Launch Loop 2.0 - Space Launch without Unobtainium

Keith Lofstrom, keithl@keithl.com

The current version of this abstract, and the paper,
webslides, and software simulations of the launch loop
will be available at http://launchloop.com/SE2107

The pdf paper will be long.

The webslide presentation will focus on the motor design,
and demonstrate the xFEMM field modelling program and
the POVRAY photorealistic rendering program.  These free
software tools will also be useful for other space
system designs.

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The launch loop is a high volume, high efficiency,
electrically-powered horizontal launch system designed
to launch large vehicles in high orbits or interplanetary
trajectories.  Version 2.0 borrows some of the best
new space elevator ideas.

A "transformer motor track" design can convert 14 km/s
rotor kinetic energy into vehicle kinetic energy with
better than 90% efficiency and little rotor heating.

Vehicles will be lifted to the 70 kilometer high west
station using acoustic climbers on a tapered Kevlar
elevator tether, accelerated at 3 gees up to 11.3 km/s
on the 2000 km launch track, and released into highly
elliptical orbits.  

Large solar power satellites in GEO, 100 degrees to the
west of the pinwheel, will transmit six gigawatts of power
to rectennas that can power one launch loop at its maximum
400 tonne-per-hour cadence (3.5 million Mt/year, 700 times
the assessment study).

If power satellites deliver one megawatt per twenty
tonnes of launch mass, the launch energy payback time
is less than two weeks.  Marginal launch energy cost
to high orbit can drop below one dollar per kilogram,
less than air cargo transport.

Launch loops can be built with 2.5 MegaYuri Kevlar with
a safety factor of 2.  Loops will depend on orbital
radar tracking of space debris in order to dodge large
impactors reentering at 100 km altitude.   Small debris
will hit motor track windings acting as a Whipple shield.

Logistics and security systems designed for the space
elevator will apply directly to the launch loop.  When
macroscale carbon nanotube materials become available,
new launch loops will cheaper to build, easier to
maintain, and launch cadence per loop can increase
tenfold.  Hundreds of launch loops can be built south
of San Diego, a few degrees south of the equator.

Think of the launch loop as a space elevator with the
middle 35,000 kilometers of hard-to-make and vulnerable
CNT tether and a slow 7 day climb replaced with a
2,000 kilometer horizontal electromechanical launcher
and a 5 hour high speed trajectory.  

The synergistic combination of space elevator and launch
loop concepts results in a system that we can build with
today's materials and technology, opening the door wide
to the migration of humanity into space.