar is a Kuiper Belt Object, just like Pluto.  We also know that it’s about half the size of Pluto, that there’s signs of water ice and methane ice on its surface, and that it has at least one moon, named Weywot (the son of Quaoar, according to Tongva mythology).

So what makes Quaoar so special?  Why would we visit Quaoar next, rather than Orcus, Sedna, Eris, or the many other strange and mysterious dwarf planets we now know are out there?  The answer is simple: location, location, location.

Just as the Moon orbits the Earth, and just as the Earth orbits the Sun, the Sun orbits the central mass of our galaxy.  That means the Sun—and our whole Solar System, in fact—is moving through space.  Right now, there are at least two mission proposals to explore the interstellar space that lies directly ahead of our Solar System.  Coincidentally, Quaoar happens to be located near the “front” of our Solar System.  So if we’re launching space probes to explore the space directly ahead of our Solar System, it just makes sense to visit Quaoar on the way.

One of those mission proposals is American.  The other is Chinese.  I have no idea if or when either of these missions will get to fly.  It would be nice if both happen.  It would create an opportunity for American and Chinese scientists to coordinate their efforts and compare notes on what they learn about Quaoar, and later about the interstellar medium that lies ahead of our Solar System.  Such cooperation often occurred, even at the height of the Cold War, whenever American and Soviet space probes happened to visit the same planet at about the same time.  Space exploration has a way of bringing countries together.

Want to Learn More?

Here’s the proposal for the U.S. mission that would visit Quaoar, and here’s an article from Space News about the mission China is considering.

Our Place in Space: Phobos

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, P is for…


Buzz Aldrin.  He walked on the Moon.  He also has ideas about how to get humans to Mars.  We talked about one of those ideas earlier this month, and now we’re going to talk about another.  What if, rather than going straight down to the surface of Mars, we first set up a little base for ourselves on Phobos, one of Mars’s two moons.

Whenever you want to land on a planet (or a moon), you’ll have to fight against gravity to do so.  That is assuming, of course, that you want to land safely.  Crashing into a planetary body is fairly easy.  Landing safely—that’s the hard part!  You need to control your descent.  If you’re controlling your descent using rocket engines, you’re going to use up a whole lot of fuel in the process.

But as you can see in this highly technical diagram, Phobos is very small.

Okay, maybe not that small.  But still, Phobos is much smaller than Mars, and Phobos’s surface gravity is significantly less than the surface gravity on Mars.  That means a rocket controlled descent onto the surface of Phobos will use up less fuel than a rocket controlled descent all the way down to the surface of Mars.

In his book Mission to Mars: My Vision for Space Exploration, Aldrin argues that we should set up a way station on Phobos before attempting to land humans on Mars.  From this Phobos way station, astronauts could get an up close and personal view of Mars.  They could get the lay of the land without actually landing.  Using remote controlled robots, they could explore the Martian surface and prepare the way for future missions.  And on the off chance that we discover alien life on Mars (current life, I mean, not fossils), then our astronauts on Phobos could study that life from afar without risking any sort of biological contamination.

Personally, I’m not 100% sold on this idea.  I kind of feel like if we’re going to go to Mars, let’s just go to Mars.  But Buzz Aldrin is Buzz Aldrin, and I’m just some guy with a blog.  The thing about the fuel costs for landing on Phobos vs. landing on Mars makes sense to me.  And if it does turn out that there’s life on Mars, contaminating the Martian ecosystem with our Earth germs (or having Mars germs contaminate us) does become a serious concern.

But otherwise, do we really need a way station on Phobos?  Is that a necessary prerequisite to landing humans on Mars?  I don’t know.  Maybe it would be helpful.  When the time comes, maybe we really will go to Phobos first and land on Mars later.  It’s possible.

Want to Learn More?

Once again, I’m going to recommend Mission to Mars: My Vision for Space Exploration by Buzz Aldrin.  Lots and lots of ideas in that book about how we might one day travel to Mars and what we might do once we get there.

Our Place in Space: The Outer Space Treaty

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, O is for…


Believe it or not, human law does extend to outer space.  There are international agreements in place saying what is and is not legal in space.  And these agreements go back decades.  It all started with the Outer Space Treaty of 1967.  Every nation with a space program has signed on to the Outer Space Treaty, and many nations that do not currently have space programs have signed on as well.  Today, the Outer Space Treaty is regarded as the founding document—the Magna Carta, of sorts—for all of space law.

According to the treaty, any human who goes to space shall be considered an “envoy of mankind,” and all space agencies around the world shall have a responsibility to avoid the “harmful contamination” of any alien environments they wish to explore.  Provisions like that reflect the idealism of the 1960’s, I feel, but there are also provisions that reflect the deeper fears and anxieties of that time.  Most notably:

  • No nuclear weapons in space.
  • Seriously, no nation may put nuclear weapons in space.  Ever!
  • No nation may use the Moon or any other celestial body for military purposes.
  • No nation may claim ownership of the Moon or any other celestial body.
  • Did I mention this already?  I may have mentioned this already, but it’s really important: NO NUCLEAR WEAPONS IN SPACE!!!

The good news is there are no nuclear weapons in space.  By all accounts, every nation involved in space exploration has followed the rules the Outer Space Treaty established (or at least no one has ever blatantly violated the treaty).  But will that continue to be the case going forward?

Of late, some concerns have been raised.  You see, when the treaty was written, it was assumed by everyone that governments would be in charge of space exploration, not private companies.  It was assumed that the people who go to space would be highly trained astronauts, not private citizens engaged in space tourism.  So should space tourists be considered “envoys of mankind”?  Are private companies allowed to claim ownership of celestial bodies?  And do private companies have any legal obligation to avoid “harmful contamination” of alien environments?  The Outer Space Treaty is a little unclear about those issues.

As I said, the Outer Space Treaty reflects the idealism of the 1960’s and also the fears and anxieties of that time.  I imagine that, sooner or later, there will be new treaties and new agreements to address the concerns of today.  The Outer Space Treaty of 1967 may be considered the founding document for space law, but it is not the final word on space law.

We live in an ever changing world.  Laws need to be updated to keep up with the times.  That’s been true for all of recorded history.  It’s still true today, and it will continue to be true even in the distant future when humanity is spreading out across the Solar System.

Want to Learn More?

Here’s an article from The Conversation on the Outer Space Treaty and some of the concerns that have been raised in recent years about it.

Our Place in Space: NIAC

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, N is for…


So far this month, we’ve talked about some pretty wild ideas for future missions in space.  We’ve talked about building an elevator to space.  We’ve talked about putting a radio telescope on the far side of the Moon.  We’ve talked about sending astronauts to Callisto, one of the moons of Jupiter, and exploring the hydrocarbon lakes on Titan (a moon of Saturn) using a robotic submarine.  As crazy as these ideas may seem, they’ve all received some amount of funding from NASA through a program called NIAC.

NIAC stands for NASA Innovative Advanced Concepts (yes, it’s an acronym that contains another acronym inside it).  NIAC is basically a program that awards grant money to researchers who are testing the limits of what we can do in space using current technology or who are developing new technologies that might one day revolutionize space exploration.  If you ever hear on the news that NASA is funding some project that sounds a little too Sci-Fi to be true, it probably just means that NASA gave somebody some NIAC funding for their research.

I once heard NIAC described as a high-risk/high-reward program.  Many NIAC projects probably won’t work out.  Some of these things really are too Sci-Fi to be true.  But what if a few NIAC projects do work?  What if some crazy idea that sounds like pure science fiction actually works!?!  Even if only a few NIAC funded projects do come to fruition, they could change everything for NASA.  More than that, they could change everything for human civilization.

I’m no expert on finances.  I’m certainly no expert on how the U.S. federal budget works.  I do know that space exploration is expensive.  Very expensive.

I also know that NASA does what it does within a very strict and rather inflexible budget.  I’m actually really impressed that NASA manages to do so much cool science stuff on such a tight budget.  This may seem weird, but I often ask myself “What would NASA do?” when I have to make difficult spending decisions.

Most NIAC projects are definitely not ready to fly and probably won’t be ready to fly for quite a few years to come.  But it makes sense to start planning for the future now.  It makes sense to do some of the research now that could help make a more Sci-Fi future become a reality.  That’s really what NIAC is all about.

Want to Learn More?

Wikipedia has a pretty thorough list of all the research projects that have received NIAC funding over the years, up to 2020.

Additionally, here’s a listing of NIAC funded projects from 2021, and here’s the listing for 2022.

Our Place in Space: The Moon Village

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, M is for…


The last time humans went to the Moon, it was motivated in large part by the Cold War.  Yes, there were scientific and humanistic reasons to go to the Moon as well, but the Cold War was a big part of it.  There’s no denying that.  Let’s hope that next time will be different.  Let’s hope that next time, human beings will set foot on the Moon as a result of international cooperation, rather than as a result of quasi-militaristic competition.

A few years ago, the European Space Agency proposed building a “village” on the Moon.  This International Moon Village would serve as the logical successor to the International Space Station.  Anyone and everyone who wanted to participate would be welcome to participate in the Moon Village program.  As the E.S.A.’s website explains it:

By “Moon Village” we do not mean a development planned around houses, some shops and a community centre.  Rather, the term “village” in this context refers [to] this: a community created when groups join forces without first sorting out every detail, instead simply coming together with a view to sharing interests and capabilities.

It’s hard to say at this point what the Moon Village would look like.  A lot depends on who decides to participate.  A lot also depends on how the various participants want to use the Moon Village once it is built.  The proposal is very open ended about this stuff.  Government run space agencies could join the program.  So could private companies.  The Moon Village could be used for purely scientific and technological research.  At the same time, it could also be used for economic interests, such as mining the Moon for resources.  Even space tourism would be welcome.

When the Moon Village was first proposed a few years ago, my understanding was that the Russian space agency was going to be a key player in this project.  That’s… ummm… I’m guessing that’s no longer the case.  I’m also a little unclear about whether or not the United States is involved.  It sometimes sounds like NASA’s Artemis Program and E.S.A.’s Moon Village Project are totally working together; other times, it sounds like Artemis and the Moon Village are two completely separate and unrelated projects.

Despite all that, and despite everything else happening in the world today, I get the sense that E.S.A. is still moving forward with their Moon Village plans.  This is a project that really could happen, and I really hope that it does happen.  Anyone who wants to participate in the Moon Village is welcome to participate in the Moon Village.  No one will be excluded.  No one will be left out.  Those are the kind of values humanity needs right now, and in the future, those are the kind of values that will help us secure our rightful place in space.

Want to Learn More?

Check out this brief statement from Jan Woerner, the Director General of E.S.A., describing what the Moon Village would be like and how it might be used.

Our Place in Space: Lava Tube Habitats

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, L is for…


The surface of Mars is not a safe place for humans.  Martian dust storms can be really scary.  The temperature fluctuates wildly from a bit too cold to waaaaay too cold, and there’s basically no protection against all the deadly radiation raining down on the planet from space.  Fortunately, humans in the distant future won’t need to live on the surface of Mars.  Mars is offering us free housing in the form of underground lava tubes.

Mars was once a volcanically active world.  In fact, the largest volcano in the entire Solar System is on Mars.  Lower gravity means volcanoes can grow much larger on Mars than they ever could on Earth.  But Mars hasn’t been volcanically active for a long, long time.  The volcanos stopped erupting and the lava stopped flowing billions of years ago.  Today, all those oversized Martian volcanoes are extinct, and all the lava tubes around them are now empty.

So what exactly is a lava tube?  Well, have you ever seen rivers of lava (either in real life or in videos) flowing down the side of an active volcano?  You know how the surface of these lava rivers starts to cool off, forming a blackened crust?  Eventually, this crusty surface lava will become thick enough and solid enough to form a roof over the lava river, while the rest of the lava continues to flow freely underneath.  This is how lava tubes form.

On Earth, lava tubes can get pretty large.  They can be wide enough and tall enough for multiple people to walk through them comfortably.  On Mars, lava tubes could (theoretically) be even larger—almost half a kilometer wide, perhaps!  Once again, this is because of the reduced Martian gravity, which allows all sorts of natural structures to grow larger on Mars than they ever could on Earth.

In the future, sections of these lava tubes could be sealed off and pressurized with air.  Dust storms could rage on the Martian surface while human colonists remain safely underground.  All that natural rock would insulate us against the extreme temperature variations on the surface, and the rock would also serve as a natural barrier against all that radiation raining down from space.  With relatively little effort, we could convert the smaller lava tubes into comfortable and cozy human habitats.  Or, using those half kilometer-wide tubes, we could build much larger and more robust human communities.

At the moment, though, finding lava tubes that would be suitable for human habitation is tricky.  Lava tubes are underground.  Therefore, fully intact lava tubes are not visible in photos taken by our orbiting space probes.  The only Martian lava tubes we currently know about are the ones where the roof has either partially or fully collapsed.  This leaves us with a bit of a Catch-22 scenario: any lava tube we can currently find is structurally compromised and, therefore, might not be suitable for human habitation.

But that seems to me like a limitation of our current Mars exploration program.  As NASA, the E.S.A., and other human space agencies send more and more orbiters, landers, and rovers to Mars, I’m sure new techniques (seismography, gravity mapping, etc.) can be used to find all the lava tubes hidden beneath the Martian surface.

Want to Learn More?

Here’s a short paper advocating for more research about lava tubes on Mars and also on the Moon.

And here’s a ten minute video from Fraser Cain describing what we currently know about Martian and Lunar lava tubes in more detail.

Our Place in Space: Kraken Mare

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, K is for…


Earth is a pretty special place, what with all this liquid water covering our planet’s surface.  You won’t find that much liquid water on the surface of any other planet or moon in the Solar System (underground, maybe, but not on the surface).  In a similar way, Titan is a special place.  Titan, the largest moon of Saturn, is covered with lakes and rivers of liquid hydrocarbons, a mix of mostly liquid methane and liquid ethane.  You won’t find that much liquid methane/ethane on the surface of any other world in the Solar System.

Kraken Mare is the largest body of… I wanted to say the largest body of water, but that wouldn’t be right, would it?  Kraken Mare is the largest body of liquid hydrocarbons on Titan.  Take all five of North America’s Great Lakes, combine them together—that’s how large Kraken Mare is.  Titan is much smaller than Earth, so Kraken Mare ends up being an enormous surface feature, sprawling across part of Titan’s northern hemisphere.

And nobody knows how deep Kraken Mare is.  Scientists were able to measure the depth of every other lake on Titan using RADAR data collected by the Cassini space probe, but the data for Kraken Mare was inconclusive.  This means either that Kraken Mare is too deep for Cassini’s RADAR equipment to measure, or some unknown substance at the bottom of Kraken Mare absorbed Cassini’s RADAR pings, limiting the data Cassini was able to collect.  Either way, wouldn’t it be fascinating to know what’s down there?

NASA seems to think so, and there are proposals on the table to send some sort of robotic submarine to Titan, to explore Kraken Mare further.  This is another of those space missions that is not actually happening yet.  It has not been approved by NASA.  It does not have the funding to go forward.  But still, it’s an idea that scientists are working on, trying to figure out if it’s feasible, with the hope that someday they can make it happen.

Could there be life on Titan?  Maybe.  Some astrobiologists clearly think it’s possible, though they probably aren’t expecting to find an actual kraken at the bottom of Kraken Mare.  Just some single-celled organisms doing some strange, alternative form of organic chemistry.  Still, that possibility is there, and it’s another reason why diving to the bottom of Kraken Mare seems like a good idea.

Fortunately, NASA has approved a new mission to explore Titan.  Unfortunately, this new mission does not include a submarine, and it won’t be going anywhere near Kraken Mare.  Instead, the Dragonfly  rotorcraft (a robotic mini-helicopter) will explore Titan’s Shangri-La region, a mysteriously dark colored region near Titan’s equator.

Meanwhile, the proposal to put a robotic submarine in Kraken Mare is still on the table.  Sooner or later, that mission is going to happen.  I’m sure of it.  Kraken Mare is simply too big and too mysterious for us humans to leave it unexplored.

Want to Learn More?

Here’s a short article from NASA, which includes a short video, on the Titan Submarine proposal.

And here’s a longer piece from EarthSky.org with more details about Kraken Mare and how we might one day explore its depths.

Our Place in Space: Jezero Crater

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, J is for…


Someday, I’d like to help dig up dinosaur fossils.  That’s apparently a thing pretty much anybody can volunteer to do.  Someday, I’d also like to live on Mars.  In the distant future, it may be possible to do both of those things.  Places like Jezero Crater on Mars may be full of ancient Martian fossils!

If you look at satellite images of Jezero Crater, it’s pretty obvious it used to be full of water.  You can see what appears to be a dried-up river bed snaking its way across the Martian landscape.  Where that river meets the crater, there’s a breach in the crater wall and a large river delta where the river would have spilled into the crater basin.

Right now, NASA’s Perseverance Rover is driving around that river delta, scoping the place out, examining the sediments and clays found in the region.

Okay, I may have taken some creative liberties with the cartoon above.  If life ever did evolve on Mars, it would have been short-lived.  All of Mars’s lakes, rivers, and oceans would have dried up fairly early in the planet’s history.  It is highly unlikely that anything as complex as fish or seaweed could have developed, and there certainly wouldn’t have been anything as awesome as a Martian dinosaur.

But in places like Jezero Crater, simple microorganisms could have been plentiful.  These microbes may even have joined together, creating larger structures like the bacterial mats we sometimes find here on Earth.  That’s kind of icky, I know, but it could have happened, and those bacterial mats may still be there, preserved as fossils beneath all that red dust.

I don’t expect questions about life on Mars (past or present) to be answered any time soon.  Even if one of our Mars rovers did stumble upon something that looked like a fossilized bacterial mat, there would be scientific debates for years—decades, even—over what that fossil-looking-thing really is and what it’s presence on Mars really means.  We’ve been through this before, when scientists found “bacteria shaped objects” inside a Martian meteorite.  Something can look like a fossilized bacterium, and yet not be a fossilized bacterium.

But someday in the distant future, we will know, one way or the other, if life ever existed on the Red Planet.  And perhaps in that distant future, humans living on Mars will volunteer to help dig up fossils in Jezero Crater, or other places very much like it.

Want to Learn More?

Here’s an interactive map from NASA showing the Perseverance Rover’s current location.  You’ll have to zoom out a little to see all of Jezero Crater.  If you do, you’ll see that the dried-up river (marked Neretva Vallis) and river delta I mentioned are pretty obvious.

And here is a NASA press release from a few years back, announcing Jezero Crater as the Perseverance Rover’s landing site and explaining why the crater was selected.

Also, here’s an article from Space.com about that Martian meteorite I mentioned, the one with those “bacteria shaped objects” inside.

Our Place in Space: An Immature Technosphere

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, I is for…


In a previous post, I told you about the DART Mission, our first real experiment to see if we can defend our planet from incoming asteroids.  I believe humanity has a tremendous responsibility to protect our planet, not only for our own benefit but for the benefit of the entire Earthly biosphere.  Incoming asteroids can do serious harm to Earth’s biosphere (just ask the dinosaurs).  But, of course, there are other threats to the biosphere that should concern us—more immediate and urgent threats, too.

The term “immature technosphere” is mainly associated with SETI research.  Imagine, if you will, a planet that is home to alien life.  Over cosmic timescales, we might expect this hypothetical alien planet to go through several phases of development.

Phase One: The Immature Biosphere
Life has begun!  The first microorganisms are swimming around in the planet’s water (or whatever liquid this planet has instead of water).  But biological activity produces biological waste, in one form or another, so as these early organisms multiply and spread, they may end up poisoning their own environment with their own waste products.

Phase Two: The Mature Biosphere
Life has found a way.  A variety of organism have now evolved, and the waste produced by one organism serves as fertilizer, food, or fuel for others.  A natural balance has been achieved.  Natural cycles have emerged.  Life not only survives but thrives!

Phase Three: The Immature Technosphere
Intelligent life has emerged, by which I mean life capable of creating and using technology.  But as these intelligent life forms begin using technology on a grander and grander scale, they may inadvertently disrupt the natural cycles and the natural balance of their world.  Life is threatened once again, this time by technological waste.

Phase Four: The Mature Technosphere
If intelligent life is truly intelligent, it will recognize the harm it is doing to its own environment and start inventing ways to undo that damage, or at least to keep the damage in check.  In time, perhaps a new balance will be achieved, with nature and technology working together in harmony.

Turning our attention back to Earth, I think it’s fair to say our planet is in the “immature technosphere” phase of development.  But an immature technosphere today implies that a mature technosphere may develop later on, and that gives me hope.

I keep saying that this “Our Place in Space” series is a highly optimistic view of humanity’s future.  Part of what I mean by that is that we will not leave Earth behind.  We will not make a new home for ourselves on the Moon or Mars or elsewhere after destroying our first home here on Earth.  I doubt that that would work anyway; any off-world colony we might establish would still be dependent on Earth for a long, long time to come.

I know a lot of people who see the state of the world and despair.  Things are bad right now, and some of the damage we are doing to our planet and to each other cannot be undone.  But a better future is still possible.  Humanity just needs a bit more time to mature.

Want to Learn More?

Earth in Human Hands by David Grinspoon is one of my all time favorite books.  It’s certainly my #1 favorite non-fiction book.  As an astrobiologist, Grinspoon has more knowledge and authority on scientific matters than I do, but his view of the future is much like the view I’ve been presenting in these A to Z Challenge posts.

So if you’re worried about the state of the world and you want to believe that a better and brighter future is still possible, I highly recommend picking up Grinspoon’s book.