Number: 927 Name: LONGTRANS 2
Address: J.E.D.CLINE1 Date: 890720
Approximate # of bytes: 20160
Number of Accesses: 15 Library: 3
LONG SPACE TRANSPORTATION STRUCTURES AND APPLICATIONS
by J. E. D. Cline 890717
Prepared for presentation to the SSI Space Studies Team.This part of the talk will be devoted to a view of threeunusual space transportation concepts:
The MOONCABLE PROJECT, a captive form of tensilestructure, or tether, attached to the surface of a lunarbody and supported by an adjacent gravitational well;supporting conductors that couple kinetic energy between thetwo gravitational wells;
The TWO-BODY-ORBITING SKYHOOK, a free spinning tethershuttling back and forth between two unequal gravitationalwells, along two abruptly changing trajectories;
The KESTS / GEO HABITAT RING, which looks like a tetherbut is actually a very long dynamically supportedcompressive structure, connecting the bottom of agravitational well with its associated geosynchronous orbit.
The picture of two objects in space connected by a longthin structure, is a common element among the subjectconcepts. The fundamental characteristics of each of thesestructures involve associated concepts, such as theMooncable's zero-gee casting at L-1 of foamed material intoatmospheric re-entry shapes; and the enormous ring of spacehabitats in GEO being accessed directly from the Earthsurface by the KESTS structure concepts.
But first I would like to remind you that space,extraterrestrial space with its abundant resources, isessential to a continued expansion of a civilized humanpopulation while taking the load off of the environment thatgave us life. Indeed, it might be said that Mother Earth isvery pregnant with humanity, and must give birth soon orboth Mother and child will perish! Perhaps it is fittingthat the form and function of the following proposed supplylinks resemble umbilicals. In that service, then, thefollowing inspirations are offered you.
THE MOONCABLE CONCEPT:
Reference figure 1.
The Mooncable concept is a long tensile structurebalanced across the L-1 libration point between the Earthand the Moon, and attached to the lunar surface at one end.With essentially equal weights in either direction from L-1,it hangs in place, forming an energy tunnel from the lunarsurface to a slightly lower gravitational energy level 1/6the way into the Earth's gravitational field. The structureis made of fiberglass, which has a strength of 500,000 lbfdue to being made and used in a hard vacuum...there is noair to force its way into the surface microcracks that arethe primary breaking mechanism on Earth. The structure istapered to provide a constant-stress-crossection, thickestwhere it passes through L-1. Conductors along the length ofthe structure couple energy generated by payload brakingdown the Earthside of the cable, over to the Lunarside ofthe cable to lift more payload up to L-1, in a processanalogous to a siphon. In the initial version of theconcept developed in 1971-72, Lunar nickle-iron meteoricdebris was to be hauled up to the manufacturing site at L-1,where solar furnaces melted this natural stainless steeland foamed it into molds casting it into re-entry glidershapes. After being dropped off the earthside end of theMooncable, and remote-controlled atmospheric entry andgliding to near seaports, tugs would go out to retrieve thefloating glider, haul it to port and saw it up for use inbuilding freeway crash bariers, fireproof homes, and impactabsorbing car bodies, for example. Pockets cast into thegliders would transport smaller amounts of other exoticmaterials and devices, such as hollow ball bearings, toEarth markets. Large spacecraft would have been built at L-1for manned exploration of the solar system in relativecomfort. It was to be built in a bootstrap process, whereone of the remaining Saturn V boosters would be used tolaunch a craft to L-1, where a micro-diameter Mooncable offiberglass would be despooled in both downward directions,and in the process soft-landing a robot glass-factory on theLunar surface at that end of it. From the solar furnacesin that robot fiberglass plant, up would be lifted fibers togradually increase the girth of the Mooncable....
The TWO-BODY-ORBITING SKYHOOK:
This is a modified Moravec-Skyhook useful fortransferring payload from the surface of a moon to a pointdominated by the parent planetary body, using the greatergravitational field of the nearby planet as an energy pump to sustain the process. A permanently orbiting spacecraftwould dangle a long tether to briefly touch the farside of the Lunar surface as it passes by, grabbing awaitingpayload. Then the combined whirling masses would continueon around the Moon in an orbit that passes near the Earth.At the precise instant that the whirling tethered mass pairh as the payload deepest in the Earth's gravitational field,the payload would be released, restoring the kinetic energyto the spacecraft that was given up when the pickup was madeoff the Moon. The tether would be reeled in or let out before release, to compensate for varying payload mass whenrestoring kinetic energy to the spacecraft...letting thewhirling payload drop deeper into Earth's well beforerelease would give the orbiting spacecraft extra energy,such as for compensating for having some of the payload moveaboard the spacecraft, for example. The tether attachmenton the spacecraft would have to loosely spin around its CG,like a yo-yo with a loose string, or a "Y" fitting to eitherside of craft's CG, unless it was unmanned and didn't careif it wobbled erratically. The spacecraft-skyhook wouldthen continue on back to pick up another payload off of theMoon. Reference figure 2.
This concept I feel the least comfortable about.Energy-wise, it seems plausable, being able to freely supplyits own transportation energy, like the siphon-likeMooncable concept. However, the orbital mechanics is veryshaky; Kepler's laws are not yet fully in my conceptualworking grasp.
It must cycally shift between two orbits, due to theabrupt energy transfers at the pickup and release points. Itmay be limited to a single spacecraft/payload mass ratio toenable the moon-to-planet path. It may require unmanned operation, due to the abrupt accellerations at the pickup and release points...or at least crews chosen for iron-gutqualities!
A supply of reaction engine fuel would be needed on thespacecraft, to be used in case of ever missing a payload pickup, to return to Earth vicinity and again to go back to Lunar pickup point for another try. If the clockwork never fails, this seems to provide extremely energy-efficient payload transportation from Moon surface to an energy levelsomewhat less than 5/6 of Earth's gravity well.
Reference figure 3.
The KESTS--acronym for Kinetic-Energy-Supported Transportation Structures--are so novel to our conventional reaction-engine-technology-thinking, and so ripe with evocative implications for massive transportation linksbetween Earth surface and Geosynchronous Earth Orbit, thatperhaps it is worth starting thinking the concept fromscratch. So let's mentally synthesize this together, rightnow, setting aside the critic part of our mind until hearingout the development of the concept as it currently stands.Picture a small object, frozen in motion as it passes byyou faster than orbital velocity. It is going so fast that it would escape out beyond GEO, were it not for the presense of the atmosphere, which would disipate its kinetic energy as it burned it up like a meteor.
However, now add to this picture atube in which the hurtling object moves; the tube occupiesthe exact trajectory path of the speeding object, andexcludes the air from the object's path, so the objectdoesn't burn up. Now let the hurtling object multiply itself, become a constant stream of similar objects, allmoving in the vacuum inside the tube along the trajectory path. Add appropriate electromagnetic and electrostaticfields between the tube and the stream of speeding objectswhich flows within it, such that the fields prevent theobjects from physically touching the tube wall, and alsodrag slightly upwards on the tube, supporting the tubes'sweight in the Earth's gravitational field. Let there be asecond stream tube attached to the side of the first one,which has its stream going in the opposite direction fromthe first one. Picture this pair of fast stream tubes asthey form a path almost horizontally past you, curving outand away from the Earth's globe, reaching out to GEO abovethe equator on the far side of the Earth from you. Createaccellerators here on Earth and along its loops in space,supplying energy to replace losses in the system. Nowpicture payload boxcars travelling along the outer side ofthis pair of tubes, which are lifted and held away from thekinetic energy stream, by the same magnetic fields that holdthe tube away from the stream pair. See these boxcarscarry people and materials between Earth surface and GEO.See space settlements being built in GEO out of materialsbrought up along the KESTS. Perhaps these space settlementsare similar to the Island One Stanford Torus designs, eacha self-sufficient habitat for 10,000 people. See many ofthese KESTS, linking each nation to some part of the GEOHabitat Ring, being built now mostly out of Lunar materials.Mass drivers/catchers, or Mooncables, or Two-body OrbitingSkyhooks, or more KESTS on the Moon, are providingeconomical transfer of material from the Moon to build thestructures in GEO. Picture the huge robot assembler-factories building the segments of the Banded Torus growingto eventially completely ring the Earth in GEO, 1.5 millionof the Island-one's, each one providing home for 10,000people and the agriculture and industries to support themthere. Picture billions of people living in this GEO HabitatRing, generally living in peaceful, constructive harmonytogether. See a spacefaring civilization starting to reachout from there toward the other resources in the solarsystem, bringing a multitude of Earth's lifeforms along withthe people as they go. Feel the adventure of building theKESTS and GEO Habitat Ring, much as it felt to help build atreehouse as a youth, and the sense of safe haven there highabove the ground.
Thank you for building this picture with me.
Consider starting small. If the stream tube is only 20thousanths of an inch in diameter each, it would onlyoccupy a volume equivalent to a cube 50 feet on a side,coiled on the Earth surface before rising up toward GEO.Such a tube might use a stream composed of a fiberglassfilament with steel particles embedded periodically alongits length. If instead of looping around the Earth, it wentupward to a reverser of the stream which would have to belight enough to be lifted by the thrust of the force thestream bouncing back down the second tube back toward theEarth, where it would be re-accellerated again for itsupward direction travel. Shifting the CG of the reverserwith respect to the force of the stream reversing process,would provide a steering mechanism. Such a tiny versioncould go up and come back down when task is finished; itcould be used to deliver respectable amounts of fiberglassto GEO; bundles of them could be used to support hugepayloads.
One short-term use of these KESTS is perhaps the onemost likely to attract the attention of contemporaryAmerica: providing large amounts of electrical power toearthsurface power distribution networks. The KESTS is usedas an energy delivering system. The principle is thatSSPS, Satellite Solar Power stations, hovering alongside aKESTS to provide power to maintain its support and materialstransport function, would also pour accellerationelectromagnetically to the downward direction stream. Theenergy from sunlight up there is converted into kineticenergy. At the earthsurface terminal, electricallyconductive coils resist the pulses of magnetic energy drivenby the mass stream's magnets, slowing the stream thereslightly, and absorbing the kinetic energy by converting itinto the current generated by the pulsing magnetic field ofthe stream. This electrical current would be rectified,inverted, and synchronized with the 60 Hz power gridfrequency, for delivery to whoever uses electrical power.Advantage is that no fossil fuels are consumed, no nuclearenergy is required, and no intense microwave beams fromspace are used.
To those who find special pleasure in deriving equations and playing with math, here are some interesting areas:
1) Derive the stream parameters in terms of stream density at the Earth terminal. This would make it easy to then model KESTS of 5 thousandths of an inch diameter, or of 5 feet in diameter.
2) Derive equations for weights to hang on thequasi-elliptical KESTS to either side of perigee, bendingthe stream so as to make necessary only one contact point onthe Earth surface. Also consider cyclical adjusting of theweight position to compensate for the pull of the Moon andSun on the considerable mass of the stream.
3) Derive equations for the magnetic field required toturn the stream around 180 degrees. If the weight of thenecessary magnets and control equipment is less than theforce of thrust as the stream pushes against the reverser,the up it goes! This would make possible differentconfigurations of KESTS, analogous to Rod Hyde's"Starbridge" concept, as well as make possible theupward-steering emplacement concept as in the Microelevatorconcept, a KESTS to GEO that can be raised and lowered atwill. Other forms of reversers can be considered, evensimple compression springs, although this would limit thestream form to discontinuous packets of mass which wouldbounce off of the spring one at a time.
4) Examine the possible use of an electrostatic fieldto hold the stream away from the atmosphere-excluding tubewalls. If it is feasable, then consider having the tubechange to a mere skin, motionless to the surroundingatmosphere, sliding on the enclosed mass stream, andresisting the atmospheric pressure by transferring thatinward pressure to the electrostatic field to the radialincompressability of the mass stream. This skin would havenegligible mass compared to the stream within it, yet wouldstill serve the function of blocking contact with theorbital-velocity stream with the Earth's atmosphere.
5) Calculation of the system energy roughly would be1/2 MV squared, using the velocity at the Earth terminalexit, and the mass that of the entire orbital stream. Theenergy would then be divided into part potential energy inthe stream as it rises losing velocity, and in losses fromsupporting the tube/skin, and losses due to moving thepayloads up and down the KESTS.
7) Investigate the stress on the web coupling thepositions of the up-stream tube with the adjacentdown-stream tube. Intuitively this stress seems greatest atapogee; remember, one stream is in retrograde orbit.
"A New Dream for Our NASA: High Efficiency Transportation From the Moon Can make Moon/Null-g Products Low Priced on Earth", by J. E. D. Cline, Feb. 27, 1972.
"The Mooncable" A Profitable Space Transportation System" by J. E. D. Cline, March 25, 1972.
Correspondence from Francis Kemmett, Director of the Staff,NASA Inventions and Contributions Board, deferring consideration of "The Mooncable: A Profitable Space Transportation System"; dated June 23, 1972. Article describing Mooncable Project, submitted to Carolyn Henson at the L-5 Society for publication in L-5 NEWS, Nov.26, 1978. Rejected due to lack of prior formal presentation to AIAA.
"Intro to Mooncable" by J. E. D. Cline, GEnie Spaceport
Library file #480,
"Mooncable Project 14", by J. E. D. Cline (J.E.D.CLINE1),
GEnie Spaceport Library file #530, Sept. 9, 1988.
"MOONCBL-LOFSROM-RESPONSE", by Keith Lofstrom (TRANSONIQ),
GEnie Spaceport Library file #542, Sept 18, 1988.
"Skyhook!" by Hans Moravec, L-5 NEWS Aug 1978 pp1-3,12.
"The Rocket/Skyhook Combination" by F. Burke Carley and Hans
P. Moravec, L-5 NEWS March 1983 pp. 4-6.
"Space Inspiration", by J. E. D. Cline, Testimony given to
the National Commission on Space, Nov. 14, 1985, GEnie
Spaceport Library file #475, July 2, 1988.
"Conceptual Synthesis" by J. E. D. Cline, GEnie Spaceport
Library file #634, Nov 20, 1988.
"Space Settlements: A Design Study", NASA SP-413, 1977
"The Launch Loop" by Keith H. Lofstrom, L-5 NEWS Aug. 1982,
"The Starbridge", by Rod Hyde, talk given to Silicon Valley
"The Launch Loop" by Keith Lofstrom, ANALOG, pp.67-80.
"The Texas and Universe Railroad", by Earl Smith, L-5 NEWS,
Nov. 1985 pp.9-11.
"Power + Transportation", by J. E. D. Cline, GEnie Spaceport
Library file #553.
"Microelevator Vers 2", by J. E. D. Cline, GEnie Spaceport
Library file #581.
"Microelevator Import", by J. E. D. Cline, GEnie Spaceport
Library file #592.
"GEO'S UMBILICAL" by J. E. D. Cline, GEnie Spaceport Library
"GEO HABITAT UMBILICAL 2" by J. E. D. Cline, GEnie Spaceport
Library file #690, Dec. 29, 1988.
"HWY TO EARTH'S GEO RING" by J. E. D. Cline, GEnie Spaceport
Library file #747, Feb.9, 1989.
"High Suburbia Commute" by J. E. D. Cline, GEnie Spaceport
Library file #819.
"Passive Stable KESTS" by J. E. D. Cline, GEnie Spaceport
Library file #880.
"GEO TREEHOUSE" by J. E. D. Cline, GEnie Spaceport Library
"LONGTRANS" by J. E. D. Cline, containing most of this talk,
GEnie Spaceport Library file #892. 890704.
GEnie "mail" address: J.E.D.CLINE1
For a copy of the page of illustrations referred to in the above text, send a stamped, self-addressed envelope to the author:
J. E. D. "Jed" Cline
5632 Van Nuys Blvd. Ste 110
Van Nuys, CA 91401
Phone: (818) 909-0143
Copyright (C) 1989 by GEnie, SPACEPORT UNLIMITED, andJ. E. D. Cline. Permission is granted for material to bedistributed without restriction, provided credit is given toGEnie, SPACEPORT, and J.E.D.Cline.