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It doesn’t really make sense, but some childhood part of me likes to imagine us as a species of explorers.

There are tons of things humans do that don’t make sense. IMO, the original moon landings didn’t make a lot of sense. We did end up benefitting in unforeseen ways from the technology developed by doing so.

If people want to sign up to fly to Mars or send hardware there to terraform, why should we stop them? I take lots of unnecessary risks mountaineering, because it’s what fills my cup.

You make great points about orbitals, and I do agree from a logical standpoint. Maybe Mars proves too impractical, but the technology developed leads us in that direction instead. I’m excited for the future either way.

Suppose it was possible to travel to Mars and survive on its surface. Even if no-one ever moves there permanently, I'm sure that many people would visit, just like people currently seek adventure in remote and inhospitable locations on Earth.

Maybe we'll even get a version of the show Alone that's set on Mars. "We dropped ten astronauts off in isolated locations on the Martian surface. Let's see who can survive the longest!" I'd tune in to that.

Very expensive snuff film

Life doesn't make sense. It's a fantastic tower of complexity fighting against entropy. Just let hydrocarbon goo sit peacefully like it apparently does on other bodies in the universe and stop this self-replication and evolution madness.

> complexity fighting against entropy.

Life helps entropy along! Humans are great at taking organized things and reducing their energy states.

There's actually an argument that says life is inevitable as a result of it the universe trying to heat death itself sooner.

> IMO, the original moon landings didn’t make a lot of sense

The Space Race made perfect sense. It was a political exercise. a proxy for war between nuclear powers. As long as civilizations have existed they've built monuments and undertaken massive tasks as a political exercise.

> ... why should we stop them?

Who said anything about stopping them? My argument is it won't happen because the costs are so high and there's no hope of a return from that.

People like to bring up human exploration as some kind of argument but every aspect of human exploration has been an economic activity. In the Middle Ages, European colonialism was pure exploitation. Columbus's famous journey West was to find a faster way to India... for exploitation.

There is literally nothing we could produce or extract on Mars that would make economic sense to bring back to Earth.

Broadly I agree about Mars vs the moon.

Two wrinkles, not really disagreements:

> Low gravity is a problem

It might be, we don't know. This ignorance is also a problem.

> Mars's atmosphere is the worst of both worlds. It's of absolutely no use to build a breathable atmosphere.

Not directly, but it does mean (1) leaks can be represurised from outside, and (2) is a source of carbon, useful for plants and ISRU fuel manufacturing.

The fuel point is useful for any initial colonisation creation, but by the time we seriously consider a million people we should be able to build a mass driver… which works better on the airless moon than the thin atmosphere of Mars.

> I firmly believe humanity's future is in orbitals (aka an incremental Dyson Swarm). This approach has so much more going for it, except perhaps the added protection of living deep underground on a planet or Moon.

I understand the appeal, but I strongly suspect they only seem good due to the failure modes having not yet been deeply investigated.

>> Low gravity is a problem

>It might be, we don't know. This ignorance is also a problem.

We did a study of prolonged stay on ISS - lower bone density, muscle loss, problems with eyes.

Our bodies evolved and adapted to live in 9.8m/s2 its not a leap of faith to think there will be issues in 3.7

> We did a study of prolonged stay on ISS - lower bone density, muscle loss, problems with eyes

Indeed, but the ISS is also zero gee.

> its not a leap of faith to think there will be issues in 3.7

I'm not suggesting it requires a leap of faith, merely that it is currently untested. Until we try, either hypothesis is plausible.

I t actually seems strange that the next 'step' isnt a spinning space science station, with simulated gravity.

Is there an obvious reason this would not work ?

Wouldn't it have to spin really fast to get workable "gravity" on board? Then if it's spinning really fast, how do people get on or off?

Through the middle

If the loop is large, you don’t have to move too fast. Fairground rides spin fast enough to exceed 1g with little kids in them, and those rides are usually not wider than 10m, often less. Speed here is distance around the circumference, so twice the radius, half the turning speed.

I don’t have the numbers in front of me, but generally it’s considered that the issue is more that if you’re standing on a spinning cylinder, you might have weird balance issues due to speed differences between head and feet. Also, you have to remember you don’t have gravity, so as you intuit, entry and exit are trickier.

Two broad ideas for entry/exit: do it at the center where the physical position is stable, then “spin up” some how, or alternately get up to external speed and lock on to something that you then elevator through the surface.

Take a really long cable, put a suitable weighted asteroid on the other end, then spin the whole thing up. As long as the cable holds, you have a decent amount of centrifugal force without needing a particularly large habitat.

I love the prospect :D

If cable holds you have gravity, if it fails you risk being slingshot into deep space

The usual design for these things have very low surface speeds, so you're not likely to go off into the deep even if it fails, as you're going to be pretty close to your prior combined orbit even without thrust, and the Δv needed to get back will be tiny.

But also, the forces are never more than the apparent gravity times the mass, so when someone does finally end up experiencing this, it will be part of a larger pattern of bad maintenance and/or engineering that likely has other things going wrong at the same time.

I was only joking, there is no way this would be singular cable without a fallback safety.

Neal Stephenson suggested having two habitats with hooks so they’d spin against each-other. Then you could have fun and climb up to see your neighbors.

you get off by running in the opposite direction and jump :D

I am only slightly exaggerating

Was assuming they do a kind of ferris wheel with center and 3 or 4 spokes to start, maybe 200m diameter, and gradually fill out the rim with modular units maintaining balance, and center of mass at central dock ?

> Is there an obvious reason this would not work ?

Nah, it's fine.

It's just big and expensive and we've already got gravity under our feet, so it's a very expensive way to remove one of the few reasons to do stuff in space in the first place.

We'll get around to it at some point, for sure. Just no hurry.

> You can cover large areas with solar panels that will generate way more energy and won't get covered in dust.

Once there are regular landings on the Moon, dust management will be an issue, either at source on the landing pad, or where it lands, which will be just about everywhere on the moon.

https://www.space.com/4956-lunar-landers-sandblasted-moon.ht...

https://www.scientificamerican.com/article/lunar-dust-could-...

https://www.nasa.gov/news-release/nasa-seeks-student-solutio...

Isn’t the moon dust sharp too? Barbed like?

Yes. From the 2nd link:

> moon dust is nasty stuff. The jagged material

It has never been smoothed by wind and water erosion or reacted chemically with the same.

I'm sure leaving a fertile land 100 000 years ago, crossing the desert on foot, having most people die in the process, not knowing if they was an end to that sand, felt the same.

Why would you do that?

Two centuries in the future, the benefit of going to mars will be obvious, because we will have progressed and gain things we don't know about now.

That's how humanity works. We try crazy stuff. And a lot of it is stupid, expensive and dangerous. Plus the result is disappointing.

But eventually something pays of big time.

And everybody says of course we should have done it retrospectively.

It's like people asking why we are still making purely theoretical math research. Surely it's no use, and it's expensive.

I have no doubt many people opposed to the moon landing as well on those grounds.

I expect fully the comments to answer "but this time it's not the same because...". But it's never the same.

It's always a different situation. That's the point.

That's what discovery is about.

> Why would you do that?

Because there was fertile land on the other side.

Moving to Mars is the opposite: it is crossing the desert to go move into a frozen hellscape of radioactive desert.

> I'm sure leaving a fertile land 100 000 years ago, crossing the desert on foot

Actually, this kind of thing basically never happened, for some values of never.

Humans didn't leave Africa by crossing the Sahara desert. When we left Africa, the Sahara wasn't a desert.

Similarly, Aboriginal Australians didn't swim or canoe to the mainland, they walked there at a time when sea levels were lower and there was a land bridge to PNG.

Until very recently, nobody did crazy long crossings over uninhabitable lands or waters. Expansion happened incrementally, over habitable areas to other habitable areas.

> But eventually something pays of big time.

There is no reason to think that there is anything of value on Mars. No oil, no arable land, no liquid water, no unique unobtanium like in the movies. Just the same eighty or so elements, in roughly the same distribution. Just colder, drier, and impossibly far from everything you care about.

Sometimes being outside easy nuclear strike capabilities of the superpowers is a good on its own. Plus lot less annoying environmentalists and I imagine plentiful fissile material.

If literally every nuclear bomb ever made was detonated in a world war, the fallout from that would be a significantly smaller problem than the steady-state radiation is on Mars right now.

The fallout will eventually decay, but Mars will stay an irradiated hellscape forever.

With a couple fairly simple genetic modifications humans could thrive in place with high background radiation, in a place where nobody can throw nukes at you for doing simple genetic modifications.

If rockets with people can get to Mars, then rockets with nuclear warheads can get to Mars.

But you have a long time to see them coming.

People didn't know there was a fertile land of the other side. Just like we don't know if there is a good thing that will come out of mars. We just know the constraints.

It's not about what you know is there. It's the potential.

There is no point for Usain Bolt to run that fast. There is not point in building the tallest tower in the world once again.

Meanwhile, the mars goal already managed to bring us spaceships that land and divide the cost of putting satellites in orbit by 10.

No other path lead to it because there was nothing to motivate it enough.

This comment is really poorly reasoned imo. To continue your metaphor, ancient peoples did not sail across the Pacific *, they sailed to the next nearest island and started colonies there (if viable). You could apply your logic to argue for colonising Uranus, or even the Sun.

> Two centuries in the future, the benefit of going to mars will be obvious IF the colonisation of Mars is successful (however you define that), the benefits of it MIGHT be obvious. Those are 2 huge conditionals; it may not be possible to colonise Mars, and if it is possible, we may still not be seeing any benefits in 200 years time.

*Of course, some did, but very much by exception. And it rarely ended well for these people, or their tribes, or humanity at large.

  >> Now compare this to the Moon.

Colonizing the Moon makes absolutely no sense and it's fascinating to watch otherwise rational people with decent science educations contort themselves into believing otherwise just for the sci-fi trope of living on the Moon.

Maybe in 50 years the Moon can be colonized by machines, but for humans if they really want to experiment with self sufficiency, they can try building Biosphere 3 in the Sahara and see if they can survive for a few weeks without constant support from the outside.

https://en.wikipedia.org/wiki/Biosphere_2

A fully isolated colony anywhere isn't going to happen in our lifetimes. This would be true even if there were another Earth. It would require multiple revolutions in compact software-defined manufacturing and a rethink of supply chains around that core.

McMurdo on the Moon is entirely possible and I think there's a good chance we'll see it. This would get us started trying to live elsewhere and we'd start learning how to deal with the challenges. We'd also find out about the challenges we don't know.

Back in 1999 I worked on a (unfunded) pre-proposal to NASA on "OSCOMAK" (Open Source Community on Manufacturing Knowledge) but, it did not go very far. https://www.kurtz-fernhout.com/oscomak/ "The project's ultimate long-term goal will be to generate a repository of knowledge that will support the design and creation of space settlements. Three forces -- individual creativity, social collaboration, and technological tools -- will join to create a synergistic effort stronger than any of these forces could produce alone. We hope to use the internet to produce an effect somewhat like that described in "The Skills of Xanadu" by Theodore Sturgeon (available in his book The Golden Helix). We will develop software tools to enable the creation of this knowledge repository: to collect, organize, and present information in a way that encourages collaboration and provides immediate benefit. Manufacturing "recipes" will form the core elements of the repository. We will also seed the repository, interact with participants, and oversee the evolution of the repository. You can read a paper we presented on this project in the Proceedings of the Thirteenth SSI/Princeton Conference on Space Manufacturing May 7-9, 2001, which we have made available on the web..."

See also my comment here: https://news.ycombinator.com/item?id=15736225 "... So where is a key area of research that should be a priority among NASA and Billionaires, but is not heavily pursued? The issue is what to do in space once you have gotten there. Because if there is a reason to be in space, then people and collectives will work to get there. And the reality is, that right now, if we could get there, there is nothing to do there short of look around and come back. And if that were the case, Space would not deserve much more investment than say tourism to Mt. Everest. The reality is that we don't know how to support human life in space -- in large part because we have only spent a pittance on thinking about that issue systematically compared to the issues of CATS and Planetary Exploration. Frankly, while we support human life on earth, we have very little meta-knowledge formally about how to do even that. And, most of figuring out how to support human life in space at a nuts and bolts level requires non-sexy activities like sitting around and staring out the window, talking, sending emails, building databases, building software tools, building some small physical prototypes on tabletops and outdoors, and just plain thinking (the hard stuff). This is all the preparation needed for the spiritual voyage into the (physical) heavens. Biosphere II was an excellent start in some ways, although the science mission was a bit dodgy at first and it seems Columbia (the recipient) seems about to abandon that effort for cost reasons --- and in any case, Biosphere II focuses on the wrong question -- we know biospheres can work and replicate (although scale is an issue) -- what we don't know is how to replicate the mechanical infrastructure (e.g. glass pane making machinery) behind them. A lot more money has gone into studying ecosystem food webs than industrial ecologies of pipe webs and assembly line webs (and frankly, a lot of people don't want their "proprietary" manufacturing processes studied or gossiped about by academics.) ..."

One of the big arguments for colonizing Mars is that a self-sufficient Mars colony could serve as a "backup" for the human race in case we screw things up so badly that we wipe ourselves out here on Earth.

I always thought this was a specious argument and that despite a lot of social media threads and Elon ravings, no one is really taking it seriously. The reason I think this is because no one ever brings up the idea of having a self-sufficient colony in Antarctica.

I mean to build a proper threat model you need to understand exactly what threats you're trying to mitigate I guess. But let's say it's the usual doom and gloom stuff, a) climate change, b) nuclear war/winter, c) meteor strike.

If anything an Antarctic colony stands to benefit from climate change. A nuclear war is scarier, but none of the fallout is going to reach the South Pole, and to be self-sufficient you had to solve your energy needs without much sunlight anyway (there are surely tons of undiscovered hydrocarbons down there waiting to be dug up and refined).

A meteor strike, well as long as it doesn't land on the colony, the problems are similar to nuclear winter.

So if you want to have a "backup" for the human race - the Antarctic Plateau is sufficiently remote, and about 10,000x easier than anything off-world.

But we don't even talk about it because everyone knows life on Antarctica is pretty depressing and PEOPLE JUST WANT TO DO SCI-FI IN SPACE.

> A nuclear war is scarier, but none of the fallout is going to reach the South Pole

The South Pole is within easy reach though, why wouldn't a colony on it get targeted as well?

If there is a self-sufficient colony there, and it consists of people from a single nation, it will be targeted. Only a non-political, mixed-heritage colony of scientists and farmers might be overlooked.

As of 1964, with the Mariner launches, the same rocket would be used to target either Antarctica or Mars.

An antarctic base/colony would not solve a number of issues:

1. A meteor strike can be big enough to obliterate anything on what was once the surface. It can heat the entire globe to 100 degrees Celsius due to tektites bombarding the surface. 2. Due to millennia of snow and ice covering it, the surface of the continent is just bare rock. Nothing will grow there without significant amounts of soil moved to it. Yes, this is also a problem for Mars, and a boat is more proven tech than a spaceship, but the removal of all ice off the surface will not change Antarctica into a bountiful oasis. Making a self-sufficient colony there is going to be extremely hard.

Musk is using SpaceX to drive down the cost of sending things into space. This greatly reduces obstacles for going to space, and makes a self-sufficient Antarctic base a bit obsolete.

Still mars colony will not be a colony, it will be an outpost.

I dont think we are even close to be able to make it self sufficient.

Self sufficient sounds nice in principle but is way more complicated. You need industry for every single part used to build colony - that is replace everything you rely on.

Soil enrichment, material wear, silicon chips... you need to have uranium mine and processing to sustain energy production.

The scale of the operation is massive. And all done underground.

Not impossible, just unlikely we will ever get there.

> You need industry for every single part used to build colony - that is replace everything you rely on.

That's actually much, much harder than it sounds, and this is the key part that everyone just hand-waves away.

On Earth, it is already unaffordable to move to many places for even relatively rich westerners. As in, your own personal economic output is unable to pay for the cost of moving the materials there, setting up a habitable abode, and then keeping you alive until the age of retirement. That's with normal-ish housing in normal-ish conditions.

We can only afford our current lifestyles with the "cheat codes on": free oxygen, free water, free temperature control, and free energy growing out of the sky[1].

On Mars, you have two compounding challenges:

1) Every aspect of staying alive is harder. Housing has to be air-tight. Instead of a mere air conditioner, you need a life support system. Instead of just food, air and water also need to be made. Space suits are needed to go outside. Etc...

2) Productivity itself is lower. The supply chain is tiny, raw materials are much harder obtain, cooling water and air is not available in bulk, and so on. Just think about how dependent modern technology is on plastics, which are made from oil. Mars has no oil!

The combination of both lower productivity multiplied by higher cost of living and ridiculous supply-chain issues for the first century (or more!) means that self-sustainability will be out of reach well past all of our lifetimes.

[1] Trees are made of air and hence grow out of the sky. Trees make wood that we can use for energy. https://www.lawctopus.com/do-trees-grow-out-of-air-richard-f...

Antarctica has the sea right there to harvest organic matter to make soil.

And of course limitless water and air, and not seething with radiation.

Fair point on #1 but I imagine the probability of a meteor strike that literally boils the planet is a lot lower than a strike in general.

Regarding #2, the solution for self-sufficient agriculture in Antarctica and on the Moon/Mars is the same: hydroponics.

Only it's much easier to do hydroponics in Antarctica. You can melt that ice for fresh water. You can harvest all kinds of nutrients from the ocean. The Antarctic seas have huge oil deposits to provide limitless energy. An Antarctic colony pretty much just needs lots of weather-hardened infrastructure, it's tough, but well within reach of current tech.

Self-sufficient Moon/Mars hydroponics is way harder. Water is far more scarce. Where do you obtain the nutrients for plant life in situ? Not sure it will all require exotic systems that haven't been invented.

My premise is basically that the political will for a self sufficient colony that "backs up" human society doesn't exist. If it did we would just have some countries agree to amend the Antarctic treaty and do it. It could probably even pay for itself by exporting oil. But no one genuinely cares so we just write scifi stories on the Internet instead.

I very much agree that the moon is a better target. Being able to send help in a few days instead of months is a big deal.

What I believe the moon is especially good for is as a launch pad for further exploration. Build mostly-automated factories in low but non-zero gravity and launch with a much smaller escape velocity. Lots of raw materials right there, easy energy from the sun (with solar panels in space for the night).

Unfortunately, the moon is "old hat" now that we've walked on it, and people want exciting new goals, not just a space factory.

You're not wrong, but if we follow that logic, we might as well shut down all the bases in Antarctica; for that matter, people should probably stop living in Las Vegas, and what is up with that restaurant on top of the Jungfraujoch? Nobody can live there!

Perhaps it's about more than mere practicality.

We do things that don’t make sense all the time. The idea that our lives and plans should be dominated entirely by rational decisions only itself makes sense if you’re willing to expand rational to include the likes of “because it’s there” and “because I felt like it”.

That said, given the unknowns and uncertainties, I believe it’s rational to devote some small amount of our resources to trying to achieve multiple sustainable off-earth communities, including in orbit, on the Moon, and yes, on Mars.

I think GP is referring to people like Elon Musk, who have a personal brand built around the idea that they’re “rational people who make data-driven decisions based on logic” and yet twist themselves into fascinating rhetorical shapes trying to argue that human colonization of Mars is possible, necessary and also imminent. I think they do this because they recognize that “some small amount of our resources” won’t actually be enough to do anything on Mars in the coming century, and they want to go to Mars in their lifetime.

In general, life, if it is to endure, has to keep pushing its boundaries. Our current niche will surely end. Through stretching to build colonies in difficult places, hopefully we will become more robust. So it’s useful for explorers to go to places where they might just barely survive.

As humans start moving beyond Earth, I think that it’s more likely that we change ourselves. We can probably make our bodies more tolerant of lower gravity and higher radiation.

> and won't get covered in dust

I thought moon dust was a terrible problem, esp because with no atmosphere it's statically charged and so sticks to everything?

Don't forget that there is more surface area on the asteroid belt than the rest of the solar system combined — and minimal gravity.

Cheap — and resources to extract.

This is important because an unmanned project could redirect asteroids to repeatably hit a chosen canyon on Mars. This increases the neighborhood metal value and begins the 50 km shaft you’d need to achieve survivable pressure underground.

And you can prod asteroids so they accidentally fall on your enemies, either in the belt or on earth.

- Lower gravity

- 2x distance to Earth compared to Venus

- No magnetosphere

- Thinner atmosphere = you boil at room temperature

Lower gravity isn’t necessarily a con. It’s great for rockets!

It's definitely a con for human habitation. Our physiology evolved in 1g and without that many of our bodily processes behave poorly over extended timeframes.

We don’t actually know what the long-term health consequences of Martian or lunar gravity are.

We know the long-term health consequences of microgravity (as in LEO) are significantly negative.

But, we lack data on long-term health effects of Martian or lunar gravity. Pessimistically, humans really need close to 1g, and anything significantly less causes serious problems-lunar isn’t going to be much better than microgravity. Optimistically, humans just need “some gravity”, and while close to zero is harmful, lunar or Martian isn’t.

The way things are going, we are likely to find out in the next 10-20 years, at least for the lunar case. If lunar gravity avoids most of the negative health effects of microgravity, Martian gravity will too. If it doesn’t there is still the chance that Martian gravity might be “just enough” even if lunar gravity isn’t

Long term yes, but people still go to the ISS in 0g.

I was just pointing out that some things that are bad for humans actually make the rocketry problem for returning easier for this bullet point.

The second point isn't accurate. You're thinking they're all static, rather than orbiting. There's times when each is closer than the other.

I assume we use distance as proxy for “how hard is to get there” (time and energy needed). Actual momentary distance is a bit tangential, because you never move in a straight line.

From low Earth orbit, transfer orbits to Venus and Mars take 3.5 and 3.6 km/s of thrust respectively. According to https://en.wikipedia.org/wiki/Hohmann_transfer_orbit

The problem with a Hohmann transfer orbit is that you rely on launch windows. You can only do it when the two planets are in a straight line from the sun (or more accurately, and the same equivalent points in each of their orbits at the same time). This is a pain as Earth-Mars launch windows only come along every two years.

If you want to launch without that issue, you're then into the world of using more delta-v, which is catastrophically expensive, unless you've got some form of propulsion for your craft beyond what we've got now. So yes, but with caveats.

Obviously, there's a giant pile of detail beyond this in terms of the calculations for trading off time of flight vs distance between bodies, vs delta-v to accelerate towards the body, and then accelerate away from it to slow your descent into an orbital trajectory, but that's more depth than I'm going into for a quick HN comment.

If you're jamming the throttle then the difference between Venus and Mars is also not very much.

Distance and time are two of the fundamental constraints for how much delta-v you're going to need to move from point A to point B, with the third being how you control your velocity when you arrive. The other child comment and my answer to them goes into this at about the highest level possible.

> Low gravity is a problem.

Isn't it a bigger problem on the Moon?

Mars makes sense to Elon Musk because it would be the culmination of his multi-decade strategy of pumping up companies on government largesse. Whether it's fat government contracts or tax credits and grants, every single one of his ventures have relied extensively on the taxpayer. Musk correctly has identified an international effort to Mars as the most lucrative, multi-governmental contract that ever existed.

As far as terraforming goes, Venus would be a much better candidate for it than Mars.

Yes, but there is also nothing on the moon worth going there for. Fusion resources are a pipe dream and anything you mine there would be much better mined off asteroids.

I’m of the opinion that if you want real space industry, leave the planets alone and go to the near-earth asteroids followed by the belt. If you want space tourism and money-sucking colonies then it doesn’t really matter which location you pick - they’re all bad.

> Fusion resources are a pipe dream and anything you mine there would be much better mined off asteroids.

More pertinently, when we actually develop a fusion reactor, the gas giants are a far easier place to get fusion fuel from than the parts-per-billion in regolith.