thoughts: an elongated massive body spinning fast, possibly with high iron content ,--fits what requirements? : interstellar travel. spin: artificial gravity at the extremities, iron? magnetic shielding. alternative theory: , it was launched with enough energy to reach us, good aim, near 1AU. but is waiting for us to snag it next time around, because it does not have the retrorocket, decellerating capacity. prototype for us to use on the return trip. move to alternate or humour.