A closed loop made of laminated iron ribbon is continuously launched to space by an asynchronous linear motor. The motor consists of high-frequency electromagnets producing an undulating magnetic field. The field moves at 14 km/s -- only slightly faster than the loop. The loop returns to the Earth at a place 2600 km away from the motor, to be accelerated by another motor and deflected by a magnet back to outer space. A sheath surrounding the loop eliminates aerodynamic drag. Cargo is transported by maglev trains riding on the loop. The launch loop may be damaged by wind, lightning, and icing. A large hole in the sheath results in a spectacular display of fireworks, but most of the sheath remains intact and descends on parachutes. The minimum mass (for 1-ton cargo) is 104 tons.
Keith H. Lofstrom, "The launch loop -- a low cost Earth-to-high orbit launch system," AIAA Paper 85-1368, 1985 (PDF file, 260 kB).