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Showing results for tags 'free return'.
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Hey all, I'm trying to do a crewed lunar flyby in RSS, and I don't really have the tech yet to build a crewed lunar orbiter yet. I was planning to use the science I got from the flyby to unlock better engines and allow a follow up orbital mission. I was planning to do a nice free return trajectory, but I seem to be having serious problems plotting what I am after. Ideally, I want a free return trajectory with the lowest possible perilune (for the science), that is less than 15 days from launch to reentry (life support), and especially a posigrade reentry. I've learned the hard way that even a lunar rated heat shield is generally not enough protection for a retrograde lunar return reentry. Delta-V is not really a barrier, as I have around 4 km/s in the transfer stage. I keep either getting retrograde reentry trajectories, or trajectories that barely enter lunar SOI and take 13+ days to complete. I guess I don't really understand how free returns actually work. I am also curious about the Apollo 13 trajectory, and specifically how the "PC+2" burn (that shortened flight time) worked. Thanks!