If the Earth is traveling 18 MPS and the object is traveling 60 MPS then the maximum would be a direct in line hit from two directions . 60 + 18 = 78. There is an extra boost in speed from actually falling to the Earth but that can’t be any more than 7 MPS which is the escape velocity for the Earth.
Whatever - I’ll take an actual astronomer’s word over your random calculation - space is not about simple math.