Catalyzing major human space activities by 2030

This October the Tennessee Valley Interstellar Workshop is hosting a special Symposium at the Y-12 New Hope Center in Oak Ridge TN that will promote safe, fast, and affordable human development of our solar system – the first real steps to becoming an interstellar civilization.

Leaders from NASA, DOE ARPA-E, Oak Ridge National Laboratory, the Y-12 National Security Complex, and several private companies will convene to evaluate how, within a decade, breakthrough technologies can greatly accelerate the establishment of permanent colonies on the moon and the first human trips to Mars and asteroids. TVIW 2018 will implement a synergistic approach to space advocacy, using the symposium to link together critical technologies that will catalyze major human space activities by 2030.

Currently there is a growing belief within private industry and NASA that nuclear power and propulsion are essential for safe and efficient space development.

1. High Impulse Nuclear Propulsion – A huge step forward in compact nuclear reactor design was proved by DARPA in the $330 Million Timberwind Program from 1988 to 2003. It remains the most advanced candidate technology for space propulsion. Upper stage nuclear rockets (i.e. used only in space) can enable human trips to Mars in thirty days rather than multiple years. Nuclear propulsion is also vital for capture and engineering of small (10-meter diameter) near-earth asteroids (NEA) that can facilitate space habitats safe from solar and cosmic radiation. Space solar power and other major industries will be rapidly enabled.

2. Fiber Optic High Energy Lasers – Key to efficient wireless power transmission and proven by DARPA for near-term applications, this very mature, high-efficiency technology can lead directly to megawatt-class power beaming capabilities for space power and propulsion. Laser light sails are a fundamentally crucial application extending to interstellar propulsion.

3. High Temperature Superconductors – This technology will radically transform all types of electrical applications when fully exploited. It has been developed for thirty years at ORNL and is ready for many game-changing implementations. For example, Magnetically Inflated Cable (MIC) technology can enable very large, low weight and rigid space structures for solar concentrators. This can implement capture of 10-meter diameter near-earth asteroids to lunar orbits, where they can be robotically engineered to solve radiation shielding and artificial gravity problems for human travel.

4. Large Scale 3-D Printing – ORNL and its innovative manufacturing spin-offs are world leaders in this vital new technology. There are direct links to in-space manufacturing possibilities using readily available regolith materials on the moon and asteroids.

5. Self-Replicating Von Neumann Machines – This concept will be a vital component to expedite robotic space habitat engineering and large-scale production capabilities on the moon, Mars, and asteroids. Hierarchal Von Neumann machines are an important next-generation spin-off: Very small machines can build ever-larger machines using ambient materials and solar energy. Ever larger and more fiscally powerful space industries will result.

6. Solar Power Satellites – Formerly regarded as “pie in the sky,” space solar power with microwave or laser power beaming to the Earth, moon, or planets is now a real possibility. Persuasive concepts already exist for in-space production and deployment of all of the components. Combining the above notions of small asteroid capture for raw materials and Von Neumann machines for ever expanding production capabilities, concepts are viable for totally pollution-free, open-ended supplies of solar energy anywhere in the space out to the orbit of Mars.

7. Lightweight Large Aperture Optics — The above MIC technology leads directly to the possibility of building enormous optical telescopes in space at orders of magnitude lower cost than present ground-based technology. Interferometer arrays of kilometer diameter telescopes will enable imaging and physical diagnostics of earth-like planets around nearby stars. The search for Extraterrestrial Intelligence (SETI) will be greatly augmented. Perhaps most importantly, the science of cosmology will be massively advanced toward ultimate understanding of the origin and destiny of our universe.

69 thoughts on “Catalyzing major human space activities by 2030”

  1. 3D printing typically requires very specific powder properties like particle size and roundness, which raw space powder is unlikely to fulfill. But it may be possible to filter and process it to something acceptable, and certain process variations like powder-binder or powder suspension inkjet may be more forgiving.

    Reply
  2. 3D printing typically requires very specific powder properties like particle size and roundness which raw space powder is unlikely to fulfill. But it may be possible to filter and process it to something acceptable and certain process variations like powder-binder or powder suspension inkjet may be more forgiving.

    Reply
  3. there is so much reactivity in the propellant too – dumping protons through a metallic reactor. It just shows how limited we are, how we are struggling with our limitations, just to think it should be done because it technically *can* be done.

    Reply
  4. there is so much reactivity in the propellant too – dumping protons through a metallic reactor. It just shows how limited we are how we are struggling with our limitations just to think it should be done because it technically *can* be done.

    Reply
  5. Run to failure in 5 minutes? great. When I hear NTR I think about incandescent light bulb filaments and how they aren’t particularly robust at temperature and in an inert atmosphere. Now, with NTR you can’t make it out of pure tungsten, because it has to have U or Pu in it, oh and we’re going to dump cryogenic H2 through it at 100 bar too. They’ve been tested, but it is a really un-clever idea for so many reasons – even if NASA and BWXT have high hopes of carrying NERVA forward into the 2020s. NTR really irritates my sensibilities.

    Reply
  6. Run to failure in 5 minutes? great.When I hear NTR I think about incandescent light bulb filaments and how they aren’t particularly robust at temperature and in an inert atmosphere. Now with NTR you can’t make it out of pure tungsten because it has to have U or Pu in it oh and we’re going to dump cryogenic H2 through it at 100 bar too. They’ve been tested but it is a really un-clever idea for so many reasons – even if NASA and BWXT have high hopes of carrying NERVA forward into the 2020s. NTR really irritates my sensibilities.

    Reply
  7. They promote nuclear and undermine how antimatter spacecraft would be more efficient, not to mention could be cheaper to produce if scientists did not undermine the documentary Overpriced or the upcoming film Antimatter Future you can bet mainstream scientists will ignore. https://www.youtube.com/watch?v=4J626vNxzAk The cost to develop antimatter could be cheaper, your not hearing that in the media because the mainstream promote nuclear and undermine more efficient solutions. Some people think antimatter is science fiction, I show in my YouTube videos how we can have cheaper antimatter production and enable the most energy efficient form of propulsion other than developing warp drives. And I present science warp drives are in the realm of possibility (NASA did a small experiment and found results which show we need more research – many scientists are pro-nuclear so they are not going to want more efficient solutions and make nuclear obsolete lol)

    Reply
  8. They promote nuclear and undermine how antimatter spacecraft would be more efficient not to mention could be cheaper to produce if scientists did not undermine the documentary Overpriced or the upcoming film Antimatter Future you can bet mainstream scientists will ignore. https://www.youtube.com/watch?v=4J626vNxzAk The cost to develop antimatter could be cheaper your not hearing that in the media because the mainstream promote nuclear and undermine more efficient solutions.Some people think antimatter is science fiction I show in my YouTube videos how we can have cheaper antimatter production and enable the most energy efficient form of propulsion other than developing warp drives. And I present science warp drives are in the realm of possibility (NASA did a small experiment and found results which show we need more research – many scientists are pro-nuclear so they are not going to want more efficient solutions and make nuclear obsolete lol)

    Reply
  9. 3D printing typically requires very specific powder properties like particle size and roundness, which raw space powder is unlikely to fulfill. But it may be possible to filter and process it to something acceptable, and certain process variations like powder-binder or powder suspension inkjet may be more forgiving.

    Reply
  10. Depends what that X-37’s been up to…That could have assembled something pretty big and modular by now. Saying that, it’s far cheaper to just use the CCTV that’s literally everywhere!

    Reply
  11. Depends what that X-37’s been up to…That could have assembled something pretty big and modular by now. Saying that it’s far cheaper to just use the CCTV that’s literally everywhere!

    Reply
  12. I think your objections on the basis of the necessary large sizes of the transmitter & receiver are valid. However will the receiver efficiency be only 25%? My understanding is that if the photons collected have just over the band gap energy of the photocell, the efficiency can be much closer to 100%. The low efficiency of solar is because sunlight is broadband with most of the photons either lower energy than the band gap & so contributing nothing to the electric output or higher energy & so the extra energy just goes to heating the photocell. Lasers tuned to the photocell band gap should allow energy transmission over less than interplanetary distances if they can be made reasonably efficient.

    Reply
  13. I think your objections on the basis of the necessary large sizes of the transmitter & receiver are valid. However will the receiver efficiency be only 25{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12}? My understanding is that if the photons collected have just over the band gap energy of the photocell the efficiency can be much closer to 100{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12}.The low efficiency of solar is because sunlight is broadband with most of the photons either lower energy than the band gap & so contributing nothing to the electric output or higher energy & so the extra energy just goes to heating the photocell.Lasers tuned to the photocell band gap should allow energy transmission over less than interplanetary distances if they can be made reasonably efficient.

    Reply
  14. What’s in a printer that isn’t self replicating? • logic chips • power semiconductors • lasers • wires • heating elements • sensors • transformers • motors • bearings, ball & slipring ferrule • flexible tubing • smooth, polished things: • … worm gears (critical) • … lucite panels (non-critical) • … laser windows (critical), usually spherical/cylindrical • elastomers etc … springs, tension bands • most fasteners of the ‘screw-and-ferrule’ type • pop rivets (maybe not needed) • thin polymer-metal sheets (flexible ‘band circuits’) • rotary encoders • passive electronics components (caps, resistors, yada, yada) That’s without tearing apart a 3D heterogenous powder-layer, or photo-set liquid, or HP ‘ink’ 3D printer. Indeed, I think that the “70%” idea must be related to overall mass. Sure, 70% of the mass of a 3D printer might be formable by the very same 3D printer. What I imaging though is perhaps something different: a rather large assembly of robotic arms-on-mobile platforms, conveyer belts, and heterogenous “speciality” 3D maker machines. That can make the things on that list, at least given source materials. Wire from wire-maker machines. Chips from scaled down chip factories. Screws and pop-rivets from similarly specialized machines. It is perhaps a not-very-sophisticated similé, but I tend to visualize the 1950s–1970s WW2 documentary (or popular) films, with the espionage and subterfuge boys trying to take out “ball bearing factories”. Making critically specialized bearings, without which ships, airplanes, tanks, and subs couldn’t be built. Today, the subterfuge would be leveled against chip factories, assembly lines, and other ‘tech’ stuff. These are the ‘key parts’ of GoatGuy’s brand of von Neumann machine. GoatGuy (+1 at you)

    Reply
  15. What’s in a printer that isn’t self replicating?• logic chips• power semiconductors• lasers• wires• heating elements• sensors• transformers• motors• bearings ball & slipring ferrule• flexible tubing• smooth polished things: • … worm gears (critical)• … lucite panels (non-critical)• … laser windows (critical) usually spherical/cylindrical• elastomers etc … springs tension bands• most fasteners of the ‘screw-and-ferrule’ type• pop rivets (maybe not needed)• thin polymer-metal sheets (flexible ‘band circuits’)• rotary encoders• passive electronics components (caps resistors yada yada)That’s without tearing apart a 3D heterogenous powder-layer or photo-set liquid or HP ‘ink’ 3D printer. Indeed I think that the 70{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12}”” idea must be related to overall mass. Sure”” 70{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of the mass of a 3D printer might be formable by the very same 3D printer. What I imaging though is perhaps something different: a rather large assembly of robotic arms-on-mobile platforms conveyer belts”” and heterogenous “”””speciality”””” 3D maker machines. That can make the things on that list”” at least given source materials. Wire from wire-maker machines. Chips from scaled down chip factories. Screws and pop-rivets from similarly specialized machines. It is perhaps a not-very-sophisticated similé but I tend to visualize the 1950s–1970s WW2 documentary (or popular) films with the espionage and subterfuge boys trying to take out “ball bearing factories”. Making critically specialized bearings without which ships airplanes tanks and subs couldn’t be built. Today the subterfuge would be leveled against chip factories assembly lines”” and other ‘tech’ stuff. These are the ‘key parts’ of GoatGuy’s brand of von Neumann machine.GoatGuy (+1 at you)”””””””

    Reply
  16. there is so much reactivity in the propellant too – dumping protons through a metallic reactor. It just shows how limited we are, how we are struggling with our limitations, just to think it should be done because it technically *can* be done.

    Reply
  17. Run to failure in 5 minutes? great.

    When I hear NTR I think about incandescent light bulb filaments and how they aren’t particularly robust at temperature and in an inert atmosphere. Now, with NTR you can’t make it out of pure tungsten, because it has to have U or Pu in it, oh and we’re going to dump cryogenic H2 through it at 100 bar too.

    They’ve been tested, but it is a really un-clever idea for so many reasons – even if NASA and BWXT have high hopes of carrying NERVA forward into the 2020s. NTR really irritates my sensibilities.

    Reply
  18. Technically, it doesn’t create a “ring image”, but rather AT FOCUS the image is beset with the ring’s edge diffraction. The net effect is if a white fog is obscuring the image. This is not a show stopper though, it is something which can relatively easily be removed from the digital images thru deconvolution mathematical algorithms. So yes, in principle, redistributing N kilograms of flight mass into a larger ring than a solid plate makes sense. Just remember that as the physical dimension gets larger, more of the N kilograms mass is dedicated to the truss-and-tube frame holding the ring elements in place. The truss scales by D²‧⁵‧ The ring, by the actual area (D²‧² – d²‧²)‧ D → entire diameter, d → unfilled inner area. Don’t forget “the tube”, which scales by D¹‧⁵ … While that’s kind of complicated, it is “nothing for a spreadsheet”, as I like to say. BEFORE we forget, remember also that — today, not tomorrow necessarily — the folk building the telescopes kind of like to build them ‘entire’, here on Planet Dirt. Prosaically, “bubble wrap ’em, nail them in a shipping container, and kick ’em to space” as a one-piece unit. The solar cells providing power are on a set of accordian self-unfolding truss doohickeys (technical term), but just about everything inside the telescope proper is non-moving. Certainly, there have been, to date, no self-assembling space telescopes LARGER than the available area inside the upper deliver nozzle of a spacecraft. PS: this is one of the reasons why you see rockets with a fairly fatter uppermost delivery stage: to hold wider loads to space, that aren’t necessarily all that heavy, just simply physically broader. Just saying, GoatGuy

    Reply
  19. Technically it doesn’t create a ring image””” but rather AT FOCUS the image is beset with the ring’s edge diffraction. The net effect is if a white fog is obscuring the image. This is not a show stopper though it is something which can relatively easily be removed from the digital images thru deconvolution mathematical algorithms. So yes in principle redistributing N kilograms of flight mass into a larger ring than a solid plate makes sense. Just remember that as the physical dimension gets larger more of the N kilograms mass is dedicated to the truss-and-tube frame holding the ring elements in place. The truss scales by D²‧⁵‧ The ring by the actual area (D²‧² – d²‧²)‧ D → entire diameter d → unfilled inner area. Don’t forget “the tube” which scales by D¹‧⁵ …While that’s kind of complicated it is “nothing for a spreadsheet” as I like to say.BEFORE we forget remember also that — today not tomorrow necessarily — the folk building the telescopes kind of like to build them ‘entire’ here on Planet Dirt. Prosaically “bubble wrap ’em nail them in a shipping container and kick ’em to space” as a one-piece unit. The solar cells providing power are on a set of accordian self-unfolding truss doohickeys (technical term) but just about everything inside the telescope proper is non-moving. Certainly there have been to date no self-assembling space telescopes LARGER than the available area inside the upper deliver nozzle of a spacecraft. PS: this is one of the reasons why you see rockets with a fairly fatter uppermost delivery stage: to hold wider loads to space that aren’t necessarily all that heavy just simply physically broader. Just saying””GoatGuy”””””””

    Reply
  20. They promote nuclear and undermine how antimatter spacecraft would be more efficient, not to mention could be cheaper to produce if scientists did not undermine the documentary Overpriced or the upcoming film Antimatter Future you can bet mainstream scientists will ignore. https://www.youtube.com/watch?v=4J626vNxzAk The cost to develop antimatter could be cheaper, your not hearing that in the media because the mainstream promote nuclear and undermine more efficient solutions.

    Some people think antimatter is science fiction, I show in my YouTube videos how we can have cheaper antimatter production and enable the most energy efficient form of propulsion other than developing warp drives. And I present science warp drives are in the realm of possibility (NASA did a small experiment and found results which show we need more research – many scientists are pro-nuclear so they are not going to want more efficient solutions and make nuclear obsolete lol)

    Reply
  21. I suspect it would create a ring image – but if it is a ring image with the desired resolution, you ought to be able to scan it over an area to fill in the missing area.

    Reply
  22. I suspect it would create a ring image – but if it is a ring image with the desired resolution you ought to be able to scan it over an area to fill in the missing area.

    Reply
  23. Just curious – what if you make a large ‘ring’ mirror – i.e. as if taking a telescope’s primary mirror and cutting a circle out of the center, leaving only the outside edge. This seems to work for a Gregorian telescope, on a more limited scale. Is the image degraded in ways other than reduced light gathering? If not, making a really big mirror that unfolds into a ring would seem possible.

    Reply
  24. Just curious – what if you make a large ‘ring’ mirror – i.e. as if taking a telescope’s primary mirror and cutting a circle out of the center leaving only the outside edge. This seems to work for a Gregorian telescope on a more limited scale. Is the image degraded in ways other than reduced light gathering? If not making a really big mirror that unfolds into a ring would seem possible.

    Reply
  25. As Daniel Ravensnest keeps going on about in his writing on the subject, you don’t need to 100% replicate your Von Neumann machine. A machine that can make 90% of itself, and then you slot in the electronics (for example) is a huge step forward. Especially if this is running autonomously, or close to it, on the moon or somewhere. Homebrew 3D printers are somewhere near 70% self replicating in theory, when measured by mass or volume if not value. Remember that to get something into space mass is pretty equivalent to value. Then you get to designs that make 99.5% of themselves (by mass) and just need some silicon brains to be brought up from Earth’s gravity well.

    Reply
  26. As Daniel Ravensnest keeps going on about in his writing on the subject you don’t need to 100{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} replicate your Von Neumann machine.A machine that can make 90{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of itself and then you slot in the electronics (for example) is a huge step forward. Especially if this is running autonomously or close to it on the moon or somewhere. Homebrew 3D printers are somewhere near 70{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} self replicating in theory when measured by mass or volume if not value. Remember that to get something into space mass is pretty equivalent to value.Then you get to designs that make 99.5{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of themselves (by mass) and just need some silicon brains to be brought up from Earth’s gravity well.

    Reply
  27. Depends what that X-37’s been up to…That could have assembled something pretty big and modular by now. Saying that, it’s far cheaper to just use the CCTV that’s literally everywhere!

    Reply
  28. I think your objections on the basis of the necessary large sizes of the transmitter & receiver are valid. However will the receiver efficiency be only 25%? My understanding is that if the photons collected have just over the band gap energy of the photocell, the efficiency can be much closer to 100%.
    The low efficiency of solar is because sunlight is broadband with most of the photons either lower energy than the band gap & so contributing nothing to the electric output or higher energy & so the extra energy just goes to heating the photocell.
    Lasers tuned to the photocell band gap should allow energy transmission over less than interplanetary distances if they can be made reasonably efficient.

    Reply
  29. What’s in a printer that isn’t self replicating?

    • logic chips
    • power semiconductors
    • lasers
    • wires
    • heating elements
    • sensors
    • transformers
    • motors
    • bearings, ball & slipring ferrule
    • flexible tubing
    • smooth, polished things:
    • … worm gears (critical)
    • … lucite panels (non-critical)
    • … laser windows (critical), usually spherical/cylindrical
    • elastomers etc … springs, tension bands
    • most fasteners of the ‘screw-and-ferrule’ type
    • pop rivets (maybe not needed)
    • thin polymer-metal sheets (flexible ‘band circuits’)
    • rotary encoders
    • passive electronics components (caps, resistors, yada, yada)

    That’s without tearing apart a 3D heterogenous powder-layer, or photo-set liquid, or HP ‘ink’ 3D printer. Indeed, I think that the “70%” idea must be related to overall mass. Sure, 70% of the mass of a 3D printer might be formable by the very same 3D printer.

    What I imaging though is perhaps something different: a rather large assembly of robotic arms-on-mobile platforms, conveyer belts, and heterogenous “speciality” 3D maker machines. That can make the things on that list, at least given source materials. Wire from wire-maker machines. Chips from scaled down chip factories. Screws and pop-rivets from similarly specialized machines.

    It is perhaps a not-very-sophisticated similé, but I tend to visualize the 1950s–1970s WW2 documentary (or popular) films, with the espionage and subterfuge boys trying to take out “ball bearing factories”. Making critically specialized bearings, without which ships, airplanes, tanks, and subs couldn’t be built.

    Today, the subterfuge would be leveled against chip factories, assembly lines, and other ‘tech’ stuff.

    These are the ‘key parts’ of GoatGuy’s brand of von Neumann machine.

    GoatGuy (+1 at you)

    Reply
  30. I’m optimistic about Von Neumann machines, but I agree that the minimum size for early ones is likely to be quite large. Not “big city” sized, but “large factory” at least. OTOH, the payoff from building even one, and delivering it someplace you can let it double without too much concern is literally exponential. So, even a city sized replicator with a doubling time less than the economy (Under 20 years, say.) would be well worth the investment, in the long run. The key to getting them smaller, without having to invent Drexler’s molecular nanotechnology, is to not try to build everything by the best techniques available that are used in a planetary economy. You need generalized manufacturing techniques that build good enough, but are very versatile, even though they may not be fast or energy efficient. For instance, can you generalize the sort of sputtering techniques used in IC manufacture to build all the parts of the machine used to do them? That’s the sort of approach that’s needed, not a huge collection of all sorts of specialized machines.

    Reply
  31. I’m optimistic about Von Neumann machines but I agree that the minimum size for early ones is likely to be quite large. Not big city”” sized”””” but “”””large factory”””” at least.OTOH”” the payoff from building even one and delivering it someplace you can let it double without too much concern is literally exponential. So even a city sized replicator with a doubling time less than the economy (Under 20 years say.) would be well worth the investment in the long run.The key to getting them smaller without having to invent Drexler’s molecular nanotechnology is to not try to build everything by the best techniques available that are used in a planetary economy. You need generalized manufacturing techniques that build good enough but are very versatile even though they may not be fast or energy efficient.For instance can you generalize the sort of sputtering techniques used in IC manufacture to build all the parts of the machine used to do them? That’s the sort of approach that’s needed”” not a huge collection of all sorts of specialized machines.”””

    Reply
  32. Technically, it doesn’t create a “ring image”, but rather AT FOCUS the image is beset with the ring’s edge diffraction. The net effect is if a white fog is obscuring the image. This is not a show stopper though, it is something which can relatively easily be removed from the digital images thru deconvolution mathematical algorithms.

    So yes, in principle, redistributing N kilograms of flight mass into a larger ring than a solid plate makes sense. Just remember that as the physical dimension gets larger, more of the N kilograms mass is dedicated to the truss-and-tube frame holding the ring elements in place. The truss scales by D²‧⁵‧ The ring, by the actual area (D²‧² – d²‧²)‧ D → entire diameter, d → unfilled inner area. Don’t forget “the tube”, which scales by D¹‧⁵ …

    While that’s kind of complicated, it is “nothing for a spreadsheet”, as I like to say.

    BEFORE we forget, remember also that — today, not tomorrow necessarily — the folk building the telescopes kind of like to build them ‘entire’, here on Planet Dirt. Prosaically, “bubble wrap ’em, nail them in a shipping container, and kick ’em to space” as a one-piece unit. The solar cells providing power are on a set of accordian self-unfolding truss doohickeys (technical term), but just about everything inside the telescope proper is non-moving. Certainly, there have been, to date, no self-assembling space telescopes LARGER than the available area inside the upper deliver nozzle of a spacecraft.

    PS: this is one of the reasons why you see rockets with a fairly fatter uppermost delivery stage: to hold wider loads to space, that aren’t necessarily all that heavy, just simply physically broader.

    Just saying,
    GoatGuy

    Reply
  33. I suspect it would create a ring image – but if it is a ring image with the desired resolution, you ought to be able to scan it over an area to fill in the missing area.

    Reply
  34. When I was writing the comment below, I was going to question whether “getting reaction mass from the outer planets” (paraphrasing you) was realistic. But, as you mention, there is so-called “aerobraking” involved. Where a pass is made, skimming through the more tenuous bits of the gas giants’ atmospheres, as a brake. I think the problem there is that “scooping up” a bit of mass is prodigiously difficult: the ONLY useful quantity would be a substantial multiple of the spacecraft’s empty rest mass. And, the only scooped bits will be that tenuous outer atmosphere, mostly helium and hydrogen. One simply cannot have a huge 10 kilobar (1 GPa or 150,000 PSIg) bottle on the spacecraft that’d take 4× to 5× the mass of the probe as reaction gas. You can’t even get tiny 150,000 PSIg bottles down here on Planet Dirt where weight isn’t an issue, that aren’t 50 millimeters thick. Multiply that from 1 liter to 250,000 liters… and well, no. No, what’s needed is to LIQUIFY the gas. But that takes an appreciable amount of heavy compression equipment. And a lot of interlocked gas systems to reduce the temperature to near-zero-kelvin. But mostly the biggest GotCha is TIME. You cannot speed up cryogenic cooling. Ultimately, every last joule of thermal energy needs to be bled off to deep space. Bled off via a combination of radiator-SIZE and radiator-TIME. Larger radiator, less time. Smaller, more. Lastly, while such a spacecraft (you’d think) might conspire to make many passes through a Jovian atmosphere for successive aerobraking maneuvers, that also is prohibited. Prohibited because the whole point of aerobraking is to lose ENOUGH relative velocity so as to not just whizz past the Jovian off to deep space again. Forever. So, aerobraking must lose most of the excess velocity in the first pass. Then, another two or three maneuvers can be arranged to lose more. To circularize the orbit, for instance. Mostly just station keeping. Post-lastly, perha

    Reply
  35. When I was writing the comment below I was going to question whether “getting reaction mass from the outer planets” (paraphrasing you) was realistic. But as you mention there is so-called “aerobraking” involved. Where a pass is made skimming through the more tenuous bits of the gas giants’ atmospheres as a brake. I think the problem there is that “scooping up” a bit of mass is prodigiously difficult: the ONLY useful quantity would be a substantial multiple of the spacecraft’s empty rest mass. And the only scooped bits will be that tenuous outer atmosphere mostly helium and hydrogen. One simply cannot have a huge 10 kilobar (1 GPa or 150000 PSIg) bottle on the spacecraft that’d take 4× to 5× the mass of the probe as reaction gas. You can’t even get tiny 150000 PSIg bottles down here on Planet Dirt where weight isn’t an issue that aren’t 50 millimeters thick. Multiply that from 1 liter to 250000 liters… and well no. No what’s needed is to LIQUIFY the gas. But that takes an appreciable amount of heavy compression equipment. And a lot of interlocked gas systems to reduce the temperature to near-zero-kelvin. But mostly the biggest GotCha is TIME. You cannot speed up cryogenic cooling. Ultimately every last joule of thermal energy needs to be bled off to deep space. Bled off via a combination of radiator-SIZE and radiator-TIME. Larger radiator less time. Smaller more. Lastly while such a spacecraft (you’d think) might conspire to make many passes through a Jovian atmosphere for successive aerobraking maneuvers that also is prohibited. Prohibited because the whole point of aerobraking is to lose ENOUGH relative velocity so as to not just whizz past the Jovian off to deep space again. Forever. So aerobraking must lose most of the excess velocity in the first pass. Then another two or three maneuvers can be arranged to lose more. To circularize the orbit for instance. Mostly just station keeping. Post-lastly perhaps

    Reply
  36. Just curious – what if you make a large ‘ring’ mirror – i.e. as if taking a telescope’s primary mirror and cutting a circle out of the center, leaving only the outside edge.

    This seems to work for a Gregorian telescope, on a more limited scale.

    Is the image degraded in ways other than reduced light gathering? If not, making a really big mirror that unfolds into a ring would seem possible.

    Reply
  37. If you optimize for ISP, you can get better than 1000s out of a nuclear thermal rocket. But that means you’re giving up other things. You can do in the realm of 2000s. But you give off a lot of radiation in the exhaust plume.

    Reply
  38. If you optimize for ISP you can get better than 1000s out of a nuclear thermal rocket. But that means you’re giving up other things. You can do in the realm of 2000s. But you give off a lot of radiation in the exhaust plume.

    Reply
  39. PS: and it works down here terrestrially… for spy satellites. Say “optical light at 550 nm”, and a high LEO orbit of 1,000 km, and being able to see detailed features as small as 10 cm. … dD = 1.22 × 550×10⁻⁹ × 1,000,000 m … dD = 0.671 m² → and we know ‘d’ of ‘dD’ so: … D = 0.671 / d = 0.671 ÷ 0.1 … D = 6.7 m You’d need a 6.7 meter diameter spy telescope in space to resolve 10 cm objects on Earth. For spy purposes, is 10 cm useful? Sure. But contrary to the popular urban myth (of spy satellites being able to read car license plates), 10 cm won’t be reading ANY license plates. Perhaps the numbers on the side of airplanes or aircraft carriers. Not cars. Of course the spy-sat could be quite a bit closer … as little as 350 km for stable orbits of a few years. That would get a 6.7 meter spy scope to see 3 cm objects. ALMOST good enough for those license plates. But what are the chances that the military has churned out enough black budget to make a spy satellite at least 25× more costly than the Hubble Space Telescope? Mmmm… I don’t think so. Could be, but it just doesn’t ring true. GoatGuy

    Reply
  40. PS: and it works down here terrestrially… for spy satellites. Say optical light at 550 nm””” and a high LEO orbit of 1000 km and being able to see detailed features as small as 10 cm. … dD = 1.22 × 550×10⁻⁹ × 10000 m… dD = 0.671 m² → and we know ‘d’ of ‘dD’ so:… D = 0.671 / d = 0.671 ÷ 0.1… D = 6.7 mYou’d need a 6.7 meter diameter spy telescope in space to resolve 10 cm objects on Earth. For spy purposes is 10 cm useful? Sure. But contrary to the popular urban myth (of spy satellites being able to read car license plates) 10 cm won’t be reading ANY license plates. Perhaps the numbers on the side of airplanes or aircraft carriers. Not cars. Of course the spy-sat could be quite a bit closer … as little as 350 km for stable orbits of a few years. That would get a 6.7 meter spy scope to see 3 cm objects. ALMOST good enough for those license plates. But what are the chances that the military has churned out enough black budget to make a spy satellite at least 25× more costly than the Hubble Space Telescope? Mmmm… I don’t think so. Could be”” but it just doesn’t ring true. GoatGuy”””””””

    Reply
  41. LOL! Good at ya… The “other way” to remember the equation is: … dD = 1.22λB In other words, the product of the two diameters — that of the transmitter AND the receiver — is a constant, and is equal to the baseline times the wavelength times a diffraction-limit factor (1.22) multiplied together. Kind of makes empirical sense: double the baseline, and one would expect that the either the transmitter mirror needs to double, or the receiver plate, or some variation on that where the product of the two doubles per distance. GoatGuy

    Reply
  42. LOL! Good at ya… The “other way” to remember the equation is:… dD = 1.22λBIn other words the product of the two diameters — that of the transmitter AND the receiver — is a constant and is equal to the baseline times the wavelength times a diffraction-limit factor (1.22) multiplied together. Kind of makes empirical sense: double the baseline and one would expect that the either the transmitter mirror needs to double or the receiver plate or some variation on that where the product of the two doubles per distance. GoatGuy”

    Reply
  43. As Daniel Ravensnest keeps going on about in his writing on the subject, you don’t need to 100% replicate your Von Neumann machine.

    A machine that can make 90% of itself, and then you slot in the electronics (for example) is a huge step forward. Especially if this is running autonomously, or close to it, on the moon or somewhere.

    Homebrew 3D printers are somewhere near 70% self replicating in theory, when measured by mass or volume if not value. Remember that to get something into space mass is pretty equivalent to value.

    Then you get to designs that make 99.5% of themselves (by mass) and just need some silicon brains to be brought up from Earth’s gravity well.

    Reply
  44. One equation: … D = 1.22λ B/d … D ← diameter of TRANSMITTER, to focus energy on a … d ← diameter of RECEIVER which is located at … B ← meters away from each other, being bathed in … λ ← wavelength electromagnetic energy. Would be my basis for refuting most everything you propose: … d = 50 meters (pretty big for a probe) … B = 750×10⁹ meters (5 AU, jovian) … λ = 10⁻³ m (1 mm sub-terahertz microwave) → → → D = 18,300,000 m Now, I don’t know about you, but a 18,300 kilometer transmitter mirror, is REALLY REALLY big. Oh, with “mathematical thinking”… one can look at the equation and see that the transmitter is inversely related to the receiver size, so “increase the receiver” to a larger size, decreases the transmitter accordingly. But to what end? The receiver becomes heavier, bigger, more flimsy, thus the receiver needs EVEN MORE power to achieve the same acceleration. OR… again looking at the equation … you could use a much smaller wavelength that sub-terahertz millimeter waves. The problem increasingly becomes tho’, how to extract the energy from them efficiently (as well as how to form them efficiently). In a nutshell, working in millimeter waves, one might speculate 35% end-to-end energy-in-to-energy-out conversion. When you go to optical “light wavelengths”, it becomes substantially worse. There is no mechanism to turn electrical energy to light, transmit it, receive it, and convert it back to electrical energy at over efficiencies greater than 8.8% or so. (35% transmit, 25% receive)… Maybe “that’s just the losses”, but do the math on that, and see: … D = 1.22λ B/d … d ← 100 meters (huge) … B ← 750×10⁹ meters (5 AU, Jovian) … λ ← 250×10⁻⁹ m (deep ultraviolet) … D = 2,300 m That’s STILL a huge transmitting mirror. Optically perfect, in the deep ultraviolet, to focus onto a 100 meter (again huge) target array of photoconverters. At 5% or lower energy-in-to-energy-out efficiency. Wow… I’d say that kind of refutes things. Just saying, Go

    Reply
  45. One equation:… D = 1.22λ B/d… D ← diameter of TRANSMITTER to focus energy on a … d ← diameter of RECEIVER which is located at … B ← meters away from each other being bathed in … λ ← wavelength electromagnetic energy. Would be my basis for refuting most everything you propose:… d = 50 meters (pretty big for a probe)… B = 750×10⁹ meters (5 AU jovian)… λ = 10⁻³ m (1 mm sub-terahertz microwave)→ → → D = 18300000 mNow I don’t know about you but a 18300 kilometer transmitter mirror is REALLY REALLY big. Oh with “mathematical thinking”… one can look at the equation and see that the transmitter is inversely related to the receiver size so increase the receiver”” to a larger size”” decreases the transmitter accordingly. But to what end?The receiver becomes heavier bigger more flimsy thus the receiver needs EVEN MORE power to achieve the same acceleration.OR… again looking at the equation … you could use a much smaller wavelength that sub-terahertz millimeter waves. The problem increasingly becomes tho’ how to extract the energy from them efficiently (as well as how to form them efficiently). In a nutshell working in millimeter waves”” one might speculate 35{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} end-to-end energy-in-to-energy-out conversion.When you go to optical “”””light wavelengths”””””” it becomes substantially worse. There is no mechanism to turn electrical energy to light transmit it receive it and convert it back to electrical energy at over efficiencies greater than 8.8{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} or so. (35{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} transmit 25{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} receive)…Maybe “that’s just the losses” but do the math on that and see: … D = 1.22λ B/d… d ← 100 meters (huge)… B ← 750×10⁹ meters (5 AU Jovian)… λ ← 250×10⁻⁹ m (deep ultraviolet)… D = 2″

    Reply
  46. My BULLSNOT METER is pegging. Sparks coming off needle. Take (№ 1) – Timberwind Nuclear Thermal example of “high ISP nuclear rocket”. Yes, indeed, this is so. Remember if you will Tsiolkovsky’s Rocket Equation: … ΔV = G₀ ISP ln( M/m ) Well, if you remember your high school math, the inversion is: … M = m • exp( ΔV / ( G₀ ISP ) ); The Big Mass is EXPONENTIALLY related to the ΔV and the ISP. SHORT of it? 250 ton payload needs 37,000 tons of nuclear thruster to JUST do the outgoing 80% of 33 day trip, ultimately achieving 50 km/s at ‘midpoint’. at ISP = 1000. (PS: 100 days trip time, suddenly the numbers become manageable. 1,300 mt midpoint mass, 250 mt delivered mass, and only 6,800 metric tons of “starting” mass.) ______ Oh sure, one could argue for higher ISP, but that really is Magic Wand thinking. VASIMR certainly can deliver higher (200 kW) ISP (at 5000, using argon, low-flow, high-ISP mode). But for a 6,000 ton starter, 800 MW is needed. For a 1,300 ton midpoint, 250 MW needed. That is a LOT of power. Magical amounts. ______ № 2 — Lasers, fiber optic type, light sails… I’m sorry… I kind of doubt that Humanity is going to cobble together lasers of sufficient power to send whiffs of magic umbrella film across the interstellar void … to see the next star system up close … and NOT be able to transmit back the images. ______ № 3 — “radically transform” … “game changing” … “magically inflated cable” … “magically transformed” … to “solve radiation shielding” and also “artificial gravity”. Woo. Mega Wu. ______ № 4 — Magical “3 d printing of regolith”. Ummm… like perhaps after the stuff is REFINED, and SMELTED and otherwise purified, retextured, and so on. A major amount of Wu goes into that readily available regolith, before one can 3D print the stuff. Sheesh… ______ № 5 — Oh noes!!! Super-duper magical “Von Neumann machines” are called for. I’ven’t ever been convinced that such a machine could be built on any scale less than “a big cit

    Reply
  47. My BULLSNOT METER is pegging. Sparks coming off needle.Take (№ 1) – Timberwind Nuclear Thermal example of high ISP nuclear rocket””. Yes”” indeed this is so. Remember if you will Tsiolkovsky’s Rocket Equation:… ΔV = G₀ ISP ln( M/m ) Well if you remember your high school math the inversion is:… M = m • exp( ΔV / ( G₀ ISP ) );The Big Mass is EXPONENTIALLY related to the ΔV and the ISP. SHORT of it? 250 ton payload needs 37000 tons of nuclear thruster to JUST do the outgoing 80{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of 33 day trip ultimately achieving 50 km/s at ‘midpoint’. at ISP = 1000.(PS: 100 days trip time suddenly the numbers become manageable. 1300 mt midpoint mass 250 mt delivered mass and only 6″”800 metric tons of “”””starting”””” mass.)______Oh sure”” one could argue for higher ISP but that really is Magic Wand thinking. VASIMR certainly can deliver higher (200 kW) ISP (at 5000 using argon low-flow high-ISP mode). But for a 6000 ton starter 800 MW is needed. For a 1300 ton midpoint 250 MW needed.That is a LOT of power. Magical amounts.______№ 2 — Lasers fiber optic type light sails… I’m sorry… I kind of doubt that Humanity is going to cobble together lasers of sufficient power to send whiffs of magic umbrella film across the interstellar void … to see the next star system up close … and NOT be able to transmit back the images. ______№ 3 — “radically transform” … “game changing” … “magically inflated cable” … “magically transformed” … to “solve radiation shielding” and also “artificial gravity”. Woo. Mega Wu.______№ 4 — Magical “3 d printing of regolith”. Ummm… like perhaps after the stuff is REFINED and SMELTED and otherwise purified retextured and so on. A major amount of Wu goes into that readily available regolith before one can 3D print the stuff. Sheesh…______№ 5 — Oh noes!!! Super-duper magical “Von Neumann machines” are called for. I’ven’t ev”

    Reply
  48. Decades of ship*years of beaming power to ships AUs away from platforms would demonstrate the reliability of systems. This would give confidence that geosynchronous power stations would be reliable, and safe. Compared to powering ships in the Jovian system, geosynchronous orbit to ground would be childsplay.

    Reply
  49. Decades of ship*years of beaming power to ships AUs away from platforms would demonstrate the reliability of systems. This would give confidence that geosynchronous power stations would be reliable and safe. Compared to powering ships in the Jovian system geosynchronous orbit to ground would be childsplay.

    Reply
  50. Something like the zeta pinch fission/fusion nuclear rocket described in an earlier article would be useful in early stages of establishing exoindustry, but the targets(fuel) expensive in terms of raw materials, and in terms of fabrication. Using this system, all the reaction mass must be on the ship at the beginning of the mission. A beamed power ship, using something like the VASIMR to produce impulse would be superior, once sufficient beamed power was available. Reaction mass for such a system would be free in many parts of the solar system. In particular ships bound to the outer solar system could pick up fresh reaction mass time, and again. A ship used for exploration could refine it’s own reaction mass from local ices. The ability to vary thrust vs isp is a valuable trait too. Higher thrust is useful for circularizing orbits, and repeated aerocapture maneuvers, while extremely high ISP is fine for long duration thrust, or mid course corrections. There is also the issue of the zeta pinch engine becoming radioactive, from neutron activation if by no other mechanism. Shielding is just that much more mass to carry, and you have to consider in transit repairs, or maintenance. I’d go so far as to place the first space power platforms in heliocentric orbit, as close to Sol as possible to operate ships. The ships would retrieve asteroidal, and cometary resources to build power platforms in geosynchronous orbit to beam power to the ground. Actual construction of platforms meant for geosynchronous orbit would probably be a on of the earth moon Lagrange points, probably L2, unless it is reserved for radio astronomy. Of the technologies mentioned, the one with the highest risk, and the highest reward is the self replicating machines. Essentially, each one must be an industrial base it itself. What you would need is something like photosynthetic bacteria, or algae that was not dependent on aqueous solutions. However, if it could be done, it would be the most

    Reply
  51. Something like the zeta pinch fission/fusion nuclear rocket described in an earlier article would be useful in early stages of establishing exoindustry but the targets(fuel) expensive in terms of raw materials and in terms of fabrication. Using this system all the reaction mass must be on the ship at the beginning of the mission.A beamed power ship using something like the VASIMR to produce impulse would be superior once sufficient beamed power was available. Reaction mass for such a system would be free in many parts of the solar system. In particular ships bound to the outer solar system could pick up fresh reaction mass time and again. A ship used for exploration could refine it’s own reaction mass from local ices. The ability to vary thrust vs isp is a valuable trait too. Higher thrust is useful for circularizing orbits and repeated aerocapture maneuvers while extremely high ISP is fine for long duration thrust or mid course corrections.There is also the issue of the zeta pinch engine becoming radioactive from neutron activation if by no other mechanism. Shielding is just that much more mass to carry and you have to consider in transit repairs or maintenance.I’d go so far as to place the first space power platforms in heliocentric orbit as close to Sol as possible to operate ships. The ships would retrieve asteroidal and cometary resources to build power platforms in geosynchronous orbit to beam power to the ground. Actual construction of platforms meant for geosynchronous orbit would probably be a on of the earth moon Lagrange points probably L2 unless it is reserved for radio astronomy.Of the technologies mentioned the one with the highest risk and the highest reward is the self replicating machines. Essentially each one must be an industrial base it itself. What you would need is something like photosynthetic bacteria or algae that was not dependent on aqueous solutions. However if it could be done it would be the most important tech

    Reply
  52. I’m optimistic about Von Neumann machines, but I agree that the minimum size for early ones is likely to be quite large. Not “big city” sized, but “large factory” at least.

    OTOH, the payoff from building even one, and delivering it someplace you can let it double without too much concern is literally exponential. So, even a city sized replicator with a doubling time less than the economy (Under 20 years, say.) would be well worth the investment, in the long run.

    The key to getting them smaller, without having to invent Drexler’s molecular nanotechnology, is to not try to build everything by the best techniques available that are used in a planetary economy. You need generalized manufacturing techniques that build good enough, but are very versatile, even though they may not be fast or energy efficient.

    For instance, can you generalize the sort of sputtering techniques used in IC manufacture to build all the parts of the machine used to do them?

    That’s the sort of approach that’s needed, not a huge collection of all sorts of specialized machines.

    Reply
  53. When I was writing the comment below, I was going to question whether “getting reaction mass from the outer planets” (paraphrasing you) was realistic. But, as you mention, there is so-called “aerobraking” involved. Where a pass is made, skimming through the more tenuous bits of the gas giants’ atmospheres, as a brake.

    I think the problem there is that “scooping up” a bit of mass is prodigiously difficult: the ONLY useful quantity would be a substantial multiple of the spacecraft’s empty rest mass. And, the only scooped bits will be that tenuous outer atmosphere, mostly helium and hydrogen.

    One simply cannot have a huge 10 kilobar (1 GPa or 150,000 PSIg) bottle on the spacecraft that’d take 4× to 5× the mass of the probe as reaction gas. You can’t even get tiny 150,000 PSIg bottles down here on Planet Dirt where weight isn’t an issue, that aren’t 50 millimeters thick. Multiply that from 1 liter to 250,000 liters… and well, no.

    No, what’s needed is to LIQUIFY the gas. But that takes an appreciable amount of heavy compression equipment. And a lot of interlocked gas systems to reduce the temperature to near-zero-kelvin. But mostly the biggest GotCha is TIME. You cannot speed up cryogenic cooling. Ultimately, every last joule of thermal energy needs to be bled off to deep space. Bled off via a combination of radiator-SIZE and radiator-TIME. Larger radiator, less time. Smaller, more.

    Lastly, while such a spacecraft (you’d think) might conspire to make many passes through a Jovian atmosphere for successive aerobraking maneuvers, that also is prohibited. Prohibited because the whole point of aerobraking is to lose ENOUGH relative velocity so as to not just whizz past the Jovian off to deep space again. Forever. So, aerobraking must lose most of the excess velocity in the first pass. Then, another two or three maneuvers can be arranged to lose more. To circularize the orbit, for instance. Mostly just station keeping.

    Post-lastly, perhaps the spacecraft could sit high above the Jovian, in a circular-ish orbit, and slowly skim the most tenuous bits for compression, adiabatic cooling and liquifying. But that’d also decay the orbit, which increases aerobraking, exponentially. Probably not something the designers would want to do.

    JUST THOUGHTS. No critique of your comment really intended.
    GoatGuy

    Reply
  54. If you optimize for ISP, you can get better than 1000s out of a nuclear thermal rocket. But that means you’re giving up other things. You can do in the realm of 2000s. But you give off a lot of radiation in the exhaust plume.

    Reply
  55. PS: and it works down here terrestrially… for spy satellites. Say “optical light at 550 nm”, and a high LEO orbit of 1,000 km, and being able to see detailed features as small as 10 cm.

    … dD = 1.22 × 550×10⁻⁹ × 1,000,000 m
    … dD = 0.671 m² → and we know ‘d’ of ‘dD’ so:
    … D = 0.671 / d = 0.671 ÷ 0.1
    … D = 6.7 m

    You’d need a 6.7 meter diameter spy telescope in space to resolve 10 cm objects on Earth. For spy purposes, is 10 cm useful? Sure. But contrary to the popular urban myth (of spy satellites being able to read car license plates), 10 cm won’t be reading ANY license plates. Perhaps the numbers on the side of airplanes or aircraft carriers. Not cars.

    Of course the spy-sat could be quite a bit closer … as little as 350 km for stable orbits of a few years. That would get a 6.7 meter spy scope to see 3 cm objects. ALMOST good enough for those license plates.

    But what are the chances that the military has churned out enough black budget to make a spy satellite at least 25× more costly than the Hubble Space Telescope? Mmmm… I don’t think so. Could be, but it just doesn’t ring true.

    GoatGuy

    Reply
  56. LOL! Good at ya… The “other way” to remember the equation is:

    … dD = 1.22λB

    In other words, the product of the two diameters — that of the transmitter AND the receiver — is a constant, and is equal to the baseline times the wavelength times a diffraction-limit factor (1.22) multiplied together.

    Kind of makes empirical sense: double the baseline, and one would expect that the either the transmitter mirror needs to double, or the receiver plate, or some variation on that where the product of the two doubles per distance.

    GoatGuy

    Reply
  57. One equation:

    … D = 1.22λ B/d
    … D ← diameter of TRANSMITTER, to focus energy on a
    … d ← diameter of RECEIVER which is located at
    … B ← meters away from each other, being bathed in
    … λ ← wavelength electromagnetic energy.

    Would be my basis for refuting most everything you propose:

    … d = 50 meters (pretty big for a probe)
    … B = 750×10⁹ meters (5 AU, jovian)
    … λ = 10⁻³ m (1 mm sub-terahertz microwave)
    → → → D = 18,300,000 m

    Now, I don’t know about you, but a 18,300 kilometer transmitter mirror, is REALLY REALLY big. Oh, with “mathematical thinking”… one can look at the equation and see that the transmitter is inversely related to the receiver size, so “increase the receiver” to a larger size, decreases the transmitter accordingly.

    But to what end?

    The receiver becomes heavier, bigger, more flimsy, thus the receiver needs EVEN MORE power to achieve the same acceleration.

    OR… again looking at the equation … you could use a much smaller wavelength that sub-terahertz millimeter waves. The problem increasingly becomes tho’, how to extract the energy from them efficiently (as well as how to form them efficiently). In a nutshell, working in millimeter waves, one might speculate 35% end-to-end energy-in-to-energy-out conversion.

    When you go to optical “light wavelengths”, it becomes substantially worse. There is no mechanism to turn electrical energy to light, transmit it, receive it, and convert it back to electrical energy at over efficiencies greater than 8.8% or so. (35% transmit, 25% receive)…

    Maybe “that’s just the losses”, but do the math on that, and see:

    … D = 1.22λ B/d
    … d ← 100 meters (huge)
    … B ← 750×10⁹ meters (5 AU, Jovian)
    … λ ← 250×10⁻⁹ m (deep ultraviolet)
    … D = 2,300 m

    That’s STILL a huge transmitting mirror. Optically perfect, in the deep ultraviolet, to focus onto a 100 meter (again huge) target array of photoconverters. At 5% or lower energy-in-to-energy-out efficiency. Wow…

    I’d say that kind of refutes things.
    Just saying,
    GoatGuy

    Reply
  58. My BULLSNOT METER is pegging. Sparks coming off needle.
    Take (№ 1) – Timberwind Nuclear Thermal example of “high ISP nuclear rocket”. Yes, indeed, this is so. Remember if you will Tsiolkovsky’s Rocket Equation:

    … ΔV = G₀ ISP ln( M/m )

    Well, if you remember your high school math, the inversion is:

    … M = m • exp( ΔV / ( G₀ ISP ) );

    The Big Mass is EXPONENTIALLY related to the ΔV and the ISP.

    SHORT of it? 250 ton payload needs 37,000 tons of nuclear thruster to JUST do the outgoing 80% of 33 day trip, ultimately achieving 50 km/s at ‘midpoint’. at ISP = 1000.

    (PS: 100 days trip time, suddenly the numbers become manageable. 1,300 mt midpoint mass, 250 mt delivered mass, and only 6,800 metric tons of “starting” mass.)
    ______

    Oh sure, one could argue for higher ISP, but that really is Magic Wand thinking. VASIMR certainly can deliver higher (200 kW) ISP (at 5000, using argon, low-flow, high-ISP mode). But for a 6,000 ton starter, 800 MW is needed. For a 1,300 ton midpoint, 250 MW needed.

    That is a LOT of power.
    Magical amounts.
    ______

    № 2 — Lasers, fiber optic type, light sails… I’m sorry… I kind of doubt that Humanity is going to cobble together lasers of sufficient power to send whiffs of magic umbrella film across the interstellar void … to see the next star system up close … and NOT be able to transmit back the images.
    ______

    № 3 — “radically transform” … “game changing” … “magically inflated cable” … “magically transformed” … to “solve radiation shielding” and also “artificial gravity”. Woo. Mega Wu.
    ______

    № 4 — Magical “3 d printing of regolith”. Ummm… like perhaps after the stuff is REFINED, and SMELTED and otherwise purified, retextured, and so on. A major amount of Wu goes into that readily available regolith, before one can 3D print the stuff. Sheesh…
    ______

    № 5 — Oh noes!!! Super-duper magical “Von Neumann machines” are called for. I’ven’t ever been convinced that such a machine could be built on any scale less than “a big city”, without extraordinary progress in micro-minaturization of high flexibility, high strength robotics, and similar progress in chemistry. These remain firmly rooted in unicorn horn powder.
    ______

    № 6 — Just got to love the open, brazen ignorance. “space solar with laser or microwave … to the Earth (possible), to the Moon (yah, sort of) and to the planets (not a chance)”.
    ______

    № 7 — Huge telescopes. I just worked this up, day before yesterday. The PROBLEM is that the materials-and-fabrication costs go up nearly as the 3rd power of telescope size. Doesn’t matter if magical robotics, using magical powdered regolith unicorn horn, assembled by magical AIs and even more magical enormous ISP fusion rocket thrusters are invoked. You still are not going to beat the profound cost of getting the scopes made.

    Just saying,
    GoatGuy

    Reply
  59. Decades of ship*years of beaming power to ships AUs away from platforms would demonstrate the reliability of systems. This would give confidence that geosynchronous power stations would be reliable, and safe. Compared to powering ships in the Jovian system, geosynchronous orbit to ground would be childsplay.

    Reply
  60. Something like the zeta pinch fission/fusion nuclear rocket described in an earlier article would be useful in early stages of establishing exoindustry, but the targets(fuel) expensive in terms of raw materials, and in terms of fabrication. Using this system, all the reaction mass must be on the ship at the beginning of the mission.
    A beamed power ship, using something like the VASIMR to produce impulse would be superior, once sufficient beamed power was available. Reaction mass for such a system would be free in many parts of the solar system. In particular ships bound to the outer solar system could pick up fresh reaction mass time, and again. A ship used for exploration could refine it’s own reaction mass from local ices. The ability to vary thrust vs isp is a valuable trait too. Higher thrust is useful for circularizing orbits, and repeated aerocapture maneuvers, while extremely high ISP is fine for long duration thrust, or mid course corrections.
    There is also the issue of the zeta pinch engine becoming radioactive, from neutron activation if by no other mechanism. Shielding is just that much more mass to carry, and you have to consider in transit repairs, or maintenance.
    I’d go so far as to place the first space power platforms in heliocentric orbit, as close to Sol as possible to operate ships. The ships would retrieve asteroidal, and cometary resources to build power platforms in geosynchronous orbit to beam power to the ground. Actual construction of platforms meant for geosynchronous orbit would probably be a on of the earth moon Lagrange points, probably L2, unless it is reserved for radio astronomy.
    Of the technologies mentioned, the one with the highest risk, and the highest reward is the self replicating machines. Essentially, each one must be an industrial base it itself. What you would need is something like photosynthetic bacteria, or algae that was not dependent on aqueous solutions. However, if it could be done, it would be the most important technological development in the history of mankind.

    Reply

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