Needed: A Way To Plot The Design Space of Space Launch Systems

by

Needed: A Way To Plot Design Space of Space Launch Systems
 A guest post by Joseph Friedlander on Next Big Future
I have long  admired the Pournelle Axes of political analysis which reduce the entire political map to a single graph–
Links about Pournelle Axes
http://en.wikipedia.org/wiki/Pournelle_chart
http://www.baen.com/chapters/axes.htm
And it occurred to me we need something like that to evaluate prospective launch systems.  Someone could make a thesis about an innovative way to plot the design space of hundreds of prospective systems. Note that although I speak of ships these criteria also apply to pipeline like systems like launch loops and hypersonic tethers.   My nominees for the most important criteria:
  • Mass lifted per liftoff (shipload cargo load altogether) –more is better to avoid launch window and rendezvous synodic period problems.  If we could anti-gravity levitate a 50 million ton city all in one unit at a penny a ton we could have massive space colonization now. (With something that looked like a really big offshore oil tower, with pressurization modules hanging all over it)  This is an utter fantasy but it illustrates the principle. But if we could lift 50 million tons of kilogram packages colonization would be much less easy. (Needing assembly, etc) Yet we would not have the problem of capturing a cloud of separate packages which some launch method proposals would generate.

·          Mass lifted per liftoff (largest container size) – if we could stargate-stream a million tons of  discrete paperclip (gram) sized cargoes at a penny a ton—we could do amazing things but it would not be automatic space colonization unless you were an ant—a way out of this might be the ability to teleport unless you can route it all remotely to an exact target like a pile on the Moon’s surface. A colony might feed off that stockpile ( encapsulated air, food, oxidizer, fuel, food, chemicals) but it would not help them get there first. (at least in one piece!) Larger container size is better to avoid massive configuration and assembly and checkout manpower problems off world—imagine the work to assemble a refinery even from 250 ton units vs. one prechecked and troubleshooted 25,000 ton unit.  I can totally believe one astronaut being the Mr. Fixit of last resort for an otherwise  automated refinery but assembling it would take hundreds of astronaut man years (At present $100,000 an hour astronaut time rates and 2000 an hour duty cycle –$200 million a man year, not $200,000). And if you had to assemble from one ton units, tens of thousands of man-years if it could be done at all (There is a reason for very large units at refineries). In kilogram lots, a Lego like snap together refinery would need a total redesign if even possible at all.  This needs emphasis— NASA has a terrible problem of saying, ‘we can easily redesign that to be flight-ready’ (meaning capable of being lifted on one of their puny Saturn V or smaller rockets) which means 10-100-1000 man years of engineering talent and support (i.e. all the staff supporting the engineers including subcontractors) billed to the single little thing you are redesigning and another 100-1,000-10,000 man years of engineering and support chasing the tail of all the changes in the system that cascade back and forth when you are not using off the shelf hardware so that way you end up with a $30 million dollar glorified rocket pack or a (no kidding) estimated $1 billion dollar lunar crane the earthly counterpart of which is under $100,000 and without super-automation in assembly (in which case you spend all the engineering money another way trying to automate assembly of tiny payloads).
  • Cost of engineering development spent to develop huge big ships –obviously bigger cost for bigger ships—but the thesis of this series is that the cargoes are so much bigger still that the costs amortize away to very low rates. 
  • Cost per kg of mass lifted (cheapness per kg) –cheaper is better as long as reliability is reasonably assured.
  • Reliability (% of launches getting through) More reliable is better, especially if you happen to be riding it.
  • Political unpalatability—I mention this in connection with Orion, Super-Orion and the Wang Bullet—drive systems that depend on nuclear explosions will almost certainly never be employed without the active or passive political shielding and backing of some government. The Aldebaran 2, focus of a previous article, https://www.nextbigfuture.com/2013/08/in-praise-of-large-payloads-for-space.html is not far behind them but although it releases the power of a nuclear explosion does not actually employ one. However given the shudders that nuclear sensitive people have on a simple passive few kg of PU-238 RTG package for an outer system probe that will literally never come back to Earth the idea of 300 gas core engines lighting up for repeat trips every month with tons of raging, active nuclear material outputting literally more power than the rest of human civilization during the few minutes of orbital insertion—well, I am sure they will receive that news calmly.  J
  •  Peak G-Force experienced.  We covered this in the Wang Bullet posts.  But we expand a bit here. The space shuttle could ride gently in the 3 G range.  Early astronauts could experience around 10Gs near burnout. 17 Gs for 4 minutes is possible for excellent physical specimens. No one knows what the limit for water and fluid immersion injection and hollow-filling (i.e. NO hollow air spaces inside the body) while fluid breathing.  http://en.wikipedia.org/wiki/Liquid_breathing But 30 Gs might be possible. If needles injected equal density blood substitute (such as a heavy fluorocarbon blood substitute such as Green Cross of Japan used to make) into every hollow in a body, suffused the tissues, carrying oxygen in solution just like blood–and the density was similar to bone– there is a remote possibility we might be surprised. This would be a fertile area for tests in lab centrifuges on Earth, at first with small creatures but later with creatures as large as livestock. Certainly there would be great economy in having farm animals off planet cheaply.   Italian experiments with sudden splatting of pregnant animals and the (short term) survival of their embryos at high G suggest (but only suggest) that very short water shielded flights at 100 Gs or over 1000 gs might be survivable (without brain damage one hopes or there is no point to it)  It is worth noting that 12 seconds at 100 gs will put you at earth escape velocity. But at 100 Gs it would be very hard to have a ship taller than 50 meters or so.  As another fantasy example, a penny a ton 4000-9000 g (artillery shell range) to escape velocity method of shooting cargoes up would enable the colonization of space but not with prechecked hardware but rather segmented high-G units that could be checked out, repaired, and connected expensively by astronauts or teleoperators after the wild ride.  If they could ride along fluid filled and passivated, amazing. But more amazing still would be the idea that the ethical studies people would—so to speak—go along for the ride. http://en.wikipedia.org/wiki/Research_ethics –Another issue is small commercial hardware with sealed voids. Typical resistance to g loads in commercial hardware seem to be 1000 Gs for flash drives, 400 for micro hard drives, 100 for regular hard drives.  Regular electronics (small devices robustly reinforced without regard to weight) can take the range from 50-5000 Gs. During WW2 there were vacuum tubes for proximity triggers in artillery shells and they took the shock—I would guess with metal not glass tube walls.  Potted epoxy electronics can take up to 30,000 gs. Much above that G force and nonsimple structures are very hard to keep functional. Possibly with another century of hardening we might get the million G resistance needed for interstellar heliobraking—direct retro in the atmosphere of a distant star to solve the slowdown problem for starships. But I doubt very much that even if there is a cheat code to reality to allow humans to ride fluid filled for a 10,000 G ride that it will work for a million G ride.
Well, that’s the data to plot and I am sure that there is a great data display waiting to happen there— Ideas are welcome in the comments. Volunteers who enjoy playing with graphs are welcome. But you can see some of the many factors that fight it out in the design space of new space launch architecture.

If you liked this article, please give it a quick review on ycombinator or StumbleUpon. Thanks

Needed: A Way To Plot The Design Space of Space Launch Systems

by

Needed: A Way To Plot Design Space of Space Launch Systems
 A guest post by Joseph Friedlander on Next Big Future
I have long  admired the Pournelle Axes of political analysis which reduce the entire political map to a single graph–
Links about Pournelle Axes
http://en.wikipedia.org/wiki/Pournelle_chart
http://www.baen.com/chapters/axes.htm
And it occurred to me we need something like that to evaluate prospective launch systems.  Someone could make a thesis about an innovative way to plot the design space of hundreds of prospective systems. Note that although I speak of ships these criteria also apply to pipeline like systems like launch loops and hypersonic tethers.   My nominees for the most important criteria:
  • Mass lifted per liftoff (shipload cargo load altogether) –more is better to avoid launch window and rendezvous synodic period problems.  If we could anti-gravity levitate a 50 million ton city all in one unit at a penny a ton we could have massive space colonization now. (With something that looked like a really big offshore oil tower, with pressurization modules hanging all over it)  This is an utter fantasy but it illustrates the principle. But if we could lift 50 million tons of kilogram packages colonization would be much less easy. (Needing assembly, etc) Yet we would not have the problem of capturing a cloud of separate packages which some launch method proposals would generate.

·          Mass lifted per liftoff (largest container size) – if we could stargate-stream a million tons of  discrete paperclip (gram) sized cargoes at a penny a ton—we could do amazing things but it would not be automatic space colonization unless you were an ant—a way out of this might be the ability to teleport unless you can route it all remotely to an exact target like a pile on the Moon’s surface. A colony might feed off that stockpile ( encapsulated air, food, oxidizer, fuel, food, chemicals) but it would not help them get there first. (at least in one piece!) Larger container size is better to avoid massive configuration and assembly and checkout manpower problems off world—imagine the work to assemble a refinery even from 250 ton units vs. one prechecked and troubleshooted 25,000 ton unit.  I can totally believe one astronaut being the Mr. Fixit of last resort for an otherwise  automated refinery but assembling it would take hundreds of astronaut man years (At present $100,000 an hour astronaut time rates and 2000 an hour duty cycle –$200 million a man year, not $200,000). And if you had to assemble from one ton units, tens of thousands of man-years if it could be done at all (There is a reason for very large units at refineries). In kilogram lots, a Lego like snap together refinery would need a total redesign if even possible at all.  This needs emphasis— NASA has a terrible problem of saying, ‘we can easily redesign that to be flight-ready’ (meaning capable of being lifted on one of their puny Saturn V or smaller rockets) which means 10-100-1000 man years of engineering talent and support (i.e. all the staff supporting the engineers including subcontractors) billed to the single little thing you are redesigning and another 100-1,000-10,000 man years of engineering and support chasing the tail of all the changes in the system that cascade back and forth when you are not using off the shelf hardware so that way you end up with a $30 million dollar glorified rocket pack or a (no kidding) estimated $1 billion dollar lunar crane the earthly counterpart of which is under $100,000 and without super-automation in assembly (in which case you spend all the engineering money another way trying to automate assembly of tiny payloads).
  • Cost of engineering development spent to develop huge big ships –obviously bigger cost for bigger ships—but the thesis of this series is that the cargoes are so much bigger still that the costs amortize away to very low rates. 
  • Cost per kg of mass lifted (cheapness per kg) –cheaper is better as long as reliability is reasonably assured.
  • Reliability (% of launches getting through) More reliable is better, especially if you happen to be riding it.
  • Political unpalatability—I mention this in connection with Orion, Super-Orion and the Wang Bullet—drive systems that depend on nuclear explosions will almost certainly never be employed without the active or passive political shielding and backing of some government. The Aldebaran 2, focus of a previous article, https://www.nextbigfuture.com/2013/08/in-praise-of-large-payloads-for-space.html is not far behind them but although it releases the power of a nuclear explosion does not actually employ one. However given the shudders that nuclear sensitive people have on a simple passive few kg of PU-238 RTG package for an outer system probe that will literally never come back to Earth the idea of 300 gas core engines lighting up for repeat trips every month with tons of raging, active nuclear material outputting literally more power than the rest of human civilization during the few minutes of orbital insertion—well, I am sure they will receive that news calmly.  J
  •  Peak G-Force experienced.  We covered this in the Wang Bullet posts.  But we expand a bit here. The space shuttle could ride gently in the 3 G range.  Early astronauts could experience around 10Gs near burnout. 17 Gs for 4 minutes is possible for excellent physical specimens. No one knows what the limit for water and fluid immersion injection and hollow-filling (i.e. NO hollow air spaces inside the body) while fluid breathing.  http://en.wikipedia.org/wiki/Liquid_breathing But 30 Gs might be possible. If needles injected equal density blood substitute (such as a heavy fluorocarbon blood substitute such as Green Cross of Japan used to make) into every hollow in a body, suffused the tissues, carrying oxygen in solution just like blood–and the density was similar to bone– there is a remote possibility we might be surprised. This would be a fertile area for tests in lab centrifuges on Earth, at first with small creatures but later with creatures as large as livestock. Certainly there would be great economy in having farm animals off planet cheaply.   Italian experiments with sudden splatting of pregnant animals and the (short term) survival of their embryos at high G suggest (but only suggest) that very short water shielded flights at 100 Gs or over 1000 gs might be survivable (without brain damage one hopes or there is no point to it)  It is worth noting that 12 seconds at 100 gs will put you at earth escape velocity. But at 100 Gs it would be very hard to have a ship taller than 50 meters or so.  As another fantasy example, a penny a ton 4000-9000 g (artillery shell range) to escape velocity method of shooting cargoes up would enable the colonization of space but not with prechecked hardware but rather segmented high-G units that could be checked out, repaired, and connected expensively by astronauts or teleoperators after the wild ride.  If they could ride along fluid filled and passivated, amazing. But more amazing still would be the idea that the ethical studies people would—so to speak—go along for the ride. http://en.wikipedia.org/wiki/Research_ethics –Another issue is small commercial hardware with sealed voids. Typical resistance to g loads in commercial hardware seem to be 1000 Gs for flash drives, 400 for micro hard drives, 100 for regular hard drives.  Regular electronics (small devices robustly reinforced without regard to weight) can take the range from 50-5000 Gs. During WW2 there were vacuum tubes for proximity triggers in artillery shells and they took the shock—I would guess with metal not glass tube walls.  Potted epoxy electronics can take up to 30,000 gs. Much above that G force and nonsimple structures are very hard to keep functional. Possibly with another century of hardening we might get the million G resistance needed for interstellar heliobraking—direct retro in the atmosphere of a distant star to solve the slowdown problem for starships. But I doubt very much that even if there is a cheat code to reality to allow humans to ride fluid filled for a 10,000 G ride that it will work for a million G ride.
Well, that’s the data to plot and I am sure that there is a great data display waiting to happen there— Ideas are welcome in the comments. Volunteers who enjoy playing with graphs are welcome. But you can see some of the many factors that fight it out in the design space of new space launch architecture.

If you liked this article, please give it a quick review on ycombinator or StumbleUpon. Thanks