Roanoke: Behind the Dissappearance

In history, Sir Frances Drake left the colonists at Roanoke Island to go back to England intending to return to Roanoke. Something happened to the colonists, and they left a note saying “Croatoa” which was supposed to be a nearby island. Unfortunately, Drake couldn’t get to Croatoa due to a major storm, so he gave up. History has wondered ever since what ever happened to those colonists?

In my novel, the back story for the colonists leaving have to do with aliens who discover Earth while they are