Lagrange
First, I’ll let you get up to speed here, as well a short summary. A Lagrangian Point is a point where you can be between the Earth and the Moon and not have the pull of either body’s gravity take you to them. There are a handful of them in the Earth-Moon System, and they are not unique to Earth either. Anywhere there are orbiting bodies, there are these gravitational “back-eddies.” These Lagrangian points are cool because you can just sit there and be pulled along with the Earth and Moon and not have to worry about falling to either of them. They each pull you an equal amount and you just float.
A Lagrangian Point is an ideal location for a micro-gravity semi-stationary space platform of significant size. On this platform, you could have a factory churning out space-ships and launching them from there. If you could take advantage of a zero escape velocity, think of all the cool stuff we could put in a spacecraft not mostly dedicated simply to getting to space, and focus on the stuff for being in space.
Getting into outer space from Earth is no small feat because you have to push so very hard. Most of the volume of a spacecraft launched from Earth is devoted to getting to orbit and beyond.
There’s a major problem with all of this though - there always is, isn’t there? I don’t see this discussed whenever I happen upon Lagrangian Points out there on the Intertubes, but what happens when the mass of whatever placed in the Lagrangian Point is no longer neglibile? It changes the system. The Lagrangian Point for a two-body system will move. Intuitively, to save energy, you would simply move the space-station to the new point. Doing so would move the point further, and continuing to move would be like chasing your own tail. The more prudent solution would be to maintain the relative position between the two bodies and hope for the best.
Then again, a non-negligible mass is nothing small. To be considered significant, the mass of such an object would be so large, that technology may have advanced enough to build a structure of such a size that we could live on it and move to wherever we wanted. Planets be damned!
“‘Once the rockets are up, who cares where they come down?
That’s not my department,’ says Wernher von Braun”
Tom Lehrer
*It turns out I just had to read further, and I’m not the only one to think of the problem of stability. Honestly, I’m not surprised – far more and smarter people than me are astronomers and physicists, and this is their bread and butter. Small observational platforms already exist in specialized orbits around other Lagrangian Points
Tags: gravity, space, speculation