Launch from Luna
Section 2.10.
Home Tour Join! Contents Team News Catalog Search Comm

Aiming Mass Driver Payloads

Mass driver on the moon

Reaching orbital velocity is not enough.

Eventually there should be a mass driver build that is big enough to launch people and delicate cargo. That makes it really long. The only way to have a large variance in the launch azimuth would be to put the whole thing on a huge turntable; unreasonably large for the size of machine we're talking about.

So we may see rotating machines for bulk cargo and very hardy payloads, while more delicate payloads settle for a long machine with very little choice of azimuth. That's not so bad. We really only have two targets for launch azimuth: the earth, and the plane of the ecliptic (the orbital plane in which most of the planets lie).

Earth wanders around in the sky inside a box 14 degrees on a side, but we can correct for the variation with course correction burns after launch.

In contrast, a lunar launcher aligned with the ecliptic will be spot on within 5 degrees of the desired orbital plane all the time; it just needs to wait for the moon's rotation to aim it correctly.

The concept of a circular mass driver is functionally the same as slinging a mass on a rope. The common bias toward mass drivers comes from the g-forces that result from trying to point the payload in the right direction once it's going at high velocity.

Why not just build a circular mass driver, or use tethers?

When you turn a corner at high speed, the acceleration is r * omega2, where r is the radius of your turn and omega is angular velocity in radians per second. Do some algebra and you'll get a = v2 / r, where v is your linear velocity, so you can see the influence of both high velocity and small radius of curvature. At orbital velocities, you can get some mind-boggling, payload-squishing, tether-breaking accelerations.

Launch from Luna

Home Tour Join! Contents Team News Catalog Search Comm
ASI W9700185r1.1. Copyright © 2007 Artemis Society International, for the contributors. All rights reserved.
This web site contains many trade names and copyrighted articles and images. Refer to the copyright page for terms of use.
Author: Gregory Bennett. Maintained by ASI Web Team <>.
Submit update to this page. Maintained with WebSite Director. Updated Fri, Aug 13, 1999.