Soft Electric Landing on Luna

Soft electric landing on Luna can be provided for an orbiting spacecraft in the following way.

• The spacecraft lines up with the runway on the equator at the same spot from which spacecraft are launched to L2.
• The incoming orbit is right down the middle of a rectangular cross section ditch.
• Two slots, one on each side of the ditch, lead to the linear electric motors that power the catcher that also races down this ditch.
• Structural members of the catcher disappear into these slots terminating in the moving portion of the linear electric motors.
• The spacecraft maneuvers so that its orbit brings it to the right place with the right velocity.
• The catcher adjusts its run to be there at the right time for a rendezvous.
• After catching the spacecraft, the catcher brakes electromagnetically, saving the energy as electricity that must be sotred in an accululator, such as a capacitor bank, batteries or induction rings.

This arrangement may be easier than soft landing by tether because a tether cannot adjust the time that it arrives at a rendezvous with a spacecraft.

The facility described above is a high capacity version of a mass driver.

This is landing at orbital speed, and would require a very long track to keep acceleration low. As V=a*t Orbital velocity= v = 1680 m/s if we add 10% to elevate the orbit a bit, with let's say 1800 m/s for an acceleration (a) of 2g, or 20 m/s2, the time required is 90 seconds. In that time d=a*t^2/2 = 81 000m or 81 km.

The same track should probably be usable for launching.

See Also

• Eddy Current Brake to Orbit
• Driving on the Moon