# How do "halo orbits" save on propellent (delta-v)?

I am trying to understand what advantage the satellite's 'Halo Orbit' has compared to LEO or Geostationary orbits.

"Lagrange points have proven to be very useful indeed since a spacecraft can be made to execute a small orbit about one of these Lagrange points with a very small expenditure of energy."

• They are in a different location for one thing. They are like Geostationary orbits (since they stay in one place) relative to non-earth bodies (as in they move at same speed around the sun as earth at allt imes) @TheMatrix Equation-balance Commented Mar 20, 2023 at 17:37
• what are the source of the quote and graphic? Commented Mar 20, 2023 at 22:30
• Commented Mar 21, 2023 at 9:27

I'm not sure I understand why there are so many downvotes, but I think the question indicates some misunderstandings:

1. The delta-V required to reach an orbit depends on a number of things, and the delta-V required to reach a Lagrange point may be higher or lower than that of reaching some other orbit depending on what that "other" orbit is.

2. The delta-V required to maintain a halo orbit around a Lagrange point is lower than that required to maintain a halo orbit around some other fixed point in space.

Point 2 is what's important here. The Lagrange points are always at a fixed position relative to the bodies that create them, so if you want a spacecraft to stay at a fixed position, the Lagrange points are the lowest delta-V points to do that. I'm not an orbital mechanician, but my guess is that the Lagrange points are the only places you can practically do that, since "staying in once place" otherwise would require huge amounts of propellant.

This low maintenance position is due to the gravitational interaction between the two bodies that produced the Lagrange points alternatively pulling the spacecraft around, effectively one nullifies what the other does.

• This being downvotes for being the next in a series of low-quality questions based on misconceptions @Michael Stachowsky Commented Mar 20, 2023 at 18:45
• I don't get the downvotes either, it's a reasonable question.
– GdD
Commented Mar 20, 2023 at 20:14
• It show a clear lack of reseach effort, which is one of the downvote criteria @GdD Commented Mar 20, 2023 at 20:41
• People upvote questions that are far worse than this one @Starshipisgoforlaunch.
– GdD
Commented Mar 21, 2023 at 8:40
• True. If thise was someones first question I would either not vote or may upvote. However, this is the latest in the string of low-quality unresearched questions. That is why the asker is suspended. @GdD Commented Mar 21, 2023 at 9:11