Looks like an orbiting giant monolith on its side to me
Just kidding to all you Martian conspiracists out there!
Though wouldn't it be so cool? As someone posted here a while back, perhaps one day we will find the equivalent of a rocket stage from a starship that came through our solar system once long ago. Even that will affect us in ways similar to the Monolith from 2001 in terms of making us aware of the realities of the wider Universe and helping us to make that next step in our evolution.