A continuing series for the gravitationally impaired.
Asteroids are the left over parts of the solar system that just haven’t hit a planet yet. Sooner or later they will either be thrown out or impact a larger body, but that may take a long time. For human purposes, asteroids represent material that can be used for building space colonies and space industries. Grabbing hold of these potentially valuable chunks of rock, ice, and gravel has always been a problem. They all spin somewhat chaotically. Two NASA astronauts came up with the idea of using gravity as a tractor beam for asteroid towing. As the mass of the asteroid pulls on the spacecraft, the spacecraft also pulls on the asteroid. It ain’t much pull, but it’s 100% efficient. So, here’s the plan, you have a small spacecraft with a big solar ion engine that can travel rapidly to the asteroid, you Hoover in the direction that you want to delta vee at an altitude that clears the highest point, and start towing. Now here’s the interesting part. Once you’ve established the tow, it doesn’t matter if the mass is on the asteroid or on the space craft, but you can increase the thrust if you transfer mass from the asteroid to the spacecraft. So you drop mining robots onto the asteroid to refine the good stuff and to also look for stuff that can be used as fuel for the engine system. The robots toss the refined ores and fuel into bins on the spacecraft. You accomplish towing, and mining both at the same time.
Tow where? I of course like the spot between Mercury and Venus, but some folks insist on an Earth destination. Rule one, you do not do Earth orbit aerobraking with an asteroid! You enter Earth orbit through the Earth Sun L2 point, which is about 933,000 miles out. The transition is very low delta vee, from a solar orbit just outside Earth’s to an Earth orbit just inside the sphere of influence. This is a perfectly safe Earth orbit entry point which does not threaten Earth with a destructive impact.
Why do this? MO MONEY! MO MONEY! MO MONEY!