#### MontBlanc2012

##### Member

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This effort is nearing (successful) completion, and I've begin testing a Lua script toos that allow one to 'lock' a vessel onto one of these close loop orbits and keep on the prescribed indefinitely (or, at least, until station-keeping fuel is exhausted). At the moment, my station-keeping Lua script testing is limited to maintaining a vessel at an L1 or L2 Lagrange point and estimating the dV required to keep the vessel at that Lagrange point. If the underlying datasets are good, the total station-keeping dV requirements should be low since the station-keeping is primarily limited to offsetting minor gravitational perturbations. For those interested, and in terms of monthly station-keeping dV requirements, my preliminary estimates of station-keeping dV requirements are as follows:

Earth-Moon L1: 1.9 m/s

Earth-Moon L2 : 2.7 m/s

Sun-Earth L1: 0.6 m/s

Sun-Earth L2: 0.6 m/s

Sun-Mars L1: 0.2 m/s

Sun-Mars L2: 0.2 m/s

Sun-Vesta L1: 0.2 m/s

Sun-Vesta L2: 0.2 m/s

These dV estimates are not large. However, The my station-keeping logic is very simple: it just 'locks' a vessel onto the closed orbit trajectory and keeps it there. More sophisticated station-keeping could easily reduce these dV requirements by upwards of a factor of 10. However, at this time, there is no real need to adopt more sophisticated approaches to station-keeping since these dV requirements are already very low and there is little to be gained by improving the algorithm further.

For those interested, I've just about written up and tested some Orbiter scenarios that illustrate this Lagrange point station-keeping. When I've finished testing in the next few days, I'll post these scenarios here on O-F. In essence, for each of the eight Lagrange points listed above, the scenario will consist of two docked (stock) Delta-Gliders. One of the Delta-Gliders will be 'locked' to the Lagrange point; and the other will initially be docked to the first Delta-Glider. One can then undock the two Delta-Gliders. The first will continue to be locked to the Lagrange point (and perform the required station-keeping to keep the vessel at the Lagrange point); and the second can manoeuvre freely. These scenarios are designed to test the dynamics in the vicinity of Lagrange points; and offer 'target practice' for those wishing to rendezvous with a vessel 'parked' at a Lagrange point.

Most of my recent posts have considered a general description of closed loop (Lissajous) orbits around the Lagrange points - not just the Lagrange points themselves. The next step after this, then, is to extend my station-keeping algorithm so that it can deal with general Lissajous orbits. Technically, the last remaining problem that I need to solve before I can do this is to properly incorporate the effect of gravity perturbations on the core station-keeping algorithm. In essence, I know how to deal with this - I just now need to formally work through the maths; write and test an updated version of the station-keeping algorithm; and then post it. This should take a couple of weeks. Again, I'll write a few more scenarios that illustrate station-keeping for planar and vertical Lyapunov orbits; Halo orbits; and general Lissajous orbits.

So, after considerable effort, the delivery of useful tools with which to perform station-keeping on closed-loop orbits in the vicinity of Lagrange points; and enable efficient transfer to/from/between the closed loop orbits around Lagrange points is now in sight.

Yay.