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A Recap of the Mars Terraforming Debate (nautil.us)
104 points by rbanffy 32 days ago | hide | past | favorite | 300 comments

There's a fantastic novel series that starts with Red Mars, by Kim Stanley Robinson. It follows a series of the first colonizers of Mars, and every time it shifts perspective it dives into a new science/technology frame.

For a few chapters you are following an engineer, and it talks about the alloys and techniques she's using to build housing. A little while later you follow a geologist and the topic shifts a bit as this geologist goes out exploring.

You follow biologists, psychologists, economists, and each time it dives into the challenges they have in how they perceive Mars and what to do with it.

Inevitably, there's a conflict between the "Reds" and the "Greens". Given the series titles (Red Mars, Green Mars, Blue Mars), I'm sure you can figure out who wins. However, it seems to suggest a result that I find fairly likely -- it doesn't matter what you say we should do with Mars, people are going to do what they want. We already don't care about externalities here on Earth, there's no way we can police them on Mars.

That said, while I used to be a huge fan of the idea of colonizing Mars, I've swung around to the idea that colonizing asteroids is far more interesting. Mars is relatively resource poor, and asteroids are incredibly resource rich. There are some kilometers wide balls of iron, nickel, and platinum group metals out there. Not to mention water and carbon. All the materials you'd need to undertake construction in space and none of the challenges of having to lift it into orbit.

On the contrary, Mars has all the resources of asteroids but the advantage of a water cycle that has concentrated and reformed minerals like on Earth. The ability to process the atmosphere directly is a massive and under-rated advantage. MOXIE proves it’s not just possible but feasible to generate fuel (carbon monoxide) and oxidizer (oxygen) from the Martian atmosphere, and nitrogen and even a bit of water (hydrogen and oxygen) as well as argon are available anywhere on the planet.

The “let’s just build cylinders” (which I think we should eventually do!!) often strikes me as a knee jerk contrarian position, an attempt to avoid hard questions about environment, and a “grass is always greener in fields further in the future and with less solid understanding.”

Planetary bodies with water cycles (or a history of them) are rich. Airless bodies have massive difficulties that are often handwaved away.

And now we have powered flight (without needing propellant) demonstrated. Mars really is a much better place to establish a permanent human presence.

Building 'cylinders' gives us an environment that's a lot easier to control, manage and safeguard compared to a whole planet. Most planets will be entirely hostile to complex earth based life to begin with. They'll require either complex terraforming or some sort of isolated environment, and that's not even bringing up issues concerning gravity.

Furthermore, in future wars planets would also be far easier, bigger and immovable targets compared to asteroids and space-stations. Just look up what happens when you drop a 10ton tungsten rod from outer-space. Thanks to gravity, when it hits the ground it has the same impact of a small nuclear device.

When humanity starts to create colonies outside of earth, I expect most planets will only become fully automated mining colonies. Colonizing planets is a Star Trek fantasy that, most likely, will not be worth it.

> Just look up what happens when you drop a 10ton tungsten rod from outer-space. Thanks to gravity, when it hits the ground it has the same impact of a small nuclear device.

Is that actually true? I mean, you could hoist two and a half of those tungsten rods into LEO with a single Falcon 9 expendable launch, and if we're just looking at kinetic energy, you can't get more out than you put in. So, the tungsten rod's re-entry wouldn't create any more energy than it took to lift it into orbit in the first place (assuming tungsten doesn't do anything weird like combust), and there'd be a lot of energy lost in the process. I wouldn't consider a Falcon 9 launch to be "equivalent to a small nuclear device" in terms of energy.

Another way to look at is is that a 10,000 kg mass at a height of 1,000 km above a planet with gravity of 9.8 m/s^2, is 10,000 * 9.8 * 1,000,000 = 9.8 * 10^10 joules. 1 kilowatt hour is 3.6 megajoules, so that comes out to 27,222 kilowatt hours of energy. A kiloton is (according to a google search) equal to 1,162,200 kilowatt hours, so that comes out to about 0.023 kiloton TNT equivalent. With some of that energy lost as atmospheric heating.

That isn't to say that dropping tungsten rods from orbit isn't a serious threat, or that you couldn't impart a lot more energy by flinging them at the Earth with much greater velocity. I just don't think the comparison to nukes is quite right.

The original idea was dubbed "rods from God" and it was proposed by the U.S. Air Force to target bunkers, silos, and other hardened targets without using nuclear detonations. The rods would have orbital velocity—7 km/s at LEO—giving them, at 10,000kg, about the momentum of a jumbo jet at cruise (an unfortunate comparison, to be sure). Except the kinetic force would be targeted at an area the diameter of a telephone pole, so they would penetrate deeply (100m or more) and cause enough of a shockwave in the earth to collapse almost any buried structure. Their thin profile and solid tungsten construction ensured most of their mass would survive re-entry at close to their original speed.

They also evaded the 1967 Outer Space Treaty, which forbade "objects carrying nuclear weapons or any other kinds of weapons of mass destruction"[0].

I'm not sure they actually reach the yield of a nuclear device, but "bunker-buster" nukes are relying on overkill in yield since they can't achieve that kind of ground penetration in delivery.

[0] https://history.nasa.gov/1967treaty.html

You're calculating the resting potential energy, aren't you?

"Dropping a tungsten rod on earth" is not picking it up and dropping it. It's firing it at the earth. Depending on what body you're firing it from, that's a lot of additional delta v.

Something coming at the earth from the Moon, for instance, is moving at least 2.3 kps, plus another kps if you fire it forward. This calculator is telling me that's 55.2 gigajoules, about 15 thousand times higher.

Assuming your math is right, and then my math is right, .35 megatons is still an exceedingly bad day.

Yeah, I was ignoring sideways velocity. I was taking "just look up what happens when you drop a 10ton tungsten rod from outer-space" perhaps a bit too literally.

If we add in 1/2 * 10,000 kg * (7500 m/s)^2, to account for sideways LEO-equivalent momentum, I have it coming out as about 0.0906 kilotons: about 4 times more energy. Which isn't too surprising, since the hardest part about getting into orbit isn't the going up part, it's the going sideways fast enough enough part.

My whole formula is this: (((10000 * 9.8 * 1000000) + (0.5 * 10000 * (7500 * 7500))) / 3600000) / 1162200

Basically, (mgh + 1/2 mv^2) converted from joules to kilowatt hours to get it into a larger unit I can sort of relate to, and then converting that in turn to kilotons equivalent TNT in order to compare with nuclear yields.

That's assuming I didn't leave off some zeroes somewhere or apply a formula incorrectly.

> Something coming at the earth from the Moon, for instance, is moving at least 2.3 kps, plus another kps if you fire it forward.

What do you mean "fire it forward"? If you fire it forward, it will never fall on Earth. To get from Moon to Earth, you need to fire it backward in Moon orbit, to slow it down. Essentially, you need to slow it down a lot if you want it to get to Earth surface, as opposed to orbiting it alongside Moon.

Not if it’s in an elliptical orbit with a low enough apogee.

10^10 Joules converted to TNT directly is 2 ton TNT. All the energy should be released at the time of impact in a short period of time. Even assuming >50% energy loss due to atmospheric interference, 1ton TNT should be left.

Living in a asteroid belt, makes the poorest person capable of getting a ion-engine on a rock the ruler over all the well-dwellers by default - after all you have the high ground.

Thus speaks the lord thy over-lord:

I. You shall not erect asteroid defences.

II. You shall not send others to space to rule beside me.

III. Once every aeon i shall send a rock to test your faith. You shall fight one another, to proof your worthiness.

IV. Be nice to one another.

V. Game-theory applies, but in a similar way for everyone living in system, to everyone else out-system.

Things are going to get weird once private orgs start doing asteroid redirect activities (as in: massive build up of orbital railguns, hypervelocity nukes etc. once someone points out that in 10 years or 50, it's trivial to setup a rock that'll end a moderate sized nation state).

> Just look up what happens when you drop a 10ton tungsten rod from outer-space. Thanks to gravity, when it hits the ground it has the same impact of a small nuclear device.

That’s... not as good as a nuclear device? Susceptibility to 10 ton tungsten rods is pretty lame to worry about when a 10 ton actual nuclear bomb would be so much worse.

You're missing the point. The point is how easy it becomes to destroy planetary targets once you start having an extra-earth presence as a society. You literally drop heavy stuff from orbit and you have a nuke. You need an actual, guidable, nuke (or self propelled object) to have the same effect on a space station or asteroid.

I don't think Earth is substantially more vulnerable than anywhere else in the solar system.

A heavy object picks up some kinetic energy as it falls into a gravity well, but realistically a tungsten rod moving at orbital velocities could destroy a space station or asteroid habitat just as effectively as it could destroy an Earth target. And there'd be somewhat of a difference: with Earth, we have an atmosphere to slow fast-moving objects down and provide an early warning that something is coming at us. (Probably not enough early warning to do usefully react, but still. A couple seconds is more than 0 seconds, and maybe there's some way to use that to a tactical advantage.) In space you'd have no warning at all, unless you can track it on radar or telescope, in which case Earth could do the same.

Earth's big advantage is that everything we do is so geographically distributed that any damage done is a temporary setback. It would be a sad day, but the human race will go on. Unless it was a really big rock, in which case it would be hard to redirect one into Earth's orbit without anyone noticing.

I suppose if you really want to be protected from flying rocks, the best bet may be to find some moon or minor planet with weak gravity, and tunnel deep into the surface and set up shop there. You could do something similar on Earth, though there's a limit to how deep you can go before it gets too hot. (In Consider Phlebas by Iain M Banks, there is planet whose original inhabitants had built a deep underground subway system where train cars house the military command structure, and in time of war the trains would always be moving around so that a nuclear-armed adversary wouldn't know where to strike. That approach could work too.)

Realistically, though, I think if humanity develops the technology to start moving large heavy objects around the solar system, then almost everyone is going to be very vulnerable. The best defense is to be on friendly terms with all your neighbors, and have very good visibility into where everyone is and what they're doing.

If you live at the bottom of a well, don't make fun of the guy peering down at you from the top.

See also The Moon is a Harsh Mistress

> You literally drop heavy stuff from orbit

If you literally drop something in orbit then it stays in orbit. In order to make it fall to the ground you first need to de-orbit it.

Does that make Tesla a nuclear power though? Or do they need to conduct a test first?

You may not realize it yet, but they've already become our new overlords. Do you think they bothered with getting a certified driving license for that puppet they put in the car they launched a few years back? They don't care about our earther laws. Yet there he is, drifting in space.

I used to be a big fan of space mega constructions until I got further into my engineering career. Now whenever I think of a O'Neill cylinder or other mega constructs I can't help but imagine stress fractures, metal fatigue, vibrations and resonant frequencies, cascading failures, and high-risk repairs.

It surely could be done, but the amount of trial and error required and the potential for high stakes failures is a daunting challenge.

Dzhanibekov effect makes me pretty sure you should spin the cylinder the other direction, in which case it doesn't have to be as long.

What do you think about Kim Stanley Robinson's hollowed out asteroids? Less efficient use of materials and angular momentum, but possibly a more stable arrangement.

"Colonizing planets is a Star Trek fantasy that, most likely, will not be worth it. "

Worth what? Some people may be willing to pay a high price in order not to be submitted to Earthly governments anymore. We do not know yet how our home planet and its politics will look like in 2050 or 2100. There is a chance that it may be a cruel dystopia.

I think a lot of it will ultimately depend on whether Mars has enough gravity to avoid the health issues that we see in orbital microgravity environments.

Do we have any idea, based on our experiences with space stations & lunar landings? Genuine question, I'd really like to know.

> Do we have any idea

IIRC, largely no - it's a very open research question.

> I'd really like to know

I fuzzily recall seeing an applicable NASA space medicine slide deck last year, but I'm not quickly finding it - sorry.

> depend on whether Mars has enough gravity

While it's common to oversimplify and exaggerate minimum-size constraints on rotational gravity, even if greater than Mars gravity is needed almost continuously, it might perhaps turn out easier engineering to maintain that on Mars (with mounted spinning things, or maybe pods in curving tunnels) than in space (spinning habitats). You still have vacuum at hand, but also support and workspace - things are more easily stopped, stood next to, and kicked.

Mars has about a third of the Earth's, so it's not microgravity and is about twice as powerful as the Moon's. There are not many reasons to expect it will create huge health issues for earthlings but if you spend too much time on Mars without exercising on a centrifuge, adapting back to Earth could be a problem. There will be some loss of muscular mass, at least.

I suppose the core of my question is just wondering what the shape of the g-dose response curve is. 1g is nominal. 0g has significant long-term problems, even with countermeasures like daily exercise.

Is the physiologic response between the two extremes linear? My intuition says no, but I don't have real data to check.

Just one data point. The astronauts on the ISS spend 2 hours a day exercising. That apparently works in that once they get back on Earth after 6 months, they don’t have issues with weakened musculature. ISS is a microgravity environment.

> what the shape of the g-dose response curve is

And to make matters more complex, that dose could be spectrum, rather than a constant value. Eg, spend X hours doing Y in the compact ~2 meter centrifuge at Z g, plus ... and ... .

> On the contrary, Mars has all the resources of asteroids but the advantage of a water cycle that has concentrated and reformed minerals like on Earth.

The water cycle concentrates diffuse elements into usable mineral deposits, yes. But those elements are only diffuse in the first place because of the planetary environment. The base abundance of industrially useful elements in asteroids can be tens, hundreds, or thousands of times higher than Earth (or Mars) precisely because these materials sank to the core or mantle of planets, or get chemically locked up in expensive to refine oxides. Indeed many of the rare metals we prize are actually of asteroidal origin, because they have been completely depleted in the Earth's crust in geologic antiquity.

What's more, chondritic or M-class asteroids typically have extremely accessible minerals, such as pure metals already in reduced form, or mixtures of loosely compacted minerals that can be sorted with a crusher and a centrifuge.

One thing you can’t ever change about Mars is its gravity though. All of our biological construction over billions of years was in 1g. Maybe we could thrive from birth, for 100 years or so, in one third G, but I’m skeptical. Even more so on an asteroid. Even on Earth, reduced muscle mass is associated with poorer health outcomes. To maintain that in reduced gravity would mean a lot of hours per day in resistance exercise.

Going from 1g to micro/no-gravity seems like a much more dramatic change than going from 1 to 0.3, so I think that's an argument for going to Mars ahead of asteroids.

That’s what I thought I said. Mars bad, asteroids worse.

It is possible that we will hack our own biology to grow stronger muscles without exercise or at least not as much exercise. Famously, Neanderthals, a very close species, were more muscular than us. It probably translated to higher consumption of food, though; a muscular body needs to eat a lot to maintain itself. That might be a problem on Mars.

> To maintain that in reduced gravity would mean a lot of hours per day in resistance exercise.

There's zero evidence for this at all. We have no experimental data on living in partial gravity, only microgravity(zero-G). It may be perfectly fine, it may be just as bad as no gravity, we truly don't know.

There was a module for the ISS that was designed to test this but it got scrapped, a massive waste IMO, as it seems to be one of the most outstanding questions we have right now for space biology. Other big issues like radiation exposure is well understood.

I agree with that. The way I look at is is that Mars has the resources needed to support a population and interplanetary travel, whereas the asteroids are (probably) where the lucrative mining opportunities are. Eventually we may colonize the belt, but if so we'll probably do it by using Mars as the local gas station and supermarket.

There is a HUGE difference in metals concentration in planetary crust and an asteroid that's mostly that element. Also a huge difference in gravity if you want the materials offworld.

You don't have to colonize them, but mining asteroids makes tons of sense.

I wanted to like Red Mars, and the science stuff was well made, but a lot of the book is about politics, and to me, those parts were painful to read.

I found it incredibly naive and unrealistic. Clearly many others disagree :)

Kim Stanley Robinson is insufferable. He has so many deep misunderstanding about politics, economics, and even things like climate science and limits to growth that are his core schtick. And the flaws are so embedded into the central plots of his books that it is really hard to suspend disbelief and ignore.

I originally encountered the Mars Trilogy as a teen and it is fair to say that it changed my life. I feel in love with the romantic portrayal of Mars colonization, and eventually ended up working at NASA. Recently I decided to go back and re-read the trilogy and found myself unwilling to finish even the first book. I just couldn't stand it. So you're not alone.

You might like Icehenge though. It works more as a stand-alone novel (or 3 novellas, really) set in the same universe, but with a focused plot and the politics mostly relegated to the background. It's a very under-rated book, being overshadowed by the more well-known RGB Mars trilogy that followed.

I couldn't really like, or care for, the characters.

The funny thing is that just when the politics were getting interesting, the author takes a detour into the effects of memory and hand-waves away all the tensions between Earth and Mars.

> We already don't care about externalities here on Earth, there's no way we can police them on Mars.

That depends very much on how the putative Martian society is set up.

There used to be an idea in cultural anthropology that a society becoming heavily dependent on technology and coordinated labour (specifically, sophisticated irrigation systems) went hand in hand with the evolution of a centralized authoritarian state to manage that.

The idea has fallen out of favour, but you can see how something similar might apply in spades on Mars. Life there is going to be marginal at the best of times; living off-grid would be a truly daunting prospect.

[1] https://en.wikipedia.org/wiki/Hydraulic_empire

You want Mars because you want the asteroids. You want the moon because you want asteroids. Moon because you need to get the material to Earth and it is better to mine in space. Mars because you need access to the asteroid belt. They are just different steps towards the same goal.

One thing I liked about Red Mars is how it brought up independence. Astronauts are well known to rebel against their respective commands (US, Russian, etc). It'll be interesting when command cannot do anything about it on a longer timeframe than your stay on the ISS (or skylab).

Also going to voice my love for Red Mars, I found Green Mars to be much more of a slog to get through, but I really like anything KSR writes. Blue Mars was a nice finale though.

I love Red Mars. The whole series is good but Red Mars itself is fantastic, one of my favorite books.

You practically get an undergrad in areology reading it. Super curious to see how our reality lines up with the timelines in the book.

Speaking of areology, there is a small subreddit for precisely that field which is quite good: reddit.com/r/Areology

Interesting anecdote, KSR as of 2015 didn't believe in mars colonization any more. The perchlorate issue really got to him and he basically said we'd never live there. Maybe he's changed his mind again but I got a chance to ask him some questions at a reading from Aurora and the scales really fell from my eyes at his answers.

> I've swung around to the idea that colonizing asteroids

Metal asteroids can, with some luck, provide us with boundless supplies of pretty much all metals, as I understand it. This will be one of the great milestones in human civilization.

But I think it's a place you go to work. Mars is far more interesting as a place to live and build a society.

You can fit a lot more people in the asteroids, and it'll be easier to transport stuff between them.

Mars has a lot of the same disadvantages that earth does. Its got a lot of gravity, and you can't communicate through the planet from one side to the other

Gravity does seem like a disadvantage, but satellites have worked pretty well for the other problem... we've even got some in place around Mars already.

Well, the underclass always gets the shit jobs, and habitat.

Owkwa beltalowda.

What you lack in the asteroid belt is the feeling of a planet with a reasonably short day/night cycle, some kind of skies and a diverse landscape. Maybe we can live without them, but for people who grew up on Earth, living on Mars might be psychologically easier.

First, I should note that I have a personal bias in that I study Mars for my PhD. I dislike Elon Musk, and I am not in favor of terraforming.

That out of the way, McKay comes off as overly aggressive at times, and wishy-washy in others. It seems contradictory to call Jakosky's model ridiculous and absurd while also claiming we don't have enough data to know for sure. Jakosky is a well-known and respected Mars researcher, and I would much rather trust his 2018 paper over a paper or two written in the early '90s before we had detailed observations of the Martian atmosphere or surface.

At the very least, I appreciate Jakosky planting an empirical stake in the ground for his position.

You're not in favor of terraforming, full stop? Elon's nukes and ground CO2 idea seems dubious, and like his dome habitats idea (turns out they're very limited in lower gravity and pressure: https://caseyhandmer.wordpress.com/2019/11/28/domes-are-very...) I think it will be dropped quickly once SpaceX gets to Mars and starts working on habitation seriously. He talks big but he acknowledges reality eventually.

However, I struggle to see a reason to oppose the concept of terraforming Mars. I don't study the planet for a living so I'd love to hear your thoughts on it.

I see no point to it. As another commentor mentioned below, humanity is unlikely to travel to another star system. To me, terraforming Mars is like going camping in your backyard. It's different, it's harder, fun, but ultimately has no real purpose. Mars is more likely to be colonized for exploitation of its resources than as some utopian egalitarian human endeavor. To me that would be a shame. I would like to see it preserved more or less as-is as a record of its own history.

I think we absolutely can travel to another star system. But more critically, this argument strikes me as goal post moving by space settlement skeptics: mass transport to Mars is increasingly appearing to be feasible, so we’ll put the goal posts on Proxima b.

The exploitation argument doesn’t make any sense because Mars doesn’t have any resources that would really make sense to ever bring back to Earth, except as a side product. It’s a new home like an island in the Pacific for the Polynesians. I don’t consider Polynesians settling uninhabited new islands to be objectionable at all, but instead an expression of what makes humanity wonderful. Preservation of a dead rock for preservation’s sake makes no sense. It’s treating stasis as better than life, and I just can’t get behind that.

I said this elsewhere in this thread, but I study surface processes on Mars, so to me the planet is still alive and active. Things change, mysteries unfold, new environmental conditions come and go.

I'm sure you wouldn't object to national parks or wilderness areas, it's just that in the case of Mars there is no (known) life. How much each of us values the presence of life will differ, but in my view it's worth preserving Mars.

I'm a lot less educated on the subject and my views are diametrically opposed to yours. Commentary like yours is mostly what has kept me hanging around HN all these years.

I'm surprised that a researcher wouldn't be enthusiastic about being able to do science directly on the planet's surface. Sure, an extended human presence there will require a lot of supporting infrastructure, and sure, that will all have a direct effect on whatever might already be there -- or might not be, and in either case, changing that environment might not be desirable.

But even at the current faster speed of remote exploration of the planet, you can expect, what, like 3 more robotic missions to Mars before you retire? And each one will be an iterative improvement over the last.

There must be so many questions you have about the planet that just won't be answered in your lifetime unless we go there and have a look around. What's your position on that?

Hey! Sorry I took so long to reply. The commenter below you is somewhat correct that I would identify as a 'Red' in Kim Stanley Robinson's trilogy.

I am not opposed to scientific exploration at all, (I work with several people who run Ops on MSL and Percy), but putting people on the surface requires much more infrastructure and expense. A sample return mission is already extremely complex and costly, and would be orders of magnitude more so if the mission also had to support human life.

Further, terraforming Mars so that people could go explore it seems completely backwards, since you would be altering the conditions you would be studying.

To your question:

>There must be so many questions you have about the planet that just won't be answered in your lifetime unless we go there and have a look around.

I'm not even sure what those would be. Almost any question we could want answered could be solved with a probe or a rover. Obviously there are questions we can't answer right now, but those are largely because we send rovers that are specialized in some areas, and totally ignorant of others. To answer those questions, it would be simpler, cheaper, and better for Mars to send more robots than to send people in my view.

He is a Mars researcher, as in he finds it very appreciable it’s current state. Basically a Martian, you are suggesting we develop and add malls to his beloved nature homeland.

Please stop contributing to the recent HN trend of putting words in other people's mouths just so you can ridicule them. I'm not "suggesting" any such thing, and if you aren't professionally in ~OmicronCeti's field of study, then I'm not interested in your opinion anyway.

I think national parks have value, but not infinite value. We should weigh up using somewhere as a preserve against other potential uses.

There are millions of Mars-like planets out there in the galaxy. I'd be more than happy to preserve, say, 10% of them. But there's only one that's in the right place to be the next step for humanity.

As I said elsewhere, I do not believe we will ever travel beyond our own solar system so we should preserve what we already have close by, instead of counting on pristine worlds elsewhere.

Pick a different planet to preserve.

Thoughtful response, thanks for your participation.

Venus is very easy to preserve.

Then he would have to do another PhD!

To me, if mars had life in its past and no longer does then we could consider it one huge grave. Lost in the terraforming debate I read is that any atmosphere we managed to kick up would be temporary. It might take a long time to leak off, but they’re not discussing any means to reverse the trend. As I understand, Mars doesn’t have an active core and thus magnetic field holding its atmosphere in place. There’s no way we’re going to fire up a core…

Turning choice, large asteroids into liveable habitats seems an infinitely more productive task.

Firing up a core is hard, but laying superconducting cables around the equator is not particularly hard (probably easier than terraforming). It could replicate a magnetosphere just fine, while also functioning as a planet wide electricity grid and a decade-long battery.

“Temporary” == millions of years.

Also honestly I think it's extremely fortunate that we have Proxima Centauri only 4 light years away as our nearest star. It's a red dwarf, and will continue to shine for at least another 4 trillion years, a thousand times longer than the sun will shine. Of course, granted it's habitability zone and other things are different, but that does not preclude us redefining habitability by inventing another life form to be our successor.

Proxima Centauri will outlive the vast majority of stars in the galaxy.

It’s worth pointing out that an a long time scale of tens to hundreds of thousands (not to mention millions) of years, the stars move around quite a bit.

The Alpha Centauri system will be just 3 light years away in 30,000 years. In 1.4 million years, Gliese 710 will pass within 0.2 light years of Earth. That’s close enough to be reached in a human healthspan with some beefed up (but still fairly sane) nuclear-electric propulsion that we could probably start building today if we had a reason to go out to 0.2 light years.

But other interstellar propulsion systems with higher performance are feasible, such as pellet stream beamed propulsion combined with a magsail. Really good fusion might work, too. Laser propulsion is feasible especially for probes but isn’t terribly efficient (pellet stream uses like a hundredth the energy for the same payload). Antimatter would be nice, but I’m not convinced feasible storage could be developed to beat the usable energy storage density of fission or fusion... or rather we’re probably much more than 100 years away from sufficiently efficient antimatter storage.

One reason not is: we're directly responsible for any suffering that then happens on that rock. A biosphere full of life means horror and suffering every day for so many living things it potentially eclipses all humanity's past crimes combined.

By that logic we should take responsibility for the suffering on earth.

Seems like the winning move is to go double or nothing and try and make life more sufferable (containing less suffering) on both planets.

Mars is a single easily avertable project, still actually free for discussion unlike profit-motivated matters like the ongoing deforestation here. Until there's a clear profit to be made from Mars, it's politically possible to make a "ok, let's not" pact.

Why not make it more sufferable here on Earth first, build all sorts of guardrails on existence, e.g. modify biology such that we all have a certain maximum to which the pain knob can be turned. And only then terraform other planets? Why be premature?

This question (your last sentence) has been asked and answered. Basically because the window of opportunity is open now and may only be open for a short time. If we wait, we may lose the chance.

You should read medical studies about people born with or who acquired a lessened sense of pain. It’s quite horrific. I’m not saying all pain is necessary but any pain that indicates damage is. It would be wiser to engineer biology to be more robust and to recover from damage more completely so that chronic pain is not a thing.

Give me some credit, I just said put some maximum on pain, not remove it. Yes it'd be nice to recover from damage better but that doesn't help when you are being predated on, like when there is a torturer to make sure you don't recover or when a parasite like the Ichneumon wasp has its whole lifecycle dependent on eating a paralyzed creature alive from the inside out. If you want a discussion please be charitable, it's no fun if you seem to assume I didn't think at all.

That’s the most suicidal perspective I’ve ever heard.

If we sit on our hands and do nothing then life on earth is doomed to extinction and we will be directly responsible. Our duty as rational beings is to preserve and spread life. If you really want to be anti suffering then figure out a way to improve things so nothing needs to suffer. We’re already on a trajectory for doing that for humans so there’s no reason to think we couldn’t do it for all life.

Even if the odds are slim it’s cowardly to not even try.

You know, I agree fully on trying and not being a coward. I wonder why it sounds otherwise to you. I just think there's no need to spread life beyond those of us who are here right now. It's worth keeping currently living individuals alive and happy as long as they want to live, because it's a great ill when something with a desire to keep living has their life forcibly taken away, but I don't see the intrinsic good in breeding.

> “A biosphere full of life means horror and suffering every day for so many living things it potentially eclipses all humanity's past crimes combined.”

This is the most astounding perspective on the value of life that I can imagine. Like the argument of a genocidal supervillain.

"I have the moral obligation to kill all the living humans today so I spare the suffering of until generations hereafter"?

That's only if you equate the value of life-that-lives-now and life-that-hasn't-been-born-yet. The majority of us value them differently: it's a lot worse to murder than to decline to give birth. Consequently, you can hold the opinion "Don't turn Mars into another biosphere" and nevertheless be against omnicide on Earth.

That’s only if you neglect the fact that reproduction is a continuance of life. Literally a part of each living being renews itself to continue living by reproducing either asexually or sexually. Not reproducing is equivalent to murdering your germ line and extinguishing all of the potential invested in you by your ancestors reaching back millions of years or further if you look beyond your own species.

Death is death whether caused by direct action or neglect.

This isn't meant as a rejoinder, but I think you should ask random people what they feel about the difference between murder and declining to be a parent. I think you've been sitting thinking this to yourself without really debating anyone.

As for me, I'm bowing out, thanks for the perspectives so far. Downvotes drain my energy.

The more appropriate analogy would be murder vs forcible sterilization or otherwise preventing/outlawing someone else from having children. No one is asking Omicron to move to Mars. Just asking him (and others) not to prevent others from doing so using threat of law.

> I would like to see it preserved more or less as-is as a record of its own history.

But on the other side, what is really the point to this?

In a couple of million years, none of this really matters.

I see it as littering, we'll all be dead in 100 years so what does it matter if I toss my trash into the bushes?

I can't help but see Mars as a dead rocky that has no special value compared to the billions of others in the galaxy. But Earth, as far as we know, is a unique jewel containing countless unique ecosystems.

It must be very different to you, having studied it. Like how a biologist may have a fondness for a particular nemotode worm which means nothing to most of us. It makes me feel shortsighted thinking of it in this way. Reminds me of pro-colonial/imperialist rhetoric like this[0].

Will our descendents see us the same way? Is there a good reason we want to extend our empire into the stars other than... seeing it a lot in sci-fi media?

[0]: https://en.m.wikipedia.org/wiki/The_White_Man%27s_Burden

Should the indigenous people of Americas, Australia, Arctic and Eurasia see themselves as a colonial force?

The ingenious people across the world are the original colonialist. Should we condemn them for what they did?

As a Polish person who inherited an extremely difficult history, I feel fine with my Slavic ancestors.

What I know is that The Sun will destroy the Solar System. The time will most likely destroy everything else with the heat death.

So, I would want to explore to learn the answer to The Last Question - does everything has to die in ever increasing entropy?

You can read the short hard science-fiction story "The Last Question" here: https://www.multivax.com/last_question.html

What about leaving behind awesome artwork?

We could turn mars into a sweet art project.

You mean add graffiti to my beloved red rocks? Blasphemy.

Can you at least tell us why you like Mars so much?

The same goes for Mars then too, right?

I would like to see it preserved too, but it seems there are some tradeoffs with respect to survivability of intelligent life in the face of potential extinction events.

This is assuming that worst case scenarios are possible on Earth as on any planet… I think that’s a reasonable assumption.

Interesting. To me, Mars is a large rock in a universe of large rocks, but it could be our second home (even if it is done for profit). In conversations like this I often consider this comic: https://www.smbc-comics.com/comic/modules

I don't care about Mars' surface processes. If I had a button to blast its outer layer off and replace it with a habitable one I would press it without hesitating - yet I imagine if I spent years studying the planet academically I would act differently, based on an amalgam of my concepts of "studying" and "Mars" I came up with on the spot and am ignoring anyway. Empathy is a poor substitute for understanding.

There's a philosophical difference here too. I don't see a problem with pulling resources from as much of the galaxy as we can reach if it prolongs Earth life, assuming we don't find other lifeforms. The galaxy only has mystique when we assign it, which we can't do if we're dead.

I mean a few hundred years ago people believed humans could not ever fly, but it happened, and we take it for granted now.

There is model for flight on Earth: birds. Humans achieved a similar feat through mimicry and the use of fossil fuels. There is no model for instellar transit. I am not optimistic that we can develop a technology that can speed transport between stars to such a degree before we destroy ourselves like every other hominid that has ever existed.

Planes work quite differently from birds. We were inspired by them, but we didn't copy them at all. Attempts in the past to copy birds mostly failed.

We got to the moon, Mars, and several other solar system bodies in the past half century without any mimicry.

Maybe you don't, but I have very strong optimism for technological advancement, and also for modifying our life form to rid ourselves of our tendency to destroy things before heading to other stars. When I say "we" will go to other stars, it won't be Homo sapiens, but another species that we will create as our successor.

We got to the moon. 12 humans have walked on it. Note that 50 years later, nobody is living there, or working there. Nobody has even returned.

We may get humans to Mars. It's technically possible. But I don't think we will ever live there.

The person you're replying to stated elsewhere that they don't believe in the conservation of energy, so (ironically) save yourself the energy of arguing with them.

Not to detract from your sarcasm but the conservation of energy only holds true in flat spacetime. So I guess you don't 'believe' in curved spacetime? That makes you a flat spacetimer I guess...

50 years isn't a long time. I'm sure some dude said the same thing about Tibet being too harsh to live in, and yet there are cities there now.

What are you talking about? People have lived in Tibet for 20,000+ years?

The distance to the moon and Mars is absolutely trivial compared to even the closest star: to Mars is 0.0007% of the way to Alpha Centauri.

>We got to the moon, Mars, and several other solar system bodies

You're conflating humans and probes, which are vastly different.

> You're conflating humans and probes, which are vastly different.

I disagree. Robots can build infrastructure far ahead of human settlement, such that everything already exists when we are ready to travel.

We can also potentially re-engineer our own life form, or create an entirely new inorganic lifeform, to withstand various conditions, including radiation and a wider range of temperatures. That will be our successor.

We are only beginning to understand genetics in the past decade. We have a long, long way to go, and a lot to understand. Science is still at its infancy.

Also, this is something I could never say in an academic context, but deep down I don't believe in conservation of energy, partly because the big bang itself violates it. Yes, I would be ridiculed for saying this in a scientific context, but so would someone in the 1500s for saying that the Earth goes around the sun. I think at some point in the distant future we will not be reliant on stars as our energy source.

'we' did not go to Mars, 'we' did not go to pluto. We sent cameras with walky-talkies. That is so vastly different than sending people to the moon, that it's not really something we can disagree on in good faith.

If you truly do not believe in the conservation of energy, I think we're done here since none of my arguments will be good enough for such wild speculation.

If we can send cameras with walky-talkies, we can invent and send (possibly silicon-based) life forms that will carry on our legacy while being a lot more resistant to the elements, require much less support along the journey, and can tolerate whatever gases and radiation may be present at the destination while still reproducing and carrying on society just as life does now.

Human bodies suck because they need to eat, need to poop, complain if what they eat isn't tasty, fight with each other, and get cancer, but our legacy as intelligent life doesn't need to continue in our current carbon-based meat bag form.

I can't believe I'm entertaining a reply, but how would a human-invented lifeform sent to the stars carry on human society if it is a) not human, and b) light years spatially distance and thousands of years temporally distant?

This reads like an ungrad astronomy major fever dream.

The question “what makes us human” is a deep one that has vexed philosophers for a long time. I don’t have the answer. If you have the answer, forgive me if I take it with a grain of salt.

I do think it’s possible that our best hope for navigating the transition beyond the singularity involves transplanting our humanness to another kind of life form. I’m not necessarily talking about uploading… more about a staggered intergenerational transition mixed in with life as we know it. I realize that to some people, this will continue to sound like crazy talk, until one day it isn’t. It’s ok if you are one of those people :-).

It would carry on our legacy as intelligent life. I don't think maintaining our current iteration in evolution is a condition that should be valued. We can evolve, or invent another life form that carries our civilization forward.

Yes, it reads like a dream. Technological breakthroughs of the past were created by people with dreams, not by skeptics.

LEO is 0.0005% of the way to the Moon, and yet once we'd done the first it didn't take us long to scale up to the second.

That's simply a facile comparison because most of the fuel is needed to get out of the atmosphere. The energy required for that 0.0005% distance is nearly 66% of the total.

Let's say it takes ~8 minutes to get to LEO vs 4,380 minutes to get to the Moon. That's a factor of ~550x longer flight time for a distance 2000x further.

Alpha Centauri is 1500x further away than Mars. It currently takes ~7 months to go from Earth to Mars (at 25,000 mph), assuming similar scaling that comes out to only 400x the flight time, or just about 230 years.

We didn’t land on the moon?

There are numerous credible designs for space ships able to reach a few percentage points of the speed of light.

Reaching 10% would be enough to visit nearby stars within a lifetime.

And once we can extend human life spans to many hundreds of years these journeys become even more achievable.

>credible designs

As I said elsewhere, I think the disconnect here is between potential and probable. Homo sapiens have twice come to the edge of nuclear oblivion already (being saved only by luck essentially), and I would wager we are are speeding much faster towards nuking each other than reaching the stars.

The breakthroughs in flying came when we stopped trying to make machines look like birds.

Submarines work well because we didn’t bother making them anything like fish.

> There is no model for instellar transit.

There is, but extrasolar objects don't have engines and do very low energy transits.

We'd need a large habitat, a power source that can last for a couple thousand years and a lot - and I mean a LOT - of reaction mass to accelerate it and to brake it when it arrives at its destination. Ideally, it'd be preceded by numerous robotic probes that'd chart the worlds ahead for possible refueling stops (that could add a couple thousand years to the mission) and have a number of possible targets lined up on a reasonable trajectory so that if the next system is not really that hospitable or doesn't have anything worth doing a very large delta-v for, it can just press ahead to the next destination.

Another thing it'd need is a lot of determination to build it, to seal it with a population, test it for generations to make sure the ecosystem works and is stable, and then send it out into the unknown without any possibility of returning to Earth. It's very long term engineering we rarely do.

The long short of it is misanthropy.

For some reason there are a lot of people around today that believe life is suffering and that the universe would be a better place with fewer humans in it.

It's a hard position to argue with because it's just so full of holes and lunacy you don't know where to start.

Spot on.

I think you can’t argue with it because it’s like an unexpected emotional vacuum. You can’t really convince someone who doesn’t like food that the carnival is an enjoyable place. They’re operating on a fundamentally separate plane.

>and I am not in favor of terraforming.

Why not? It would seem that's something we're going to have to master in order to populate the galaxy. Seems like it would make sense to figure it out somewhere close to home so we can have all the appropriate gear onboard a flight out into the cosmos.

As the commentor below stated, I do not believe humans will colonize anything but our own solar system. Things are simply too far away, even assuming there is some breakthrough that speeds up travel by two or three orders of magnitude.

There have been several order-of-magnitude breakthroughs in travel speed for the past 200 years. We have several hundred million years of time on Earth to go, and a couple billion on the solar system, to figure it out. We also have plenty of time to figure out how to re-engineer and evolve our own bodies to deal with radiation and other hazards.

We will figure it out.

We simply exploited fossil fuels.

You are extremely optimistic about having several hundred million years left on Earth, when the longest living hominid existed for only ~2 million years.

I firmly believe that homo sapiens will self-destruct long before that point, as we have greatly overstressed the planet in only 200,000 years, mostly in the last 200.

This is a pretty terrible argument, mostly because it seems to support Musk’s and Zubrin’s position that if we stop progressing we risk falling into stagnation, decay, and ultimately extinction and yet you’re somehow using it to say we SHOULDN’T try expanding to other planets or star systems. It doesn’t seem logically consistent!

My view is that learning to master inhabitation of Mars and other places in space will enable us to revert Earth from a bunch of agricultural land and farms and suburban sprawl back into a garden (dotted with dense, luxurious cities) which we camp out in during the weekend.

Space development shows how to thrive WITHOUT fossil fuels. It’s so strange to me that folks seem to have this backwards.

I totally accept extinction. It's natural. Homo sapiens will burn bright and briefly, and the planets will continue to spin. I would argue that it would be much more worthwhile to spend money improving Earth for humans while we can, than dumping trillions of dollars into spaceflight (which I say unironically as someone who is currently paid by NASA).

>Space development shows how to thrive WITHOUT fossil fuels.

Not sure how that's the case given the staggering emissions of Falcon 9 for example.

From your comments I feel like you gotta be familiar with Kim Stanley Robinson's novel SF _Red Mars_ (if not you'd like it), but here's how he tries to make you feel better about your NASA budgetted job, while agreeing with your basic analysis on things like terraforming and many other things you've said (the plot of his earlier novel notwithstanding, he's partially doing penance for it).

> However, even if slower, terraforming Mars remains a great long-term goal; but long-term meaning like ten thousand years. Which means we have to get our relationship to our own planet in order for anything interesting to happen on Mars…

> The main project for civilization now is creating a sustainable way of life here on Earth. That’s the necessary first step; anything beyond would rely on that succeeding, so exploring space is less important now. That said, space science is an earth science. What we learn around the solar system can often illuminate the project we have here of keeping this planet’s biosphere healthy. So I like the space program, and feel it is not funded out of proportion to its importance. Robotic missions are already doing a lot of what we need done, but humans are better at many things than robots, and it’s more exciting to see humans on the other planets than it is to see robots. So, on balance, I’d like to see more investment in space science and less in areas like weaponry. Our taxpayer bailout of the banker gamblers who lost their bets in 2008 cost us about ten thousand times the entirety of what we’ve spent on NASA.


This interview in particular is worth reading for this whole topic being discussed here.

I commented elsewhere about how much I like the series.

Every satellite in orbit that lasts more than a week or two uses solar or nuclear energy. Starlink is solar powered and uses electric rockets to reach final orbit and maintain position.

Hydrogen is one of the most common rocket fuels, and Starship will need to used synthesized methane (which we actually make on board ISS using direct cabin air carbon capture and the Sabatier process using hydrogen made from water split with solar electricity) on Mars to return to be reused, and Musk said SpaceX would eventually use synthesized methane for Earth-side refueling of Starship as well.

Human extinction is likely linked to extinction of all higher order life forms on earth.

The 6th extinction is well underway IMO

> My view is that learning to master inhabitation of Mars and other places in space will enable us to revert Earth from a bunch of agricultural land and farms and suburban sprawl back into a garden (dotted with dense, luxurious cities) which we camp out in during the weekend.

How does that work, exactly?

In space, any food produced would have to be grown inside, sealed away from the outside environment to protect it from the vacuum or near-vacuum of space or Mars. We will grow it in greenhouses or perhaps vats (staples like corn or wheat can be replaced by fermented foods like @solar_foods or @feedkind, using ultimately solar power, this is actually more efficient than photosynthesis and with a much smaller environmental footprint than agriculture) and certainly not have free grazing cattle (which is the biggest land use in the US). On Mars, we’re already beginning to master solar/battery-electric flight, so perhaps we may not need so many surface roads and we can place trains and such underground. Our footprint on the planet Earth could shrink by an order of magnitude even as our economy and quality of life improve (the density effect on economic productivity is well-established—and Mars will be really expensive to live on unless in large, dense cities... suburban sprawl being prohibitively expensive). These are all things that are fairly hard to prove on Earth as the whole system has an inertia due to developing with abundant fossil fuels, but on Mars we will be forced to rely entirely on renewable (mostly solar but perhaps wind and geothermal) or nuclear power, so a Martian society becomes a blueprint and a powerful proof of concept of how Earth life can be..

We use the rare Martian mineral handwavium

>We simply exploited fossil fuels.

This hand waves away all the accomplishments in seafaring prior to the 19th century.

What were the order of magnitude speed developments in seafaring before 1800? I'm not familiar with the topic.

Navigation techniques improved substantially. While not inherently a speed improvement it increased the effective range of mariners by a ton resulting in effectively the same thing.

> While not inherently a speed improvement it increased the effective range of mariners by a ton resulting in effectively the same thing.

There were loads of innovations around the shape and profiling of ship hulls depending on conditions in which they operated. Same for sails and stuff, not to mention doing away with rowers. This improved speed quite a lot on top of range.

Thanks, that's more insightful!

Navigation is irrelevant to the space flight argument though, we know how to navigate between planets and stars (in theory). Speed is the limiting factor.

> We simply exploited fossil fuels.

Not simply, but mostly: progress started before the steam engine. But yeah, pop sci is hyping a lot of things that are very, very unlikely in the near future, and it looks like we won’t have much beyond that.

If you firmly believe that homo sapiens will self-destruct in such a time, then why would there be any value in preserving Mars?

If I may: homo sapiens has self-destructive tendencies, which we acknowledge and for which we sorrow. But we love them anyway, and wish to see their continued survival, if it happens. We accept that populating another planet does not fix our psychosocial problems, but it may help us get through the great filter.

We could learn how to "simply exploit" atomic fuels. That should be good for another magnitude or two, right?

The funny thing is that we know already quite a bit about how to exploit them. Now, putting that into practice is another matter.

Which parts of our solar system do you think we should colonize?

None besides Earth.

It seems that you're implying that humans shouldn't interfere with any celestial bodies because of the inherent value of their pristine existence.

There's so many engineering and scientific advancements needed to make space-based sustainable colonies using materials sourced solely from Earth that your position would delay any colonization of space past a few great filters.

I was enjoying your takes on preserving Mars, but saying that humanity should only be allowed to change Earth is nihilistic in the extreme.

Not even a cozy hotel on the moon, overlooking the earth?

I'd be down, but it's more likely going to be an awful penal mining colony armed with nukes pointed back down at us.

The moon is a useless place to locate military weaponry for use against earth.

It would take those nukes three days to reach earth, which is a huge amount of time for countermeasures to target and destroy them. And a handful of responding nukes could easily wipe out all lunar military sites and personnel, while lunar weapons could barely nick Earths military capabilities.


Why should we spend trillions of dollars to put a few people on a distant rock when we could spend that money to help many more people right now, and potentially avert the need for a colonial life raft? It feels self-evident to me.

> Why not? It would seem that's something we're going to have to master in order to populate the galaxy.

I think the unstated premise here is that populating the galaxy is something we should do. Looking around at what we're doing here on Earth, I think humanity populating the galaxy would be a net negative for the galaxy.

You know how the aliens from Independence Day are portrayed as a race that goes from planet to planet draining its resources until there's a husk left? That's exactly what humanity would do. There's no question about that.


"The Harvesters are a race of highly intelligent and incredibly technologically advanced hive-mind extraterrestrial beings. They are a threat of universal proportions that seeks to harvest and destroy planets to refuel their ships, to grow, and to perfect their technology at the expense of driving indigenous races to extinction."

We are the Harvesters in this story.

We aren't going to populate the galaxy. We aren't even going to populate Mars. We are going to live on Earth until something cataclysmic happens, and then we will be gone.

I strongly disagree with this. We have several hundred million years left, and we've only been around as an intelligent civilization for what, 100K years?

200 years ago nobody would even think of flying on Earth, and yet here we are, taking it for granted that you can get almost anywhere on this planet within 24 hours for a couple thousand dollars, and within a century of inventing the car we landed a robot on freaking Mars.

Now I do think that we will take charge of evolution and invent a form of life that will be our successor to withstand a much harsher range of conditions and absent from the "bugs" of current life such as cancer and heart disease, rather than our current unreliable meat bags, but we'll make it happen nonetheless.

All that said -- I do want to see more attention toward terraforming Earth as well. Even with zero global warming, the sun's brightness will increase such that our oceans will boil away within 1 billion years, even though it won't actually engulf the Earth for another 4 billion. I would think it's realistic to extend the habitable period of life on Earth from ~300 million years to maybe 2 billion years with some terraforming tricks. That will buy us more time to terraform Mars or Saturn's moons in preparation for the red giant phase of the sun.

Also, learning to terraform the Earth can reverse global warming, because, you know, politicians don't give a fuck about stopping it, so we should attempt to learn to reverse it as a backup plan while the political environmental efforts continue in parallel.

I think the disconnect here is between potential and probable. Humanity likely has the potential for interstellar travel, but our nature will prevent it in my opinion. Homo sapiens have twice come to the edge of nuclear oblivion already (being saved only by luck essentially), and I would wager we are are speeding much faster towards nuking each other than reaching the stars.

If nuclear war breaks out, it will be sad, we will lose a lot of our population, and cities will be destroyed, but I do not think a nuclear breakout will result in the death of humanity. I cannot see a realistic war scenario in which we will destroy every habitable corner of the planet.

And if we can cure cancer in the next 50 years (I think realistic), we'll have even better odds of surviving an event, as a species.

The collapse of all plant life would mean the death of humans. Nuclear winter is a well-studied and modeled phenomenon.

I don't think we would collapse all plant life.

While we have the theoretical capability to destroy all plant life, I think realistically we'd end up obliterating a few cities before war would cease, and a full-on nuclear winter is unlikely.

> I don't think we would collapse all plant life.

I mean it's not really about what you think. See the top two links here about the devastating effects of small-scale conflicts

- https://doi.org/10.1038/d41586-020-00794-y

- https://doi.org/10.1073/pnas.1919049117

- https://doi.org/10.1126/science.222.4630.1283

- https://doi.org/10.1029/2019JD030509

- https://doi.org/10.1080/03036758.1986.10423349

- https://doi.org/10.1029/2006JD008235

You don’t need to kill all plants, just enough of those we can eat. Not even all of those, either. Look into history to see what happens when enough people don’t have enough to eat.

The person you are replying to has said he would not mind if all humanity were to die and go extinct. Ugh.

Why should I mind? Species come and go.

Then you shouldn’t mind people making use of Mars in the meantime. Planets come and go as well.

> We have several hundred million years left, and we've only been around as an intelligent civilization for what, 100K years?

This sounds wildly optimistic, considering our chronic inability to fix our behaviour before it results in excessive damage. Never mind the occasional asteroid.

> 200 years ago nobody would even think of flying on Earth, and yet here we are, taking it for granted that you can get almost anywhere on this planet within 24 hours for a couple thousand dollars, and within a century of inventing the car we landed a robot on freaking Mars.

The myth of Icarus is a bit older than 200 years. So are Leonardo da Vinci’s drawings. Plenty of people did in fact think of flying, most probably before they had any way of writing it down for us to read.

It's been 241 years since the first manned unpowered flight, in a hot air balloon. Granted that's a long way from getting anywhere on the planet, but I'm skeptical that 41 years after that event no one was thinking of flying.

Not with that attitude.

That's really likely to be true if you walk into the future believing it.

Seems a little grandiose considering its just a comment on HN.

Better to master our behaviour on our own planet first before we go and trash another.

A lot of early stage Mars terraforming talk always seem to deal in oddly limited human terms - and imposes limits we have on Earth which don't apply anywhere else in the solar system.

What does Mars need? An atmosphere. Doesn't really matter what it's made of, we need more pressure on the surface. But no one lives on Mars! It's not "oh how much work would this be" it's "redirect a comet and let it crash into the planet".

Most of the big early stage terraforming problems offer disproportionate returns on investment - you can do extinction-level event damage with no consequences and amazingly reasonable delta-V investments.

Personally, I've been hoping we'll get lucky and a suitably large comet would just hit Mars. A couple years back a retrograde comet looked like it would, but missed. It wouldn't have taken much effort at the right part of it's orbit to guarantee that hit.

This is what does make me wonder about the "oh it's too hard" people. We know there are bodies in the asteroid belt with more water then all of Earth's oceans. The gases and liquids we need are already in orbit and once we know where they are, getting them to Mars is comparatively very simple.

What does the terraforming argument look like once you change some of those initial assumptions people start with? Once CO2 in the atmosphere is warming it up, and surface pressure is 0.3 atmospheres? And once liquid water has filled all the low land areas?

These aren't insurmountable hurdles for us with todays technology - but they are catastrophic sort of changes which you can only do in the early phase. But once we're looking at a planet which is still "uninhabitable" but with sunlight, water and CO2...well that's an environment where Earth's greenery is going to go crazy colonizing.

> We know there are bodies in the asteroid belt with more water then all of Earth's oceans.

Can you say more about the technology to redirect that much mass to make it collide with Mars?

(I understand that shifting an orbit is much different from escaping from a gravity well, but I don't have a good intuition for how different, maybe because I haven't played Kerbal Space Program or something.)

It's all essentially asteroid redirect stuff, so the trick is finding something with what we want, on a close enough orbit, with some reasonable timeframes (i.e. it'd be preferable to do an impact with a 20 year arrival time so the people planning it can live to see it).

So either gravity-tug with ion thrusters do a minor correction, or more likely a solar reflector to turn part of the bodies mass into it's own propellant. Or a nuclear charge on the right side of it.

I suspect if we were committed to this as a thing we were doing, then once you turned more resources to it the actual calculus would get more complicated: you'd want to map out and characterize everything in orbit, and then start looking for second or even third order redirect candidates - i.e. use a smaller body on a more useful orbit to collide into a larger one for a redirect.

The technological criteria are much more reasonable for all of this though: we need to be able to get to what we're going to redirect reasonably quickly, several times so we can characterize and put the gear in place to do the mission. At this point you'd hopefully be using a bunch of Starships running on autopilot.

If you take some near-future tech into account, then if end up building the laser array for the Breakthrough Starshot project, a decent use of that most of the time would be lasing the surface of redirect candidates from Earth.

EDIT: Just realized I didn't answer your question very well - changing an orbit is much cheaper then escaping a gravity well. To go to the Moon from Low Earth Orbit takes maybe 1000ms-1 of delta-V (weak-boundary transfer and such - I'm probably a little off on that) under the right conditions.

To get into Low Earth Orbit through you need to blow through at 8km/s of Delta-V and then a lot more to overcome atmospheric drag.

But to return form a Near-Earth Object (say an asteroid) back into the Earth's atmosphere can be done with as little as 60 ms-1 of delta-V in some cases (a little more if you're aiming to hit the ground and not just plough through the atmosphere).

Basically with the right timing, orbital adjustments can be incredibly cheap.

EDIT 2: Basically it's quite likely there's more then a few comets out there which are going to make close passes to Mars already, where for the cost of an impactor, we could ensure they hit Mars instead if we found them early enough.

Wait. There's an asteroid with more water than Earth? How?!?

Aren't there only a handful of asteroids over a 100,000 cubic kilometers? Even if they were entirely ice - aren't there 1,350,000 cubic kilometers of water in the oceans?

Even if the largest asteroid was completely ice - it still couldn't have as much water as the ocean, right??

Ceres is believed to have more water in it then Earth's oceans. Ceres is huge, of course, and we probably can't redirect it.

But deorbiting more amenable bodies into Mars from the numerous comets that impinge on our solar system is achievable. And of course if there's water somewhere, then there's water almost everywhere (which there is - if nothing else there's a huge amount of it in Saturn's rings).

The point is, what you can do terraforming Mars, is quite different to anything you could do to Earth, because you can't just freely cause some cataclysmic events here.

EDIT: The other key point is all this work is largely fire-and-forget once you know how. An automated solar reflector probe can be launched and happily continue causing some body to outgas for years, with no human intervention at all.

Doesn't Ceres have a diameter of less than 1000km?

Even if it's entirely ice - pi*500km^2 = ~785,000 cubic kilometers of water, right?

Isn't that half of what's in the oceans? What am I doing wrong??

What would be the intended result of crashing comets into Mars? Do comets have enough mass that the addition of that much dry ice, regular ice, and assorted rubble would make a noticeable change in the climate, or is the goal to use the re-entry heat to warm things up? And would a large impact cause a dust cloud that would take years/decades to settle? (Which could be an acceptable side effect if the benefits are worth it, or if the dust itself creates a warming effect.)

I remember reading that Mars doesn't have a magnetic field like Earth's to protect it from solar wind, therefore the atmosphere mostly gets swept away. Is that not the more difficult problem here? This debate seems to center on generating enough CO2, but that seems a bit irrelevant if it would just blow away. How would you even go about fixing the magnetic field of a planet?

We can create a magnetosphere at Lagrange point between Mars and Sun that has a tail that would protected Mars from solar radiation. Radiation from other stars is still a problem I think? https://phys.org/news/2017-03-nasa-magnetic-shield-mars-atmo...

True, but at least the magnetic field could redirect solar wind (or, at least, its protons) to impact head-on and replenish Martian hydrogen instead of pushing the atmosphere away.


> In answer to this challenge, Dr. Jim Green – the Director of NASA's Planetary Science Division – and a panel of researchers presented an ambitious idea. In essence, they suggested that by positioning a magnetic dipole shield at the Mars L1 Lagrange Point, an artificial magnetosphere could be formed that would encompass the entire planet, thus shielding it from solar wind and radiation.

It's all about the rate of loss. If it's 1% per year, that's probably not going to work; if it's 0.0001%, that's a different matter altogether.

Everything is temporary in the long run.

From the paper in the article:

>"MAVEN has observed the Martian upper atmosphere for a full Martian year, and has determined the rate of loss of gas to space and the driving processes; 1–2 kg/s of gas are being lost."


Oh, I was thinking in terms of the cost benefit of terraforming. If you magically make the planet's atmosphere 1 bar of co2, how long would that last at a usable level - say at or above 0.5 bar - assuming no replacement?

If that's 10k years it's less appealing, but 1m years might be worth it.

Build a worldhouse instead of full terraformation ?


No need to worry about atmosphere loss & you can start incrementally and get usable land almost at only, not only after long years of terraformation.

Agreed. Para-terraforming is a criminally underrated concept.

With "terraforming" you'd have the problem that dozens of generations would have to work their proverbial asses off without ever experiencing the fruits of their labour. Not exactly a strong suit of the human race.

Another advantage of the world-house approach is the possibility to leave sites of interest as-is by not including them. With terraforming it's impossible to preserve select areas for scientific or cultural reasons.

No problem - we just need to melt the outer core to get the dynamo effect - will only require 1 trillion nuclear bombs once we figure the technology to drill down to that depth.

Perhaps that's the end-game for lord Musk's Boring Company

That's probably a problem on billion year scales. I wonder what the annual loss would be.

Its estimated Mars had at atmosphere for the first billion years. But loss is not linear. The less you have, the faster it's eroded.

So to rebuild it, might want to quickly get to a sustainable value before its blown away again? I favor crashing Saturn's icy asteroids into Mars to release gigatons of water vapor.

Isn't it the reverse? The more atmosphere is present the faster it erodes away?

Not according to the papers.

Which papers? That's really counter intuitive to me. I'd expect that a higher atmosphere concentration would have a higher rate of loss because the solar wind would grab more of it.

Does this mean that mars is losing atmosphere faster today than it did 500million years ago? That's really fascinating!

Can't find it now. Curiosity has an instrument to measure isotopes, which tells how its air chemistry changed over the aeons. It showed disparity in heavy vs light gasses trapped in rocks of different ages. Light gasses are lost first, so that gave a clock on atmosphere loss. And a profile of that loss over time.

Here's a sunday-supplement summary I did find: https://science.time.com/2013/07/23/revealed-how-mars-lost-i...

From the paper in the article:

>"MAVEN has observed the Martian upper atmosphere for a full Martian year, and has determined the rate of loss of gas to space and the driving processes; 1–2 kg/s of gas are being lost."


The math is clear. A new atmosphere would take millions of years to get swept away.

Last math I saw suggested 100,000 years, but if we're still on Mars for that long and dealing with atmospheric bleed-off, we done fucked up already.

Even if it’s only a hundred thousand years, we can set up a magnetic field in Mars orbit that would substantially reduce losses far easier than actually making the new atmosphere.

Earth’s magnetic field comes from consisting of a massive ball of molten iron surrounded by layers of rock, soil, and, ultimately, monkeys.

The critical component for the magnetic field (the molten iron ball) is hard to replicate.

The necessary magnetic field is actually easy to replicate.

By that logic it's pointless to pump a tire, since the air will eventually leak out.

Terraforming will in part be a permanent process. The atmosphere lost will have to be continually replaced. And that's fine.

Our biggest problem is that we don't yet know how to terraform. Certainly we have some theories but we haven't yet been able to put any of them into practice.

We need to learn the ins and outs of how to terraform, at first, at home, on Earth.

We have several current problems on Earth that are good candidates for terraforming:

How to reduce CO2 in the atmosphere.

How to produce drinkable water in places there aren't any.

How to grow plenty of food on land that is sub-optimal.

If we can do those things here on Earth, then we might possibly have some chance of success in terraforming alien places like Mars.

Martian soil is a fine, toxic dust. The planet is far from the sun. It is also too light to generate the gravity we evolved in.

We should be living in spinning space stations in warm-and-toasty solar orbits

The “toxic” part of the soil, perchlorates, are easy to process and remove.

There is no evidence that 1/3 Gee won’t be fine for humans to live in. NASA has already figured out how to have humans life in zero fee for long periods (low rep, high force exercises).

Mars had enough sunlight to power solar panels and grow plants.

Spinning space stations have their use as well, but have to import 100% of resources. Mars is lousy with water, CO2, and easily accessible elements such as Iron.

Mars might end up being Archaea's time to shine, assuming they aren't there already. Apparently they and some bacteria can eat it as well.

It's likely that you feed yourself with hydroponics, and use the waste materials and imported inoculate to start a composting operation, where, like earth gardeners, you feed a little bit of dirt into each batch. If you can tune that to break down perchlorates, then soon you'll have compost you can grow more food in, at which point you start getting compound interest. Assuming, that is, that you send actual soil scientists and not industrial ag people, who think soil is something you wear out and then buy at a store.

Strongman competitions in 1/3 gee are going to be so ridiculous.

Personally I'm more excited to strap on wings and flap around high pressure low grav domes.

> The “toxic” part of the soil, perchlorates, are easy to process and remove.

On a planetary scale? How?

Why would you need to do it on a planetary scale?

Just the soil colonists will be using is all you need.

So... only that part of the soil that gets picked up by the famous Martian dust storms then? Aka the entire surface?

Nothing will be grown outside on Mars for hundreds of years. Even with an active terraforming operation, they will need some kind of dome enclosures to provide enough air pressure to grow plants for centuries.

Until then, just rinse off your suit and boots when you enter the dome.

Assuming a para-terraforming model there might not be a need to cater for a planetary scale removal I suppose.

We can try living in both, see which one's better.

That would be the best outcome. Also, the Moon, it’s right next door

Mars has enough gravity to live life more-or-less as normal, and any kind of soil is a much easier way to protect yourself from cosmic radiation than having to build multi-meter-thick walls from nothing.

The entire surface area of Mars is less than 5x that of Siberia plus the Sahara desert plus the Australian outback, areas currently not worth developing.

> The entire surface area of Mars is less than 5x that of Siberia plus the Sahara desert plus the Australian outback

This is such a weird statement. It's less than five times three very large areas combined... It leaves me with no idea how large it is. For those curious, it's about the same land surface area as earth has (removing oceans).

Its three large areas we aren't putting effort into putting people and terraforming.

They've got the same challenges but are easier

Thats the first thought I always have when terraforming is discussed, we can't even fix earth, how would we fix another planet.

Earth has a lot of people living on it, and any effort at repair is just as likely to wreck it. You can't "colonize and terraform Siberia" without turning the US into a scorching desert.

Mars has 0 people living on it, and is already uninhabitable. We literally cannot make it worse for anybody, and are in no danger of wrecking anything we need to survive by trying.

I would much larger we try planet-scale geo-engineering on Mars, then try planet scale geoengineering on Earth (and we're already flirting with that because of climate change).

There is a wealth of information to be gained from attempting dramatic changes to a planet's condition, and establishing a biosphere, which would be extremely important for any attempt at large scale Earth biosphere repair.

> You can't "colonize and terraform Siberia" without turning the US into a scorching desert.

How does it work?

permafrost methane release

We could if we had the political will. There are terraforming-like approaches that would e.g. reduce global temperature, but good luck getting the political consensus to actually put them into practice.

Some random ideas off the top of my head for why developing Mars is better than developing the outback:

* Do scientific research and exploration

* Win fame and prestige

* Enjoy having no existing property claims or cultural heritage to disturb

* No laws. Make your own laws. Escape persecution.

* Build a low light-and-RF-pollution observatory

* Create the ultimate off-site backup

Are you arguing that the surface area is too small or too inhospitable? What does the development of those areas have to do with Mars?

I think he's pointing out that we have cold and arid environments with a standard atmosphere and surface gravity, and a magnetosphere to deflect cosmic rays that we don't colonize right here on Earth. Traveling millions of miles at huge expense to try this on Mars doesn't seem like a sensible endeavor right now regardless of its feasibility.

I believe they are saying that the Mars landscape is akin to the regions he listed and that these native locations are far easier to develop or live on than going to another planet.

They are hundreds of times easier to settle than Mars, and probably richer in resources, so settling them would seem like a good first step before thinking of cities on Mars.

This piece from the NYT suggests that Siberia may be the new frontier: https://www.nytimes.com/interactive/2020/12/16/magazine/russ...

It gets easier by the day, whilst the permafrost melts away.

That, even if successful, it's not worth it.

Comparing Siberia, Sahara, Antarctica or the Australian outback to Mars seems flawed because there are many places that are a lot better suited for human activities and settlement on Earth. We would not want to go there unless other options are ruled out. So emphasis is "on Earth".

Mars might not have regions that are better suited than these inhospitable parts of Earth but it has the feature of "not being Earth".

Consider it a backup/fallback for the "single point of failure" that Earth currently is not just for humanity but for all of life in the universe that we know of.

Now that we are developing the technical abilities to be able to remove this possible failure point and to finally add some redundancy for life, I think we are almost morally obligated to do so.

The point where Mars could be some sort of viable backup of anything on Earth is centuries and trillions of dollars away. Up until a Mars colony(ies) has enough local infrastructure and industry to be entirely self-sufficient it's survival will require access to Earth's infrastructure and industry.

Mars also has fewer natural protections than Earth: a thinner atmosphere, no magnetic field to speak of, and no giant moon that deflects or absorbs at least some percentage of objects that would otherwise impact Earth. So Mars is more susceptible to dangerous radiation and object impacts than Earth.

For the same cost outlay (or way less) as trying to make Mars an effective backup for Earth Earth could be made more robust and dedicated purpose-built backups could be created.

Mars as a backup of Earth is like a cheap eBay thumbdrive hanging from a wind chime on your patio is a backup for your data.

I would take a cheap eBay thumbdrive hanging from a wind chime on my patio over "no backup at all" any time.

> See it as backup/fallback for the "single point of failure" that Earth currently is (not just for humanity but) for all of life in the universe that we know of.

What could happen to the Earth that would make it even close to as inhospitable as Mars?

Very little, if anything. Which means that it'll be a lot easier to resettle Earth from Mars if something cataclysmic happens to civilization here than it was to settle Mars in the first place.

It hardly matters that the apocalyptic Earth is more hospitable to human life than Mars currently is if we don't have any humans left to resettle Earth.

What could kill all humans on Earth, while leaving it hospitable and re-settleable from Mars?

Even if a huge asteroid hit, we could almost certainly build shelters where more people could survive the initial impact than we can settle on Mars in the foreseeable future.

Even a partial ecosystem collapse would make it a tremendously difficult multi-generational effort to return to modern levels of technology.

An analogy: a bunch of important files become corrupt (cataclysmic event) and the domain expert is no longer with the company (loss of knowledge and industry). It is much easier to move forward if one has a way of contacting a subject matter expert (Mars colony) to restore or rebuild what has been lost.

What would make Mars more suited for housing such expertise, that couldn't as easily be stored in an artificial environment somewhere on Earth?

Even if we distribute such library and manufacturing vaults and ensure they are staffed by those who can use them - the world that arises post-cataclysm may not be one of great cooperation. I can foresee scenarios in which such valuables are used as tokens of power to subdue neighboring factions.

I believe we also need a colony to hold on to seeds of civilization in the very sense of the word.

Again, why would the colonists on Mars, a much more resource-restrained environment than the post-cataclysm earth, be any more willing to cooperate or bring back or perpetuate civilization as we understand it today?

So of course it takes some time for the Mars colony to be at an appreciable enough size to be viable as an Earth backup. But once it is there, the colony would be have the incentive to start Earth back on the path to being support for Mars.

Sorry, but again - so would everyone on Earth, to the same extent. And if some on Earth would be unwilling to share resources and information with each other, they would have even less reason to trust Mars.

We could, and we have, but how useful would they be? What are they missing?

It's like making a backup of your computer but never testing restore. The chances of that backup not being complete or recoverable are fairly high.

The backup of human civilization on Mars will probably be theoretically worse than one that can be made on Earth. But it will be supporting life, making it fully tested and thus practically better.

Yes, but it would cost millions of times more resources and energy, and it will not be achieved until well after such technology becomes trivial to deploy everywhere on Earth.

A cheap backup missing a crucial bit of information is worthless.

It does not take an event that makes Earth as inhospitable as Mars. It only needs to be bad enough to remove our capability to go beyond Earth to doom life to be limited to Earth itself. If life should persist in the long run, we need to start spreading it beyond Earth.

We might not colonize a neighbouring star system in the near or medium term future but I am convinced that if we do not start moving out into the solar system, we never will go anywhere else either.

I still don't understand what kind of event could make the Earth so inhospitable that we lose the ability to leave it, but it would leave Mars with this ability intact.

Mars has no fossil fuels, so that can't be it. Minerals cant really be destroyed or exhausted. Technological knowledge is much easier to preserve from cataclysmic events on Earth than it is on Mars (if we fall under some kind of technophobic super empire that seeks to destroy this type of technology, that will as easily spread to Mars as to the rest of the Earth).

Specifically preventing us from leaving earth?

If our low earth orbit space gets too full of debris, we become stuck until we can find ways to clear it out.

That seems much more doable than having a completely self-sustaining space industry on Mars (from mining to chip manufacturing and everything in between, all life support functions intact, all underground or in heavily radiation-shielded buildings, and no fossil fuel plastics, all spanning the Martian globe to actually get access to the various minerals).

Quite. What I would like to hear from all these gung-ho types, is how we go about producing quantities of a simple 2-core power cable, on Mars, or in the asteroids or the Moon.

But no doubt they will say: use broadcast power.

Back in the 1980s, some Stanford AI lab people were talking about self-replicating robots on the moon by 2000. I asked "how soon can you do it in Arizona". They didn't like that.

I'd like to see a system that, allowed to order any stock catalog item on Amazon or Digi-Key, could self-replicate.

I don't know how but I am convinced that we are capable of finding out if we actually try.

What gives you this conviction? Have you considered how many processes and materials producing a power cable involves on Earth?

Look at the history of humankind and the progress that we have made in the last two centuries alone, what other conviction could one have with that in mind?

A nuclear conflict would do it. You don’t even need that many nukes to kick up enough dust to doom us all

If we were able to build self-sustaining colonies on Mars, surviving on a nuke-ravaged earth would be easy as pie.

Sure, temperatures would go down (but nowhere near as cold as Mars) and it would be hard to harvest plants, but we would still have fossil fuels to generate electricity for grow rooms, and we would still have earth soils that are ultra-rich in nutrients. The surface would be nowhere near as radioactive, so people could still work outside, allowing mines and so on to keep operating as today.

Overall, while it would be a huge tragedy, kill billions, and destroy our civilization as we know it, it would still leave the Earth as an absolute paradise compared to Mars.

Having your name be immortalized forever in history is something that appeals to a lot of people, especially billionaires who have run out of things to buy.

None of those are on another planet - it changes the value proposition.

Yes, it makes it much less valuable, since anything of value you can produce is much harder to bring into our normal economy.

If we were talking about another planet in another solar system, you could have some arguments about long term survival, but otherwise the earth will at worse become as inhospitable as Mars, until the sun burns them both to a crisp at about the same time in a distant future.

There are all kinds of cataclysms that would end humanity on Earth while leaving Mars untouched. Global nuclear war, asteroids, and solar flares are three relatively likely ones that come to mind.

Global nuclear war would neither wipe out humanity nor leave the earth in any shape nearly as bad as Mars, either in terms of temperature, radiation, atmosphere, soil quality etc.

Similarly, any asteroid impact of a size that the Earth has seen since life appeared would neither wipe out ALL of humanity nor leave the Earth in a shape as horrible as Mars is in right now.

Edit: we know this for sure, because even after the asteroid that wiped out the non-avian dinosaurs, human sized and larger animals survived and thrived through the impact and fallback, despite having no access to any kind of technology or preparation. If the cold-blooded crocodiles could do it, I'm not worried about our chances.

Solar flares do not count as earth-ending events, at worst they could destroy our current electric networks and kill and strand maybe millions, but they are not in any way civilization-ending, nevermind life-on-earth ending as far as I know.

On both of those places you have to deal with the Russian and Australian Governments who will take a significant % of the value you create.

You also have a deep gravity well.

Land on Mars is free, there are zero taxes, no political system or unwanted populations.

There is no waiting for regulatory approval on a new building, no requirements to hire x % of your workforce as y demographic subset of the population. There is no national Government to negotiate with. Your population is completely comprised of high-IQ, motivated and skilled people, making for the best human gene pool of any place in the galaxy.

When SpaceX gets to Mars, it can simply... build, without limits. This is something not seen on Earth since the colonisation of the new world (which even then had native populations to contend with).

> When SpaceX gets to Mars, it can simply... build, without limits.

Until SpaceY gets to Mars. Then the absence of governments and regulation stops being an unmitigated benefit for SpaceX.

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