Exploring ALL Interstellar Propulsion Concepts

Kelvin Long explores the Advanced Space Propulsion Landscape and goes from all of the concepts from different energy drives (chemical to antimatter), beam concepts, space drives and time drives.

Kelvin has worked on various fusion propulsion, laser sails and evaporating black hole drives.

Kelvin is also looking at hybridized concepts for things like combining nuclear fusion propulsion with beamed power and sails.

SOURCES- Space Studies Institute
Written By Brian Wang, Nextbigfuture.com

59 thoughts on “Exploring ALL Interstellar Propulsion Concepts”

  1. Orion is like the entry level interstellar propulsion, it's barely capable of getting you to the nearest star in a generation at high mass ratios, a LOT more than a few dozen megatons. An interstellar trip would basically require the entire world's nuclear arsenal. And, yes, at that point the total energy deployed approaches the mass energy of the payload, though not the rocket structure.

    Once you're talking relativistic, and take into account inefficiencies, the energy deployed outweighs the payload many times over.

  2. Easier than convincing the whole world to adopt a 1 child policy; Even China, a totalitarian state, found that difficult. When your first step is, "Conquer the world and impose a dictatorship that dwarfs anything the world has ever seen.", mere technological challenges look easy.

    And orbital rings don't require any new physics, or advances in materials, and the engineering is fairly well understood. They're just big and expensive.

    The US yearly fatal accident rate includes all age groups. I'm assuming that a perpetually young population wouldn't be carefully guarded like children, or cautious like the elderly, but instead would have active lifestyles.

    But maybe after the first few broken limbs, they'd get cautious despite not aging?

  3. If you had a thorough grounding in biology, and understood cancer, you'd grasp just how hard it is to cure.

    It isn't one disease, it's several hundred diseases, that have uncontrolled cell reproduction in common. Some of them are very easy to cure if you catch them early, most of them are very difficult to cure once they've spread.

    The basic problem is that cancer cells typically look just like normal cells to the immune system, (The ones that don't we never see, because it kills them first.) and are biochemically almost identical to normal cells. The cells are easy enough to kill, but the things that kill them kill regular cells, too.

    That's why chemo is so hard on people: You have to practically kill the person in order to have a hope of getting all the cancer cells, because they're only a little bit more vulnerable to the chemo drugs than regular cells. And if you don't get all the cells, it just comes right back, only already resistant to that treatment, so you have to use another.

    We will eventually conquer cancer, but only by developing a very complete control over biology, of the sort that would easily solve aging and other diseases.

  4. I messed up my "1 child" calcs – doing 1 child for about 4 generations would probably stabilize us at around 20B and we could move back to a 2 child policy or let population fall. Shipping people to space is pretty much a rounding error compared to that.

    Global fertility was about 2.4 as of 2018. If it falls a bit each generation we'd probably hit around 40B as fertility declined to or below 1.5. Some danger of that becoming unrecoverable unless social policy changed dramatically to encourage births.

    The US yearly fatal accident rate is around 52/100K, meaning a 99.95% yearly survival rate. Assuming it would continue at that rate and be random, that'd give an individual a half life of around 1386 years? Murder and suicides would reduce that some – maybe to 700 year expected lifespan? How did you get to 350?

    Also – orbital rings – "easy"?!?! 🙂

  5. Elon is going to Mars as a lark. He dies, its done. His reason for going is valid but most people don't understand that human existence is very precarious.

  6. No profit to be made. That is the major problem with capitalism. It does do anything if there is no profit to be made. Why haven't a cure to cancer been found. There is no profit in curing cancer. Only profit in prolonging the suffering.

  7. Watch the first video again, their first models weren't very capable at first, and toward the end they weren't able to build more of the more advanced due to the bombings. They have matured the technology only after the war.

  8. What if you had a small nuclear explosion against a blast plate. It would require a small amount of fuel and you could accelerate to a very high velocity.

  9. As Brett says, the military interest in rocket weapons gave government a several decades-long edge for space launchers.

    But that edge rapidly engendered bureaucracies, which then became calcified and unable to do much progress, because their goal is self preservation as institutions with some symbolic feel-good deliverables, not actually furthering human space settlement and industrialization.

    The true space age will come when there are commercial providers selling the launch services, and when regular people can buy a ticket to go to space because they want.

    I want to emphasize: no government will provide space settlements for people to go live. It's like having government building an amusement park and resort for a few. It's wasteful and the voters will never allow it. Small off-world bases for research, maybe, but cities and factories, just forget about it.

    And I extrapolate that to the future: if privately created space settlements will have governments (as we can expect), they will be ever busy ensuring the place remains habitable. Not spending on pie in the sky lets-go-to-Proxima projects.

    And history will repeat again.

  10. You do not need astronomical amounts of energy for an Orion.
    Maybe a few dozen megatons of bomblets?

  11. But the problem with the very nice stuff you describe is that we don't have it yet, yet can still make progress. This seems a common theme, either the idea is too far out or too near. I'm not thinking of a well developed plan, I'm thinking race for survival. Of life itself, perhaps. When we run out of Space worker humans, we will have made progress, even tho it is a bummer. Too many jobs in Space for people to fill. Totally depressing! I joke, obviously.

  12. That's because until recently, most space activity was just stunts for public relations, and because the ICBM programs had given government an edge in rocket technology.

  13. More like a mountain into a dust grain, actually. But the black hole evaporator would have to use a black hole quite a bit less massive than a mountain, to get a decent power output.

  14. The problem with replicating with human help, is that you're stuck with a largely fixed ratio of available infrastructure to population, and a lot of what we're discussing requires a radically higher ratio, if it's not to be restricted to rare stunts.

  15. I keep pointing this out: Every developed nation is below replacement, well below. We're not seeing 2 children per woman. It's more like 1-1.5. The only reason any developed country doesn't have a crashing population is immigration from the third world. Japan is a good example of an advanced nation that doesn't permit much immigration, and that's what they're looking at:


    Now, granted, you're right: Even at below replacement, at anything short of actual immortality population peaks before declining again. Roughly speaking, the peak would be about 10B times the increase in life expectancy. Assuming a reasonable 350 year life expectancy, (You'd get that from just accidents, in an otherwise eternally young population.) 50B. But it would take a long, long time to reach that peak. Centuries.

    Plenty of time for solutions, including, yes, extended prepubescence. Which actually strikes me as a good idea.

    "Is there any way we could realistically ship more than 2M a year off Earth?"

    Easy. An orbital ring system would have no trouble reaching or exceeding those sorts of numbers. Reaching orbit would be about as hard as driving to the next state.

  16. Not pleasant to contemplate, but here gov is military, then some civilian but still race w/ Russians.

  17. I don't even want to wait for advances here. We have an industrial base that *replicates* with vast human help, but it does replicate. Exponential growth in the future with more advanced stuff will not happen instantly, but it really makes a lot of difference to be even a little further along when it starts. The base of the exponential growth is *saved* as the seed that gets so big.

  18. If anyone manages to flee Earth/the solar system, and they have enough people with them to constitute a self-sustaining colony, they're liable to find the usual quotient of 'busybodies' along too. That's human nature – you have to learn how to get along, to get along. If you put in a 'No busybodies!' rule, you might find some of your kin classing you as the prime busybody. In fact, with a vacuum outside the hull, plus enough ambient radiation to scramble most Terran DNA, and resources spread out at mind boggling distances, it's likely that a very authoritarian form of government would evolve.

  19. The official line is that the nazis lost the war. If they'd been gallivanting round Antarctica in supersonic flying saucers in 1940, how could they not win ?

  20. You do realize until recent all advances in space was done by government. The government has one ability that private enterprise doesn't. They don't have to make a profit.

  21. Star ships are nice, but humanity will likely face a big 'space transportation' challenge well prior to that.

    If we fully conquer aging, we'll face a linear growth population explosion ultimately peaking around 250B to 300B (at current US accidental death rate ~50/100K/yr and assuming 2 children/woman) . [All numbers are approximate at best…]

    Even if we could move 1M people off Earth every year and ONLY moved young people who haven't had kids yet, it'd take 85 generations (~2000-2500yr) to get Earth's population to start shrinking, peaking at ~150B.

    Shipping off 2M young people a year, we might peak around 65B to 70B on Earth after just 17 generations (425 years).

    If we implement a 1 child/couple policy and ship off 1M/yr, population peaks at 55B in generation 54. 40B in generation 32 if we ship off 2M/yr.

    Artificially delaying childbirth to have a 50 year generation (unlikely, IMO, unless we artificially extend prepubescence) could keep us to about 25B population on Earth, with the 1child and 2M/yr shipped policies. (The high population and 1 child policies ought to provide enough incentive to leave Earth…)

    Is there any way we could realistically ship more than 2M a year off Earth? Space Elevators and such cycle too slow. Launching ~55 big rockets a day (with 100 people) might start to have real consequences for the atmosphere. Etc.

    (I'm assuming population growth off Earth won't be a problem even at 300B or higher peak.)

  22. Bio-engineering of humans and other organisms to tolerate/flourish-in zero-G is likely an option in the timeframe such a project could take place, and gives some really big structural engineering advantages.

  23. Yeah, anything crewed taking 50-100 years to go to Proxima, can't be done without artificial gravity and a whole habitat inside.

    1 – You are sending just information of organisms to be 3D printed.
    2 – You send embryos to be grown and raised there.
    3 – Frozen corpsicles to be resurrected on arrival.
    4 – you are sending just AIs and robots (which may overlap with the other solutions).

    But outside of those speculative technologies, any human crewed worldship idea will most likely be big and hence, slow (several centuries trips at least), with all the potential problems of wordships.

    But if we can build really, really fast smaller ships, the outlook might be different. Something going at about 50% c could get to Proxima in 8-9 years, making it much more viable. Probably allowing to send waves over waves of robots that will start building settlements and gather resources before humans go there, building even a system for braking on destination, like a giant laser or a mass rail.

  24. No worries, before we can create a block hole evaporator drive we will have to figure out how to turn a mountain into a mole hill, literally.

  25. Yup. It's funny how that is already taken as a given, and we start talking about Kardashev level II and III civilizations as if they were just milestones of a previously seen project.

    They're not. We are just dreaming of these things. They have never existed.

  26. Besides of requiring some technological developments first (like fusion rockets, or even feasibly building big things like an Orion in space, maybe self replication/repair with advanced AI and robotics), this will require strong enough economics.

    I do believe things like these are indeed possible, but will only happen when the resources of our civilization allow it, by being negligible compared with the riches of a government; or most likely affordable for a private company/rich person.

    That will require some kind of great future expansion of Earth's economy into the Solar System, to allow us actually greater-than-Earth levels of wealth, and come to a situation where space-economy trillionaires are a common thing.

    At that point, one or more would be able to just decide to do it from their own pocket. Kind of a future Elon Musk, who is doing it for current humanity.

    I'm skeptical of a government ever doing something like this, unless it becomes so common tech that they start ordering them in series from a company building them!

  27. My call for a deep space drive is a dense plasma focus device, fusing boron11 and hydrogen. Alpha particles are the reaction mass.

  28. Interstellar travel? I think we need to work on colonizing and commercializing our own solar system first. Walk before we try to run. Our solar system is a big enough project as it is, will give us the necessary resources to do interstellar later, and really is all we are capable of anyway for now beyond PowerPoint projections and wishful thinking. That being said "full speed ahead and damn the torpedoes" for solar system development.

  29. Manufacturing the bombs shouldn't be that expensive. It can be automated. But the infrastructure to produce the quantity of Plutonium need would be expensive and therefore the Plutonium would be expensive.

    Laser driven implosion of He3 beads might be possible but that will take decades to develop. Then you need a large source of He3.

    Any way you slice it, going to the stars ain't for the poor.

  30. You are a genius. You have seen the difference between momentum and energy, and are looking for a way to transfer the momentum without losing the energy. Check out the launch loop or space fountain, which *bounce* mass between the ground and a load supported by the top bounce, or direction reversal, without losing energy. The loop keeps going, so the energy is the same, but by changing directions, the momentum is transferred and holds the weight up.

  31. Considering that the super-rich, like Gates, have recently been buying up farmland, that might not be a bad move. Everybody with financial chops is forting up for an economic crash.

  32. Not at all. Systems which can replicate with the assistance of people are feasible right now. You therefore only need enough money to build the first copy.

  33. So, we agree that launched GEO SPS is just a test, and the goal is ISM/RU big Space Solar at L5 or Moon. And the O'Neill settlements are just a test, before we go to belt, or just as vehicles for interstellar, and should start now. You want to live on nice planet interstellar after you get there in a nice O'Neill, go ahead. Live on Mars, forget it!

  34. O'Neill Space is the way to go. If they come, you build on and go. Planets are death traps, you cannot escape. They are tiny and easy to control. They have no economic path to help escape, whereas O'Neill is where the economy will be centered. And, O'Neill is easier.

  35. Money rules everything. To know how we will get to the star figure out which options are the cheapest to develop and the cheapest to build. We are talking $trillions here.

  36. This makes me wonder how much it will cost for the first pioneers to escape busybodies. That's one reason I want to get put of the city and buy land somewhere up in Wyoming or Montanna. But another planet works. Even though currently unfeasible

  37. The photos in the first video are hard to discredit. A consistent line of testimonies, some brought here and many more in other places is as good evidence as any.

  38. I argue close SPS only because it allows starting at a smaller scale. Really expensive projects always have to be begun at the smallest feasible scale, so as to minimize capital requirements and start producing revenue ASAP, or they never happen at all.

    Besides, as I've said, as larger systems displace GEO SPS, you can just outfit those satellites with electric thrusters, and move them elsewhere in the solar system.

    As for colonization of trans Lunar space, while that can provide living space, it can't provide independence: Too close to Earth for that.

  39. So, we solve the actual problems of Earth with Space Solar, etc, and the
    power addiction problem by escaping to Space. Think about this. You argue the far out escape to interstellar or belt, while I want to go close with
    O'Neill cislunar, and you argue close SPS while I want to go far out
    LSP. The great power of Leary's SMI2LE Space Migration slide show was to
    show that we are on a continuum of tech development, and it is
    happening fast, from a longer view of things. We need to find the things
    to do that support both the near and far objectives. Bezos is clear
    about this strategy, do stuff that you know will have to be done either
    way, even if you don't know which way will be done. Also, avoid doing
    things that constitute a decision too early. The public's knowledge about other planets, this sun's or others', is vast compared to the public's actual knowledge of O'Neill, current things to do, not just an awareness of Island 3. Yet O'Neill offers the only choice that is helping the Earth, rather than only an escape. That is a big difference. Forget Mars. Forget planets. Really!

  40. I certainly hear you on that! The flip side is that the power addicts, not merely busybodies (I know you realize that), are going to fight leaving Earth for that very reason. The very thought of leaving Earth is a threat to their domination, as prisoners with an escape plan are far more dangerous than those with no hope. Many of these power addicts seem quite addicted to the power they get from solving Earth problems, as that is an essential task, justifying any control. Without them, the Earth is destroyed. Without Space opportunities, I would have a hard time disproving their view, and that scares even me!

  41. Vasimir falls under "electric" on the left edge of the diagram. It's just another way of using electricity to accelerate reaction mass.

  42. The key to all these approaches is that you need access to virtually astronomical amounts of energy, amounts of energy easily comparable to the mass energy of your ship. Once you have that sort of energy, there are all sorts of ways of using it, but the energy itself is the key.

    And, barring seriously major physics/engineering advances, the only way to have access to that sort of energy is by using self-replicating machinery to build energy collecting infrastructure on a scale that dwarfs planets.

    That makes self-replication of machinery the key to the key. It is the one big enabling development, not just for interstellar flight, but also the large scale colonization of the Solar system.

    Because the infrastructure needs of life in space dwarf the needs of life in a preexisting biosphere, life in space will always be a marginal thing so long as infrastructure scales with human labor. Whereas, once the growth of infrastructure is decoupled from human labor, the ratio of infrastructure to population can grow exponentially, enough to enable space habitats at low population densities consistent with human thriving, and enough to enable the energy expenditures needed for interstellar travel.

    It fundamentally doesn't matter if replication is achieved by nanotechnology, or by "clunking replicators" using automated conventional manufacturing processes. But self-replication is essential, and we should be throwing massive efforts at achieving it.

  43. The goal of interstellar colonization is similar to the goal of in-system colonization: 

    To get far enough away from busybodies to do your own thing without being harassed. 

    This is the motive that's going to drive people into space, and once in space, further and further from Earth. To Mars and Venus, to the asteroid belts, to the moons of the gas giants, out into the Kupier belt.

    Interstellar colonization brings the further promise of having first dibs on the resources of an entire stellar system, rather than just a large rock. But it's still primarily about escaping busybodies.

  44. Black hole evaporator drive. ….. Mm-MM! NOPE! I've seen Event Horizon, I'm good!

    But, honestly, sign me up. 😉

  45. Where is the entire family of plasma drives in that diagram?
    (e.g. Vasimir and the suggested Ebrahimi reconnection drive that looks promising).

    I believe that exploration will be conducted through remote astronomy. Especially now that launch capability is taking off. Space ships and interstellar logistics can perhaps be managed by building up some infrastructure that does energy management better than traditional space ships.

    What we need is to re-use kinetic energy as a valuable resource, i.e. collect it and spend it on return traffic at the destination. Like a rotovator could do for low velocities. A laser sail can brake a ship at the destination with a pre-deployed laser array. The reflected light from the light sail can be used to accelerate outgoing traffic. Interstellar travel at high speed requires huge amounts of energy but if it's reused, it's only like a loan with some interest (losses).

    One can compare this to the SpaceX vision of reusing spaceships and boosters instead of throwing them away after one trip. At some point, the cost of kinetic energy is higher than the value of the actual spaceship and the energy must be reused in order to reach some economy.
    I seldom see discussions on how to dump kinetic energy into some form that can be reused. It's all about expending propellant, aerobraking etc.

  46. I hope people are not desperate for this, on the belief that we have no other living options for trillions of people in our solar system. That would really be depressing.

  47. The Nazis already had anti gravity flying saucers, we have inherited their program under a guise of chemical rockets NASA and spaceX financing it with Black budgets as corroborated by multiple inside sources. By now we have reached anywhere in the universe…




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