The next mission is the "Destroy UE Convoy" mission, available 25% of the time at any Voinian planet as long as you have a record of almost "Role Model" and a "Deadly" combat rating. It orders you to attack a UE convoy near Outpost Alpha, but it turns out to be a group of warships instead, and all you have to do is return to Ylynn Outpost. The next mission, if you've already completed this one and this is what you mean by "Destroy Station Alpha", is to defend Ylynn Outpost -- available 100% of the time in the Ylynn bar after you've completed the "Destroy UE Convoy" mission. After that, the missions to observe, then destroy Verril Prime immediately follow, and are easy to find. Hope this helps.
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