Short Intro

• Launch loops are assembled over and float the ocean for safety and security

  • A good place is 8 degrees south, 120 degrees west, west of Ecuador and south of San Diego
    • The "most boring weather in the world" according to one meteorologist

• Launch vehicles will travel on a magnetically levitated and coupled sled

  • Aerodynamically shaped launch vehicles are 5000 kg, and ride above a 2000 kg magnet sled

  • Magnet sleds (perhaps 50 meters long) couple to the rotor through a velocity transformer track

  • Magnet sleds will use a lot of expensive Neodymium magnets
    • Nanostructured iron nitride may be a cheap, earth-abundant replacement someday; theoretical for now
  • After payload release, sleds are decelerated, retested, repaired, and reused

• Launch loops must be very long

  • at 30 m/s² (≈ 3 gees) payload acceleration to 11.1 km/s exit velocity:
    • 370 seconds of acceleration, and a 2053 km launch path.
  • at 150 m/s² (≈ 15 gees), the empty sled stops in 74 seconds over 411 km
  • A 2500 km launch path means a 6000 km total rotor length

• The launch loop rotor masses 3 kg/m, with a 4 cm hexagonal cross section

  • Each hexagonal is a row of iron-faced bolts, each perhaps 10 meters long.

• Loop failure

  • The entire rotor stores almost 2e15 joules
    • A "1 megaton" bomb releases 4.2e15 joules instantly
  • The rotor circulates in 430 seconds
  • The rotor "power rate" is 4100 GW
    • A failing launch loop releases some rotor at the point of failure

    • most will be deflected and fanned into the ocean at two places, boiling a LOT of seawater fast

  • some material may be thrown into Earth escape orbit
  • a very small amount of material will re-enter
  • the bolts should be designed to disintegrate into small fragments during re-entry or ocean penetration

• The launch loop track and stabilization cables mass 6.5 kg/m

  • the track contains velocity transformer coils, which couple sled magnets to the rotor

• Stabilization cables to the surface transmit N/S and radial forces

  • cables must be aluminum-sheathed to carry lightning strokes
    • perhaps they can be actively charged to "cloud neutrality", but this seems unlikely

• Launch loop launch altitude is 80 km

  • Post-release payload drag and blunt nose heating will be significant but not extreme
  • The tenuous atmosphere above 80 km will de-orbit smaller (and hard to track) space debris
    • Larger debris objects must be dodged or intercepted.

• Launch loop inclines descend from the tracks to turnaround ambits at the ends

  • an upwards curve supports "west station" at 30 km altitude

  • the inclines enter upward deflector structures at the ocean surface at a 20 degree angle

  • presuming a 6 km turn radius, and a 100 meter superstructure:
    • the deflector structures will descend 300 meters below the ocean surface
    • they will deflect the rotor back up to 50 meters below the surface and wave agitation
    • they will be able to release a failing rotor into the ocean floor

• The return track will also be at altitude

  • the return track will support most of the stabilization cable mass
  • the return track can provide backup power (through optical fiber) to the track above
  • the return track can be an additional reference platform for stability
  • it will help support west station:

• West station will be on the upward eastward incline at 30 km altitude

  • This is above lighting and most of the wind loading

  • multiple vibration-powered elevator cables will carry vehicles up to west station

  • vehicles will be loaded onto magnet sleds and accelerated on a 5 km coilgun catapult to 500 m/s at west station
    • Power levels of 100 MW will be needed at the end of the catapult, 2MW per meter for 100 milliseconds
    • Power will be transferred from the rotor "somehow"
  • vehicles+sleds will undergo some brief "shake tests" to verify the sled release is working right

• Launch loop ambits will deflect six "tracks" of separated bolts

  • turn radius estimated 6000 meters
  • The ambits will have GW power plants and 10 km long linear motors
  • The ambits will be associated with "spare bolt racetracks"
    • These will also store burst power
  • High speed inspection stations will photograph each bolt at speed, to micrometer resolution
  • Bolt measurements will be "synopsized" by large parallel computers, and compared to previous measurements
    • Significant changes will cause a bolt to be diverted into a "used bolt racetrack

  • The ambits and deflection magnets will resemble a low-tech version of the Large Hadron Collider

    • Loop design will shamelessly steal technologies and best practices from LHC
    • If no particles are discovered after the Higgs, thousands of brilliant technicians may be available

• Launch loops require Server Sky constellations overhead

  • Providing redundant and precision interferometric positioning to the loop controllers
  • Providing redundant whole system control in case of failure
  • Capturing diagnostic information for modelling and optimization
  • Tracking vehicles and managing orbital traffic
  • Tracking incoming debris objects and planning mitigations

Power Storage

• At realistic launch market growth rates, it will be decades before launch loops are profitable

  • Space solar power has been just around the corner for half a century

  • Missions to Mars will be robotic, and humans can't compete economically
  • Mars will never be a practical "second Earth" (the asteroids might).
  • Deep space missions to deflect asteroids are way too expensive
  • Asteroid mining missions are proposed only by non-geologists and non-miners
  • We will do all of these things someday, but advocates must first start talking economic sense.

• Grid scale energy storage is an urgent need

  • Grid demand varies hourly and seasonally
  • Wind and solar is intermittent and unpredictable
  • Nuclear is steady but not "peakable"
  • Carbon fuel stinks

• Loop technology can store huge amounts of power

  • The fast loop described above stores 500 GW-hours
  • A slower, heavier loop running at 7900 m/s will "orbit" in its tunnel without vertical deflection forces
    • A kilogram of 7.9 km/s rotor stores 17 kWh.
    • Cycled 200 times per year, buying power at \$3/MWh and selling at \$10/MWh, a kilogram earns \$24 per year

    • purchase and automated forming cost might be \2 per kg ... ≫≫profit!≪≪

  • Most of the system losses are in the ambits; a longer "straightaway" adds storage with little loss
    • power storage loops can span the Pacific Ocean, time-shifting power across 10 time zones.
  • Much heavier rotors can store more energy
  • Power storage rotors can be simpler and safer than launch rotors
• Lessons learned from power storage will speed the design of launch loops
• Manufacturing lines for power storage can be used to build launch loops