L1 orbits. (SpaceX launch delayed 1 day.)

[racookpe1978]

Was watching the SpaceX countdown, but it got scrubbed at about 3 minutes to launch. Blast!

regardless, a reader on the webcam asked how multiple spacecraft orbit the L1 position. I can "see" the L1 points as moving points in space as the earth rotates the sun, but each as a fixed point relative tot he earth.

But how does a spacecraft "orbit" a position that is itself not a gravity well, but the opposite of a gravity well - a gravity "plain" if you will where there local forces of gravity from several bodies all cancel? Doesn't seem logically possible.

 

[Sparweb]

It can oscillate around the "central" L1 point. Picture a skipping rope between the Earth and the Sun, and swinging the rope a little. That's the path of the oscillation, without getting far enough away from L1 to lose its position. I Just checked the old SOHO mission - they called it a "halo orbit" around L1.

Just guessing here, but I bet the oscillation can be 1/n years in period, so there's probably a rationale they can use to station multiple spacecraft in the region, and avoid conflicts.

For a real mind-bender, look up "Lissajous orbit".

STF