I was thinking about when a space ship returns to Earth (or another world), what a waste of energy when it decelerates.

Would there be a way for a ship to exchange this ‘incoming energy’ with a ship that wants to leave Earth (or another world)? In other words, it decelerates by accelerating another ship.

Now before you shake your head and say this is nuts, think about this.

Say we have a ship returning from Mars. As it heads for the Earth, a ship bound for Mars comes out to meet it. Some how they link (tether maybe) and then they somehow switch velocities (acceleration/deceleration). The incoming ship looses its energy to the outgoing ship. Kind of like those co-orbital moons of the Gas Giants, where they switch orbits and velocities when one sneaks up on the other (I know, their orbital energy is based on their distance from Jupiter).

Drawing it out on paper, it looks feasible, but I know there are a lot of factors involved. I am not an engineer.

Probably, at best, they would do only a partial transfer of energy and their velocities would balance out. You would have to have one hell of tether to connect.

I hate seeing energy wasted, especially when it could be put to good use.