Interstellar Flight: Perspectives and Patience
centauri-dreams.org
centauri-dreams.org
If you go to something like Trappist (40 ly) at 0.01c (very optimistic), it's not just that everyone you know will be dead when you arrive. Your entire nation will have disappeared to the sands of time. The landfall announcement you send back will be incomprehensible because of language shifts, and you won't live to see the reply. Meanwhile, such a trip would be an enormous investment, requiring multiple nations to bankrupt themselves, with no hope of even surviving to see the outcome.
With that, it's very hard to imagine interstellar travel being feasible with our current understanding. There would have to be something like FTL travel or wormhole. The only "realistic" development, (much) better engines that can do 0.1c, would not actually change much.
There’s a book called Count to a Trillion which explores these ideas, and others. At the end of it the main character’s wife sets out on a mission to M33 and isn’t expected to return for at least 70,000 years. He gets stuck on Earth, unable to catch up with her, and promises to be here when she returns. The sequel is all about what he has to go through to keep Earth a going concern while she’s away.
That raises the question who would want to travel and why. And what's wrong with them. Because the profile for people that want this would be hard to distinguish from somebody that is depressed and suicidal.
Same problem: the best-case outcome is that we never hear anything interesting from that rocket ever again. But it should be a lot cheaper.
Those age too. Especially out there without the earth's shields. If you make one that lives longer than a human it's already quite the feat, add only a bit more radiation, it only gets worse. Computers are much worse with failures than brains too.
The nice thing about biological systems is the self-assembly from tiny molecule parts. Worst case, you can create a closed system with birth/death renewal. For tech the machines that build the machines, and the machines that build or repair those in turn, will all have to be brought along too, or you need to have some impossibly tough requirements for the product to last.
We may need some similar automatic self-assembly for tech for such use cases. The whole spaceship and all its components will deteriorate too.
Even when we sent out ships to venture around the world they had to be able to do replacements for broken parts, like masts. We probably need that capability for space ships too, to stop at some asteroid and rebuild. But then you get the equivalent of the rocket equation: On the one hand, you need a lot of stuff to support that manufacturing, on the other hand, every item you add itself needs maintenance and rebuilding at some point. The way out is this molecular-level self-assembly. You throw a few tiny nano-machinery dust spores on an asteroid, and ten years later you grew some useful machinery...
Yes it is, but what does that have to do with my comment? It does not change anything I wrote regardless of if it was already real, is feasible but not now, will never be possible.
Humans are just a stepping stone. Earth intelligence will transcend our 77 year lifespans and primate brains.
Our lungs are adapted to gas exchange on this particular gravity well and its unique biogeochemistry. There's no reason redox reactions need to happen like this, or indeed even be the primary propulsion mechanism.
This is our frail biases speaking. We are limited by our biology, but we won't be forever.
The trick will be to remain -human- perhaps. Or we just accept the fate of the loser of natural selection, and are replaced by our children of an obsolete god.
I have posited an idea on how this could work and done a bit of world building in that space, perhaps I will overcome my reticence toward writing fiction and publish one day.
Even with massive advancements in tech, and getting close to the speed of light, interstellar travel will be a lot of "one way heading into the unknown forever" kind of initiative. Interstellar empires only work with truly sci-fi tech that mostly ignores distances, like in sci-fi (instant subspace comms or warp travel with no relativistic effects)
This will never be the same kind of age of exploration as when we crossed the oceans and explored our planet. The scales are so mind blowing that even the fastest speed known to mankind is too slow. The times and distances involved to move and even just send signals (both ways!) and relativistic effects means at best we can "seed" a distant planet and hope that turns into a new (human?) civilization, forever separated from us for all practical purposes.
I recently read this in an interview with Juergen Schmidhuber:
> Of course, such life-like hardware won't be confined to our little biosphere. No, variants of it will soon exist on other planets, or between planets, e.g. in the asteroid belt. As I have said many times in recent decades, space is hostile to humans but friendly to suitably designed robots, and it offers many more resources than our thin layer of biosphere, which receives less than a billionth of the energy of the Sun. Through life-like, self-replicating, self-maintaining hardware, the economy of our solar system will become billions of times larger than the current tiny economy of our biosphere. And of course, the coming expansion of the AI sphere won’t be limited to our tiny solar system.
Of course, this is in the realm of science fiction but so is interstellar travel.
Greg Egan's Diaspora has a fantastic treatment of interstellar travel - it involves sending copies of your consciousness to different spaceships traveling to different destinations. On arrival, a preset program will verify if the planel/galaxy is worth waking up to. If not, the clone is terminated.
If more than 1 clone wakes up in a hospitable environment, then you have a problem of two copies of yourself separated by light years.
Avoiding spoilers it would basically be through hibernation and/or generational ships. Which basically implies of losing all ties to earth and anyone/anything you left there.
But, then again, why would nations invest in such expensive endeavours if there is no prospect of seeing something back out of it. I imagine only an emergency situation would cause this no?
I bet you're right about emergency situations. On top of that, people have been getting on boats and pushing off into the ocean for at least 25,000 years[1] when there was plenty of good land to keep them occupied. It's not that we're talking the same time scales, but rather the fact that they probably did it despite completely unknown time scales. It makes me wonder if the right philosophy or religion will come along that makes somebody try a generation ship for non-emergency reasons.
I think that Physics-compliant sci-fi novels are more entertaining because the solutions (feasible or not) are more ingenious and the consequences more surprising.
Interstellar travel probably has a similar problem, even if you have an engine that can do 0.1c, you have to be sure in 5 years you won't have one that can do 0.2c, or that ship would beat you.
And the relativistic mass equation imposes a very lower upper bound. Light is slow.
Sometimes it's hard realize the with have a good understanding of only 5% of what composes our universe. Let's hope there's still some surprise lest for ours Centauri Dreams...
Clearly such a mission is beyond the capabilities of our world currently. Like, obviously such a mission is something that capitalism cannot accomplish. That communism or anarchism or any -ism just cannot do. And I think that when people look at jaunts out to Alpha Centauri and think in terms of cost, they whole thing is hopeless from the get-go.
To make something like a trip out to Vega, even with just a probe one way at .1c, that's 500 years (right?). We can't fathom doing that right now as staying around to check out any answer. The ultimate 'plant trees in whose shade you'll never sit.'
Generation ships out there, even with magic hibernation tech, I just don't think we have the mental capabilities as great apes to think about this properly. The time scales, the advances in tech, the costs, just even thinking about things in this way shows to me that we're not at all ready to be serious about this.
You don't build a ship by teaching people how to hew oaks or caulk bulkheads. You build a ship by teaching people to yearn for the sea.
Space is still 'not worth it'. Until just being there in the void elicits the same feelings you get when reading about the bowsprits, white with sea-foam, before a quick and fast wind, look, we're not going to do this.
We have to love the trip itself first. The first stars until morning. The good ship to guide by them.
If you were to create a constitution for a multigenerational space trip, it might look like the Rule of St Benedict. Many of the monastic rules were intended for “families” whose lifespan were intended to infinite.
There’s already some very good sci-fi on this topic, but it seems most of it is quite old. Most recent would be Babylon 5, that I know of.
More than barely. "A 40-year one-way interstellar flyby mission to the nearest stars will require a relativistic spacecraft speed in excess of 6000 AU/yr (i.e., > 0.1c)" [1].
That means, practically speaking, nuclear-fusion, antimatter-annihilation and directed-energy propulsion. All of which are TRL ≤ 2.
My bet would be on fusion propulsion. It's inherently easier than fusion power since you don't need to bother converting the energy to electricity. That said, solar sails [2] and directed-energy anti-drone weapons [3] are seeing quiet progress.
[1] https://ntrs.nasa.gov/api/citations/20200000759/downloads/20...
[2] https://www.nasa.gov/mission/acs3/
[3] https://en.wikipedia.org/wiki/Silent_Hunter_(laser_weapon)
Nobody debates this. The point is that 0.1c propulsion is not necessarily 100+ years away. And its 40-year transit time is not "barely feasible," it's comparable to present deep-space mission timelines [1].
I have three wild-eyed theories: (1) eukaryotism is an unbelievably exotic step; (2) and/or the moon is required and ultrarare; or, (3) advanced civilizations eschew yellow stars for being inconveniently short-lived: maybe they prefer brown dwarfs, white dwarfs, or black holes for their energy gradient.
We are simply the first.
>I just wonder if humanity’s adventurous nature is leading us away from a proper focus on the sustainability of our civilization, our specie, and our fragile planetary environment?
But we still need spaceflight at least for planetary defense against asteroids, mining asteroids(so we don't have to mine Earth), etc.
With chemical rockets, not much.
With "a propellant-less propulsion propulsion system such as solar sails or electric sails," bringing water (propellant) to low-earth orbit starts making sense [1], as does mining platinum, but only if "the quantity of platinum from space would substitute an equal quantity of terrestrial platinum," i.e. moving heavy industry off the Earth's surface [1].
Given asteroid-mining profitability is dominated by "the throughput rate, which depends on the mining process," it's possibly to see a path to certain rare-earth minerals becoming profitable to mine in space if environmental controls on Earth are tightened while constant-thrust propulsion technologies advance.
Yes. (Deöbiting from LEO is cheap, like 90 m/s for the Space Shuttle, because you can use the atmosphere.)
That way by offloading mining and refining into space to prevent the damage that these activities incur on earth you're also undoing damage to Earth from past human activities.
The energy involved in chemical rocketry is actually not that much. Getting a kilogram to LEO is roughly as expensive (in energy) as flying it to the other side of the world in an airliner. Getting stuff back from an earth-crossing asteroid can also be very cheap energetically, with very small delta-V (if one is willing to wait long enough).
Also, the materials we're talking about from asteroid mining, like platinum group elements, probably are shipped by air, just for security.
This whole argument is reminding me of the facile and bogus argument that launch to earth orbit from planet's surface is expensive because of the energy needed.
So far we have... "maybe platinum." Maybe!
Aside from the conspicuous absence of math, "maybe platinum" isn't remotely important enough a factor in earthbound mining to justify asteroid mining on the basis of preserving earth, obviously.
I don't need to argue things are practically mineable in space to rebut the point. I just need to argue if they aren't practically mineable, energy consumption isn't a reason.
I have already given you the counterargument.
> we have maybe platinum
Those making the energy argument need to rebut every possibility. The "it takes to much energy to ship back" is ludicrously wrong for platinum. The argument destroyed, why would we need to say more?
It takes as little as 0.1 km/s delta V to get onto an Earth-intersecting orbit from known NEOs. The energy of a mass moving at 100 m/s is 5x10^3 J/kg, or 1.4e-3 kWh. If a kWh costs $1 in space, this would be a fraction of a cent per kilogram. This delta-V is so small that the energy cost of sending back base metals would be affordable. Hell, the energy cost of shipping gravel from space would be affordable! Other costs, probably not, but that's not the claim we're addressing.
So far that's the best answer, so thanks for providing it.
You may also find in your scrolling that I did not say "it takes too much energy to ship back." I said "What resources are on asteroids that justify the energy expenditure to get from space and back?"
Obviously getting down is not the expensive part. We've all heard of gravity. Getting the equipment up that is needed to get stuff down is. This is also due to gravity.
I'm afraid you misread my first comment and responded as if I thought it was energy expensive to drop stuff onto earth.
By moving mining off planet to the moon and asteroids we eliminate the carbon emissions and environmental damage that occurs from these processes.
So how do we do it? We don't need to start sending fleets and fleets of crafts into space which is energetically expensive and time consuming, what we need to do is develop self-replicating mining equipment that we can send to turn the things we want to mine into more things that can mine for us. We won't achieve full self-replication immediately but we can definitely send machines that can do partial self-replication at first and work on improving the ratio of material sent to material returned.
What do we send back? titanium, platinum, aluminum, nickel, iron, whatever we find there. If platinum was as cheap and plentiful as aluminum was now we would have all sorts of catalytic uses for it that would significantly clean up our Earth based industrial practices.
How do we send it back? If we're sending it back from the moon that's easy -- a space elevator or rail gun. If we're sending it back from asteroids inefficient but cheap iron ion thrusters. Use iron from the asteroids as fuel.
Bonus points: Send it back covered in ablative material like mined olivine that can react with CO2 in the atmosphere to sequester it, that way the whole process isn't just moving environmentally damaging industrial practices to other solar bodies but we're undoing some of the damage from past human activities.
We'll have to get very very creative with nickle-iron and silicates to build a small automata civilization on big flyby rocks.
... but this won't happen unless it's economically advantageous, with all risk, transit, and upfront investment included
We already don't have the political will to force single-digit increases in cost of output to reduce environmental damage. Why would we then?
Not too sure! Probably one part is to disabuse people of the notion that we have alternatives available if only we could just dedicate more brainpower to space travel.
The real answer is to eliminate the tradeoffs through scientific innovation. As mentioned elsewhere, the real way to protect earth (and our species) is to produce better plastics, proteins, and pesticides. Each smart person wrapped up in sci-fi fantasies of simply off-planeting heavy industry is another brain dedicated to -- as far as I can tell (thus my questioning here) -- an almost completely useless endeavor.
Which is why I believe the aforementioned disabusal is critically important. There's just no evidence that big explosions and adventures are what we need. We need people in labs nudging molecules over and over with a 0.0001% success rate.
If so, when do you think this will start to occur? 50 years from now? 100? 200?
If not, why not?
Mostly because outer space sucks and there's no reason to be there, as evidenced by the inability for anyone in this thread to come up with compelling reasons to do it aside from "ah the adventure!" (from people who haven't done anything that could be described as 'adventure' here on earth, ever).
Firstly we're now at a point where we have lots of cheap energy available, principally chemical. Depending on many factors it's conceivable that we are in fact at or near peak human energy output (e.g. WW3 or civilization collapse - the next iteration of civilization won't have so much cheap oil to exploit).
Secondly LEO is not yet full of junk, meaning that it's trivial to find launch windows to LEO and beyond. That could easily change very much for the worse in a relatively short time (I infer decades from the books).
Finally it's unrealistic to expect us to colonize the Moon or Mars using only Earth-mined materials. You can launch a spacecraft to Mars easily, but to launch a small city's amount of construction equipment and raw materials is beyond our capabilities.
Conclusion: now is the best time to mine asteroids. We can do all of the processing and much of the construction in LEO (or even better at Earth-Moon or Earth-Sun lagrange points) and then, with relatively low delta-v, we'd actually have a chance of becoming an interplanetary species!
But, the novels warn, the window of opportunity will eventually ("soon") close. Well worth the read.
Maybe someone else more familiar with the arguments, who has also read these novels, can offer a critique?
Nuclear fission is more stable, less maintenance, less risky, less upfront and ongoing environmental damage, less vulnerable to all sorts of risks, and produces way way more energy.
> We find the SBSP designs are more expensive than terrestrial alternatives and may have lifecycle costs per unit of electricity that are 12-80 times higher
https://www.nasa.gov/wp-content/uploads/2024/01/otps-sbsp-re...
> This study assessed lifecycle cost and emissions based on the following scenario: SBSP systems are developed on the ground in the 2030s and launched to low-Earth orbit (LEO), and then transferred to and assembled in geostationary orbit (GEO) in the 2040s.
Furthermore, one main benefit of SBSP over nuclear is that the receivers don't need to be connected to the grid; each household or piece of infrastructure can have one. This would help manage situations like the power outage in Spain earlier this year or the situation at the start of KSR's Ministry for the Future where a deadly heatwave in India is made 10x worse by coinciding power outages.
> This would help manage situations like...
Aren't these situations trivially solvable with batteries if there were political will to be prepared for them?
Since nuclear fission is enbarrassingly uncompetitive on Earth, where is this "especially" coming from? The comment seems to be impeaching the credibility of the study, if it concluded nuclear on Earth would be the top contender non-fossil energy source.
> study isn't credible based on misreading of a comment about the study
No, nuclear isn't the best in $/TWh, though it is quite close. The reason it's so uncompetitive has to do with the gigantic payback period and the fact that renewables (increasingly) eat into its demand intermittently which lengthens the payback period even further.
But if you include environmental impact, nuclear is absolutely amazing. Which, if you'll recall, was a dimension named as important by the GP: "[space based solar generation] would be highly useful for reducing climate change and increasing climate resilience"
It seems you have plenty of time to form your opinions about what's scientifically and economically sound based on sci-fi novels, but not enough to read the executive summary of a NASA study that actually investigated the proposal at hand.
In any case, a nearby planet or its orbit would seem to be the most logical place to start for any supervillain species seeking to colonize its galaxy. :-)
You’re making a big jump to conclusions there. Globally we (EU and US) do care about this risk and in fact are spending hundreds of millions per year.
Or at least we were spending that amount. There’s some idiots cutting that budget in NASA AFAIK.
Let's say being multiplanetary gives you 99% risk mitigation of asteroid decimation.
My point is that we could pursue that level of risk mitigation via detection and deflection methods by pouring more money into it.
It is obviously far cheaper to achieve 99% risk mitigation by dumping money into detection and deflection than it is to colonize another planet to the point of self-sufficiency.
A couple trillion dollars might get us to a basic self-sustaining colony on Mars, but you could defend earth, and all of its immense natural and man-made assets, to a similar degree for orders of magnitude less money. We already choose not to do this because we don't care to achieve that level of risk mitigation even at the lower price point.
I suggest re-framing the the question as the cost of preserving the objectively limited and to the best of our knowledge singularly unique in the Universe resource, which is the surface of Earth.
Acquiring resources that do not deplete or spoil the future of life on this planet should be in everyone's best interest.
The reality is that saving our environment will be a whole set of difficult and profoundly boring solutions to real, known problems.
Would be cool if we could solve it with badass rockets, explosions, big noises, and adventure, but the complete lack of even remotely convincing answers to first order questions on how this actually works belies the fact that it doesn’t. It makes no sense.
We need to develop better plastics, proteins, and pesticides. Not send protein blobs to other planets because it looks cool in sci fi movies.
The reality is more people get passsionate about working on things that look cool in sci fi movies than developing plastics, proteins and pesticides for a mediocre paycheque. This lesson--that the path to groundbreaking technologies is through inspirational moonshots, not committees prescribing what is and isn't necessary--is so thoroughly repeated throughout history that it's a wonder we keep missing it.
Groundbreaking technologies are not created via moonshots. They’re created by decades of slog. Moonshots can launch from an unremarkable platform of slog, but the slog had to happen. You just cannot speedrun the vast majority of questions that need to be answered to power a breakthrough.
That’s why I’ll question glory-chasers who want to sit on the rocket but can’t take a few thousands of pay cut to stare for a few years at a true problem that needs solving.
Our species’ actual heroes are those who powered through the slog.
The slog is almost always in pursuit of a moonshot. The moon justifies the slog. We don’t slog for the sake of it.
At 53 and good health, i'm contemplating that my end in 30-40 years would be me buying a one way to Mars and just exiting the habitat out without suit after enjoying a dinner with a Martian sunset view, breaking, even in such a small way, the chains of "We come from the earth, we return to the earth" :)
Seems much easier to reframe the "chains" of earth into acceptance of a remarkable cycle that we're privileged to get a glimpse of from the inside and just die happily here with your loved ones.
This works for most people. Most humans didn't leave Africa or Mesopotamia or the Old World, either originally or in the Age of Exploration, and most Americans today don't have a passpport.
The acceptance would have me still in Russia :)
Novelty, for one.
Obviously one is free to want that. When I think of the opportunity costs involved, it seems repugnant to be honest. The opposite of glorious.
I hope you achieve your dream though (and that you devise a more pleasant way to do it ;))
And art and scientific endeavour and exploration and possibly all the things that make us human, but sure.
>We're not starting to inhabit new bodies of land for a long time now.
Last century has been aviation - start of the expansion into the 3rd dimension - and later - space.
But sure, we should solve all the problems on earth with one hand tied behind our backs until we can launch any more rockets.
Humans, simply by existing on Earth, have a huge and often negative impact on the environment. If we could somehow shift the human population off Earth, either by terraforming planets (like Mars) or creating artificial space habitats, it would have a huge positive impact on Earth's environment. We don't currently have the technology to do so - we would need space elevators to feasibly move humanity off Earth - but that doesn't mean we should move our attention away from space in the meantime.
There will be never enough resources for "sustainability of our civilization, our specie, and our fragile planetary environment".
If we ever end up unable to outrun ourselves we might as well end it?
The odds of a spacecraft hitting a single particle of dust while in space are 100%.
A spacecraft hitting a single particle of dust at 0.2c will impart tens of millions of joules into the body of the spacecraft, the equivalent of getting hit with hundreds of pulses from the most powerful laser ever created by humanity-- simultaneously.
Or concentrating several kilogram's worth of TNT into the size of a particle of dust and detonating it.
In any case, we should launch more than one.
Most of the designs for a system like this are "chip" designs where a single 1cm x 1cm silicon wafer is towed by the sail.
This design prevents the need for lasers so large that they create enough ozone to kill the entire human race.
The contents of the chip vary, based on who is speculating, but tend to contain exotic, uninvented, circuitry capable of both harvesting energy from the laser and doing "something" of use besides zipping by the target at 0.2c deaf, dumb, and blind. Sometimes it's even an AI-enhanced swarm! (Shoulda figured out how to work blockchain in there, post-doc guy)
Regardless, during the 40 trillion kilometer voyage to Proxima Centauri, that 1x1cm silicon wafer (and the sail) will hit space dust, and numerous other atoms and molecules (including carbon rings) because empty space... isn't.
Technically yes. I think there's a significant variety of sizes of dust or larger-than-dust particles in interstaller medium but I don't really have much to back that up.
> how often you’re likely to hit one in the interstellar medium is quite speculative.
Also technically yes. But unless you can map every single particle of dust, and their trajectories, I think the risk is absolutely real.
As far as i see with today's tech - like Starlink's ion thruster + classic nuclear reactor - we can get to 300km/s in about 4 stages. Straightforward improvement of ion thrusters - mainly voltage increase and associated engineering (which will immediately happen once we start flying to Mars and beyond as ion thruster currently our best/fastest option inside the Solar system) - can get us to 1000-2000km/s, i.e. under 1000 years to Alpha Centauri (that for a large populated spacecraft, and for just tiny probe to announce our existence (and to send back photos which we'd receive using Sun's gravitational lensing) we can do even better). And using interstellar gas and dust scramjet-style will improve on those numbers (as such ship is mostly limited by the working mass it starts with while the reactors would be able to continue produce the energy much longer).
This is a Bussard ramjet [1]. The interstellar medium is too thin to make it work. (Maybe we'll find the husk of an ancient ramjet from an earlier era of the universe floating around one day...)
Edit to add: we basically understand the physics of accelerating something to a high speed, what it would need to be made from, etc., afaik all within the realm of possibility- if we could gather and direct that much energy and then wait long enough to decelerate at the other end.
It seems like the questions that are completely unaswered are: keeping people alive and healthy for that long, and how the ship could survive if it hit something.
Whipple shields [1].
> Something that's not "energy shields"
The interstellar medium contains lots of charged particles [2]. Electromagnetic deflection is perfectly realistic.
[1] https://en.wikipedia.org/wiki/Whipple_shield
[2] https://www.space.com/interstellar-space-definition-explanat...
As far as the laser goes, ~2MJ is the total output. Energy that reaches the fuel pellet due to inefficiencies throughout the path of the laser, the actual "hitting power", is hundreds-ish kJ.
the other thought is a space ram jet sucking in particles heard of some idea like this
2. Enough incident light could vaporize the specs entirely leaving only gas or plasma, which doesn't carry the same danger to the ship.
First, to clarify, a Dyson Swarm is a cloud of orbitals around a star to use most or all of its energy via solar collectors. This was originally called a Dyson Sphere but was renamed because of confusion: people thought a Dyson Swarm was a rigid shell. It never was.
Anyway, the classic orbital is an O'Neil Cylinder, which would be 3-4 miles in diameter and 10-20 miles long. You spin it to get earthlike gravity. With this diameter the rotation isn't likely disconcerting and the centrifugal forces aren't so large as to tear it apart.
This kind of structure could be built with a material no stronger than stainless steel and using solar panels for power. It's relatively low tech. There aren't any exotic physics or exotic static states of matter required. It's basically an engineering problem and can be built incrementally.
Why do I mention this? Because fo rthe distances involved, an interstellar starshhip is basically just an O'Neil Cylinder. You need to support people for centuries. Such a cylinder could get 10s of thousands of people, possibly 100k+ to another system in relative comfort.
So how do you get to another star? The tyranny of the rocket equation means any form of propulsion where you need to carry to propellant just won't work with the possible exception of nuclear fusion.
But what if you didn't have to carry propellant at all? To accelerate or decelerate. That makes it way easier. But how would yo udo that? Easy, at least in theory: solar sails. The solar wind carries pretty significant momentum. A sufficiently large solar sail (and it would have to be large for such a ship) would absolutely be capable of accelerating a ship to at least 0.01c. And you can decelerate with the same solar sail.
You can do even better by collecting energy from the Sun and concentrating it on the sails, which is yet another reason to build a Dyson Swarm.
The energy budget to travel to even our closest star is so vast that we would need to do things like collect most of the Sun's output energy. I personally don't believe FTL is possible. Time dilation only really kicks in meaningfully at >0.99c and I just don't think that's parctical and, if it were, the energy required is even more vast.
In fact, at 0.99c you would suffer drag from the interstellar medium (gas and dust)..
So any intersteallar ship is going to be a generation ship, a habitat.
It would make more sense to use fusion reactors to power colonies in the outer reaches of the solar system than to go to a rogue planet.
I think for a civilization capable of sending reasonable amount of people people at reasonable speeds to colonize such planets, creating suitable atmosphere, lighting and heating is very much possible. Gravity is the only hard requirement.
Humans have developed various things that are better for certain purposes than anything used by a living being, e.g. metals and semiconductor devices (most of the human-only technologies are a consequence of the control of fire, i.e. of the ability to perform manufacturing processes at high temperatures, unlike the living beings, which are limited to temperatures close to that of the ambient). On the other hand, for other purposes the use of organic substances and of the methods of chemical synthesis used by living beings are unbeatable.
So any future descendants will have to use hybrid technologies, like the "cyborgs" of many SF novels/movies, except that I have never seen any SF "cyborg" that combined the right parts from "machines" and from living organisms.
As an example, for the problem of energy storage for powering a machine, for providing short-time high power bursts capacitors and batteries are better than the chemical reactions used by living beings, e.g. ATP & phospho-creatine hydrolysis and anaerobic glycolysis. On the other hand for storing high-amounts of energy for long-time autonomy at a moderate power level, none of the fuel cell or battery technologies that have ever been attempted appears to have the potential to ever match the performances of the enzymatic oxidation of hydrocarbons that converts their chemical energy into ionic gradients in living beings, e.g. in our mitochondria. So an ideal autonomous machine would combine high-power capacitors/batteries with high-energy biologically-derived fuel cells.
Mandatory advertising for Greg Egan: read his novel, Diaspora. Truly mind-expanding on the subject.
There's literally nothing there, why go all that way? The distances are so incredibly vast. It seems like we ought to be content with staying put.
In fact, technically, there's nothing here. It's all out there.
Jupiter: ~0.095% of the total mass, and ~71% of the non-solar mass.
Saturn: ~0.03% of the total mass, and ~19% of the non-solar mass.
Uranus and Neptune: Contribute a small percentage to the remaining non-solar mass.
All other objects: (inner planets, dwarf planets, moons, asteroids, comets, etc.) account for less than 0.002% of the solar system's total mass.
Your brain mass is about 3 disposable water bottles in weight and we can debate what parts of that are thinking and actually "you".
You are insignificant on the scale of the solar system let alone the universe.
>Into one end he plugged the whole of reality as extrapolated from a piece of fairy cake, and into the other end he plugged his wife: so that when he turned it on she would see in one instant the whole infinity of creation and herself in relation to it. To Trin Tragula’s horror, the shock completely annihilated her brain...
~Douglas Adams, The Restaurant at the End of the Universe
Are we the chemicals or just the electrical signals, that makes the mass that makes up "you" even less of an thing.
For whatever reason, humanity's attitude in this regard has changed drastically in the last century. We can't even bother to make the next generations, and a shrinking population eventually (quite quickly, really) shrinks to zero. Not only do they want to "stay put", they want to lay down and die.
That doesn't seem like a strong argument to me. It seems like a distraction from the crowd that would save the planet by extinguishing humanity if that's what it took. Though what value the planet might have with all of us gone I leave as an exercise for the reader.
The first priority of any society that wants to continue to exist into the future must always be to make the next generation. If you do not do this, or if you just leave the task to others hoping that someone else will do it, then you are behaving in a way that will in all probability lead towards there being no next generation sooner or later. The "global warming is the apocalypse" movement constantly talks about how the best way to reduce your carbon footprint is to have no children.
>The only large-scale planetary engineering in humanity's history is Veniforming its home world.
So it is claimed, but from my point of view it looks very much as if it's intent on making itself extinct through fertility decline. But at least carbon dioxide levels will return to normal, eh?
By "literally nothing there," I mean there's literally nothing for us. Three stars and a few Earth-sized planets in the habitable zone that are, more than likely, uninhabitable by humans. There's nothing there worth going all that way for.
I like sci-fi as much as the next person but the reality of the situation, it seems to me, is that the universe is mostly empty, vast, and inhospitable to human life.
So is the Pacific Ocean for practical definitions of emptiness. You don't got to the empty places.
I’m not sure that after spending a lifetime in an ample space colony its inhabitants would feel nostalgic of the time we spent sitting on round rocks cooking around a star.
Ask ten different scientists about the environment, population control, genetics, and you'll get ten different answers, but there's one thing every scientist on the planet agrees on. Whether it happens in a hundred years or a thousand years or a million years, eventually our Sun will grow cold and go out. When that happens, it won't just take us. It'll take Marilyn Monroe, and Lao-Tzu, and Einstein, and Morobuto, and Buddy Holly, and Aristophanes, and - all of this - all of this - was for nothing. Unless we go to the stars
That's the fallacy in the given argument.
Might very well be the last question we need to ask ourselves.
“Literally everything is in space.”
There was literally nothing there? Why go all that way? To see what was there. And then to make something there.
[Edit, because I'm rate limited: No, interstellar space is something to cross, to get to stellar space. You think the New World was rich? How about a whole solar system of untapped resources?
That's why people will try to go.]
No there wasn't. There was a whole continent of untapped resources.
You can argue that the solar system is a lot of untapped resources too. Harder to extract than sailing a piece of wood across an ocean growing some food, and killing the people who are already there. Harder than colonising Antarctica or the surface of the sea too, but there are resources - not just minerals but solar energy too.
But interstellar space? Beyond the Oort Cloud? There's no evidence of anything other than perhaps some very sparse dust. That is nothing, and (jokes aside) completely incomparable to Ohio.
The hypothetical riches were quite obvious: same stuff we have over here, but not owned by someone yet.
What are they hypothetical riches of outer space?
This is a question we should think about clearly and logically without resorting to stuff like "oh tally-ho the adventure!" type nonsense.
Just imagine the economic output of a civilisation a million times the size of ours.
Then we can use all of that new productivity to start working toward the next rung?
Our economy is not currently throughput limited on water or space so I don’t find this compelling.
In the past, I've challenged the "Let's colonize Mars!" people to do something that's far easier: Move to Bouvet island, now.[1]
This is a frozen uninhabited rock that is nonetheless a tropical paradise compared to Mars. It's far easier to reach, has free unlimited oxygen and water, and gets more solar radiation also for power! It's luxurious compared to the colder, dryer deserts of Mars where there's only dry rocks and near-vacuum.
If you really want to spice things up, donate $10,000 to a charity per pound of material you take to the island (what does a shelter weigh?), take 100% of your food and water with you, and never go outside without wearing full scuba gear. For "realism mode" sprinkle a small amount of radioactive powder evenly everywhere around your habitat area.
"Yay! Adventure! Honey, tell the school we're unenrolling the kids and taking them with us to this wonderful opportunity to start a new life!"
You miss the whole point. The point of becoming an interplanetary civilization is not to fill every barren rock you see (and there are plenty on Earth, and, if climate change isn't controlled, there'll soon be more). The point is to put just enough humankind on all the places we can easily reach (at that given time) so we can expand from there with in-situ resources rather than only expand from here, using only Earth resources (which WILL run out).
Some humans seem to have evolved a motivation to explore their surroundings. At first we walked, then we learned to ride animals, wheels, boats, airplanes, and, recently, spacecraft. We travel to learn both about other places as we do to learn about ourselves. Some people might feel content with our current reach, but I feel constrained.
You can't answer that from Bouvet Island, can you?
If you have an argument for why the reverse ordering, or in parallel, would be better, that's what I'm asking for: what's the argument?
Flesh it out beyond just "imagine if we succeed with no substantial opportunity loss!"
The benefit, however, is minuscule compared to what an expansion into quadrillions of highly educated humans could create.
You can't do a solar slingshot like you can with (say) Jupiter because the sun is essentially at rest with respect to the rest of the solar system. You could still do an Oberth manoeuvre.
Your speed once you get to 1AU would I assume be far higher than if you had simply started at Earth
[0] https://www.nasa.gov/solar-system/its-surprisingly-hard-to-g...
But not with respect to other star systems.
Of course you can. Galileo, Cassini-Huygens and Giotto are Earth-launched spacecraft that used Earth for a gravity assist. If you need to accelerate with reference to the galaxy, you can use the Sun’s motion through it to slingshot.
They have an unfortunate name because it's not just the assisting body's gravity that provides the assist. It's the combination of gravity and velocity.
As Voyager nears Jupiter, Jupiter's gravity grabs it. Then, Jupiter's velocity relative to Voyager drags Voyager - that is, transfers energy to it. Without that relative motion, all Voyager's gravity does is add energy on the way in and then remove exactly the same energy on the way out.
Current thinking is quite hostile to doing the work. You might not be able to build the things you think you can. You certainly won't build the things you think you can't.
How strange was nuclear before innital discovery?
I'm not aware of [other] approaches that will allow us to travel to the stars.
That doesn't have to stop us from much more practical and realistic striving though.
We have an entire universe in mini right here around us in the form of our own solar system, filled with so many resources that we probably couldn't over-consume them in millennia, and possible extra-planetary homes for billions of us using technologies that are just this side of realistic.
We're still talking about at least decades of fantastically costly investment, but at least it would begin as investment for a shining future within a human lifetime.
Colonizing the solar system doesn't sound as impressive on text as stories of strange and wonderful alien landscapes in distant star systems, but I don't think anyone being able to gaze with their own eyes from the peaks of Verona Rupes 90 years from now would care.
And we have these human-centric systems that are unusable and inefficient, not to mention a terrible economic system that rewards the virus-like entities in society.
We aren't going anywhere.
https://gridwhale.com/program.hexm?id=GCJ5TL7Z&file=GCJ5TL7Z...
Basically, nothing short of antimatter rockets will get you a self-contained interstellar ship.
Ion propulsion, even with nuclear reactors, can't get you enough speed.
Fission-fragment reactors can get you up to 1% lightspeed, but that's still 400 years to Alpha Centauri--I'm not sure I would trust a generation ship to last that long. Advanced fusion might cut that down to 100 years. Antimatter can reach 20% lightspeed, which means 20 years to Alpha Centauri.
ChatGPT kept asking to design a laser sail (external power source) to avoid the tyranny of the rocket equation, but I just don't think that can scale to crewed travel.