For how long a time is Mars reachable from Earth?

So Earth and Mars have seperate orbit times because they are different distances from The Sun. But what I need to know is how long Mars is theoretically reachable from Earth without The Sun being in the way. By which I mean how much time there is from when Mars is reachable from Earth to when it isn't. Sorry if... show more So Earth and Mars have seperate orbit times because they are different distances from The Sun. But what I need to know is how long Mars is theoretically reachable from Earth without The Sun being in the way. By which I mean how much time there is from when Mars is reachable from Earth to when it isn't. Sorry if I'm unclear. Thanks for the help
Update: Can I change this to, say we are in the future and the travel time is something like a day but ships still travel in a straight line-ish so you needed to get there during the period I previously described. Then what would the window be?
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