It’s difficult to determine the history of the Solar System.  The planets have been in their current orbits for Billions of years, and any signs of prior activity or configuration has to come from leftover geologies of smaller, rocky worlds.  It makes it especially difficult when the Billions of interloper asteroids and comets throughout history have to be accounted for, adding to the already complex task.  But if there is one thing humanity has going for us it’s the ability to theorize, model, simulate, and test scenarios here on Earth.  We can try new ideas and see if they match...