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Last Exit: Space is a new documentary on Discovery+ that explores the possibility of humans colonizing planets beyond Earth. Since it is produced and narrated by Werner Herzog (director of Grizzly Man, guest star on The Mandalorian) and written and directed by his son Rudolph, however, it goes in a different direction than your average space documentary. It's weird, beautiful, skeptical, and even a bit funny.
In light of the film's recent streaming launch, father and son Herzog spoke with Ars Technica from their respective homes about the film's otherworldly hopes, pessimistic conclusions, and that one part about space colonists having to drink their own urine.
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Why Werner Herzog Thinks Human Space Colonization “Will Inevitably Fail”
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-- Hester Pryne
(Score: 4, Insightful) by FatPhil on Tuesday March 15 2022, @04:55PM (16 children)
There's precisely zero evidence that there will be any.
I've heard a few - to me loony - pundits that seem to think that fuel is free, but the last back-of-a-fag-packet-calculation I did indicated that fuel would a million times more expensive than any possible profit. In order to get stuff back where there's a shortage of the minerals on the asteroid you need to take the fuel you'll need to get back with you. The leverage is something like 14 orders of magnitude. The gold just ain't worth it. And it ain't worth shit on the asteroid itself, either, as it's abundent there, allegedly.
All I see is modern-day fairy stories and dreams.
Ask me again in 10000 years, and I might have a different opinion, but probably won't. Our access to natural world is a logistic curve, not an exponential one, and nobody seems to understand the difference, which is why they fly off on these flights of fancy.
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 3, Interesting) by Immerman on Tuesday March 15 2022, @06:14PM (15 children)
Worst case scenario, assuming Falcon 9 class shipping costs of ~$60M per launch for 23 tons... 23 tons of gold is currently selling for $1.3 billion. That's a whole lot of profit margin to pay for the mining from. And in reality getting from the Belt to Earth only requires (very roughly) 20% the delta-V as getting from Earth to orbit, so you can actually move about 5x the mass for the same amount of fuel, for $6 billion in profit. Actually even more since you're not dealing with the *hideous* inefficiency of a launch from a deep gravity well in an atmosphere You could make bank even at SLS prices.
The thing is, it's getting *into* space that's expensive - getting back to Earth is relatively cheap and easy. Just wrap something in a cheap ablative heat shield (charcoal actually works great, and is easy to produce from local materials) and launch it on intercept course with our atmosphere.
Fuel is actually a relatively minor problem once you're in space. Firstly because you're already most of the way to wherever you want to go, energetically speaking (and like I said getting to orbit is hideously inefficient compared to traveling through space). Secondly because fuel is easy to make from local materials almost anywhere. And lastly because once you have the infrastructure, you don't actually need fuel except for fine-tuning and in special circumstances. Consider:
"Fuel" is mostly oxygen (about 80% by mass for Starship) - which is plentiful just about everywhere in the solar system. Lunar regolith is about 60% oxygen by by mass, and Sadoway has already developed a prototype electrolytic refinery for NASA that will extract oxygen from raw lunar regolith, with steel and other refined metals as a byproduct, using technology he originally developed for carbon-free steel production here on Earth (it's not yet cost competitive in the absence of a carbon tax, but it's a far simpler process and not dramatically more expensive.) Methane or hydrogen is a bigger problem on the moon due to the paucity of carbon and hydrogen, but most everywhere else those are plentiful as well.
Meanwhile a full-scale SpinLaunch system, already being tested in smaller prototype form as a first-stage Earth-based launch system, would need only a slight improvement to launch cargo from the lunar surface completely free of the Moon and into high Earth orbit (e.g. arriving at the Lagrange points) for less than 1kWh/kg, with no fuel needed. You could even reach Mars transfer orbit with only a 20% increase in launch speed - and with a clever trajectory you could harness a combination of gravitational capture and aerobraking to reach the surface of Mars while requiring only enough propellant for minor course corrections and final landing maneuvers.
Mount a similar system on a rich asteroid, and you could ship cargo back to Earth the same way. Or you could just convert local materials to rocket fuel - it's a relatively simple process, and you only need about 20% as much delta-V as needed to reach orbit from Earth, which means *way* less than 20% as much fuel thanks to the rocket equation.
(Score: 2) by FatPhil on Tuesday March 15 2022, @09:51PM (14 children)
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 1) by khallow on Wednesday March 16 2022, @05:23AM (8 children)
We've already solved the problem in hand, we just don't have the infrastructure up there yet.
(Score: 2) by FatPhil on Wednesday March 16 2022, @08:28AM (7 children)
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 1) by shrewdsheep on Wednesday March 16 2022, @12:10PM (6 children)
Reading posts in this thread, I find plausible points in all of them. Why not give the less informed/intelligent - like myself - today's uplift by spelling out some of the arguments?
(Score: 3, Informative) by FatPhil on Wednesday March 16 2022, @02:17PM (5 children)
He responds "just create new tech that permits X, and put it in place".
That's not how engineering works. You can't just wish things into existence.
Anyway, just pin yourself to your telly or your favourite fact-filled fanboy youtube streamers - Musk will have his first manned settlement on Mars in, >checks calendar<, 6 months! Unless the fantastic futuristic fairy stories that have been repeated dozens of time have actually been bogus bullshit.
For reference, there was a proposed mission to do what khallow suggests, where they never even worked out how sample return would be performed, and it would have taken hundreds of thousands of kilos of fuel just to get the 100kg mothership and 20kg lander that would collect (and through unknown mechanism, return) mere tens of grams of ore that would contain just grams of the intersting metals. However, that got 2nd place in the final vote, so they decided against it. Anyway, just ponder over "hundreds of thousands of kilos of fuel" to get "grams" of metal. That's why I keep saying people are many orders of magnitude removed from reality with their fantasies. And yes, this was specifically a *solar sail-powered mission*, as khallow suggested, so the time-scales would have been horrific too. You do realise that solar sails get thrusts measured in millinewtons, I trust, compared to rockets' meganewtons?
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 1) by khallow on Wednesday March 16 2022, @03:08PM (4 children)
That's standard in space development actually. Both Apollo and the development of the Falcon/Starship systems pulled it off quite nicely. You don't try to fully develop your entire technology tree before starting something. Instead, incremental technology development with work on new technologies, manufacturing techniques, and infrastructure started a bit before they're needed.
And really, the science behind this technology development has already been done. There won't be magic problems that will make space mining or electric/solar sail propulsion physically impossible.
Sample return has a return far in excess of the market value of the grams of potential ore that would be returned. There's two things going on that you miss here. First, it would be a technology demonstration of most of the transportation process from start to finish. Second, it would return valuable information on the potential ore body to the best location in the Solar System for testing such: Earth. No point to mining an asteroid (and investing billions of dollars) when you don't know what's there, right?
(Score: 2) by PiMuNu on Wednesday March 16 2022, @03:35PM (3 children)
To be quantitative:
https://en.wikipedia.org/wiki/Delta-v_budget#/media/File:Delta-Vs_for_inner_Solar_System.svg [wikipedia.org]
delta-v for earth to LEO is about 10 km/s
delta-v for LEO to moon is about 6 km/s
If I understand correctly the delta-v to get from moon to LEO is 6 km/s and LEO to earth is "free" due to aerobraking.
So the delta-v is double from earth to LEO to get to the moon and back. Similar to get to one of Mars's moons (not the surface of Mars).
Note that delta-v is not linear in terms of fuel costs.
Nb: I'm not a rocket scientist, but I _have_ played KSP so I guess I am pretty highly qualified (that was a joke).
(Score: 1) by khallow on Wednesday March 16 2022, @05:03PM (2 children)
Second, there are acceleration and thermal loading limits to aerobraking stuff. IIRC, one of the abort modes for Apollo missions had astronauts entering atmosphere somewhere between 12 and 15 km/s. That was considered a survivable situation. Meanwhile, typical meteorites hit Earth's atmosphere at least 25 km/s with most of the meteorite burning up in atmosphere. A lump of gold or platinum group metal encased in a heat shield should be able to survive reentry well below those speeds (especially if you don't mind a small crater when it hits ground).
(Score: 2) by PiMuNu on Wednesday March 16 2022, @05:54PM (1 child)
Just out of interest, what is the energy cost of, say, sifting sea water for trace elements? How does it compare with the energy cost of bringing an asteroid to LEO assuming conventional rockets?
(Score: 1) by khallow on Thursday March 17 2022, @01:46AM
Depends - where is the source for the propellant for that rocket? If it's coming from Earth, it's not going to be competitive with Earth-side mining (you need a bunch of orders of magnitude of propellant to move one kg of material from any asteroid). For example, I could see three to four orders of magnitude more propellant required to move an asteroid from near Earth orbit to say L4/5 (Lagrange points leading and trailing the Moon in its orbit by 60 degrees). If the propellant is part of the asteroid itself and energy is provided by local solar power (for example, a rail gun or some sort of electric propulsion), then that's a very different proposition.
It also depends on how fast you want to move that asteroid. If you're willing to take your time, you can get a lot of delta-v from gravity assists with Venus, Mars, Earth, and the Moon to get it into the desired position. If you're trying to do it right now (well, within a couple of years), it takes a lot more delta-v and energy.
(Score: 2) by Immerman on Thursday March 17 2022, @06:49PM (4 children)
You're right - you're doubting the bootstrap and here I am telling you about the mid-term technologies that will make it much cheaper once enough money starts rolling in to pay for the obvious upgrades that are already well on their way to becoming reality.
So - the bootstrap technology version: Hydrogen-oxygen rockets - Blue Origin has a nice reliable, flight-proven, highly reusable one in New Shepard. That'd get the job done just fine, we don't actually need much delta-V to get back to Earth.
Hydrogen and oxygen are easy to make - all you need is water and electricity. Very simple and reliable technology that we've been been using industrially for decades.
Water ice exists pretty much *everywhere* in the asteroid belt. And it should be easy to extract - just heat the surface of icy rock to above freezing in a near-vacuum, and pump away the resulting water vapor, as one of many examples.
So - you've got propellant waiting for you wherever you go beyond Mars, with only relatively minor infrastructure requirements that could easily fit in, say, a single Starship.
I'm sure you'll be happy to make blustery noises about how it's impossible for vague reasons you can't be bothered to mention, but the fact is that the minimum technology needed all exists already. The only part that we're maybe not ready for is the actual mining - a.k.a. collecting and sorting gravel in milli-gravity. And there's several companies currently developing the technology to do just that, in anticipation of Starship lowering launch costs enough to make it affordable to get started. It's not exactly rocket science.
(Score: 2) by FatPhil on Friday March 18 2022, @10:00AM (3 children)
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 2) by Immerman on Friday March 18 2022, @06:48PM (2 children)
Come now, you can troll better than that!
There's this thing you may have heard of called the sun? It delivers plentiful energy to everywhere in the inner system, and solar panels are a relatively mature technology.
Solar density is admittedly pretty low in the asteroid belt, about 20% what we get on Earth's surface, but the lack of atmosphere and 24 peak-sun hours/day of sunlight (compared to well under 5 in most places on Earth) means that the average power yield in the Belt would actually be about the same as on Earth - over 1 MWh/acre/day.
Moreover, the lack of weather or gravity means that solar panels can eliminate virtually all the protective and structural elements they need to survive on Earth, making them dramatically lighter, so that a single Starship could easily deliver many acres worth.
(Score: 2) by FatPhil on Sunday March 20 2022, @11:45AM (1 child)
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 2) by Immerman on Sunday March 20 2022, @03:13PM
Prototype? Water electrolysis and solar are both large scale industrial technologies - the prototypes were discarded decades ago. Well - aside from the ones chasing ever greater energy and cost efficiency, but I'll ignore those for the sake of a conservative estimate.
I'm going to have to make some really rough estimates - I can't actually find a lot of information on the propellant loads of real-world hydrogen rockets. The only two I can think of offhand are the Space shuttle and New Shepard, and either they're either both a bit secretive, or just not interesting enough for enthusiasts to have collected the details in easily found places.
So what I'm going to do instead is ignore the hydrogen and just look at the amount of oxygen needed in a Starship-class methane rocket - after all oxygen dominates the the propellant mass, and regardless of fuel type is consumed in roughly the right amount to completely consume both. Methane is a much heavier and considerably less efficient fuel than hydrogen, so looking at methane engines consuming the same amount of oxygen will overestimate the amount of oxygen needed for a hydrogen rocket with similar specs. Probably by a very large amount once you consider how hydrogen's higher Isp gets further amplified by the rocket equation.
Sounds like practical electrolysis typically consumes about 50kW/kg [wikipedia.org], and another 15kWh/kg for the ridiculously high compression necessary for use in a car. In space of course it's easy to reach cryogenic temperatures with nothing more than a sun shield - the James Webb Space telescope can get down to 38 Kelvin for example. The belt is getting only about 20% the sun, so a similar shield, or maybe something slightly improved, should be able to directly liquefy the hydrogen with zero energy consumption and skip compression altogether (H2 boils at 20K at atmospheric pressure). But I'll use 65kWh/kg just to be conservative and include any other energy-intensive processing I might have overlooked.
The mass ratio of hydrogen to oxygen in water is 2:16, so we'll also be producing 8x as much oxygen - or about 8 kWh/kg oxygen
Starship, which is *vastly* more rocket than we need to return a bunch of valuable cargo, contains a total of 1200t of propellant, ~80% of which is oxygen (=960t)
At 8kWh/kg, that means we need 960t * (1000kg/t) * 8kWh/kg = 7,700 MWh of electricity
Assuming 10 acres of solar panels, producing over 10MWh/day, that will take less than 770 days to completely fuel a Starship-class rocket. Which is a bit more than the time between launch windows to Earth (which will be a year and some months apart), but more solar panels or a smaller rocket could easily solve that.
And of course a Starship offers vastly more delta-V than is actually needed to get back to Earth, so you could actually bring back far more than 100t. The Falcon 9 second stage delivers about 6km/s of delta-V, and I imagine Starship will have a similar flight profile. But returning from the asteroid belt to Earth only requires about 2km/s, much of which can be provided with aerobraking in Earth's atmosphere. So you're likely looking at a payload well over 300t even before you even consider the gains to be had using hydrogen instead of methane. Or just send the ship back partially fueled with 100t of cargo (so it can actually pull off gentle landing.)