I've been using GMAT to make various trajectories involving the Sun-Earth L2 point. Earth-L2-Mars, Earth-L2-Earth flyby-Mars, etc. However, the main source of optimal launch windows I've been using is NASA's Trajectory Explorer, which doesn't have the option for trajectories involving flying to the Lagrange points.

Until now I've basically treated Earth and Sun-Earth L2 as one with regard to Mars launch windows, so if it takes 28 days to get to L2 from Earth, and I want to leave for Mars after a 28-day halo orbit, then I use Trajectory Explorer's launch window for an optimal Earth-Mars transfer that best fits my year, delta-v, and travel time preference, and I launch the spacecraft from the Earth 56 days before that date, so that by the end of the L2 orbit the launch window departure date is reached.

While I have gotten some decent results with this method, I would still like some implementation that treats the Lagrange points as points in space that the spacecraft can arrive and depart to, so that I can be sure my trajectories are truly optimal. I would also like this option for optimization of trajectories involving gravity assists. For example if I want to go from an L2 halo orbit to an Earth flyby to Mars, and I want to find the best dates for that trajectory.

Is there a software that offers that option? I have tried Trajectory Optimization Tool, but it does not have the option to use Lagrange points as waypoints for the spacecraft's trip.


1 Answer 1


So if the question is:

'what tool/resource allows you to define L2 as an actual lagrange point and then go on with what you want to do',

then this article shows how it can be done in a specific tool. I am aware that this tool gives basic license for free, but maybe you should check if the propogator used in the article is available in that license.

This article gives a longer explanation about trajectory design to Earth-Moon L1. however the propogator used in this is certainly not included in free license. Temporary access request is possible I think if you're a student.

Trajectory planning in the same context could be done as shown in this.

The best course of action could probably be to define the Lagrange point so that it shows up as an object in the browser tree and then use it as you design trajector in patches. I'm sure there is more documentation about optimizing different variables once you have a scenario ready. Hope this helps!


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