Exodus Fleet

Video Statistics and Information

Video
Captions Word Cloud
Reddit Comments

I loved the "all you eggs in one Sol system" pun.

👍︎︎ 7 👤︎︎ u/jaycatt7 📅︎︎ Aug 02 2018 🗫︎ replies

The suicidal satellite breaking is something I had never thought of.

👍︎︎ 5 👤︎︎ u/jood580 📅︎︎ Aug 02 2018 🗫︎ replies

This stronfly reminded me of that Kim Stanley Robinson novel, Arora.

👍︎︎ 2 👤︎︎ u/Mark_Tuchinsky 📅︎︎ Aug 02 2018 🗫︎ replies

This episode seemed to me like a recap of previously mentioned ideas, nothing new for SFIA fans. But probably good one for newcomers.

👍︎︎ 2 👤︎︎ u/daMesuoM 📅︎︎ Aug 02 2018 🗫︎ replies

Issac mentioned 1G of acceleration of a light sail stellaser combo. is that feasible is that. how much incoming light would be needed and would it damage the sail.

even if you start with a perfectly reflective sail it wont stay that way, its going to get hit by dust and have dust settle on it. the light can be absorbed by this material causing heating damaging more of the material, this will not end well.

you need to keep the incoming light level low enough that it wont heat imperfections hot enough to damage the reflective properties of the rest of the sail. can you do that and expect a massive ship to hit 1G.

👍︎︎ 2 👤︎︎ u/theZombieKat 📅︎︎ Aug 03 2018 🗫︎ replies

Can anyone tell me how big of an impact a single atom has at relativistic speeds? Could it damage steel, or if not that, maybe some solar panels?

👍︎︎ 1 👤︎︎ u/Lacksi 📅︎︎ Aug 03 2018 🗫︎ replies
Captions
Some might argue that the journey is just as important as the destination. When you’re travelling at high speed through interstellar space, this takes on an entirely new dimension. We recently discussed the concept of a Generation Ship, a type of interstellar vessel designed to cross the vast expanse of deep space and keep its crew alive, or at least their descendants, as such voyages can take many decades or even centuries to reach the nearest stars. During that episode we also discussed some alternative approaches such as freezing people or using robots, cyborgs, or artificial intelligence to do the job, concepts and technologies which have emerged in recent times, and which, even if they don’t replace the generation ship, are likely to be incorporated into it to address some of the problems which emerge as we learn more about space travel. And we’ll be exploring those new problems and potential solutions as we follow up on that first episode. Today we will be looking mostly at the ships themselves, the engineering concerns associated with getting such ships up to speed, keeping them powered during flight, and slowing them back down when they arrive. Next time we’ll look more at the problems of transporting whole ecologies on such ships and transplanting them to alien worlds in “Exporting Earth”, and we’ll follow that with a deeper look into the psychological and sociological difficulties in “Ark of a Million Years”. But for today, our focus is on that core ship. How do you get it moving, how do you keep it powered, repair it, maneuver it around obstacles, and finally, slow it down on arrival? Big problems, and part of the solution to those big problems is with big ships. They can carry more shielding, proportionally, than smaller ones. They can carry more people of course, allowing not just more hands to work on a problem, but a wider range of specialization and expertise. They can also carry more backups. But no matter how much we prototype these ships, there’s always a risk of catastrophic failure from something deemed acceptably improbable or simply something we didn’t even know was a danger. So in this regard, it’s not just about a ship carrying more backups and redundant components, but having backup ships. Not just a colony ship, but a colonial fleet. Yet our title, Exodus Fleet, does not simply refer to one such colonial fleet migrating out from our solar system. We’ve discussed first colonial ventures before, today we’re a bit more interested in when interstellar colonization has entered its pinnacle phase. Not one or two early experiments to the nearest systems but a massive operation hundreds of years later. In the Outward Bound series we’ve looked a lot at the colonization of our solar system, and indeed even colonizing the Oort Cloud, and our first trip to Alpha Centauri. In those videos, we’ve usually taken a few minutes to reference how this or that interplanetary colony could serve as a foundation for interstellar travel. We will not repeat all of that today, but what we saw was a budding solar empire gearing up to levels of industrial might that dwarf anything we have nowadays, decades after the Industrial Age. They have room, and resources, for trillions or even quadrillions of people to live with a degree of prosperity that would awe kings. These are also civilizations that probably do not regard our solar system as having 8 planets. For all the discussion of Pluto and other dwarf planets, it’s easy to forget that originally we had two classifications, minor and major planets. Dwarf planets were added in between later, and arguments about that topic have tended to eclipse that there are nearly a million identified planets in our solar system. These may be minor planets but each one can be home to new civilizations and nations, and those living on them are likely to view the solar system as quite a cluttered place, consisting of much more than a Sun, 8 planets, and some other stuff. Similarly they will probably better realize what we tend to overlook in discussions of colonization. That we will want to colonize every star system, directly from this solar system, within at least a few hundred light years of us, and that those number in the hundreds of thousands. We will not be building a handful of colony ships, we will be building millions of them over the course of a few centuries. Launching dozens or even hundreds of them every single day, ships carrying tens of thousands of people and measuring kilometers in length, probably each taking years to build and outfit, so that at any given time the drydocks of the solar system may have a million or more vessels under construction. Such a task seems daunting, and yet only a civilization creeping up on full solar colonization, what we call a Kardashev-2 civilization, has any motive to send out more than a few colony ships. Until mankind has settled most of those million minor planets, until we number ourselves in the hundreds of trillions if not quadrillions, there are only a few reasons to settle another solar system. Even just a few colonies outside our solar system gets some of our eggs out of the Sol basket, plus the voyage gives you a lot of data and experience for doing it in the future, and the work of colonizing a system on the other end does too. Simulations, even incredibly realistic ones, can never match the real thing since the simulators can’t program in what they don’t know. Unmanned probes can tell us a lot, but manned trial voyages make sense to acquire real data to overcome and adapt to any unforeseen issues in future missions. But beyond that, you have no real reason to colonize more until it is practical and desirable, but once you do, it makes sense to do it big. You have the resources to do it big too, if you can do it at all, because all the devices and tech that let you miniaturize such missions also make it easy to go about it in a grand fashion. A self-replicating von Neumann probe sent to colonize and terraform the galaxy can stop at its first destination and get to work replicating copies of itself, then terraform that system while some of the copies journey to new ones, or it can just stop at the nearest asteroid in our own solar system and replicate there first. Or it can just build tons of giant spaceships humans could man too. It’s hard to guess how humanity will roll out to the stars, but just as two examples, on the extremes, we might grow our population locally on the slow side, just 1-2% population growth a year as we have in the last century, and sometime around the year 3000, as we’re filling up most of the easy targets in our solar system and number around a quadrillion people, decide we need to build several million ships and send them all off crewed with tens of thousand of people each. Such an endeavor would use up not even a single percent of our economy to build by that point, even if we were doing it with modern production rates, and use such a small percent of our population that most of us may know only a single colonist who was a casual acquaintance at most. On the flip-side, someone might get a clanking self-replicator going in the next few decades. Indeed I’d actually be surprised if that didn’t happen, and such things are not, in and of themselves, dangerous in the way popular culture imagines Skynet or any sort of grey goo. Nothing very sophisticated need necessarily be involved, and it’s certainly possible, since nature and humans produce stuff all the time, the difference being that nature’s modern complexity is the byproduct of billions of years of trial and error corrections, and humans are smarter than our factories, and can function in a versatile fashion when incorporated into one, saving a lot of trickier steps in automation. Were that to occur, we could start building giant ships in space a few years later, and if we could talk 100 Million people, about 1% of our population, into getting on board these, say 100,000 people to a ship or small fleet of ships, we could launch 1,000 expeditions a year later and settle most of the star systems within a hundred light years of us. There’s no ifs on that, no other missing technologies. All you need is a self-replicating machine, be it a tiny nanorobot or a factory complex, that before breaking down is able to make two complete copies of itself and do at least some other work while it’s at it, like refining metal and making simple hull plates for a ship. All the other tech we discuss here can help with that, make it easier and better, but nothing else is actually needed. It’s making all these interstellar ships small enough we can build them, and yet still large enough able to survive the journey with its crew and equipment intact that’s hard and high-tech. Here on SFIA, we tend to like to incorporate fusion into spaceships, tech we don’t have yet, but if we got it that gives us interstellar travel, as it would be capable of providing the necessary speed, the power to live through the journey, and the ability to slow down on arrival. That last one is the trickiest part. Since we have discussed fusion a lot for spaceships, today we are going to look at an alternative. There’s quite a few, but we settled on the lowest tech and fastest one we could come up with. This will incorporate the Stellaser we looked at in Colonizing the Sun, a stupidly powerful and long range laser that requires little more than large mirrors orbiting close to the Sun. We will also use fission or radioactive decay power plants for the journey’s power source, explosives for any fast maneuvering, and we’ll review a few options for slowing down. Fusion is still nicer, even if you are using the Stellaser to get up to speed, since it’s all self-contained, but it isn’t actually necessary. Ship size is also highly variable, as is overall design, and is ultimately very dependent on available technology. The higher your tech, the smaller your ship can be and safely bring along everything you need. But this is mostly a matter of scale. Hypothetically, while a generation ship could cross the cosmos at 1% of light speed or lower, this should never be necessary. We should have no problem at all keeping a laser on a big target like several square kilometers of reflective sail till way out past Pluto, and if the ship and crew can handle a 1 gee acceleration, the equivalent of normal gravity, they’d be out past Pluto in just two weeks and cruising off at 4% of light speed, arriving at Alpha Centauri in a century and any of those 1000 or so nearest solar system in under 2500 years. This is, incidentally, slow enough to brake from using some of our existing fission based designs. This is important, since you have to be able to slow down on arrival, but we’ll come back to that in a bit. The longer you can keep that laser on the ship, the faster it can go, and speeds far in excess of 4%, or even 40%, of light speed are on the table. We talked about that more in Interstellar Highways, but to do this you need to either make the sail bigger or the laser more focused, and eventually that becomes impractical unless you have stations along the way helping out to re-focus the beam or emit one themselves. Those stations need power and your ship needs power once it’s off from the laser, and keep in mind once you’re light-days away from the source, they need days to even be aware that there’s a problem if the beam goes off target. Also it doesn’t have to be a light beam. Microwaves are handy, as we discussed in power satellites, so is a particle stream. For that matter you could do what we decided to call a Pacman ship, one that catches up on supply or fuel pods launched ahead of it and eats them, or where the pods are launched afterward, but faster, and catch up to the ship. The big constraint on acceleration with a manned ship is what the crew and cargo can handle, so a pod whose structure and contents can handle 100 gees instead of one, can accelerate to a final speed ten times higher than the manned ship could on the same track length, for however far your laser can stay on target. Trying to coordinate all those pods to reach the ship, or be caught up to by the ship, at the right time and place and at a speed it can intercept safely, is a bit tricky, but you can afford to lose some of those. Moreover, it means the ship needs some way to maneuver a little bit. We want that anyway though, so that it can change directions to a new system if something turns out to be wrong with their destination as they approach. The most logical one, for this setup, would be an ion drive. They are slow to accelerate, but provide a great acceleration to fuel mass ratio, so long as you’re patient. They can let you make some course corrections and grab some supplies, and firing them up occasionally to do that also helps makes sure they’re still working as they should. We’ll get to what’s powering them in a moment, but those pods represent our first example of what we mean by a colonial fleet. They can be strung out behind and in front of you, gathering information, acting as relays from back home if signals are getting weak or you’re off your original course, giving you advance notice about any dangers in front of you, mapping out the destination system and alternate systems ahead of you, and so on. Now if you do see something dangerous in front of you, you’ve a number of ways to deal with that, and the sooner you see it the better. We talked about that more in the Interstellar Travel Challenges episode, but if you haven’t got much time to dodge something ahead, you either need to vaporize it, which takes power or explosives, or dodge it quick, which an ion drive can’t do. Ironically shaped explosive charges on your outer hull are probably best. They can sit there for long times and still be detonated as fast as thought, or even your navigation computer’s thought. So long as you’re not getting excessive, it can give you a quick shove to the side without damaging the ship or killing everyone inside from too fast of an acceleration. You don’t want to be standing on the ground of a rotating section of a ship when it suddenly bucks at 5 gees for a second and you find yourself twenty-five meters off the ground and falling back down. Needless to say everything in there just experienced that too, so as you plummet, you’re doing that alongside all those nice ponds and forest critters you landscaped in there. So the ship wants to do the minimum shove, and you do want that automated, so it can react as fast as possible and with the smallest shove needed to dodge some unseen rock it can’t vaporize in time. The case we just mentioned was extreme, and potentially very lethal to many inside, but less so than getting hit by a few kilograms of relativistic space debris, and having a computer figuring out what the options are and picking the least horrible action is ideal. This is another reason you want a fleet, not a ship. The bigger your ship is, the harder it is to dodge, and ultimately you have to worry about any lone ship getting destroyed by an improbable event. However a pack of ships moving together, but say 100 kilometers apart from each other, gives a lot of redundancy. They don’t need to actually leave or arrive at the same time either, they can use a little slow thrust to get into formation for the long voyage, and at 100 kilometers apart, nothing they could encounter would cause a chain-reaction threat to each other, even a ship with an antimatter drive isn’t carrying so much energy that if it exploded it would destroy it siblings at that range. It’s still close enough for shuttling back and forth too. These ships may all be plowing through space at a decent percentage of light speed but they are not moving relative to each other, and there’s no air to cause drag between them, so a shuttle can just pop back and forth between such ships. That wouldn’t take much fuel but it doesn’t actually have to take any. Truth be told those ships don’t really need to be that far apart, but this is space and they can just launch tethers between each other for a pod to ride around on. Indeed if they’ve got enough tethers and those are strong enough, they can actually use those as winches to move each other around. It’s weird to think of them this way, but in many ways, for these long voyages through emptiness, these are not ships, they’re space stations, and they could assemble all sorts of stuff between each other during the mission. Indeed, they might all sit at the outer corners of a very large thin mirror being used to keep a beam on them longer than otherwise possible. Once they are at cruising speed, everything is relatively stationary, they can drop a telescope off to a side, extend pods out serve as temporary extra space, and so on. All of these ships are likely to have a lot manufacturing capability of their own and considering the voyage duration, a temporary structure behind the ship made for some extra elbow room that has to be brought in and recycled eventually isn’t likely to be a concern, as ‘temporary’ is decades or centuries. Your big concern in that regard is that, depending on your speed, you have a rather large radiation wind coming in from plowing through the interstellar medium. The faster you go, the worse this is, the faster your exterior add-ons will break, and the shorter you’ll get to use them. So there’s presumably a velocity at which these shanty towns around your armada get pointless. Though you can also carry such things behind you, shielded from that by your ship. The other handy part about those multiple ships is that when the time comes they can all split up for multiple destinations, rather than just one planet in a solar system. You wouldn’t be likely to head straight for a planet you want to terraform, it makes more sense to set up your space infrastructure first when you arrive, rather than landing and having to rebuild all that launch ability when you need it, which is probably right away, since a planet needing water for terraforming is best bombarded with icy comets before you start building homes on it. But what is powering everything? Initially that Stellaser beam of course, and they can turn that on low and just let it send a decent trickle of diffuse power for quite some time after you’d be out of main pushing range. Potentially, this works for the whole trip, but I personally wouldn’t trust that on its own. After that, of course, if you’ve got fusion, that would be nice, but if not, we have both fission and passive decay, radioisotope thermoelectric generators. Fission is handy on such ships, pound for pound of fuel, it’s almost as energy dense as fusion, and if radiation and waste is a concern, you can tow it behind you and kick your trash out the side, where it will sail off into the void never to trouble humanity again, unless a big wad of fission products slams into some alien civilization’s home world at relativistic speed of course, which might cause a diplomatic incident. But an RTG holds some interest for us too. These produce a nice, long, stable, albeit inefficient power supply, and so long as you pick an isotope with a half-life similar to your voyage time, you have an object supplying energy, and heat, which ships need in the interstellar void, that is so dumb-simple and durable that it is foolproof. Many of them would ironically make excellent radiation shielding too, and decay into byproducts that are quite safe and handy. If you’re worried about skills and abilities being lost during a voyage of many centuries, or even millennia, a bunch of RTGs running some very sturdy LED lighting might keep a habitat lit that whole time and livable. I wouldn’t want to bet my colony on it though, since you have a lot of time for things to break, hence why you need onboard manufacturing ability and the expertise to use it, but there’s not many things as sturdy or reliable as an RTG. Okay, now the big challenge, slowing down. Reaching your destination as fast as possible is nice, but the faster you go, the harder it is to slow down, and we would like to do it with no fuel. At all, not one drop. This is easy on Earth, if you want to slow down, just wait, friction and drag will get the job done. But in space we have neither. Except we actually do. There is no vacuum, just relative degrees of emptiness, and the faster you are going the more you are slowed when you hit any random speck of space dust. As on Earth, we can slow down faster by extending a parachute, so we hit more space dust. This won’t be viable to slow you all the way down probably, but every bit of speed you can lose this way saves you fuel. A lot too, under the classic rocket equation, a ship that massed a megaton, half fuel, half payload, changes speed 69% of whatever the exhaust velocity of that propellant is. To do double that, it would need to be 750 kilotons fuel, and 250 kilotons payload, and to quadruple that it would need to be just 60 kilotons of payload, and 940 of fuel. So even though your parachute might cost a lot of mass itself, if it can let you slow down from 40% of light speed to just 10%, that is an immense savings in fuel. Another option is the Bussard ramjet, which originally looked promising as a way to propel a ship by having it magnetically suck in passing hydrogen gas and slam it down a nozzle to collide and fuse and produce thrust. Only on examination it turned out that it would actually lose more energy than it would take in, causing the ship to slow down. Not good for propulsion but just fine for braking. And so too, a magnetic field dragging on a huge volume of charged particles in the interstellar void, is also a good giant parachute. Somewhat energy demanding though, similarly that physical parachute, even if it’s just a couple molecules thick, has to be rather massive, though you could probably use it for forward shielding or make it during the voyage, stick it out to slow you down, drag it back in and recycle it once you’ve slowed and it’s taken damage. Ideally we’d like to use a laser to slow us down, but there isn’t one on the other end yet. This is one case where extra ships are handy as you can all transfer a lot of fuel to one ship in your fleet, have it pick up some extra speed while slowing its sister ships down a bit, so it arrives sooner, and then build a stellaser at their destination to slow them down. Robotic probes could do this, or even a satellite which simply includes the mirrors needed for the stellaser. Of course the point of such a pushing laser is to focus light. As you approach a star, you will be getting more and more anyway. Even a probe with a rather large solar sail won’t slow down too much before ramming into a star this way, but if it is concentrating that light to shoot behind it or power a laser beam, it could push on another probe behind it, which can slow more and thus have even longer to decelerate from light from that new Sun. As can the one behind it. Indeed they can do some sun-diving and use that mirror braking on the Sun’s atmosphere before colliding or disintegrating to slow even more, giving them more time to push on their siblings. Each one of these can be taking more and more detailed photos of the system as they go in, and as this chain proceeds you eventually get one slow enough to finish braking in the Sun’s upper atmosphere without being destroyed, and now you have a big mirror near a Sun, and then another, and now you have a Stellaser that can push on your incoming fleet. Smart self replicating probes might be nicer, but this is a comfortably low-tech approach that works, and involves no dangerous AI either, though at least AI used here are just a few months or years ahead of your Armada, not roving hundreds of light years ahead and mutating outside your scrutiny. You could also use these probes to skim past the star, do a course correction, and keep bouncing light to their siblings on their way out to the next star. It’s a little debatable if we can say this doesn’t use fuel, since you are still using mass for those probes, but overall it’s a nicer approach than most others on the table with our current tech, and of those, the most obvious one is probably to slow down by launching hydrogen bombs in front of you. Of course that works for these too, since they are essentially just a giant sail, and they could detonate a bomb quite a long way ahead and slow down on that themselves, which gets around the problems of detonating a nuke right in front of your manned ship. The other nice thing is you only need that last probe, or last two probes, to carry a full-sized pair of mirrors for a stellaser, and the number of ships and mass of those ships doesn’t matter too much toward that, especially since you could send in another bigger pair of mirrors for that first stellaser to slow down, your whole fleet can now slow down as can any subsequent vessels following behind you, who can follow even faster now that the infrastructure is in place. Once down to more modest planetary speeds you can use the usual array of methods to finish slowing if you need to. Not all of those require fuel either, for instance gravity-assist, so often used for speedings ships up, can also be used to slow them down. We’ll look more at how big these ships need to be in the next installment of the series, Exporting Earth, in order to contain all the ecology we’d need, but for today we’ve established that even just with current technology, we’ve got what we need to reach other solar systems far faster than the original generation ship concept envisioned. So we were talking about how to get out beyond our solar system today and how we’d be able to use the Sun to power those efforts. While the basic principle is sound, there’s still so much we need to understand about our own sun before we can visit other ones. There’s a lot of other reasons to go study the Sun up close and our friends over at Cheddar have just released a video discussing those reasons and what NASA is doing to find out more. I’ll link it in the video description. They’ve been sponsoring science videos like this one and recently started their own channel covering topics like this and many more, and I’d suggest checking it out and don’t forget to subscribe while you’re there. Hey guys I'm Patrick Jones from Cheddar and I'm here today because we made a video that I tihnk you're really gonna like. It's all about two upcoming missions from NASA and the European Space Agency to study our Sun. So if you like Isaac's channel, like we do, we think you'll like our video and our channel. So come on by! Next week we have a two-parter, as we team up again with Joe Scott of Answers with Joe. We’ll examine 5 ways the world might end, then what we could do to prevent those happening. The week after that we’ll be discussing what sort of careers folks might pursue in an increasingly automated workforce, in Jobs of the Future. For alerts when those and other episodes come out, make sure to subscribe to the channel, and if you enjoyed this episode, hit the like button and share it with others. Also as a quick note I did an interview with Matt Ward of FringeFM a little while back, and I’ll leave a link to that in the video description too. Until next time, thanks for watching, and have a great week!
Info
Channel: Isaac Arthur
Views: 244,981
Rating: 4.9532194 out of 5
Keywords: generation ship, ark, interstellar, space, galaxy, colonize, planet, starship, spaceship, physics, future, fleet, Cheddar, FringeFM
Id: 9TteoCHmXTc
Channel Id: undefined
Length: 28min 34sec (1714 seconds)
Published: Thu Aug 02 2018
Related Videos
Note
Please note that this website is currently a work in progress! Lots of interesting data and statistics to come.