Solar Dawn

Lagrange Points

In this blog post, I will discuss the Earth-moon Lagrange points and their importance in the Solar Dawn series of books.

Leonhard Euler proposed the Lagrange points around two celestial bodies orbiting each other in 1750, finding the three collinear ones, and Joseph Louis Lagrange located the other two equilateral ones two decades later.

Lagrange points are the positions where the gravitational and centrifugal forces between two orbiting bodies are equivalent, so that any third smaller item in these positions remains stationary relative to the two main bodies.

The three collinear Lagrange points, L1, L2 and L3, are gravitationally unstable. If a small body, such as a spacecraft, deviates from those positions by any significant distance, it will drift away from that position and become unstable, resulting in it either falling towards Earth or the moon depending on its direction of travel. They need external forces, thrusters, to keep their positions long term.

 The two equilateral Lagrange points, L4 and L5, are points of stability. Objects in these positions stay there. If a disturbance moves them, an opposing force brings them back into the stable position. This property results in many asteroids parking in these positions. The Earth-sun L4 and L5 points collect asteroids too, and so on, with the other solar system planets and moons. Objects in these positions are often called Trojan objects, given that name because they shouldn’t be there but have drifted there and stay because of the location’s gravitational stability.

I use these Lagrange points in my Solar Dawn series, and touched on the L4 and L5 space stations in these positions in my earlier article and won’t elaborate on them any further.

I use the L2 Lagrange point within my Solar Dawn story, where a satellite with huge solar panels is located. These panels collect the sun’s light and convert it into microwaves that are beamed to the lunar surface where a collection station near the South Pole receives and converts this energy into electricity for both Asgard’s and Shangdu’s use. They can direct the microwaves toward the L4 and L5 space stations, too, although they have their own solar panels for normal use.

So there you have it. These are what Lagrange points are, and how I use them within the Solar Dawn series. In the next blog, I discuss power supply further, and talk about water and air production on the moon and Mars.

I’ll see you then.