Lunar Rocket-sled to Orbit

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Using a lunar rocket-sled to orbit (LRSTO) provides the chance to recapture nearly all rocket exhaust and recycle the precious hydrogen while providing man ratable transportation to escape velocity. Since a rocket-sled moves nearly horizontally, it is possible to encase the track on which the vehicle rides in a long pressure vessel set upon the lunar surface for that portion of the track the rocket uses while burning. An open door at the end of the vessel allows the rocket to escape. Then a short section of track is moved out of the way and the door is closed to trap the exhaust gasses.

This rocket-sled would ride on a magnetic levitating track. An electric tractor would push the sled up to 850 meters per second in 18 seconds with a maximum acceleration of 50 meters per second squared. The sled would coast for 1.2 seconds while the tractor drops back. The remaining 1550 meters per second squared to escape velocity would be provided by a liquid hydrogen-liquid oxygen rocket with an exhaust velocity of 4300 meters per second. So 70% of the mass of the vehicle at rocket ignition would reach escape velocity. Rocket acceleration would start at 34.9 meters per second squared and reach a maximum of 50 meters per second squared before burnout. The trip through the long pressure vessel would last 55 seconds and cover 68 kilometers or 42.5 miles. If the track lifts the rocket-sled until circular orbit velocity is reached and then merely provides a means of correcting the position of the rocket-sled to stay in the center of the long pressure vessel, then the pressure vessel would follow the elliptical to parabolic orbital path and end up near 300 meters higher than the starting elevation.