Completing the mission doesn't result in anything new since the CG completed. You can also still get it after turning in, un-docking, then re-docking.
There are 2 missions involving ruins, one is repeatable currently, involves scanning obelisks with items in cargo, the second is just collecting data from obelisk, alpha, beta, gamma , epsilon, that junk that goes in your data inventory, the latter is the one that just finish.