Mercury and the Moon share certain peculiarities that suggest both were used to launch lightweight crustal elements from Venus and the Earth outward to the Asteroid Belt. At that point those materials would be further launched to awaiting mining ships around the rim.
Vesta in those times would have had an enormously long carbon fiber boom arm as well as some advanced design atomic engines to power its rotation.
Other, smaller, asteroids would be attached to the other end of the boom arm, and then launched by the rotating Vesta/boom array out beyond Jupiter.
Fortunately for us only 60% of Earth's phosphate and organic crust was stripped away before the galactic hive ships moved on to another system. Venus, alas, was totally stripped and today is a wasteland of heavier lower mantle materials and CO2.
No doubt NASA will be launching robot satellites to Vesta to check out the possibility of there being any higher technology debris there. We are already launching probes to the Moon's South Pole in the vicinity of the deepest crater in the Solar system smack dab dead center there.
What have you been smoking?(can I have some?)
I like the way you think!
So are the Harvesters going Galactic Spinwards or Anti-Spinwards? And if so, what is the timetable to come back for the Organic materials they missed the first time?